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Combustion and Alternative Energy

2002;():1-9. doi:10.1115/ETCE2002/CAE-29006.

Composition and temperature induced natural convection within an open topped vertical circular enclosure has been numerically investigated. A theoretical model that describes the mass, heat and momentum transport processes in a 2-dimensional axisymmetric domain is presented. The model included consideration of the transient development of natural convection flow, density and thermophysical property variations. The results presented are for a n-Pentane liquid vapor diffusing into Air. A description of the transient temperature and concentration gradients development is given along with their effects on the flow field progression.

Commentary by Dr. Valentin Fuster
2002;():11-20. doi:10.1115/ETCE2002/CAE-29007.

A numerical simulation of a turbulent natural gas jet diffusion flame at a Reynolds number of 9000 in a swirling air stream is presented. The numerical computations were carried out using the commercially available software package CFDRC. The instantaneous chemistry model was used as the reaction model. The thermal, composition, flow (velocity), as well as stream function fields for both the baseline and airswirling flames were numerically simulated in the near-burner region, where most of the mixing and reactions occur. The results were useful to interpret the effects of swirl in enhancing the mixing rates in the combustion zone as well as in stabilizing the flame. The results showed the generation of two recirculating regimes induced by the swirling air stream, which account for such effects. The present investigation will be used as a benchmark study of swirl flow combustion analysis as a step in developing an enhanced swirl-cascade burner technology.

Commentary by Dr. Valentin Fuster
2002;():21-28. doi:10.1115/ETCE2002/CAE-29008.

The aspect ratio effects of elliptic co-flow on the structure of a turbulent propane diffusion flame from a circular tube have been presented. Pollutant emission, flame radiation, flame structure, and soot concentration have been measured. The fuel jet exit Reynolds number is 2700, and the exit Reynolds number for the co-flow is 4010 and 8025 based on the minor and major axis respectively. The results are compared with the measurements from the experiments in a circular co-flow, which is the baseline condition for the present study. The pollution characteristics and the structure of the flame in the elliptic co-flow are significantly different from those in the circular co-flow. The NO emission is higher and the CO emission is lower in the elliptic co-flow. Elliptic co-flow flame produces less soot than circular co-flow flame. The study shows that the elliptic co-flow aspect ratio has a controlling influence on various combustion characteristics. In general, it is seen that as the aspect ratio of the elliptic co-flow is increased from 2:1 to 4:1, the entrainment of air increases and thus the combustion characteristics are enhanced. Compared to 2:1 AR co-flow flames, the flames with 4:1 AR co-flow are more stable, have a lower flame height, produce more NO and less CO, the flame peak temperature is higher, are less sooty, and radiate less. Flame spectral measurements show that the 4:1 aspect ratio flames produce more OH, CH, C2 and H2 O radicals in the near-burner region than the 2:1 co-flow flames as a result of higher fuel oxidation.

Commentary by Dr. Valentin Fuster
2002;():29-35. doi:10.1115/ETCE2002/CAE-29009.

The effects of buoyancy on the flow regimes of submerged gas injection were studied in this investigation. A capillary tube submerged in water was used for gas injection in microgravity and terrestrial conditions, and the resulting flow regimes and bubble sizes were documented. The effects of liquid co-flow and reduced surface tension were also analyzed. Under reduced gravity, three flow regimes were observed over the range of conditions tested. At low gas flow rates, the bubbles did not detach from the injector, forming an interconnected bubble cluster that adhered to the injector. Single bubbles started detaching and moving away from the injector when the Weber number reached a value around 3. At gas flow rates corresponding to a Weber number value of 10, the bubble coalescence regime was observed near the injector. It was found that the absence of buoyancy prevented the formation of the jetting regime. For all gas throughputs, the co-flowing liquid aided the detachment of the bubbles, resulting in the generation of more uniform bubbles than in quiescent liquids. The presence of co-flow resulted in a smaller bubble size accompanied by an increased frequency of bubble formation. Reduced surface tension produced a similar effect, resulting in smaller bubbles.

Commentary by Dr. Valentin Fuster
2002;():37-46. doi:10.1115/ETCE2002/CAE-29010.

It has been observed in previous experimental studies that round helium jets injected into air display a repetitive structure for a long distance, somewhat similar to the buoyancy-induced flickering observed in diffusion flames. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis of a round helium jet injected into air was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. The temporal growth rates of the disturbances increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity.

Topics: Density , Stability
Commentary by Dr. Valentin Fuster
2002;():47-54. doi:10.1115/ETCE2002/CAE-29011.

The main purpose of this study was to comprehend the effects of burner diameter and fuel type on smoke point characteristics of a hydrocarbon diffusion flame and its radiation emission. The critical mass flow rate of pure fuel at this smoke point was measured. At nine different fractions of the critical mass flow rate, nitrogen gas was supplied along with the fuel to achieve smoke point. At each condition, flame radiation and flame height were measured. The axial radiation profile at the critical fuel mass flow rate for one burner was also measured. Three fuels of differing sooting propensities were used: ethylene (C2 H4 ), propylene (C3 H6 ), and propane (C3 H8 ). Three different burners with inner diameters of 1.2 mm, 3.2 mm and 6.4 mm were used. Results showed that propylene had the highest critical fuel flow rate and the highest nitrogen dilution required to suppress smoking and total flame radiation, followed by ethylene and propane. For all fuels, the curves of nitrogen flow rate required for smoke suppression versus fuel flow rate exhibited a skewed bell shape. The variation of Reynolds number at the critical fuel mass flow rate with the burner diameter showed a linear relation. On the other hand, the variation of total flame radiation with burner diameter was nonlinear.

Commentary by Dr. Valentin Fuster
2002;():55-62. doi:10.1115/ETCE2002/CAE-29012.

A polymer electrolyte membrane (PEM) fuel cell has been analyzed by applying the conservation principle to the gas channels, electrode backings, catalyst layers and polymer electrolyte. The conservation equations used are conservation of species, momentum and energy and the Nernst-Planck equation in the electrolyte. Oxygen reduction at the cathode is modeled using the Butler-Volmer equation while the adsorption, desorption and electro-oxidation of hydrogen and CO at the anode are modeled by the Tafel-Volmer and “reactant-pair” mechanism, respectively. Comparison of the anode electrochemical kinetics model to experimental data indicates that CO adsorption kinetics are Temkin. One-dimensional simulation of a PEM fuel cell operating with reformate fuel gas indicates an optimum operating pressure. Preliminary two-dimensional simulation verifies the one-dimensional assumption for mass transfer but indicates that a two-dimensional analysis is necessary for the catalyst layer.

Commentary by Dr. Valentin Fuster
2002;():63-67. doi:10.1115/ETCE2002/CAE-29014.

The blowout limit of a jet diffusion flame was shown experimentally to improve significantly through the introduction of an auxiliary fuel in the surrounding air. A small experimental burner was devised so that the auxiliary fuel could be introduced and controlled independently of the main jet fuel, through a number of small pilot jets uniformly distributed around the main central fuel jet. This burner arrangement eliminated the likelihood of a flame flashing back into the surrounding atmosphere and some fuel escaping combustion. The burner was tested with methane as the fuel both for the main jet and the auxiliary side jets. Tests were made for both co-flow and cross-flow air streams of uniform velocity. It is shown that the arrangement adopted for auxiliary fuel introduction produced improvements in the flame blowout limits of the burner under both types of surrounding flow conditions. For the conditions considered, the blowout limits were of higher values in cross flow than for the corresponding co-flowing air streams.

Commentary by Dr. Valentin Fuster
2002;():69-75. doi:10.1115/ETCE2002/CAE-29015.

The instantaneous unsteady heat transfer during rapid compression and expansion of air within a pneumatically driven piston in a cylinder arrangement which offers simple, well-controlled and known boundary conditions was examined. Values of the instantaneous apparent overall heat flux from the cylinder gas to the wall surfaces were calculated using a thermodynamic analysis of the experimentally measured pressure and volume temporal development. Corresponding heat flux values were also calculated through the application of a zero-dimensional model that incorporates the use of the k–ε turbulence model. Comparison of the results of the model with corresponding experimental data showed fair to good agreement for the wide range of compression ratio values used (8.4∼24.3). Also, correlation of the derived data using an effective velocity which is based on the distribution of mean kinetic energy, turbulence energy and piston motion and a characteristic length that is a function of the instantaneous height between the piston top and the cylinder head and bore diameter as the parameters to use when calculating the Reynolds, Prandtl and Nusselt numbers resulted in the following workable relationship: Nu = 0.01Re0.205 Pr0.033 .

Commentary by Dr. Valentin Fuster
2002;():77-83. doi:10.1115/ETCE2002/CAE-29016.

A Co-firing technology with coal:biomass blends is expected to reduce land application requirements for manure based biomass wastes, and provide a renewable, low cost, and zero net fossil based CO2 fuel. The choice of low BTU biomass fuels may include conventional agricultural or unconventional animal based biomass fuels depending upon local availability and transportation costs. For power plants located near feedlots where cattle are fattened for slaughter, the best choice of renewable biomass fuel is feedlot manure, properly referred to as feedlot biomass (FB). Coal can be mixed with FB in a 90:10 (coal:FB) ratio by mass and fired in existing boiler burners. A 30 KW (100,000 BTU/hr) boiler burner facility was built and tested for firing coal or coal-FB blends at Texas A&M University. FB has a moisture content ranging from 20% to 40% moisture, but most of the previous data have been generated using low moisture FB (<10% moisture) due to problems processing moist manure. The current work will investigate the effect of different moisture levels using external water injection. The boiler burner was modified with an air atomizing water injector. At a fixed equivalence ratio and swirl number for the secondary inlet air stream, the effect of different moisture levels and different biomass particles on boiler performance was investigated. NOx , O2 , and CO profiles along the axis of the furnace were obtained. The effect of atomizing air on the co-firing performance was also investigated. The results are summarized as follows: just with atomizing air is the wter injector, the NOx concentrations increased from 350 ppm to 650 ppm while CO decreased from 46,000 ppm to 18,000 ppm. External water injection decreased the NOx pollutant emissions from 570 ppm (zero external water) to 300 ppm (40% water in FB), but increased CO emissions from 2,500 ppm (zero external water) to 10,500 ppm (40% water in FB) due to incomplete combustion. Smaller sized particles of FB in the blended fuel produced less NOx but more CO.

Commentary by Dr. Valentin Fuster
2002;():85-91. doi:10.1115/ETCE2002/CAE-29017.

Convectional free flame combustion causes the temperature rise in the vicinity of the flame to be very steep, resulting in high temperatures, consequently NOx formation enhances. The fact is that the thermal conductivity of gases are very low, i.e., poor thermal conductors. Combustion in porous media elevates this problem by enhancing heat conduction and thermal radiation from the flame zone, which reduces the flame temperature and NOx formation. Also, heat transfer from the free flame to a load is mainly by convection, while heat transfer is by convection and radiation from combustion zone in porous medium to a load. Moreover, it is easy to stabilize the flame in a porous medium, where the thermophysical properties of the porous medium can engineered for specific application. Most of the work is done on flat type porous burner, where the axial flow of gaseous fuel air mixture forces through a layer of porous medium. In this report a concept of cylindrical porous burner is introduced, where the fuel air mixture is forced to flow radially. Mathematical models and simulation results are introduced for both burners, axial and radial flow burners. Preliminary results of the comparison between the thermal performances between the mentioned burners are discussed. The results revealed that the cylindrical burner has superiority over the convectional flat burner. The cylindrical burner has a wide range stability limits and may produce less NOx than the flat type burners.

Commentary by Dr. Valentin Fuster
2002;():93-98. doi:10.1115/ETCE2002/CAE-29018.

The stability behaviour of jet diffusion flames in a co-flowing stream of air was examined. Their lift-off, reattachment and blowout limits were established for methane, propane, ethylene and hydrogen. The co-flowing air stream velocity affected significantly the mechanism of flame stabilization. Different flow regimes where the blowout of lifted flames or attached flames can occur were recognized. A transition region in which both the blowout of lifted flames as well as that of attached flames was observed and identified with respect to the value of the air stream velocity. It was found that the blowout limits for lifted flames in this region were much smaller than for the attached flames. The effects of changes in the nozzle geometry and co-flowing stream composition were also considered.

Commentary by Dr. Valentin Fuster
2002;():99-105. doi:10.1115/ETCE2002/CAE-29062.

Anytime flammable gas mixtures are handled, there is a risk of combustion hazard. This is particularly true in many oilfield applications where space is limited and equipment is located near sources of ignition. Unfortunately, there is a lack of understanding of combustion phenomena within process equipment such as mufflers, rotating blowout preventers, liquid traps, and dry gas seal assemblies. These vessels have small internal volumes, complex internal geometries, and are often connected using small diameter piping. This paper discusses the results of a parametric study which was carried out to establish the nature of combustion within small diameter vessels and exhaust tubing. Flowing, pre-mixed fuel/air mixtures were used. This study has been conducted using a testing system capable of emulating real process equipment under realistic field operating conditions, for example, flow rates, back pressures, and fuel type. The results from a representative sample of 79 tests, from the 5,000+ tests that have been completed, are discussed herein. Typical pressure and temperature responses are presented and analysed. In addition, methods of detecting the presence of combustion are discussed. In particular, it is demonstrated that flames can be remotely detected and located using only high speed pressure data.

Topics: Ignition , Vessels
Commentary by Dr. Valentin Fuster
2002;():107-113. doi:10.1115/ETCE2002/CAE-29063.

Flue gas injection into light oil reservoirs could be a cost-effective gas displacement method for enhanced oil recovery, especially in low porosity and low permeability reservoirs. The flue gas could be generated in situ as obtained from the spontaneous ignition of oil when air is injected into a high temp erature reservoir, or injected directly into the reservoir from some surface source. When operating at high pressures commonly found in deep light oil reservoirs, the flue gas may become miscible or near miscible with the reservoir oil, thereby displacing it more efficiently than an immiscible gas flood. Some successful high pressure air injection (HPAI) projects have been reported in low permeability and low porosity light oil reservoirs. Spontaneous oil ignition was reported in these projects, at least from laboratory experiments; however, the mechanism by which the generated flue gas displaces the oil has not been discussed in clear terms in the literature. An experimental investigation was carried out to study the mechanism by which flue gases displace light oil at a reservoir temperature of 116 °C and typical reservoir pressures ranging from 4,028 psi (27.77 MPa) to 6,680 psi (46.06 MPa). The results showed that the flue gases displaced the oil in a forward contacting process resembling a combined vaporizing and condensing multi-contact gas drive mechanism. The flue gases also became near-miscible with the oil at elevated pressures, an indication that high pressure flue gas (or air) injection is a cost-effective process for enhanced recovery of light oils, compared to rich gas or water injection, with the potential of sequestering greenhouse gases.

Commentary by Dr. Valentin Fuster
2002;():115-121. doi:10.1115/ETCE2002/CAE-29064.

Combustion processes with excess enthalpy are described with examples given. It is shown that different processes, such as heat and mass transfer, phase and chemical changes are involved. Moreover, flames with excess enthalpy can be encountered in a variety of forms such as laminar or turbulent, within homogeneous or heterogeneous systems involving stationary or unsteady processes, with pulse or spin combustion and as cellular flames. It is to be shown that mainly due to the increase in the chemical reaction rates within the combustion zone, the excess enthalpy state can lead to substantial increases in the burning rates, widening the associated flammability limits and modifying the preignition processes. Some applications that can benefit from the use of such flames are outlined.

Topics: Enthalpy , Flames
Commentary by Dr. Valentin Fuster
2002;():123-128. doi:10.1115/ETCE2002/CAE-29065.

Results are presented of an experimental laboratory investigation of the oxidation reactions of heated low velocity streams of homogeneous lean fuel-air mixtures within a packed bed tubular reactor at atmospheric pressure in the presence of non-noble metal oxides catalysts. The main fuel considered was methane, however, other common gaseous fuels, i.e. propane, carbon monoxide, hydrogen and ethylene were also examined for comparative purposes. It was shown that binary cobalt oxide/chromium oxide catalysts can be effective in the oxidation of very lean fuel-air mixtures. Furthermore, there is an optimum value of their mass ratio that could produce a significant improvement to the low temperature oxidation of the lean mixtures examined and the corresponding resulting emissions.

Topics: Fuels , oxidation
Commentary by Dr. Valentin Fuster
2002;():129-135. doi:10.1115/ETCE2002/CAE-29066.

This investigation is directly relevant to various applications associated with the safety aspects of underbalanced drilling operations where de-oxygenated air may be co-injected with oil-based drilling fluid. However, de-oxygenated air often still contains up to 5% oxygen by volume. This residual oxygen can react with oil during the drilling process, thereby forming potentially hazardous oxidized hydrocarbons and compromising the safety of drilling operations. This article examines the conditions and processes by which oxidation reactions occur and may be helpful in reducing risk in drilling operations. This project characterizes the oxidation behaviour of several oils and a typical oil-based drilling fluid at atmospheric and elevated pressures using thermogravimetry (TG) and pressurized differential scanning calorimetry (PDSC). Tests performed on mineral matrix (core) from the oil reservoirs showed no reactivity in both inert and oxidizing atmospheres. In an inert atmosphere, tests on all hydrocarbon samples showed only vapourization, no reactivity. In an oxidizing environment, the tests on hydrocarbons showed several oxidation regions. The presence of core had no effect on the behaviour of the hydrocarbons tested in an inert atmosphere but accelerated the higher temperature oxidation reactions of the oil samples. The oil-based drilling fluid exhibited the opposite effect — the presence of core material retarded the oxidation reactions. This is perhaps due to the presence of an oxygen scavenger reacting with oxygen containing clays present in the mineral matrix. In all tests performed on mixtures of hydrocarbon and core in oxidizing atmospheres, elevated pressures resulted in acceleration of the lower and higher temperature reaction regions.

Topics: Drilling , oxidation
Commentary by Dr. Valentin Fuster
2002;():137-145. doi:10.1115/ETCE2002/CAE-29174.

A Predictive Emission Monitoring (PEM) model for predicting NOx emission from a gas turbine combustor has been developed by employing an optimized Neural Network (NN) architecture. The Neural Network was trained by using actual field test data and predicted results of a Computational Fluid Dynamics (CFD) model of the combustor. The field tests were performed at a natural gas compressor station driven by a General Electric (GE) LM1600 conventional gas turbine. The model takes eight fundamental parameters (operating and ambient) as input, and predicts NO and NOx as outputs. The data used for training the model covers the entire operating ranges of power and ambient temperature for the site. The CFD model employs a non-equilibrium (flamelet) combustion scheme and a set of 8 reactions including the Zeldovich mechanism for thermal NOx , and an empirical correlation for prompt NOx formation. The results predicted by the CFD model were within 15% of the measured values. Results of the field tests demonstrated that the spool speed ratio of the gas turbine remained constant throughout the tests, the power output of the engine was linearly proportional to the spool speeds, and the NOx emission was proportional to the site power output. A Multi Layer Perceptron type Neural Network with two hidden layers, each with four neurons was found to be the optimum architecture for the model. The NO levels predicted by the PEM model based on the optimized NN had a maximum absolute error of approximately 7%, mean absolute error of 2.3% and standard deviation of 1.97%. One year operating data for the site was submitted to the trained NN model with ambient temperatures varying from −29.9 °C to 35.7 °C and output powers from 5.8 MW to 17 MW. It was found that the model produced consistent contours of NO emissions. As expected, the NO levels were found to increase with increasing power and/or ambient temperature.

Commentary by Dr. Valentin Fuster

Composite Materials Design and Analysis

2002;():147-152. doi:10.1115/ETCE2002/CMDA-29069.

Use of syntactic foam as core material in the sandwich structured composites is increasing due to its higher compressive strength, damage tolerance and low moisture absorption compared to the open cell structured foams. Extensive microscopic examination of the syntactic foams tested under compressive and three-point bending conditions is undertaken in this study. The aim of the investigation is to determine the local fracture mode and correlate it with the microscopic structure of the material. Local stress states are identified in the material based on the microscopic fracture features. Syntactic foam tested in the study has resin to microballoons ratio of 1.52 by weight. Compression tests were conducted on the syntactic foam specimens having two different aspect rations, which were 0.4 and 0.91. Three-point bend tests were conducted on the sandwich structures containing syntactic foam as core material and glass fabric as the skin material.

Commentary by Dr. Valentin Fuster
2002;():153-160. doi:10.1115/ETCE2002/CMDA-29070.

FRP composites are finding increasing use in the civilian applications such as highways, bridges, pipes etc. This analysis focuses on the FRP piping systems used in the Petrochemical industries under extreme conditions. Due to the high operational and maintenance costs involved with pipes made from traditional materials, there is a need to develop a smart inspection system that replaces or eliminates the traditional inspection and maintenance techniques, providing continuous and reliable monitoring of the structure. Smart FRP pipes have an embedded smart sensor system incorporated in them, providing continuous and reliable monitoring of the pipe structure. This helps in preventing catastrophic failure of pipes thereby reducing the costs involved with the pipe failure. Smart FRP systems have a very high initial investment cost, and therefore a cost comparison model is needed in order to justify their use against traditionally used materials. A Life Cycle Cost (LCC) comparison model has been developed in this paper, which shows that despite high initial investment costs, large savings could be made in the operational and maintenance costs with the use of Smart FRP pipes. This cost model Calculates the life cycle costs of Steel, FRP and Smart FRP pipes, and determines the alternative with the lowest life cycle cost. To deal with an uncertainty associated with the cost factors, used in calculating the LCC of the three alternatives, an uncertainty analysis has been performed. An computer spreadsheet has been programmed in order to perform the LCC and Uncertainty Analysis. This analysis has laid down the basic foundations for a larger cost model, wherein; several other alternatives materials and factors could be included. This would further help in widening the scope of use of Smart Structures in various industries. Certain aspects of the data used in this analysis may be disputable, however for the purpose of modeling and procedural demonstration, the gathered and available information was used to perform our analysis. Therefore, use of this data outside of the scope and context of this report is not warranted.

Commentary by Dr. Valentin Fuster
2002;():161-168. doi:10.1115/ETCE2002/CMDA-29071.

The engineering applications of spreading and adhesion phenomena involving fluids on solids are numerous. The adhesive and spreading interactions at the solid-fluid interfaces are well characterized by dynamic contact angles. This study reports on the results of an experimental investigation into the effect of solid surface roughness on dynamic contact angles in solid-liquid-liquid (S-L-L) systems. The experiment involved the use of Wilhelmy Plate apparatus to measure adhesion tension (which is the product of interfacial tension and cosine of the contact angle between the liquid-liquid interface and the solid surface), the DuNuoy tensiometer to measure the liquid-liquid interfacial tension, and a profilometer to characterize the roughness of the solid surfaces used. The components of the solid-liquid-liquid systems studied consisted of: (i) smooth glass, roughened quartz and an actual rock surface for the solid phase, (ii) normal-hexane and deionized water as the two immiscible liquid phases. The dynamic contact angles (advancing and receding angles) of the three-phase (rock-oil-water) system provide essential information about the wettability of petroleum resrvoirs. The wettability of a reservoir is an important parameter that affects oil recovery in primary, secondary, and enhanced recovery operations [1]. Contact angle measurements on smooth surfaces are generally used to characterize reservoir wettability. However pore surfaces within reservoir rocks are essentially rough and hence it is important to determine the effect of such roughness on measured contact angles. There is very little information in the open literature on the effect of surface roughness on dynamic contact angles in S-L-L systems. In the present work, four levels of roughness of solid surfaces of similar mineralogy (quartz and glass) were tested in hexane-deionized water fluid pair. The advancing and receding contact angles measured at ambient conditions were analyzed for wettability effects. It was found that as surface roughness increased, the dynamic contact angles also increased. The wettability of the rock-oil-water system shifted from weakly water-wet for the smooth glass to intermediate-wet for the roughened surface. The general trends observed in our study were found to be in good agreement with other published results. However, the generally held notion of increasing contact angle hysteresis with increasing roughness appears to be incorrect in solid-liquid-liquid systems.

Commentary by Dr. Valentin Fuster
2002;():169-175. doi:10.1115/ETCE2002/CMDA-29072.

An analytical model of the behavior of an adhesive-bonded taper-taper composite joint under axial compressive loading has been developed using the Ritz Method. The model was based on laminated beam theory. A Fourier series was used to represent the transverse displacement variable and the Ritz method was used to derive an eigenvalue equation for adhesively bonded taper-taper composite joint. The smallest eigenvalue is the critical buckling load. Finite element analyses were performed on two unidirectional laminated beam joints with various taper angles to verify the analytical model. The effect of varying the taper angle, adhesive thickness and adhesive modulus on the critical buckling load were investigated analytically.

Commentary by Dr. Valentin Fuster
2002;():177-183. doi:10.1115/ETCE2002/CMDA-29073.

Modeling of a heat-activated coupling process of fiberglass reinforced epoxy composite pipe with a copper nickel 90/10 (Cu 90% Ni 10%) alloy pipe was investigated in this study. A nonlinear-coupled two-dimensional heat diffusion model was used to capture the essentials of in-situ thermal transport during the curing process through the thickness of the prepreg wrapping layers. The resulting nonlinear boundary value problem was solved using an Alternating Direction Implicit (ADI) finite difference model (FDM). Transient temperature distributions and degree of cure were predicted for the prepreg layers with and without a heating source at the side of the alloy pipe. A reasonable agreement was found between the predicted temperatures and the experimental results. Measures to improve the curing quality of prepreg layers were discussed based on the modeling results.

Commentary by Dr. Valentin Fuster
2002;():185-190. doi:10.1115/ETCE2002/CMDA-29074.

Finite element analyses were conducted using commercial software ABAQUS to analyze the mechanical behavior of single-lap adhesive-bonded joints. Adhesive was characterized for the stress-strain relation by comparing the apparent shear-strain relations obtained from finite element analysis and experiments following ASTM D 5656 “Standard Test Method for Thick-Adherend Metal Lap-Shear Joints for Determination of the Stress-Strain Behavior of Adhesives in Shear by Tension Loading.” With the established stress-strain relation, two failure criteria using equivalent plastic strain and J-integral were used to predict the failure load for joint specimens following ASTM D 5656 and ASTM D 3165 (Strength Properties of Adhesives in Shear by Tension Loading of Single-Lap-Joint Laminated Assemblies), respectively. Bondline thicknesses of 0.013”, 0.04”, 0.08”, and 0.12” were used in the investigation. Good correlation was found between the finite element results and the experimental results.

Commentary by Dr. Valentin Fuster
2002;():191-198. doi:10.1115/ETCE2002/CMDA-29075.

In order to accurately predict particle velocity profiles of steady shock wave fronts propagating in solid materials, a new numerical calculation method was proposed. The present method was based on one-dimensional Lagrangian finite difference wave code, and shock viscous stresses evaluated theoretically were introduced into the present numerical code. The shock viscous stress that is one of the important parameters to shape the rising profile of the shock wave front was calculated by the inside temperature estimate method for the steady shock wave fronts. The present calculation method was applied to the uniaxial strain problem of 6061-T6 aluminum at some stress levels below 8.86 GPa, where the elastic and plastic steady shock waves will appear. The results of the present calculation could reproduce more accurately the experimental data measured by the velocity interferometer system (VISAR). In addition, the present calculation was applied to a shock stress level of 20 GPa to investigate the shock viscous effects in the overdriven shock wave rising profile.

Commentary by Dr. Valentin Fuster
2002;():199-204. doi:10.1115/ETCE2002/CMDA-29076.

An electrical resistance welding method was applied under atmospheric conditions by using one of metal powder medium or media mixture which was sandwiched in the space between the two solid metal bars of specimen (i.e., solid specimen material), and was compressed longitudinally by oil pressure servo control electrodes (upper and bottom) and simultaneously current was conducted to generate Joule thermal heat. In the joining experiments, a solid aluminum specimen material was used as a basis material, and was joined to another solid aluminum specimen material or one of four other solid specimen materials with different melting points by using resistance-welding apparatus. Some fundamental data on the mechanical properties of the joint were obtained by material testing. In the experiments, the specimen used as solid specimen materials in this study were pure aluminum, copper, stainless steel, carbon steel and titanium bars of solid specimen, and the powder media were aluminum, nickel and silicon powder. Proper mixed ratios of total amount of the powder media were determined for reliable joining, and material testing was prepared for mechanical properties. The obtained data were examined with the intent of optimizing the method using metal powder media between a pair of specimen materials and were compared with that of the solid specimen material, in terms of tensile strength, Vickers hardness, bending U-shape flexure stiffness. On the tensile strength and Vickers hardness, they were found to be reliable, but on bending U-shape flexure stiffness, they were not definite enough.

Commentary by Dr. Valentin Fuster
2002;():205-217. doi:10.1115/ETCE2002/CMDA-29077.

Smart systems have recently been used for active control of vibration in structural engineering applications. One class of components often used in these systems includes piezoelectric materials, whose two electromechanical direct and converse effects allow them to play both roles of sensors and actuators. This paper presents the analytical and experimental investigations conducted using piezoelectric materials with polymer concrete as elements of intelligent structures. A piezoelectric film (PVDF) was tested as an embedded stress-strain detector in a polymer concrete beam that was dynamically loaded in axial compression and in flexural configurations. The reliability of the stresses detected via PVDF film was compared with the theoretically predicted values. The results from the comparison are promising, even if some improvements must be adopted in order to apply this technique extensively. Two single-sheet PZT actuators were surface-mounted on a simply supported thin polymer concrete beam. When the beam was transversely excited, oscillations were measured, and they approximately matched predictions by a single-mode Rayleigh-Ritz model under the assumption of Bernoulli-Euler strain distribution.

Commentary by Dr. Valentin Fuster
2002;():219-225. doi:10.1115/ETCE2002/CMDA-29078.

The forced torsional vibratory motion of an external circular crack in a transversely isotropic composite is investigated by using the method of Hankel transforms. A pair of vibratory torques of equal amplitude is applied at infinity. The infinite integral involved is evaluated through a contour integration to be discontinuous in nature. An exact expression for the dynamic stress intensity factor is obtained in terms of the frequency factor and the anisotropic material constants. The maximum value of the normalized dynamic stress-intensity factor is shown to occur at different frequency factors for the sample fiber-reinforced and metal matrix composites. The distortion of the dynamic crack surface displacement from the associated static displacement depends also on the forcing frequency and the material anisotropy.

Commentary by Dr. Valentin Fuster
2002;():227-241. doi:10.1115/ETCE2002/CMDA-29079.

A new method, designated as Spiral Notch Torsion Test (SNoTT), is introduced for determining fracture toughness KIC of materials ranging from metallic alloys to brittle ceramics and their composites. A round-rod specimen having a V-grooved spiral line with a 45° pitch is subjected to pure torsion. This loading configuration creates a uniform tensile-stress crack-opening mode, Mode-I, with a transverse plane-strain state along the grooved line. This technique is analogous to the conventional test method using a compact-type specimen with a thickness equivalent to the full length of the spiral line. KIC values are determined from the fracture load and crack length with the aid of an in-house developed 3-D finite element program (TOR3D-KIC). A mixed mode (modes I and III) fracture toughness value can be determined by varying the pitch of the spiral line or varying the ratio of axial to torsion loads. Since the key information needed for determining KIC values is manifested within a small region near the crack tip, the specimen can be significantly miniaturized without the loss of generality. Limited results obtained for various materials are compared with published KIC values, showing differences of less than 2% in general and 6% maximum in one case. The experimental technique and theoretical basis of the proposed method are presented in detail.

Commentary by Dr. Valentin Fuster
2002;():243-246. doi:10.1115/ETCE2002/CMDA-29080.

The high temperature composites have been studied for applications to secondary structures due to their light weight and thermal resistance. Relatively few studies have been conducted to consider them for primary structural load bearing capabilities. These studies focused on titanium matrix composites to characterize their material behavior [1], unidirectional [2], simple loading conditions [3, 4] in a laboratory environment or unrealistic structural geometry [5]. The purpose of this work was to study fatigue damage and determine fatigue life in titanium matrix composite panels at unloaded fastener holes subjected to thermo-mechanical fatigue loads with variable amplitudes and temperature ranges. The test panels were machined from a prefabricated structural component with pre-drilled fastener holes. The test material was a 32 ply, quasi-isotropic, approximately .224 inch thick titanium matrix laminated composite with SCS-6 fibers and Ti-15-3 metal matrix. The material was HIP consolidated followed by slow cool to room temperature. The thermal zone area was 2 inches long along specimen length and 1.875 inch wide with a .3125 inch fastener hole at the center of the thermal zone. All specimens were machined using a 3-D water jet cutter. The test system consisted of a closed loop servo-hydraulic 30 Kip test system equipped with an MTS model 458 control system, a 486 PC containing a Keithley Metrabyte DAS 1601 computer card. The specimens were gripped using MTS model 647 side load hydraulic wedge grips equipped with surfalloy grip surface. The thermal loads were provided by an Ameritherm 5 kilowatt induction power supply and a total temperature instrumentation model MC-125 temperature controller. The temperature controller was equipped with analog set point and recorder output of temperatures with both set for 1–5 volt signal levels for 0 to 1832 F. The computer generated the temperature and load profiles and monitored error band for temperature. The computer system was set to null pace the temperature and loads if the temperature exceeded a 18 degree F variation. In effect all processes would hold until the temperature error returned inside the error band. This temperature error control was accomplished by comparing the command signal to the temperature controller to the process temperature signal from the temperature controller. The nominal uniform temperature zone was one inch long centered at the specimen geometric center and maintained required temperatures within 10 degrees. The variations in temperatures along the crack line were controlled to with in 5 degrees. Cooling blocks were attached to the test samples at the end of uniform sections near the fillet blend. These blocks were cooled with water passages and compressed air was passed through holes in the blocks and impinged on the samples to provide additional cooling at the end of the thermal ramp during cool -down. The air was turned on by the computer at about 400 degrees F during each block. On all notched test samples, an extensometer was mounted across the center flaw to obtain load-deflection data (COD). The optical crack lenth measurements were made using a 20 X Gaertner traveling microscope. The load versus crack mouth opening displacement readings were taken to compare with the optical measurements of the crack length. The thermomechanical load spectrum was developed from the distribution and frequency of loading that the airframe will experience based on the design service life and typical design usage. The loads and environmental spectra are used to develop design flight by flight stress environment spectra. The data and failure surfaces were analyzed to study the high stress and low stress failure, environmental degradations, surface cracks in matrix and the effect of notch on crack initiation failure mechanism. During this investigation it was observed that the most difficult task in thermomechanical fatigue testing is to control the cooling rate as required by the thermal profile. The results show that the fatigue life depend on the applied maximum stress, increased temperatures and hold levels of both the loads and the temperatures. The variation in experimental fatigue life is with in the order of magnitude typical of fatigue data considering the complexity of the test and loading conditions. The SEM photographs and micrographs showed that in titanium matrix composite, the mode of cracking is under partial bridging of fibers at the matrix crack. The COD data was of little use for totally automated measurements when comparing with the crack sizes measured.

Commentary by Dr. Valentin Fuster
2002;():247-249. doi:10.1115/ETCE2002/CMDA-29085.

Ceramics without oxides (i.e. nitrides) are vulnerable to oxidation in the presence of plasmagenic gases or oxygen from atmosphere during plasma spraying. Initially there were two ways of oxidation’s avoidance: first, modification of powder material and second, limitation of an oxygen’s stream flowing into plasma. The modification of the powder material consisted in covering of ceramic granules with material limiting contact with oxygen or usage of easily oxidizing material getting oxygen away (i.e. a graphite thin layer over carbide’s granule). This method seemed to be less economic due to additional increase in powder’s price. Eventually the second conception of limiting of oxidation was considered as worth developing. Originally the process of spraying was carried out in vacuum (VPS – Vacuum Plasma Spraying). Then application of atmosphere under control was examined (CAPS – Controlled Atmosphere Plasma Spraying). It includes process of spraying with application of different gaseous controlled atmospheres under different pressure (decreased, normal and increased). There are three kinds of atmosphere: neutral (argon, nitrogen), reductive (carbon monoxide, methane) and acting with spraying material. Eventually the process was carried out under atmospheric pressure with gaseous ring-shaped protective gas jet. Moreover the experiments with spraying of nitrides were described (AlN, TiN, Si3 N4 ). The most suitable characteristics of the process was chosen and some properties of coatings were examined as well.

Commentary by Dr. Valentin Fuster
2002;():251-253. doi:10.1115/ETCE2002/CMDA-29086.

In the paper development of used ceramic materials and ways of their production with the aid of heat spraying is presented. According to a needness of continuous increase of coating’s mechanical resistance (high wearability, low brittlesness), corrosion resistance and profitable thermal and electric properties, current ceramic materials characterized by more and more attractive useful properties are described. Also a role of flame and plasma spraying including developmental trends towards prodution of coatings are underlined. The paper contains the own solution of plasma spraying of coatings consists in operation of the process under atmospheric pressure with gaseous ring-shaped protective jet. Additionally, proper choice of spraying’s parameters and some interesting characteristics of coatings are presented along with the examination of their structure (i. e. a rate of fusion, an oxidation of granules in a coating). Moreover the applications of coatings on machine parts (i. e. mechanical seal of impeller pumps, blades of turbines) are mentioned.

Commentary by Dr. Valentin Fuster

Computers in Engineering

2002;():255-265. doi:10.1115/ETCE2002/COMP-29056.

In today’s volatile market, it is crucial for companies to fine-tune their organizations and processes toward increased profitability and productivity, to have a strategy for continuous improvement, and to institute a means for graduated measurement. In putting together a continuous improvement strategy, a roadmap is essential. The roadmap must be clear and easy to follow. The roadmap that is most easily understood and accepted by an organization is one that is started from a base case, or simplified visualization of the current environment, that is called the ‘As-Is’ case, to the target environment, the ‘To-Be’ case. This roadmap clearly depicts the route to be taken and is based on business process modeling, scoring of actual practices relative to best practice, and gap analysis. A series of activities and process improvements are identified to move towards the desired ‘To-Be’ state of business processes, supporting information technology, and improved methods to measure and review performance. A well-designed roadmap will move the organization in a series of step changes toward higher profitability and productivity.

Topics: Profitability
Commentary by Dr. Valentin Fuster
2002;():267-278. doi:10.1115/ETCE2002/COMP-29057.

This paper presents an ongoing project which enhances the design and implementation of the automatic classifier for classifying the Web pages, known as Automatic Classification Engine (ACE). The enhancement focuses on the use of the ontologies of the domains to carry out classification. To articulate the underlying theories of an ontology, the meaning of a concept, a terminology and a gestalt instance is elucidated. The enhancement results in better classification in terms of accuracy.

Topics: Ontologies
Commentary by Dr. Valentin Fuster
2002;():279-284. doi:10.1115/ETCE2002/COMP-29058.

In spite of the great variety of potential advantages, it is also necessary to illuminate the real effects of Standard Software in practice. Recent studies have revealed that 81% of companies interviewed using SAP, do not fully exploit the software’s ability to optimise business processes, though 61% stated that SAP offers very good process optimisation opportunities.[CS01] Therefore this paper evaluates popular life cycle models with respect to their suitability to implement Standard Software in a process driven way.

Commentary by Dr. Valentin Fuster
2002;():285-292. doi:10.1115/ETCE2002/COMP-29059.

The improved approach is considered as a life-cycle model that combines the necessities of process improvement projects and the implementation of modern integrated Standard Software systems. To improve the company’s business processes by means of the Standard Software implementation, each phase of the entire implementation life cycle puts its focus on optimising the customer’s underlying business processes. In addition, to intensify the benefits resulting from the process-oriented system implementation, the presented approach is extended by a certain guidance to organise a process-driven project team.

Commentary by Dr. Valentin Fuster
2002;():293-295. doi:10.1115/ETCE2002/COMP-29061.

The development, management, and exploitation of Intellectual Property is critical to the health and prosperity of the Petroleum Industry. This paper provides a summary of how Petroleum companies can protect their proprietary software. Specifically, this paper will address the risks and benefits associated with protecting proprietary software through copyrights, patents, or trade secrets. With this background, the paper will address how Petroleum Companies can optimally develop, manage, and exploit their Intellectual Property to maximize industry production, efficiency, and profitability.

Commentary by Dr. Valentin Fuster

Drilling

2002;():297-304. doi:10.1115/ETCE2002/DRILL-29030.

This study measured the liquid fallback during simulated blowout conditions. The purpose of the study was to establish a basis for developing a procedure for controlling blowouts that relies on the accumulation of liquid kill fluid injected while the well continues to flow. The results from full-scale experiments performed with natural gas and water based drilling fluid in a vertical 2787-foot deep research well are presented. The results show that the critical velocity that prevents control fluid accumulation can be predicted by adapting Turner’s model of terminal velocity based on the liquid droplet theory to consider the flow conditions, velocity and properties of the continuous phase when determining the drag coefficient. Similarly, the amount of liquid that flows countercurrent into and accumulates in the well can be predicted based on the concept of zero net liquid flow (ZNLF) holdup.

Topics: Fluids
Commentary by Dr. Valentin Fuster
2002;():305-315. doi:10.1115/ETCE2002/DRILL-29031.

Significant part of axial compression load transferred to the bit while drilling of wells with high zenith angles is resisted by service drill pipes. By the action of static critical load, buckling of drillstring occurs initially in the shape of a sinusoid and subsequently, as the load increases, in the shape of a helix. Drillstring rotation promotes the occurrence of critical modes. As a result the drillstring can start snaking motion at the low side of the hole. When the rotary speed grows, whirling of the drillstring can occur with axial load much lower than the buckling load. In this paper, a nonlinear mathematical model of lateral vibrations of a rotating drillstring in straitened space of a straight inclined hole is proposed. A numerical method to solve drillstring motion equations has been developed that allowed to reduce time of computation. This made it possible to conduct a detailed study of how the main drilling parameters (compression load, drillstring rotary speed, hole angle, friction factor, etc.) effect drillstring motion in the well. Results of the study may be used to choose drillstring operation modes for rotary drilling of inclined and horizontal wells.

Topics: Wells , Drilling , Vibration
Commentary by Dr. Valentin Fuster
2002;():317-324. doi:10.1115/ETCE2002/DRILL-29032.

The occurrence of barite sag is a well recognized but poorly understood phenomenon in the drilling industry. Industry experts have offered a variety of measuring parameters, based upon empirical data, that only partially correlate with the occurrence of barite sag. The industry’s lack of understanding of the mechanisms and types of barite sag generally result in a poor correlation between laboratory results and field observations of barite sag. The financial impact of barite sag on drilling costs, usually resulting from rig-time lost while circulating and conditioning the mud system, is not trivial. There are reported incidences where recurring barite sag problems have resulted in the loss of drilling projects. The accuracy and relevance of technology utilized to manage barite sag can help reduce drilling costs. In the field barite sag frequently occurs in deviated wells where pipe eccentricity creates conditions conducive to dynamic sag. With the exception of a flow loop, laboratory tests do not simulate field conditions. Historically, laboratory tests characterize density variations arising from a vertical fluid column as static or dynamic sag without proper consideration to angle, pipe eccentricity, annular shear rates and annular flow. This paper reviews traditional and newly-emerging barite sag technology and compares their ability to predict barite sag potential. This potential will be determined under dynamic and static conditions in a sophisticated flow loop configured to match certain field conditions.

Commentary by Dr. Valentin Fuster
2002;():325-333. doi:10.1115/ETCE2002/DRILL-29033.

Comparative wear tests were carried out on a new Thermally Stable Polycrystalline Diamond (TSP) composite and Tungsten Carbide (6% Co) (WC) cutters, by machining rock cylinders in an instrumented lathe. Cutting tests were performed on Berea Sandstone and Sierra Granite rocks. It was observed that the new TSP material removes 1.4 times more Berea Sandstone rock than WC and 13 times more Sierra Granite than WC. In addition its volumetric wear is 25 times less in Berea Sandstone and 10 times less in Sierra Granite than WC. WC was also found to have much higher coefficient of friction, which can limit its use in abrasion resistant applications.

Commentary by Dr. Valentin Fuster

Environmental Engineering

2002;():335-340. doi:10.1115/ETCE2002/EE-29067.

Reports from onshore E & P activities in Nigeria have shown that operating in the Niger Delta region poses some of the toughest challenges in the world. This region has witnessed a spate of attacks on oil and gas facilities, staff and contractors. Consequently, major oil and gas players have to contend with complex operational uncertainties due to increase pressure from the local communities for improved environmental control measures. To effectively de-risk this region of this category of operational uncertainties, the industry must begin to see environmental performance as not only a measure of how well she can comply with existing environmental regulations, but also as a measure of how well she can pre-empt environmental pressures as well as maintain constant harmony with all concerned stakeholders and seeing herself as responsible to the environment with a view to improve performance. In this project, we have been able to develop SMART * models based on continuous consultation, integrated management approach and continuos improvement attitude (CIA). With a good FOCUS * approach, this will help in safe and effective operations, pre-empt pressures, maintain harmony with local communities and effectively manage operational disturbances within complex environmental settings like the Nigerian Niger Delta area. Finally, we are of the opinion that every industry that seeks to remain efficient and relevant in this millennium should constantly be looking for ways of becoming more environmentally responsible — because no business can call itself efficient if it threatens the environment within which it operates. • SMART is an acronym for Specific, Measurable, Achievable, Realistic and Time Bond. • FOCUS is an acronym for Fair, Objective, Consistent, Unbiased and Succinct.

Topics: Pressure , Regulations
Commentary by Dr. Valentin Fuster
2002;():341-346. doi:10.1115/ETCE2002/EE-29068.

INA-Industrija nafte d.d., is one of the largest companies in the Republic of Croatia. Its principal activities are oil and gas exploration and exploitation, oil refining and processing, oil and gas transportation and sale of fuels and associated products. Such a type and scope of activities requires a major responsibility and a systematic approach to planning, implementing and monitoring the environmental protection. In 1998 INA management adopted so called “green” documents for the purpose of improving the environmental protection activities: “Decision on establishing an integral environment management system” and “Environmental protection policy declaration”. The system implementation activities are under way and four organizational units of INA have obtained ISO 14001 certificate for the successfully implemented environment management system. This paper provides an insight into INA’s environment impacts as well as information about the performed environmental protection management activities and achievement of sustainable development. The attention is drawn to the way company’s units carry out their activities to comply with the current environmental legislation. The information is also provided on INA’s way to participate in national eco-projects and cooperation with international institutions in order to achieve eco-efficiency. Following the requirements according ISO 14001, as well as by major investments, INA contributes to the environmental improvement on local, regional and global levels.

Commentary by Dr. Valentin Fuster
2002;():347-353. doi:10.1115/ETCE2002/EE-29122.

It has to be the vision of an international oil and gas exploration and production company to explore for and produce oil and gas in the most economically efficient, social responsible and environmentally acceptable way. Based on this aim and due to the fact that Austria is a country with a environmental awareness and a high tourism level, OMV as the leading domestic oil and gas company had to elaborate strategies for the benefit of the company, its employees and shareholders, but also for the benefit of local communities maintaining the image of a healthy, clean and relaxing environment. The paper describes the different ways of implementing environmentally relevant technique and strategies beginning with exploration process and ending with the monitoring of oilfield wastes. Case histories demonstrate the concept of converting onshore drilling projects into action in environmentally sensitive regions using the idea of “ecological compensation”. Further a new technology of water treatment based on “microbiological clarification” is shown. With the new water treatment technology a valuable contribution to the protection of environment could be shared by OMV, because this method works without any application of biocides. Finally, innovative methods of calculating the risk potential of oilfield deposits using micro-geophysical surveys are illustrated. This measuring practice takes care of the electric resistivity contrast between oilfield deposits to its surrounding, so that any leakage can be observed immediately due to the change of electric resistivity profile. Generally the paper has the goal to illustrate acceptable ways to meet the environmental sensitivities of communities and authorities.

Commentary by Dr. Valentin Fuster
2002;():355-357. doi:10.1115/ETCE2002/EE-29123.

There is a need for a reliable staining technique to distinguish between live and dead organisms following LC50 tests. This is especially so in cases where organisms can be stressed or even become unconscious and appear dead to the aided or naked eyes. Visual observations under such conditions can result in an LC50 value shifting to the lower concentration thereby imposing stiffer guidelines for compliance. Aniline blue can only stain individuals which are physiologically dead imposing an accurate live-dead evaluation and producing a true LC50 value. Guidelines imposed using such data will facilitate compliance and provide an accurate value for an LC50 .

Commentary by Dr. Valentin Fuster
2002;():359-366. doi:10.1115/ETCE2002/EE-29134.

3D Seismic survey of an area approximately 70km2 was conducted in South-East Central Trinidad in the Naparima Mayaro Reserve from January to July 1999. This activity was done with the expectation of drilling exploratory wells for finding commercially viable oil reservoirs as a joint venture operation between Vintage Petroleum Trinidad Limited (formerly Cometra Energy (Canada) Limited) and Petrotrin. The companies initiated a number of proactive Environmental Management Programmes to comply with both local and international regulations. These programmes include: • Preliminary Environmental Impact Assessment Study for Seismic Survey of a 70km2 area. • Environmental Baseline Survey for Seismic Survey inclusive of descriptions of physical, biological and socioeconomic environments, environmental audits, training and monitoring (noise and water quality). • Environmental Impact Assessment for drilling of exploratory well. • Development of Oil Spill Contingency Plan for drilling operations. The implementation of these studies resulted in a number of benefits to the joint venture oil companies, such as: • 100% compliance with Certificate of Environment Clearance Rules and International Association of Geophysical Contractors (IAGC) Guidelines. • Improved corporate image. • Enhanced relationship with Government Agencies. • Improved environmental performance through proper planning. • Trained and empowered workforce in environmental management issues. • Zero oil spills and environmental incidents to date.

Topics: Drilling
Commentary by Dr. Valentin Fuster
2002;():367-373. doi:10.1115/ETCE2002/EE-29135.

The aim of this study was geochemical and mineralogical assessment of materials from two already closed pits. Total testing and leachate testing (Equilibrium Leach Test and Sequential Leach Test) of topsoil, waste stabilized with lime and underlying rock was performed on composite samples. Analysis of underground water from underlying rock was also accomplished. Major pollutants in stabilized waste from investigated locations differ. High total values of some heavy metals in stabilized waste from one of the investigated locations can probably be attributed to high barite content (mercury, zinc and cadmium) and pipe dope (lead). Mercury, zinc and cadmium are enriched in the organic-sulfide fraction that might indicate they are tied up as sulfide impurities in barite. In distilled water lecheate of stabilized waste from this location higher concentrations of Pb, Hg and TOC were observed. In the stabilized waste from the second location high total values of TPH, PAH and BTEX were detected, while distilled water lecheate is enriched in Hg, AOX, TOC and TPH. This investigation shows that stabilization with lime is not always suitable method for treatment of wastes from petroleum industry, particularly those that are contaminated with both organic and inorganic contaminants. Proper characterization of the waste material to be processed is needed in order to select the most appropriate method of treatment. Our ongoing research study uses different pretreatment techniques and different absorbents (organophilic clay, zeolite, calcined siliceous earth, etc.) to preferentially absorb organic contaminants that can be used before stabilization/solidification.

Commentary by Dr. Valentin Fuster
2002;():375-381. doi:10.1115/ETCE2002/EE-29136.

We know petroleum hydrocarbons degrade in soil via chemical, physical, and biological pathways. Innovative remediation technologies enhance degradation by one or more pathways e.g., in-situ and ex-situ. The typical goal of degradation is to achieve the applicable regulatory criteria. Some, State Agencies, e.g., Louisiana, Texas, require oil total petroleum hydrocarbon (TPH) contamination levels be reduced to ≤10,000 mg/kg. However, other agencies, e.g., New Mexico and California, require oil contamination levels reduced to <1,000 mg/kg. Even 100 mg/kg is not uncommon, e.g., Los Angeles, County, CA. Microbial populations and substrate availability often limit biodegradation at petroleum hydrocarbon levels <1,000 mg/kg. Conventional laboratory biodegradation microcosm studies require an inordinate amount of time to evaluate petroleum hydrocarbon treatability (as measured by loss of analyte) and even more time to optimize treatment parameters that facilitate or improve kinetics (lower half-life values). Two studies discussed here demonstrate the utility of oxygen consumption respirometry in evaluating oil impacted soil treatability. In the first study, oxygen consumption rates were measured after a 1-week incubation period at varying TPH levels (5800 and 1000 mg/kg), carbon:nitrogen (C:N) ratios (100:1 and 25:1), and manure content (0, 0.5, 1.0 and 5.0 percent). Results showed TPH and C:N ratios significant at < 1 percent level and manure significant at < 5 percent level. The second study, a longer-term study (132 day) showed oxygen consumption resulted from degradation of gasoline range (GRO) and diesel range (DRO) fractions of TPH. These studies provide a means of evaluating treatability of low concentrations of petroleum hydrocarbon and a method for assessing treatment options that are passive in nature, but less destructive to the environment.

Topics: Oxygen , Soil
Commentary by Dr. Valentin Fuster
2002;():383-387. doi:10.1115/ETCE2002/EE-29137.

How to fulfill requirements of environmental protection set by operator so that their fulfillment does not overburden the financial part of the Contract or violate the local legislation? Are these requirements always the same, or they differ depending on the operator, or the part of the world and country where operations are being executed? In Crosco, we believe that we have the answers to those questions. The fact that we have succeeded to survive in the competitive world market and that Crosco’s share in that market is constantly growing speaks in favor of that. Since December 17th 1996, when the part of INA-Naftaplin dealing with exploration and exploitation drilling including well services was separated from Naftaplin as an independent drilling contractor under a new name, Crosco Co. Ltd. was forced to turn to the world market overnight. Up to that moment Crosco was fairly safe and comfortable as a part of INA, the state-owned oil company. But from that moment on, Crosco had to face the challenge of the foreign market and particularly, the operators’ requirements for the environmental protection. The requirements varied a lot and so did the environmental policies implemented by operators. To qualify for tendering, not to speak of successfully winning a contract, Crosco and its employees were forced to step suddenly into a completely new area — the Environmental Protection. Crosco has succeeded in overcoming that obstacle and finding its own way of how to satisfy operator’s environmental requirements and local legislation optimally. Crosco’s method has shown to be efficient, simple and inexpensive. The paper will expound and analyze the following: • Operators’ requirements and their environmental policies. • Local legislation, environmental discharge limits and available methods of waste treatment. • Ways how Crosco as contractor fulfills the set environmental requirements.

Commentary by Dr. Valentin Fuster
2002;():389-396. doi:10.1115/ETCE2002/EE-29139.

Firstly, the main regulatory characteristics of the Brazilian petroleum and natural gas industry are presented, with emphasis in the oil refining segment. Secondly, it is stood out the binomial “technical standards” versus “regulation acts.” It is worth to point out that the last ones are compulsory and they can be written considering technical standards as a basis. Finally, it is outlined the Brazilian Petroleum National Agency strategy for elaboration of refinery regulations, focusing on the adopted prescriptions for environment damage prevention and protection.

Topics: Oil refining
Commentary by Dr. Valentin Fuster
2002;():397-403. doi:10.1115/ETCE2002/EE-29140.

Consideration of a global viewpoint in modern impact analyses suggests that we should favor the efficient use of available infrastructure over the wasteful development of new infrastructure when comparable volumes of oil and gas production are concerned. This global benefit of efficient development is overlooked in traditional environmental impact analyses that typically focus on local concerns within a narrow geographic range. This traditional approach, which is common in more affluent developed countries, may actually contribute to increased global impacts by establishing stringent regulatory regimes discouraging development that would allow the efficient long-term use of that infrastructure. This disregard for global efficiencies favors development in underdeveloped countries where economic development goals may overshadow local concerns for environmental protection. This paper is based upon the results of a study of onshore industrial infrastructure capacity in Central California sponsored by the U.S. Minerals Management Service. This study evaluates the oil and gas production potential of offshore leases that could be accommodated by existing infrastructure and a balanced program of facility replacement. Though these oil and gas resources were originally identified over ten years ago, local environmental policies have delayed their development. An example of oil and gas production activities in other parts of the world that provide energy supplies equivalent to this unrealized potential is described along with an overview of selected environmental characteristics. This paper concludes that environmental review procedures addressing oil and gas development should include consideration of global implications of locally restrictive approval policies.

Commentary by Dr. Valentin Fuster
2002;():405-411. doi:10.1115/ETCE2002/EE-29141.

This paper describes a gas re-injection project designed with the dual objectives of emissions reduction and enhanced oil recovery in an Australian offshore oil field. While gas injection for enhancing oil recovery is common oilfield practice, there are fewer projects that look exclusively at greenhouse gas (GHG) control (either by sequestration or emission reduction), although there is increasing environmental awareness in the industry on the benefits of doing so. The predominant contribution to total GHG CO2 -e emissions is from flaring. Significant reductions in flaring have been achieved since completion of commissioning of injection. Flare CO2 emissions at the beginning of 2000 (February-March) reduced from approximately 163,000 tonnes per month to an average of approximately 26,000 tonnes per month over the remainder of 2000, and to 9,800 tonnes per month, over the first half of 2001. GHG efficiency, evident in the ratio of GHGs emitted per tonne of hydrocarbon produced, reduced from approximately 0.4 tonnes CO2 -e per tonne of total hydrocarbon produced before injection to 0.08 after injection over the remainder of 2000, and to 0.06 over the first half of 2001. Miscible displacement is expected to add around 6 million barrels to ultimate recovery from the Corallina reservoir. The use of stored gas as a fuel is expected to achieve significant reductions in operational expenditure later in field life.

Commentary by Dr. Valentin Fuster
2002;():413-420. doi:10.1115/ETCE2002/EE-29142.

This paper analyses which parameters may be in fact contributing for changing in water quality in Suruaca coastal lowland region, north of Espirito Santo, Brazil (Fig. 1). It is a low and plain area, with freatic level near surface, highly deforested, where there is a dominance of activities such as petroleum exploration and production, extensive cattle breeding and plantations of eucalyptus trees. Water quality monitoring surveys that have been carried out comprise 27 parameters at total, and some anomalies have been reported. From bibliographic search and interview with people who know the area, main economic activities in the region are defined, as well as raw materials utilized by them. Raw materials are analised by means of leaching, solubility, X-ray diffraction and X-ray fluorescence. Thus, it is tried to find links between parameters with anomalous concentrations and economic activities. Besides human sources, there are natural sources that are also contributing for changing the water quality of the region, but they are only mentioned in this paper. This paper shows that not all parameters analised need a continuity of monitoring, since both the characteristics of the economic activities placed in the studied area and the monitoring results give this away. On the other hand, there are other parameters that demand deeper researches, since they occur at concentrations higher than expected. For these latter parameters are related, as possible, the activities more likely of being contributing for its presence with concentrations above the allowable level. It is not possible to evaluate the origin of the anomalous concentrations for barium, lead and mercury.

Topics: Water pollution
Commentary by Dr. Valentin Fuster
2002;():421-428. doi:10.1115/ETCE2002/EE-29143.

The present paper describes the financial assurance system (bonding system), an incentive approach being adopted by several countries to guarantee or fund environmental obligations and ensure environmental performance. Environmental compliance involves meeting all end-of-leasing obligations, including closure and decommissioning operations. This paper also identifies the main forms of potential environmental damages resulting from upstream activities and their potential financial impact on the regulatory agency. It will be demonstrated how bonding instruments may help reduce such risks by: (1) providing financial incentive for environmental compliance; (2) safeguarding government and taxpayers by attaining reasonable protection from default at a minimum increase in project costs; and (3) protecting the environment from potential harm resulting from failure to carryout proper closure operations in a timely fashion. A model is proposed for a hypothetical scenario and an analysis is performed in order to identify potential financial impacts on oil projects.

Topics: Bonding , Mechanisms
Commentary by Dr. Valentin Fuster
2002;():429-434. doi:10.1115/ETCE2002/EE-29144.

The Petroleum Company of Trinidad and Tobago Limited (Petrotrin) has developed and implemented a Health, Safety and Environmental (HSE) Management Audit System of its Exploration and Production, and Refining and Marketing Strategic Business Units. The main objective of this internal company audit was to determine the missing ‘gaps’ or elements from the current HSE Management System and to recommend alternate HSE Management System elements to create a more efficient Management System. The audit checklists and results effectively listed the observations, problems, and compliance issues, as well as corrective actions for improvement in accordance with the ISO 14001 and HSE Guidelines of the Exploration and Production Forum and 29CFR 1910.119 - Process Safety Management of Highly Hazardous Chemicals, Standards as well as the Company HSE key strategic directions including: • 100% compliance with local Environmental and Safety Regulations; • Targets of zero accidents and oil spills; and • Certification HSE Management Systems, for all Company operations. Senior personnel or drivers of the management systems within the Company were interviewed using this structured approach. The results from this company wide internal audit revealed that generally the overall HSE Management Strategies have been developed, but are not fully implemented, although they are formalized in the Environmental and Occupational Health and Safety Policies of the Company. HSE is undoubtedly regarded as a priority issue within Petrotrin’s operations, however there is the need to improve the documentation of formalized HSE Management System Procedures, thereby improving the enforcement and maintenance of the management system.

Topics: Safety
Commentary by Dr. Valentin Fuster
2002;():435-441. doi:10.1115/ETCE2002/EE-29145.

In Croatian Podravina relatively large quantities of natural gas was discovered. From various fields (Molve, Kalinovec, Stari Gradec) natural gas is pipelined to Gas Treatment Plant (GTP) Molve. Here, at GTP Molve III, technological procedures for purification of natural gas and its distribution are performed. With yearly natural gas production of 3,5 109 m3 GTP Molve III is major Croatian energy resource. Its safety and environment impact is matter of concern. Continuous acoustic emission leak monitoring system for Gas Treatment Plant (GTP) Molve as an improvement in technological and environment safety is considered. Application of a leak monitoring system under industrial conditions is a problem setting specific demands. In the paper attention is paid to some aspects of acoustic emission system implementation and the acoustic background noise definition problem. Acoustic noise measurements at a GTP Molve III were performed and some results considering background noise are presented. In the paper acoustic noise measurements performed at a GTP Molve III were presented. Across the GTP Molve III acoustical background have different spectral and amplitude characteristic. In the input area, measurements presented at a first group of measuring points included the impact of sand moved by gas fluid. Sand hits should be distinguished from acoustic emission caused by growing cracks. Motors noise and turbulence around valves are probably the main source of background noise on second group of measuring points. The conclusion is that background noise across the plant is highly different. Patterns found in one part of plant could not be applied on others measuring points. Background noise and its characterization are one of main problems solved before reliable operation of acoustic monitoring system could be applied. It is found that at GTP Molve III acoustic background is complicated, consisting of different sources at different part of a plant.

Commentary by Dr. Valentin Fuster
2002;():443-449. doi:10.1115/ETCE2002/EE-29167.

During oil and gas extraction in the Gulf of Mexico (GOM), water and pollutants are produced from wells. The Environmental Protection Agency (EPA) has mandated a permit system to help control the discharge of these waters into the GOM. The National Pollutant Discharge Elimination System (NPDES) contains both requirements and standards for discharge in offshore Texas and Louisiana federal waters. This review summarizes permit (GMG290000) requirements, effluent limitations, standard conditions, and monitoring requirements for NPDES general permits in EPA Region 6.

Topics: Pollution
Commentary by Dr. Valentin Fuster
2002;():451-458. doi:10.1115/ETCE2002/EE-29168.

Despite continuous research and development on drilling fluids and waste minimization during the last 40 years, offshore drilling waste (OSDW) remains a significant environmental concern for the petroleum industry. OSDW contains three types of contaminants namely, heavy metals from drilling fluid, oil from oil based mud or petroleum contamination and naturally occurring radioactive substances from exposed formations. In this study a promising and permanent solution based on recycling of OSDW as road construction materials has been investigated. It has been revealed previously that five to ten percent of some waste materials such as recycled asphalt pavement, tire rubber, glass, roofing shingles, polythene etc. can be added to hot mix asphalt (HMA) concrete without sacrificing its strength and performance. These wastes can be added to the HMA by either replacing the mineral filler or proportionately reducing the amount of virgin material in the original mix. In this laboratory test study, different percentages of OSDW were added as aggregate replacement and the properties of resulting blends were evaluated. Three beneficial actions, namely, incineration, dilution and solidification took place. At the end, the effectiveness of using OSDW was determined with the Marshall stability and flow, permeability of HMA concrete, leachability and resilient modulus. It has been found that for the drilling waste used in this research the percentage that can be used in HMA concrete without sacrificing its properties is as high as 20%. Even though the percentage of waste that can be used as aggregate replacement varies with waste types and properties, the proposed technique offers significant promises for OSDW recycling.

Commentary by Dr. Valentin Fuster
2002;():459-466. doi:10.1115/ETCE2002/EE-29170.

An offshore survey and environmental assessment was conducted on the Brunei continental shelf offshore oil and gas concession area in 2000–2001. The results of the comparison of the environmental effects of previous ocean disposal of oilbased mud (OBM), water-based mud (WBM) and ester-based synthetic mud (ESBM) was used to prepare guidelines for atsea disposal of mud and cuttings based on the sensitivity of the receiving environment. The ranking, in terms of sensitivity of environmental components are as follows: 1) Shallow coral reefs; 2) Deep reefs; 3) Juvenile shrimp nursery areas; 4) Adult shrimp shallow coastal areas; 5) Adult shrimp mid-shelf areas; 6) the Brunei continental shelf; and, 7) Continental slope and deep water. Detailed instructions are presented for the handling and disposal of WBM and ESBM for each offshore zone. The guidelines are presented in a user-friendly format and provide: description of the environmental zone and it’s sensitivity; the disposal management strategy including options for disposal in order of preference; and requirements for planning, disposal and recommended monitoring and follow-up.

Commentary by Dr. Valentin Fuster
2002;():467-474. doi:10.1115/ETCE2002/EE-29171.

Decommissioning offshore oil and gas production facilities have been progressively increasing the concern of the industry, government and other interest groups through the last years. There are at least two reasons for this sudden regard. First, it is the maturing of several oil and gas fields around the world in recent years. Second, it is the growing impact of environmental concerns in international affairs. Despite several works published address to some techniques and to potential problems and risks related to decommissioning offshore oil and gas production installations its procedures are in some extent an innovative issue, especially in Brazil. Therefore, the motivation of this paper is the novelty of the subject in Brazil, since the national industry is just beginning to deal with the end-of-leasing obligations, which involve decommissioning operations. The main ambition is to stimulate debate about appropriate issues.

Commentary by Dr. Valentin Fuster
2002;():475-482. doi:10.1115/ETCE2002/EE-29172.

Benzene emissions occur during operations. These emissions are regulated in several counties. Accordingly, we developed one-dimensional benzene diffusion model advancing in the vertical direction. Unlike other models, the instant model is based on a 1/10 scale modeling of eddy diffusion at the liquid surface during initial loading operations and advection under tank roof during final loading operations. The model input parameters include loading rate, flow rate, cargo tank size, and temperature dependent saturated concentrations. The validity of the model is demonstrated by comparisons with onboard measurements. Other models exist. However, they are based on empirical estimate rather than rational modeling.

Topics: Tankers , Benzene
Commentary by Dr. Valentin Fuster
2002;():483-488. doi:10.1115/ETCE2002/EE-29173.

This paper will give a brief presentation of experience gained over the last 5–10 years of decommissioning of offshore installations in the North Sea. Focus is given to safety and environment issues, as this is the driven factor towards decommissioning and deconstruction of offshore installations. The establishment of cleaning criteria is based on experience from The Ekofisk I Field where a number of installations should be out of production and shut down prior to final disposal. The disposal solution was not yet defined; therefore a “cold phase” was defined. The installations would stay in place for an unknown period of time. Cleaning of large storage tanks, such as Brent Spar, Maureen Alpha and The Doris Tank is a challenge due to the size and layout of the tanks and the content, such as H2 S, wax, scale, sediments, etc. Special cleaning techniques and methods are developed for each tank. Reuse of installation or part of the installation is a target. Re use of the installations to what they were originally designed for, has been a main issue, but not yet succeeded. In the North Sea, no installations so far have been re used. Lot of effort is put into risk management and waste management. Risk related to deconstruction work, both onshore and offshore, is a major concern. All statistics demonstrates challenges towards work performance in deconstruction projects. It is important for the offshore industry to maintain a good reputation and to be a reliable and orderly partner for safety and environmental aspects of the industry.

Commentary by Dr. Valentin Fuster

Manufacturing and Services

2002;():489-498. doi:10.1115/ETCE2002/MANU-29102.

First oil production from a deep-water oil field is to be achieved by the installation of an Initial Development System (IDS). Well testing is required for field development and reservoir management. The well testing system requires high accuracy oil and water rates to provide the data needed for decision analysis in ongoing drilling programs. The well testing system must also be integrated with other platform operations such as well clean up after drilling. The concept of a certain type of multiphase meter in a feedback control loop with conventional separation technology for process control is simulated to extend the capabilities of both technologies. The principle of GVF control as a supplementary to level control system has been developed for performance enhancement of oil field well testing. Concepts demonstrated here can also be easily applied as retro-fits to existing separation facilities which show accuracy or upset problems because of the simplicity and compact size of the additional multiphase meter component and non-disruptive supplementary integration with existing level control systems.

Commentary by Dr. Valentin Fuster
2002;():499-506. doi:10.1115/ETCE2002/MANU-29103.

The feasibility of using Liquid-Liquid Cylindrical Cyclone (LLCC© ) as a free water knockout device for bulk separation of oil-water mixtures in the field strongly depends on the implementation of control systems due to its compactness, less residence time and possible inlet flow variations. In this investigation, the LLCC control dynamics have been studied extensively both theoretically and experimentally. A linear model has been developed for the first time for LLCC separators equipped with underflow watercut control, which enables simulation of the system dynamic behavior. A unique “direct” control strategy is developed and implemented, capable of obtaining clear water in the underflow line and maintaining maximum underflow rate. Dedicated control system simulations are conducted using Matlab/Simulink® software to simulate the real system dynamic behavior. Detailed experimental investigations are conducted to evaluate the system sensitivity and dynamic behavior of the proposed control strategy. The results demonstrate that the proposed control system is capable of controlling the underflow watercut around its set point by obtaining maximum free-water knockout for a wide range of flow conditions. (inlet water concentration of 40% and an inlet mixture velocity of 1.5 m/s).

Commentary by Dr. Valentin Fuster
2002;():507-515. doi:10.1115/ETCE2002/MANU-29105.

Well testing is routinely performed to evaluate the performance of a well, which establishes the allocation factor for the lease, which in turn establishes tax and royalty basis. Most well testing is done with conventional gravity separators, which separates the produced stream into oil, water, and gas components and measures these individual components as individual streams. New multiphase measurement technology improves well test results through improved accuracy, consistency, and more frequent well testing. This paper examines the implication of these improved capabilities to recognize well problems and optimize production. A simple economic model is provided that an operator can use to assess the balance between the cost of performing periodic well tests and the benefits of more quickly discovering well problems that can result in less than expected production. The model relates the cost of decreased production, as the result of unforeseen changes in the well, to the frequency and accuracy of the well tests. The model derives an optimum test interval that minimizes the total cost of well testing and deferred production on the basis of the probability that a higher than normal decline in production rate can be detected by well testing. The model is then used in several field examples to assess the optimum period between well tests and how the optimum period can lead to reduced cost of operation and improved production.

Commentary by Dr. Valentin Fuster
2002;():517-520. doi:10.1115/ETCE2002/MANU-29106.

A physical description and the operating characteristics for a multiphase flow test facility are given. The facility is designed for wet-gas conditions where the gas-void-fraction (GVF) is typically greater than 0.95. However under many conditions, the liquid flowrate can be increased which results in a lower GVF. Lean natural gas, whose typical energy content is less than 1100 BTU/ft3 , is used as the flowing gaseous media. The flowing liquid can range from a pure hydrocarbon liquid (such as decane) to a mixture of water and hydrocarbon liquids (condensate). Several investigations into the performance of various single-phase flowmeters and gas-liquid separators have been conducted for wet-gas flowing conditions. Present work includes the modification of the test facility to study hydrate formation and methods that can be employed to inhibit the hydrate formation. Visual images obtained with a high-pressure viewing section will be presented which show the different flow patterns that can exist within pipes that are contain multiphase fluids.

Commentary by Dr. Valentin Fuster
2002;():521-529. doi:10.1115/ETCE2002/MANU-29110.

The use of Gas-Liquid Cylindrical Cyclone (GLCC© ) separators for gas-liquid separation is a new technology for oil and gas industry. Consequently, it is important to understand the flow behavior in the GLCC© and effect of different geometrical configurations to enhance separation. The main objective of this study is to address the effect of different inlet configurations on flow behavior in the GLCC© by measuring velocity components and turbulent kinetic energy inside the GLCC© using a Laser Doppler Velocimeter (LDV). Three different inlet configurations are constructed, namely: one inclined inlet, two inclined inlets and a gradually reduced inlet nozzle. Axial and tangential velocities and turbulent intensities across the GLCC© diameter were measured at 24 different axial locations (12.5” to 35.4” below the inlet) for each inlet configuration. Flow rates of 72 and 10 gpm are selected to investigate the effect of flowrate (Reynolds number) on the flow behavior. Measurements are used to create color contour plots of axial and tangential velocity and turbulent kinetic energy. Color contour maps revealed details of the flow behavior.

Topics: Flow (Dynamics)
Commentary by Dr. Valentin Fuster

Offshore Technology

2002;():531-534. doi:10.1115/ETCE2002/OT-29019.

The elastic moduli of granular assemblies are sensitive to the confining conditions as well as the volume fractions of each of its constituents (i.e. solid, fluid, gas). Theoretical estimations using granular mechanics are based on assumed distributions of contact normals and branch vectors using idealized particle shapes and therefore cannot quantitatively predict the moduli. This paper presents a new method to use the moduli of the granular skeleton and those of the matrix to estimate the moduli of the composite and makes it possible to back-calculate the moduli of the skeleton from the moduli of the composite and the matrix.

Commentary by Dr. Valentin Fuster
2002;():535-540. doi:10.1115/ETCE2002/OT-29112.

The natural frequency of a thick rectangular sandwich panel was studied using refined shear deformation theory. Both faceshheets and core materials are orthotropic. Nonlinear behavior of shear deformation of sandwich panel was described by a proposed polynomial function. The effect of transverse shear modulus of sandwich core on flexural vibration of the panel was investigated. Comparison was made among the classical thin plate theory, low order shear deformation theory and high order refined shear theory. Results from finite element analysis were also provided to verify the theoretical predictions.

Commentary by Dr. Valentin Fuster
2002;():541-546. doi:10.1115/ETCE2002/OT-29146.

There is currently a need to develop high pressure composite butt-weld joint to meet the needs of deepwater activities. In this study, a tapered butt-weld composite joint configuration was proposed. Finite element analysis was conducted to validate the proposed structural configuration through stress-strain distribution analysis. Test samples were assembled using hand lay-up technique. The prepared specimens were hydro tested. The test results justified the proposed joint configurations. About 35.7% increase in bursting pressure in tapered butt-weld composite joint was observed over currently used composite butt-weld joint.

Commentary by Dr. Valentin Fuster
2002;():547-553. doi:10.1115/ETCE2002/OT-29147.

Preliminary study of a composite pipe Tee-joint using heat coupling technology was conducted in this paper. The cutting process of the pipes for the Tee-joint was developed. Because the cutting edges of the pipes were coarse, it is necessary to smooth them. Both epoxy resin and prepreg were applied to the joined areas of the pipes. Shrink tape was also applied to the outside of the prepreg to add pressure and compression force. An optimized cure cycle for the epoxy prepreg used as the bonding materials was determined from the thermal cure analysis. The cure process of the joined pipes by epoxy prepreg was conducted in a specially designed oven. The total cure time was about 138 minutes. Several factors, including the thickness and length of the prepreg applied and the adhesive applied to the joints, have been considered in designing Teejoints. The hydrostatic pressure test results showed that the thickness of the wrapped epoxy prepreg had a very important effect on the quality of the joined pipes in terms of pressure.

Commentary by Dr. Valentin Fuster
2002;():555-560. doi:10.1115/ETCE2002/OT-29148.

Virutal reality is emerging as an important tool for training and entertainment by creating an environment in a computer that allows a user to interact with objects perceived as real. The cost of providing such a virtual reality interfaces is often prohibitive thereby making it unavailable to many institutions for their research, training, and students’ projects. Critical components of this system have been identified as sensors, electronic interfaces and software. This paper explores different sensors available to make a low-cost virtual reality project possible. Using cheaper available quality components, the authors are in the process of developing a low cost cyber glove for education and training. Availability of such a system will also open doors for training for oil industry workers, etc. especially in hostile or dangerous environments without being physically exposed to such hazards.

Commentary by Dr. Valentin Fuster
2002;():561-565. doi:10.1115/ETCE2002/OT-29149.

Experimental attempts were carried out on ultrasonically joining glass fiber composite materials using fiber reinforced adhesive. Two sets of specimens with different energy guides were investigated. All the samples failed by shear at the interface of the lap joint. Finite element analysis was conducted to justify the test results and the effect of adherend surface treatment.

Commentary by Dr. Valentin Fuster
2002;():567-572. doi:10.1115/ETCE2002/OT-29150.

The need for the rehabilitation of bridges and structures is becoming more apparent as the number of deficient civil structure grows and the cost of replacement is becoming prohibitive. These leads to the search of alternative methods, such as rehabilitation, to put the deteriorated structures back to normal operation with the least possible cost. One such method is the use of composite plates adhesively bonded to concrete as reinforcement and to prevent the propagation of crack within the concrete structure. In this study the load transfer and the resulting stress distribution in the composite-concrete adhesion system is investigated using the finite element method. The effects of the different bond parameters are studied using the finite element. In addition, results of the finite element analysis are proved to be in agreement with the analytical solution of shear stress distribution in the adhesion layer that was developed in previous studies by the authors.

Commentary by Dr. Valentin Fuster
2002;():573-580. doi:10.1115/ETCE2002/OT-29151.

A fuzzy control (FLC) approach has been developed to control the curing process of a polymeric laminate used as the bonding material for the heat-activated coupling (HAC) of a fiberglass composite to Cu-Ni alloy pipe. Controlling the temperature of the curing environment is required in order to achieve uniform cure within the bonding prepreg. Without temperature control, the alloy side of the coupling is essentially a heat sink. Therefore, a controlled heat source on the alloy pipe is needed to compensate for the heat sink effect that tends to decrease curing temperatures within the laminate. The simulation results obtained show that the curing process of HAC of a composite-to-alloy pipe is significantly improved with required uniform cure characteristics being obtained through the thickness of the laminate.

Commentary by Dr. Valentin Fuster
2002;():581-587. doi:10.1115/ETCE2002/OT-29152.

Analysis of polymer-matrix composite sucker rod systems using finite element methods is performed. Composite sucker rods fail mainly due to fatigue loading. In majority of cases, the failure is in the region of the joint where the composite rod and the steel endfitting meet. 2D and 3D Finite Element Analysis and experimental tests are carried out in order to observe the stress distribution and to find the regions of stress concentrations inside the endfitting. The causes of fatigue failure of the composite sucker rods are identified. These are overloading of the rod causing high transverse compressive stress that results crushing of the rod, and high stress concentrations present at the grooves of the endfitting that initiate premature fatigue cracks. Based on the result of this study, enhanced design of the composite sucker rod system can be accomplished.

Commentary by Dr. Valentin Fuster
2002;():589-596. doi:10.1115/ETCE2002/OT-29153.

Stiffened cylindrical shells are major components of Aerospace structure application. Two models were developed for assessing the universal buckling load of a generally cross and horizontal stiffened composite cylinder. The first model uses a simple conservation of volume and direction of stiffener orientation, while the second model analyzes the force and moment interaction of the stiffeners and the shell. Based on these models the A, B and D matrix stiffness parameters were determined for the overall cylinder panel. The buckling load was solved for a particular stiffener configuration by using the energy method. Buckling test was also performed on a stiffened composite cylinder and compared with buckling load results of both analytical models, and conclusions were drawn on the degree of reliability of the models developed. Finally, parametric analysis of some of the important design variables was performed based on the ‘Force Smearing’ model.

Commentary by Dr. Valentin Fuster
2002;():597-604. doi:10.1115/ETCE2002/OT-29154.

The rheological properties of curing process of epoxy prepreg were measured by Bohlin Rheometer. The variations of storage modulus, loss modulus and viscosity are monitored vs. the cure time and temperature. Viscosity profiles were described by different models. Except the first order viscosity models, new viscosity models based on Boltzmann function were proposed. In the new models, a parameter called critical time was introduced. Critical time is a function of temperature and also meets an Arrhenius law. The activation energy calculated by critical time closes to that obtained by initial viscosity. The kinetic rate constants in the old and new models are comparable at each temperature, and the kinetic activation energies calculated from rate constants in the old and new models are very close. The fitting results show that the proposed new viscosity models are better than the old models for both isothermal and dynamic cure processes.

Commentary by Dr. Valentin Fuster
2002;():605-611. doi:10.1115/ETCE2002/OT-29157.

The classical finite element and finite difference formulation in structural dynamics leads to an algebraic eigenvalue problem whereas the continuous model however leads to a transcendental eigenvalue problem. This paper demonstrates the discrepancies between continuous systems and their discrete approximations and, introduces a finite dimensional transcendental eigenvalue method, which approximates the spectrum of the continuous system accurately. Illustration of the effectiveness and applicability of such a model has been shown with an example of an axially vibrating tapered rod.

Topics: Approximation
Commentary by Dr. Valentin Fuster
2002;():613-617. doi:10.1115/ETCE2002/OT-29176.

A method to achieve nodal control at the point of excitation in a Bernoulli-Euler beam is developed. It is shown that, for a uniform Bernoulli-Euler beam, the steady state motion at the point of excitation can be absorbed by means of a control force determined from displacement information at the point of application. A closed form solution for the control gain is presented.

Commentary by Dr. Valentin Fuster

Plant Engineering and Reliability

2002;():619-634. doi:10.1115/ETCE2002/PER-29124.

This paper deals with common errors that occur while implementing and executing plant reliability improvement programs. Case htstories are included to provide real world examples of these problems and the financial impact of mistakes. Recommendations are included to avoid pitfalls. In some cases actual tools are provided to solve the problems.

Topics: Reliability
Commentary by Dr. Valentin Fuster
2002;():635-649. doi:10.1115/ETCE2002/PER-29125.

This paper will discuss how to use Risk-Based Inspection (RBI) results to justify and manage a Corrosion Under Insulation (CUI) program that can be validated by using key performance indicators. A step-by step methodology to provide guidance on how to recognize, develop, and implement a CUI remediation program will be shared based on experience from 19 plant sites. Recommendations, based on actual plant experience, are included to facilitate the sharing of best practices and prevention of common errors.

Commentary by Dr. Valentin Fuster
2002;():651-662. doi:10.1115/ETCE2002/PER-29126.

In 1997, heat exchanger tube failures accounted for 31% of the unplanned downtime in the Lyondell’s Gulf Coast plants. This resulted in over $12MM of unplanned production interruptions. A multi-disciplinary team studied the tube failure modes and developed a systematic program to improve the heat exchanger reliability. The team issued recommendations in the areas of heat exchanger design, construction, operation, maintenance and inspection. This paper mainly discusses the three critical areas surrounding the reliability of heat exchanger tubes. They are tube testing, strategy on retubing exchangers during turnarounds and design improvements.

Commentary by Dr. Valentin Fuster
2002;():663-667. doi:10.1115/ETCE2002/PER-29128.

In this dynamic presentation, attendees will learn proven strategies and techniques for developing and implementing a successful maintenance skills training program. The seminar will introduce the optimum methods and practices to develop, execute and maintain a successful maintenance skills training program. In the course of this discussion, the following topics will be covered: • Maintenance Skill Development’s Impact on Equipment Reliability; • Identifying “Best Maintenance Repair Practices”; • How to Determine an Organization’s Training Needs; • How to Determine the Current Skills Requirements for a Maintenance Position; • Proven Maintenance Training Strategies for Short Term and Long Term Results; • How to Calculate Return on Investment for Training; • Managing the Skills Training Process.

Commentary by Dr. Valentin Fuster
2002;():669-674. doi:10.1115/ETCE2002/PER-29132.

Given a negotiating life cycle that includes preplanning, formal planning, performing the negotiation, and post negotiation review, this paper is oriented toward project team members without formal negotiation training that are looking for easy-to-follow “guideposts” to pre-plan and get ready for negotiations with vendors, business unit representatives, and other project stakeholders. The guidepost, or checklist, items are meant to serve as: a “mental launching pad” for an upcoming negotiation or as an organizer for the planning of a larger full-blown negotiation.

Topics: Negotiation
Commentary by Dr. Valentin Fuster

Pipeline

2002;():675-681. doi:10.1115/ETCE2002/PIPE-29026.

In this paper the effect of a bolted joint on the dynamic response of a pipe will be presented. The problem is analyzed both experimentally and by computer modeling. Standard 2-in. (51mm) Schedule 40 steel piping with a Class 300 RFWN flange is used. The pipe is used as a simply supported beam at its ends with a 14.5-ft (4.42 m) span. It is connected at the midspan by two flanges, with or without a gasket, and high strength bolts. The gasket used is a flexible spiral wound steel gasket of 0.180in. (4.57mm) thickness. Two values of pre-tensioning, 25,000 psi (172.5 MPa) and 50,000 psi (345 MPa) are used in the high strength bolts connecting the two flanges. Experimental values of fundamental frequency are comparable to the values obtained by computer modeling. It is found that the presence of the gasket and the loading exerted by the bolts on the flanges had very little effect on the fundamental frequency of the pipe system.

Commentary by Dr. Valentin Fuster
2002;():683-692. doi:10.1115/ETCE2002/PIPE-29027.

This paper presents the results of a study on how the burst of steel tubes is influenced by elevated temperature between 75°F and 350°F (24°C and 177°C). The study involves experiments and modeling of burst. Burst tests were conducted on UNS S32750 super duplex stainless steel. Part I is concerned with rate independent burst, while part II (to be published) is concerned with rate dependent burst. Two models were used to simulate the burst experiments. In the first model, the tube is represented as a cylindrical expansion membrane. In the second model, the tube is modeled as a finitely deforming shell which allows a bulge to grow in the unsymmetric manner seen in the final stages of the experiments. Both models produce the burst pressure accurately. The second model has the advantage of being able to study the effect of local thickness imperfections.

Topics: Pressure , Temperature , Pipes
Commentary by Dr. Valentin Fuster
2002;():693-698. doi:10.1115/ETCE2002/PIPE-29028.

A patent application has been filed for a new and unique compact flange that shows promise of superior performance. Considerable testing and analysis has been completed as outlined in this paper. This development continues as a work in progress. The author is open to suggestions and guidance for future tests and development.

Topics: Flanges , Pipes
Commentary by Dr. Valentin Fuster
2002;():699-706. doi:10.1115/ETCE2002/PIPE-29029.

The new regulations, Part 195 Section 195.452, require that special integrity assessments be made to address potential seam-defect problems in low-frequency-welded ERW (electric-resistance-welded) pipe materials where a failure of such materials could have an impact on a high-consequence area (HCA). The spirit of this requirement appears to require action if, and only if, significant seam-related deficiencies are in evidence or if they can be reasonably anticipated. This leaves open the option of categorizing these types of pipelines by performance such that potentially problematic pipeline segments can be subjected to special (i.e., seam-quality) inspections while those that show little or no propensity for such problems can be subjected to metal loss and deformation inspections only. This document is intended to establish a systematic procedure to permit an operator to characterize the relevant ERW pipe segments as to the likelihood of significant seam-related deficiencies. The author is particularly grateful to Rich Turley of Marathon Ashland Pipe Line LLC for helping to formulate the essential steps in deciding when an integrity assessment is needed. Rich made significant inputs to Figure 1 of this document.

Topics: Pipes
Commentary by Dr. Valentin Fuster
2002;():707-727. doi:10.1115/ETCE2002/PIPE-29053.

Vortex Induced Vibration (VIV) prediction is one of the key areas of interest in Deepwater Riser Engineering. Several Joint Industry Projects (JIPs) are currently in progress in this field, which results in an increase of experimental data available to design engineers, in revisions of specialized software and in development of new engineering tools. This paper presents VIV predictions for a hypothetical Steel Catenary Riser (SCR) using the latest versions of the SHEAR7 and the VIVA/VIVARRAY Programs. Both built-in and extended program capabilities are utilized and detailed plots of computation results are presented. Sensitivity studies on the influence of variations of selected design parameters are also included in the paper. Finite Element Analyses (FEAs) results and simple engineering tools were utilized in parallel to built-in program features. The calculations demonstrated, that for the riser investigated and presumably also for a wide variety of similar SCRs, that the built in program features are sufficient to predict VIVs conservatively. Notes on VIV predictions in a real ocean and on selected areas that require investigation are also included.

Commentary by Dr. Valentin Fuster
2002;():729-735. doi:10.1115/ETCE2002/PIPE-29054.

Formation of gas hydrates in gas production pipelines is one of the major problems in deepwater development. Most of the research work has focused on the problem during normal operation conditions. However, this problem can arise during pipeline commissioning and get worse after commissioning, even though export gas is dry enough to be considered as a hydrate-free fluid under normal operation conditions. This is because the water content that was left in the pipeline during commissioning can initiate formation of gas hydrates when export gas is introduced into the pipeline. The water content depends on the commissioning procedure and fluids used during the commissioning. This paper presents a systematic method to optimize the commissioning procedure. An application example is also presented.

Topics: Pipelines
Commentary by Dr. Valentin Fuster
2002;():737-745. doi:10.1115/ETCE2002/PIPE-29133.

The paper is a description of the author’s experience in the pressure testing of airport underground fuel hydrants with aviation kerosene type fuel, Jet A-1. The paper will discuss pressure testing codes, useful and practical proof (strength) test and leak test acceptance criteria. Equipment to be used for the measurement of test pressures and temperatures will be discussed. Problems and advantages with testing with fuel will be covered. Interpretation of leak detection results by correlating pressure test response with temperature measurements and presentation of the concept that the trend is more important than the absolute values of pressure and temperature will be covered. Promotion of the idea that research is needed into the sensitivity of leak detection. The author has experience in the pressure test in a variety of fuel hydrants, but most recently with the fuel hydrant at the new Hong Kong International Airport at Chek Lap Kok, Hong Kong.

Commentary by Dr. Valentin Fuster

Production

2002;():747-753. doi:10.1115/ETCE2002/PROD-29035.

Behavior of Electric Submersible Pumps (ESP) handling two-phase flow is a subject of primary concern, especially in the petroleum industry, where significant amounts of free gas may be found in oil wells production. Several attempts have been made in order to predict the performance of such kind of pumps, nevertheless, limited success has been achieved due to the complexity of the flow dynamics inside the impeller. Geometry, gas void fraction (GVF) and suction pressure seem to be the main parameters affecting ESP performance. Furthermore, the higher the GVF of the mixture is, the higher the degradation of head that it is experimented by the pump. This complex phenomena is not well understood so far. In this work, a two fluid model is used in 3D CFD simulations carried out in order to obtain the pressure, liquid velocity and gas velocity fields as well as the GVF distribution in an ESP impeller of known geometry; using flow rates, bubble diameter and GVF at the suction as independent variables and an incompressible fluid hypothesis. The gas pocket in the impeller blade reported from other researchers is obtained and comparison with experimental results has shown good agreement. The obtained variables from the simulations are the cornerstone that allows the prediction of the performance curve of the pump for different GVF and in this way, estimate the head degradation of the pump.

Topics: Pumps , Submersibles
Commentary by Dr. Valentin Fuster
2002;():755-760. doi:10.1115/ETCE2002/PROD-29036.

The main goal of the present work is to establish the tools of the analysis and performance prediction of an axial pump stage under two-phase flow presence of liquid and gas. This knowledge is very important for different applications, for example in the oil industry. The transport of two-phase flow (oil and gas) that comes from the well implies the utilization of separation and treatment facilities before they are pumping. It means that a lot of economical resources are involved in this kind of industrial operation. Therefore, depending on the function optimization of this type of two-phase pumps, it would permit the substitution of the traditional expensive facilities in addition with energy cost savings. In order to predict the fluid dynamics characteristics of an axial pump stage under two-phase flow conditions and in view to improve its performance, the present research will describe a multi-fluid model in order to solve the momentum equations (Navier-Stokes) coupled with the continuity equation. Here, we will take into account the viscosity of the liquid phase and the compressibility of the gas phase, using the CFD simulator: CFX 4.0. Finally, an experimental facility was designed and built to test one axial pump of two stages. Therefore, experimental data is shown in order to validate the previous numerical results obtained.

Topics: Pumps , Two-phase flow
Commentary by Dr. Valentin Fuster
2002;():761-769. doi:10.1115/ETCE2002/PROD-29038.

A numerical model of transient two-phase in a wellbore after startup of electrical submersible pump (ESP) was developed in the present study. The model consists of three modules. The first module, the wellbore model, predicts two-phase gas-liquid flow in the wellbore. The second module describes performance characteristics of centrifugal pumps. The third module, the reservoir model, predicts the variable well inflow after startup of the pump. The wellbore model is based on a drift-flux model (three equation model) of two-phase flow. The relative velocity is determined using a flow regime-dependent slip correlation or a mechanistic steady flow model. Field data collected during a startup of an ESP well were analyzed. This analysis showed that the response of the system to the ESP startup is governed by dynamic interacticn between the well and reservoir. The results obtained can be used for the development of production startup or restart procedures for wells equipped with ESP systems.

Commentary by Dr. Valentin Fuster
2002;():771-785. doi:10.1115/ETCE2002/PROD-29039.

The paper presents the field performance of mobile multiphase flowmeters in more than 500 well tests during the last three years. The field tests were conducted on land or offshore in a wide range of field operating conditions, such as high flowing pressure, heavy oil, viscous fluids, gas and wet gas, gas volume fraction ranging from 10% to 99.6%, and water to liquid ratio frcm 0 to 100%. An in-depth analysis of the lessons learned shows the benefits and limitations of the technology in comparison to the traditional test separators and illustrates the expected range of accuracies that can be readily achieved in the field environment. Statistics from over 600 comparison tests provide a complete understanding of the accuracies of oil, gas, and water flow rates achieved with the multiphase flowmeter. The dual-energy spectral gamma ray venturi multiphase flowmeter requires the measurements of few basic well site fluid properties. A procedure, detailed in the paper, explains the utilization of a field kit specifically designed for this application when no prior information of fluids is available, which is frequently the case in well testing in new areas. The paper presents how the specifically engineered test-design software provides a rapid-decision tool to the selection of the best well testing solution (multiphase flowmeter or test separator). Finally, some operational recommendations for performance of well tests using multiphase flowmeters shares the experience acquired in these 500 operations performed worldwide.

Commentary by Dr. Valentin Fuster
2002;():787-810. doi:10.1115/ETCE2002/PROD-29113.

In Zhang et al. [1], a unified hydrodynamic model is developed for prediction of gas-liquid pipe flow behavior based on slug dynamics. In this study, the new model is validated with extensive experimental data acquired with different pipe diameters, inclination angles, fluid physical properties, gas-liquid flow rates and flow patterns. Good agreement is observed in every aspect of the two-phase pipe flow.

Commentary by Dr. Valentin Fuster
2002;():811-820. doi:10.1115/ETCE2002/PROD-29114.

A unified hydrodynamic model is developed for predictions of flow pattern transitions, pressure gradient, liquid holdup and slug characteristics in gas-liquid pipe flow at different inclination angles from −90 to 90 deg. The model is based on the dynamics of slug flow, which shares transition boundaries with all the other flow patterns. By use of the entire film zone as the control volume, the momentum exchange between the slug body and the film zone is introduced into the momentum equations for slug flow. The equations of slug flow are used not only to calculate the slug characteristics, but also to predict transitions from slug flow to other flow patterns. Significant effort has been made to eliminate discontinuities among the closure relationships through careful selection and generalization. The flow pattern classification is also simplified according to the hydrodynamic characteristics of two-phase flow.

Commentary by Dr. Valentin Fuster
2002;():821-830. doi:10.1115/ETCE2002/PROD-29116.

A common concern with the reduced capacity of compact gas/liquid separators, such as the GLCC© , is that flow fluctuations are passed through the separator with little dampening. Rate sensitive devices, e.g., meters, hydrocyclones, etc., located downstream of the compact separator often have a desired turn-down of less than 10 to 1. However, in slug flow, the instantaneous liquid flow rate in the body of a slug can easily exceed 10 times the average liquid flow rate, with a dynamic range closer to 100 to 1. Consequently, use of the GLCC requires careful consideration of the downstream systems and their susceptibility to flow fluctuations. The slug damper was developed to reduce the magnitude of short period flow fluctuations by providing an inexpensive way of increasing liquid retaining capacity of the inlet piping to the GLCC. These preliminary results show that the slug damper system does indeed dramatically reduce exiting flow rate fluctuations from incoming slug flow. Furthermore, the slug damper performed in a predictable manner with no observed instabilities or unusual operation modes.

Topics: Dampers , Slug flows
Commentary by Dr. Valentin Fuster
2002;():831-838. doi:10.1115/ETCE2002/PROD-29117.

This paper describes a method for planning a pressure survey (a series of pressure, depth measurements), and for using a pressure survey tool, so that the user can predict in advance the number of pressure tests needed to be performed in a pressure survey such that the resulting pressure gradient will be accurate within a desired standard deviation. It further describes a method and process for performing a pressure survey, including measuring pressure gradient and standard deviation thereof for downhole fluid bearing formations, using information collected from pressure survey apparatus, such that the requisite amount of information is collected to ensure the measurements actually received are within the desired standard deviation. There is a patent pending in the U.S. Patent Office for the technology described herein.

Commentary by Dr. Valentin Fuster
2002;():839-845. doi:10.1115/ETCE2002/PROD-29119.

A unified two-fluid model for multiphase natural gas and condensate flow in pipelines is presented. The hydrodynamic model consists of steady-state one-dimensional mass and continuity balances for each phase and a combined energy equation to give a system of five first-order ordinary differential equations. The hydrodynamic model is coupled with a phase behavior model based on the Peng-Robinson equation of state to handle the vapor-/liquid equilibrium calculations and thermodynamic property predictions. The model handles single and two-phase flow conditions and is able to predict the transition between them. It also generates profiles for pressure, temperature, and the fluid velocities in both phases as well as their holdups. The expected flow patterns as well as their transitions are modeled with emphasis on the low liquid loading character of such systems. The expected flow regimes for this system are dispersed liquid, annular-mist, stratified smooth as well as stratified wavy.

Commentary by Dr. Valentin Fuster
2002;():847-855. doi:10.1115/ETCE2002/PROD-29120.

Multiphase flow is prevalent in many industrial processes. Therefore, accurate and efficient modeling of multiphase flow is essential to the understanding of these processes as well as the development of technologies to handle and manage them. In the petroleum industry, the occurrence and consequence thereof associated with such hydrodynamic processes are encountered in offshore facilities, surface facilities as well as reservoir applications. In this paper, we consider the modeling of these processes with special consideration to the transport of petroleum products through pipelines. Multiphase hydrodynamic modeling is usually a trade-off between maximizing the accuracy level while minimizing the computational time required. The most fundamental modeling effort developed to achieve this goal is based on applying simplifications to the basic physical laws, as defined by continuum mechanics, governing these processes. However, the modeling of multiphase flow processes requires the coupling of these basic laws with a thermodynamic phase behavior model. This paper highlights the impact of the techniques used to computationally couple the system’s thermodynamics with its fluid mechanics while paying close attention to the trade off mentioned above. It will consider the consequences of the simplifications applied, as well as inherent deficiencies associated with such simplifications. Special consideration is given to the conservation of mass as well as the terms that govern its transfer between the phases. Furthermore, the implications related to the common simplification of isothermal conditions are studied, highlighting the loss of accuracy in the material balance associated with this computational time-saving assumption. This paper concludes by suggesting remedies to these problems, supported by results, showing considerable improvement in fulfilling both the basic constrains which are minimizing time and maximizing accuracy.

Commentary by Dr. Valentin Fuster
2002;():857-865. doi:10.1115/ETCE2002/PROD-29162.

Accurate prediction of slug length distribution and the maximum slug length in a hilly terrain pipeline is crucial for designing downstream separation facilities. A hilly terrain pipeline consists of interconnected uphill and downhill pipe sections, where slugs can dissipate in the downhill sections and grow in the uphill sections. Furthermore, new slugs can be generated at the dips (bottom elbows) and dissipate at the top elbows. Although existing steady-state models are capable of predicting the average slug length for pressure drop calculations and pipeline design, they are incapable of predicting detailed flow characteristics such as the maximum slug length expected at the exit of a hilly terrain pipeline. A transient slug tracking model based on a quasi-equilibrium formulation was developed to track the front and back of each individual slug, from which individual slug lengths are calculated. The model was verified with large-scale two-phase flow hilly terrain experimental data acquired at the Tulsa University Fluid Flow Projects (TUFFP). The results show a fairly accurate match between the model predictions and experimental data.

Topics: Pipelines , Slug flows
Commentary by Dr. Valentin Fuster
2002;():867-876. doi:10.1115/ETCE2002/PROD-29163.

The mechanisms of phase re-distribution of gas/condensate flow in a deepwater steel lazy-wave riser after system shutdown have been studied numerically. The investigated system consists of a 15-mile long subsea pipeline tieback to a floating vessel, via a 9,800-ft long lazy-wave production riser. The subsea well is located at 6,350 ft of water. The system is insulated, and transports a gas-condensate mixture with liquid loading of 10 stb/mmscfd. This study reveals that besides pressure, the internal heat transfer during system cool-down is a key factor for the phase re-distribution between gas and liquid, and along the system. The liquid holdup variations are caused by the interfacial mass transfer between gas-liquid interface and phase re-distribution due to the combined effects of gravitational and buoyancy forces. Fluid cool down temperature “overshoot” in the lazy wave riser valley during system cool down has been observed. The pressure effect on the cool down temperature overshoot has been studied. The phenomenon is discussed based on fundamental heat transfer, phase equilibrium, and multiphase flow principles. The lazy wave riser configuration is a promising option for deepwater development, and gas/condensate flow is a multiphase flow phenomenon commonly encountered in raw gas transportation. The results of this study improve the understanding of multiphase flow transient behavior in deepwater pipeline/riser systems, and benefits gas/condensate production system design.

Commentary by Dr. Valentin Fuster
2002;():877-885. doi:10.1115/ETCE2002/PROD-29164.

The twin-screw multiphase pump has been studied as an alternative system to substitute the conventional one (fluid separation, liquid pumping and gas compression) in petroleum boosting. By “pumping” simultaneously gas and liquid, the multiphase pump could reduce production costs in deepwater activities. This paper presents a thermodynamic model of a twin-screw multiphase pump to determine performance parameters such as: absorbed power, discharge conditions and efficiency. To overcome problems with the complex flow field inside of this novel equipment, the multiphase flow was divided into a sequence of simpler processes. Such approach helps determine energy and mass balances and enables the use of a process simulator (Hysys.Process v2.1) to construct the model. The model prediction when compared to the literature show that the assumption of a smooth turbulent flow, considering the pressure loss in the entrance and discharge of the gap, fits better the phenomena than the turbulent flow when calculating the flow through the gaps. In addition, the comparison for absorbed power indicates that the assumption of gaps filled only with liquid is not valid under all operation conditions.

Topics: Screws , Pumps
Commentary by Dr. Valentin Fuster
2002;():887-896. doi:10.1115/ETCE2002/PROD-29165.

Horizontal well application to mitigate water coning problems have gained wide industry acceptance. However, horizontal wells themselves have not been free from water coning (cresting) problems. A major challenge before industry operators is the effective modeling of water crest development in horizontal wells. More often, mathematical models developed for fluid flow in horizontal pipes have been adopted for modeling horizontal well performance but these have been largely inadequate. This paper presents a more encompassing tool for evaluating the performance of horizontal wells with bottom water drive which incorporates all the effects of perforations, 2-phase liquid-liquid flow and axial influx of fluid into the wellbore. A new value of equivalent pipe roughness function is developed for use in the numerical simulators to accommodate the inadequacies of the current commercial softwares. The empirical results using published data from the North Sea indicate a more practical representation of the phenomenon of water cresting in horizontal wells and the level of severity. Two major factors affected by the application of the new approach are; a reduction in the time to water breakthrough as previously predicted by analytical tools, and an effective representation of the geometry of water cresting in horizontal wells similar to field experiences. The paper also shows that direct application of horizontal pipe models in horizontal well is grossly inadequate. Finally it shows use of horizontal wells in the development of reservoirs underlain by water needs adequate evaluation.

Commentary by Dr. Valentin Fuster

Structural Dynamics and Vibrations

2002;():897-904. doi:10.1115/ETCE2002/STRUC-29002.

In this paper, we discuss results of rock drilling tests at Sandia National Laboratories’ Hard Rock Drilling Facility (HRDF). The HRDF incorporates a drillstring with axial and torsional compliance and is equipped with a coring bit having PDC (Polycrystalline Diamond Compact) cutters. We measure and analyze chatter and show evidence of stick-slip as well as coupling between axial and torsional vibrations. We show the coupling signature in axial vibration data in the form of side bands indicating frequency modulation at the torsional natural frequency. The influence of operating conditions on the bit response is shown.

Commentary by Dr. Valentin Fuster
2002;():905-911. doi:10.1115/ETCE2002/STRUC-29003.

A two-part electronic system was designed to monitor and maintain the alignment of a bridge which is to be constructed in clay terrain. Previous bridges constructed along this Motorway in Southern Italy were closed for beam misalignment resulting from pillar displacement. The current two-part system was developed to provide a means to continuously monitor the position of the pillars and restore deck-pillar realignment when pillar displacement is detected. The monitoring system measures relative pillar position using a new multiple laser system. The repositioning system is composed of a number of computer controlled mechanical actuators bearing six degrees of freedom. A hydraulic piston coupled to a ring nut gear will be used for lifting, and will hence be intrinsically safe, since this configuration will not allow retrograde motion in case of power failure. Each actuator will allow motion along three perpendicular directions and spherical rotation about a point, to permit rotations of the bridge beams with respect to the pillars during deck-pillar realignment.

Commentary by Dr. Valentin Fuster
2002;():913-918. doi:10.1115/ETCE2002/STRUC-29004.

The paper presents the most recent developments on electronic bridge control applied to a bridge located along a southern Italian Motorway in an area where a landslip is in slow yet continuous motion. A previous bridge was closed for beam misalignment caused by the landslip action. A new bridge was recently designed with much sturdier foundations, but even during the initial construction phases it was evident that a static solution was undesirable, if not impossible. Jet, based on the observations of the last twenty years, the foreseen movements are relatively small, 20 cm being the maximum horizontal measured displacement in that period. A further version of the bridge has thus been proposed, characterised by lighter and longer decks, in order to negotiate the section with fewer elements. Moreover, the monitoring and repositioning systems have been thoroughly redesigned, to allow an almost continuous adjustment of the bridge decks, severely limiting the realignment times, in order to reduce traffic interruptions. A reduced number of interferometric lasers have been used, using rotating drums with mirrors individually preset to sweep the entire measuring field. The lifters, in their present version, should substitute the props, being used as active connections between pillars and decks, thus being able to support all traffic induced dynamic stresses in the vertical direction. The lifters have also been made sturdier eliminating all ball bearings in favour of teflon sheets. In addition, computer controlled lateral supports have been added to the system, allowing to move the deck horizontally while transmitting traffic or hearth-quake shocks to the pillars. On the top of each lifter an elastic interface bearing strain gauges will enable the measurement of tangential stresses as well as uneven distribution of the load, providing further information on the need of beams realignment.

Topics: Displacement , Traffic
Commentary by Dr. Valentin Fuster
2002;():919-925. doi:10.1115/ETCE2002/STRUC-29005.

Dynamic instability induced by the initiation and development of mechanical faults in a rotary element is known to have a large negative impact on the reliability and operation safety of an entire system. This type of nonlinear system response is generally perturbed by shock impulses of extremely short time scale and amplitude. Thus difficulty presents itself in identifying and isolating features indicative of the presence and progression of faults possibly leading to mechanical deterioration. The perturbed and deteriorated states of a bearing-shaft system subjected to the actions of various types of commonly seen mechanical faults are investigated using the Numerical Hilbert Transform. The presented approach characterizes and realizes temporal events of both short and long time scales as instantaneous frequencies in the joint time-frequency domain. Examples are given to demonstrate the feasibility of applying the approach to the characterization of various deteriorating bearing states and the identification of parameters associated with several failure modes.

Commentary by Dr. Valentin Fuster
2002;():927-932. doi:10.1115/ETCE2002/STRUC-29020.

Elevators designed to suspend tubing and drilling pipes in tripping operations are complex structures in petroleum drilling processes. Due to complexity of structure of elevators designed to suspend tubing in tripping operations used in oil well service, many stress geometrical concentration zones occur, and the three dimensional stresses can’t be calculated accurately with sufficient precision and easily by analytical and numerical procedures. To determine and optimise the real stresses occurring at these structures, the photoelasticity method is used reliably. Three dimensional models made from optically sensitive materials and freezing of strains technique are applied to analyse the stresses throughout in the present analysis. The obtained results can be applied to test the currently existing package programmes and to write new computer algorithmes for the related systems.

Commentary by Dr. Valentin Fuster
2002;():933-940. doi:10.1115/ETCE2002/STRUC-29021.

In the present work, the free vibration analysis of rectangular cross-section uniform beams on two-parameter elastic foundation, considering shear deformation and rotatory inertia is made by the finite element method. In this analysis, two different thick beam elements are used. The first 4 degrees of freedom thick beam element has two nodes with two degrees of freedom at each node such as transverse displacements and cross-section rotations. In the second beam element, the nodal variables are the transverse displacement, the cross-section rotation and shear deformation. The elastic foundation is idealized as a constant two-parameter model characterized by two moduli, i.e., the Winkler foundation modulus k and the shear foundation modulus kG . In the case kG = 0, this model reduces to the Winkler model, i.e., the elastic foundation is idealized as a constant one-parameter model. Axial displacement of the beam is also considered. Three kinds of end conditions, i.e., simply-supported, clamped-clamped and clamped-free ends are considered in this study. The effects of axial force, foundation stiffness parameters and partial elastic foundation on the natural frequencies of the beam are examined. In this analysis, the vibration calculation results are presented in the tables and their importance in design are discussed. The numerical results obtained from this analysis are compared with the exact or available solutions, wherever possible. Numerical results and comparisons show the effectiveness of the proposed method.

Commentary by Dr. Valentin Fuster
2002;():941-948. doi:10.1115/ETCE2002/STRUC-29023.

Modern design techniques primarily consist of finite element analysis of the vehicle body in a computational media. In this study, an actual double-deck bus body of domestic production has been modeled in three-dimensions by means of IDEAS program in order to calculate its fatigue strength. In other words, an approximation algorithm has been developed to obtain service loads. The effects of dynamic and static loads on the bus body have been calculated and included to the FEM analysis. As a new approximation technique, during the service life of a vehicle under dynamic loads (straight good road, straight bad road, cornering bad road and singular obstacle road) arising from the road conditions as taking into account, load spectrum has been constituted. In the design spectrum that has been utilized in our calculations, considering the equivalence damage effect rule, instead of using straight good road conditions, other fifty percent of forces that have been mentioned above, accepted as hundred percent of dynamic and static forces caused by bad road conditions acting on the bus body. As a result of this study, the calculated results have been compared to the theoretical and experimental data taken from literature review. It can be seen that this approximation technique that we used in our calculations can be used for this kind of fatigue analysis of vehicle components or bodies.

Commentary by Dr. Valentin Fuster
2002;():949-956. doi:10.1115/ETCE2002/STRUC-29024.

Lateral and torsional vibrations of a robot manipulator with an elastic arm sliding in a prismatic joint are analyzed. The elastic arm is assumed as an Euler-Bernoulli beam. The mass of the end-effector is assumed as a point mass attached at the end of the elastic arm. The prismatic joint experiences 3-dimensional translational and rotational motion. The prismatic joint is assumed as rigid and frictionless. Rotational inertia of the beam is taken into consideration in obtaining the equations of motion. Elastic deformations are assumed as linear and small displacements. Axial vibrations are not considered but the effect of axial force is taken into account in the analysis. Elastic arm experiences both bending vibrations in two directions and torsional vibrations. The equations of motion are obtained by Lagrange’s equation of motion. Numerical solution of the equations of motion are obtained by Runge-Kutta method. A computer program is developed for implementation of the presented technique. Numerical simulations are presented in the form of graphics. Presented method is found to be versatile in dynamic analysis of elastic robot arms.

Commentary by Dr. Valentin Fuster
2002;():957-962. doi:10.1115/ETCE2002/STRUC-29025.

There are extremely important applications to investigate the control of contact between the end-effectors and the object. During controlling an object, static or in motion, the robot arm should not be damaged. Forces are important in such conditions. The forces between the end-effectors and the object have to be controlled. The motion of the robot arm changes forces. Thats why, to control forces, a force kontrol algorithm must be developed. Previous conventional force control algorithms could not control the robot effectively by only considering the variation of working environment. In this study, a control algorithm strategy to achieve the desired interactions forces between the robot end-effector and the environment during contact tasks, has been developed. The surface of the object and robot are very stiff, thus contact spring coefficient Kc is very large, because of this Kc effect, the results of the forces simulation results, but we get suitable results. Study include, modelling robot arm, evaluating measured forces during contact and constructing a suitable force control algorithm, dynamics, kinematics and simulation results. In this study, we used impedans control which the surface of the object is very stiff, as known as impedance control does not try to track position and force trajectories directly, but rather to regulate the dynamic relationship between the contact forces and manipulator positions, namely the mechanical impedance. Impedance control focused on the design of a robot’s dynamic behavior as seen from the environment. In this control strategy, no hardware or software, switch is needed in the robot’s control system when the robot travels from the free motion space to the constrained space. The force feedback loop closes naturally as soon as the robot interacts with the environment, which changes the robot’s impedance as seen from the environment. By controlling the manipulator positions, and regulating their relationship to the contact forces, the manipulator can be controlled to maintain appropriate contact forces.

Topics: Robots , Force control
Commentary by Dr. Valentin Fuster
2002;():963-972. doi:10.1115/ETCE2002/STRUC-29042.

In this paper, a new mesh adaptation method which deals with a space-time finite element approach is proposed to solve frictional contact contitions. Firstly, this method is performed on an elementary elastodynamic example and on a contact problem.

Commentary by Dr. Valentin Fuster
2002;():973-979. doi:10.1115/ETCE2002/STRUC-29043.

A fan blade automatic modelling and design technique is proposed. Starting from axial flow fan nominal head H, flow rate Q and revolution speed ω, a numerical constrained optimization procedure is proposed. Fluid-dynamic, as well as geometrical, structural and vibration constraints are taken into account in the evaluation of the optimal objective function. Details of the numerical implementation, as well as results concerning a real application example, are reported and discussed.

Commentary by Dr. Valentin Fuster
2002;():981-988. doi:10.1115/ETCE2002/STRUC-29046.

When vibrating structures are subjected to large displacements, coupling may occur between the vibrations and the displacements inducing possibly strongly non-linear behavior. In this case, linear control algorithms and independent control strategy are no longer suitable. This study deals with the nonlinear control of Bi-articulated structures. A model that combines both finite element (FE) discretization, taking into account strains/electric field coupling, and global behavior is carried out. Multivariable control is carried out by electromechanical and piezoelectric actuators. The control strategy developed consists in weighting the output of parallel state controllers, calculated for the p discretized operating points crossed during the progression of the structure’s dynamic behavior. The multivariable control u is obtained by weighting interpolation functions fi of the linear quadratic control gains Ki of each controller optimized according to large displacements. The first application to Bi-articulated rigid beam systems shows, in comparison with a stable linear control, that non-linear control is by far the better of the two. This is mainly due to increased efficiency of motor torque use. The second application of the proposed nonlinear control algorithm concerns a Bi-articulated flexible beam system modeled by two rigid body modes and five flexible modes. The control obtained is robust regarding both stability and performance. Quasi-steady controlled dynamic behavior is obtained during movement.

Commentary by Dr. Valentin Fuster
2002;():989-996. doi:10.1115/ETCE2002/STRUC-29047.

This article is devoted to the study of the contact between the drill-string and the well during drilling operations. The study focuses on the Bottom-Hole-Assembly (BHA), which is submitted to compression. The work is motivated by the need to understand the complex behavior of such a system, in order to improve control their constructive and destructive potentials. The contact, which is supposed to be localized on the drill-collar or stabilizers, is prejudicial and involves a premature abrasive wear of the drill-string, reduction of the rate of penetration of the tool into the rock (ROP) and reduction of the mean time between failure (MTBF). The proposed mathematical model is expressed in terms of four independent degrees of freedom. They include the effects of bending and torsion; the whirling motion of the drill-string as well as the phenomena of friction between the drill-string and the well. The tangential effect is modeled by using Coulomb’s law of friction. The nonlinear equations of the movement are derived using Lagrange equations and are solved numerically to obtain the response. Specific attention is paid to the study of friction and a consistent contact model which is capable of taking into account the rolling of the drill-string, both with and without slip, is included in the model. This paper also presents a parametric study on the influence of the initial position of the string and the friction coefficient of the contact on the dynamic behavior of the structure. An experimental set-up, equipped with two optolineic devices, is used to validate the model.

Topics: Drill strings
Commentary by Dr. Valentin Fuster
2002;():997-1003. doi:10.1115/ETCE2002/STRUC-29048.

The abilities of neural networks combined with fuzzy logic offer interesting prospects for the active control of structures. By identification, they permit discarding the often delicate modeling step and they also permit the automatic regulation of the controllers that have non-linear characteristics. This study describes the application of neuro-fuzzy control to the dynamic behavior of structures. The study first explains the process chosen, which consists of two parts: • the first part is essential for the adjustment of the associated controller and concerns the neural identification of the structure studied; • the second part describes the controller development and the training stage; the controller is based on the simplest neural network model possible. This network is also able to translate Sugeno’s fuzzy function and optimize its performances according to a reference response. The study then presents two applications: the first deals with the identification and control of a linear mechanical system with two degrees of freedom. The second deals with the identification and control of the non-linear dynamic behavior of active electromagnetic actuators along one acting axis. In both cases, the results show the abilities and the efficiency of this process and underline the main advantage of this type of controller operating even on in a strongly non-linear system.

Commentary by Dr. Valentin Fuster
2002;():1005-1010. doi:10.1115/ETCE2002/STRUC-29158.

The paper presents a method to collect and save only relevant data from a machine. The data can be used for training the system to identify running situations that have already occurred in the monitored machine or similar types of machines. This method can be used to give direct notice or alarm in a control room with clear indication of the problem. Modern software development tools, like Java for instance, offer new technologies for operation monitoring of machines. The system can be accessed via Internet using common browsers. The paper presents practical experiences in the application of the method. It demonstrates, how the system will adapt into various environments and running situations. The method presented in this paper is applied in operation monitoring of machines, but it can be also used for other monitoring purposes.

Commentary by Dr. Valentin Fuster
2002;():1011-1018. doi:10.1115/ETCE2002/STRUC-29159.

A modern paper machine is equipped with various finishing units e.g. calendars and coating units to produce better optical and printing properties. Today’s trend is to supply these finishing units with polymer covered rolls. Tampere University of Technology (TUT) has built up an experimental set-up to study both vibration phenomena and polymer behavior. One of the essential task is to determine and verify the soil-machine interaction. This paper presents the preliminary analysis of the vibratory behavior and experimental results of modal analyses.

Commentary by Dr. Valentin Fuster
2002;():1019-1023. doi:10.1115/ETCE2002/STRUC-29160.

Polymer covered cylindrical rolls are typically used in different paper machine sections like in calenders and in coating units. The main reason for the use of soft-coated rolls is that by using the soft rolls the contact area becomes larger. Strongly loaded line contact causes deformations and heat generation in the polymer cover. In paper production process impurities, like paper pieces, may catch on the surface of the roll. Impurities cause locally larger deformation in the cover. The local deformation produces a higher local temperature area, which can cause cracks in the cover, to loosen the cover from the base and to fracture the cover locally. If a local failure happens the fragments of the cover can damage also the other rolls. In this paper an operation monitoring system for on-line monitoring of roll cover is presented. The system is installed in a laboratory pilot roll installation, where the rolling contact consists of a hard and a soft roll. The measurement system consists of on-line measurement of acoustic emission (AE) of the roll. Additionally the temperature distribution of the roll, the ploymer cover and the position angle of the roll are measured. The measurement signal is transferred from the rotating roll via wireless local area network (WLAN) to the measurement computer. The measurement control computer is connected to the LAN of the laboratory and the measurements can be followed and analyzed with different computers and also via Internet. The paper describes the principles of acoustic emission signal processing and analysis and the construction of the wireless Ethernet-based operation monitoring system.

Commentary by Dr. Valentin Fuster
2002;():1025-1028. doi:10.1115/ETCE2002/STRUC-29161.

A heat leveler machine can create valuable economical losses in fault situations. By applying on-line monitoring of the vibration signatures, the machine can be followed continuously and the changes in the process and in condition of the mahcine can be detected immediately. The on-line monitoring consists of the on-line adjustment of drive parameters as well as quality control. Generally several kinds of different sensor types are applied into the system. On-line monitoring of rolling bearings usually includes vibration measurement sensors. A heat leveler operates at differnt speeds and loads and the direction of process can be reversed during run. The reliability of the results of the on-line monitoring can be increased by measuring simultaneously different parameters that influence on the vibration of the machine. This method is called multi-parameter monitoring. This paper focuses on the possibilities of on-line monitoring of the support bearings in a metal slab heat leveler by vibration measurements. The leveler is equipped with vibration sensors of low frequencies as well as high frequency acoustic emission sensors. The main issue is experimenting different kind of signal processing methods and optimal procedures are then programmed to the on-line monitoring computer. The measurements in this study were performed in industrial circumstances, in a steel mill. The test machine was a heat leveler machine in normal industrial usage. A method of varying limit values is presented. For this, acoustic emission and acceleration rms-signals are applied. Values are determined by the forces in the leveling cylinders. Forces correspond to the deformation resistance of the steel plates.

Commentary by Dr. Valentin Fuster

Tribology/Design Methodology

2002;():1029-1040. doi:10.1115/ETCE2002/TRIB-29093.

The transient response of the thrust slider bearing has been studied numerically. Of greatest interest is the mode of boundary layer formation and the subsequent development of the pressure in the supporting film in the slider bearing as it is subject to tangential acceleration. It is planned to study two basic types of bearings — the first being the fixed-shoe type, while the second is the tilting-pd bearing. The bearings are subjected to types of loading (a) a constant load and (b) an inertial load due to the displacement or load on the runner. The computer solution is based on a simplified form of the Navier-Stokes equation in the tangential direction to determine the velocity distribution and a modified form of Reynolds’ equation to determine the pressure distribution along the pad or shoe of the bearing. The resulting formulation is a simple explicit tangential velocity difference equation in time and a fully implicit difference equation solution for the pressure, which is independent of time. The results of this endeavor are quite interesting and significant. For a simple fixed geometry case which allows the supported load to vary, the load versus time curves compare extremely well with previous findings by other investigators using an entirely different mathematical approach. The supporting film is found to be fully developed in the course of a few milliseconds for a step acceleration. For a step deceleration, the squeeze film concept is demonstrated in the flow field. In cases considering inertial loading due to the thrust runner, a tangential acceleration may produce a damped oscillation in the transverse direction. But in all probability, the most interesting discovery was that in a tilting-pad bearing or any simple slider bearing, the center of pressure which corresponds to the pivot point is a function of the film ratio (see equation (I 1)).

Commentary by Dr. Valentin Fuster
2002;():1041-1045. doi:10.1115/ETCE2002/TRIB-29094.

It is the purpose of this study to investigate the effects of fatigue loading on two variations of hybrid composite tubes. The two types of samples are both composed of AS-4D/carbon fibers and e-glass fibers. The key distinctions between the two samples being the orientation and the number of layers. The samples were composed of the following orientations [90/20/90/20/90/20/20/90/20] and [90/90/20/90/20/20/90/20]. The experiment is designed to not only compare the two samples, but to develop some experimental data for a fatigue curve for similar materials. All loading for this experiment takes place in a controlled environment. Both temperature and the specific gravity of the water are measured and controlled.

Commentary by Dr. Valentin Fuster
2002;():1047-1049. doi:10.1115/ETCE2002/TRIB-29096.

Magnesium-aluminum (Mg-Al) based layered double hydroxide (LDH) polymer nanocomposites were developed through the implementation of a rehydration technique. Organic anionic surfactant sodium dodecyl sulfate (SDS) and an anionic polymer, poly(styrene sulfonate) (PSS) were used for intercalation in the cationic intergallery spacing of LDH. This rehydration technique was performed by calcination of the LDH precursor for removal of carbonate anion followed by rehydration of organic anionic phase in a nitrogen rich atmosphere. The resulting nanocomposites were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and powder x-ray diffraction (XRD).

Commentary by Dr. Valentin Fuster
2002;():1051-1054. doi:10.1115/ETCE2002/TRIB-29098.

An experimental procedure is used to machine 20 vol.% Al2 O3 /6061Al metal matrix composites using coated tungsten carbide cutting inserts in a finish turning operation. The turning operations were carried out at various cutting speeds and feed rates, at a constant depth of cut, and with the application of a coolant. Tool wear lengths at two locations, at the flank of the primary cutting edge and at the flank of the nose of the tool were measured for each cutting test after the removal of a predetermined volume of material. It was found that the wear lengths at both locations of the tool increased with a decrease in feed rate due to the increase in cutting time as the feed rate decreased. It was also found that for a given speed and feed rate the wear on the flank of the nose was higher than that of the primary cutting edge. This was attributed possibly to the presence of the built-up edge on the rake face of the tool. Surface roughness, generally, increased with an increase in cutting time that was explained in terms of an increase in nose wear length as the cutting time was increased.

Commentary by Dr. Valentin Fuster
2002;():1055-1059. doi:10.1115/ETCE2002/TRIB-29100.

This paper presents ways for modeling the unilateral contact with friction between solids in order to simulate a collection of polyhedrons during evolution. In a first stage 2D problems of polygon collections are explored, then the friction conditions are easy to take into account by several available equivalent modeling. In a second stage 3D problems of polyhedron collections are considered. The aim of this paper is to propose efficient algorithm to solve the 3D numerical problems in granular material simulations.

Commentary by Dr. Valentin Fuster

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