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IN THIS VOLUME


Gas Turbines

1979;():V01BT02A013. doi:10.1115/79-GT-113.
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Based on a hub-to-shroud stream surface solution of the flow in a centrifugal compressor impeller, the equations governing the production of vorticity in a centrifugal compressor impeller are solved. The results are similar to experimental ones for shrouded and unshrouded impellers. Furthermore, assuming that the circumferential gradient of vorticity is zero, a picture of the three-dimensional velocity field is obtained. The picture obtained is similar to experimental ones, although the vortex associated with the suction side is smaller.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A014. doi:10.1115/79-GT-114.
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The high thermal efficiency of the combined steam and gas turbine cycle makes it an attractive candidate for gas pipeline drivers. This paper discusses some aspects of the performance which can be achieved, and the economics associated with this cycle using currently available equipment. One equipment selection has an output capability of over 20,000 hp with a net thermal efficiency of approximately 40 percent. A second equipment selection has an output capability of over 35,000 hp with a net thermal efficiency of approximately 47 percent.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A015. doi:10.1115/79-GT-115.
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A particular arrangement applicable to open or closed recuperative gas cycles, consisting of a heat generator partly by-passing the low pressure side of the recuperator, is proven to enhance the advantages of gas cycles for energy production. In this way, the cogeneration of both power with high efficiency owing to the recuperator and high temperature process heat becomes possible and economically attractive. Furthermore, additional possibilities appear for power generation by combined gas and steam or ammonia cycles. In any case, the overall utilitization coefficient of the primary energy is increased and the combined production of low or medium temperature heat can also be improved. The great operation flexibility of the system for combined energy generation is worth being emphasized: the by-pass arrangement involves no significant change in the operating conditions of the main turbocompressor as the heat output varies. Applications of this arrangement are made to open and closed gas cycle power plants using fossil, nuclear and solar energies. The overall heat conversion efficiency is tentatively estimated in order to appreciate the energy conversion capability of the investigated power plants.

Topics: Heat , Cycles , Generators
Commentary by Dr. Valentin Fuster
1979;():V01BT02A016. doi:10.1115/79-GT-116.
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In the integrated gas turbine high temperature gas cooled reactor (GT-HTGR) plant, all of the helium turbine power conversion machinery operates on the reactor coolant helium and is installed inside the reactor vessel; therefore, it is important that maintenance aspects be considered during the plant conceptual design phase. The primary objective of the GT-HTGR plant maintenance and inspection plan is to provide facilities, equipment, and component designs of reasonable cost that will yield good plant availability. It is, therefore, a matter of policy to design the reactor and the power conversion system installation, as well as the related maintenance facilities, for practical operation for both planned and unplanned maintenance. All primary system equipment is designed for full plant lifetime, with no limited-life parts, and the influence of maintenance considerations on the design of the major components and the plant configuration is discussed. Turbomachinery change-out is regarded as a planned maintenance activity and the sequence of events, together with the necessary equipment items, for removal and re-installation of helium gas turbine is discussed. The maintenance and repair of components such as the heat exchangers, ducting, and valves, which are designed to last throughout the plant lifetime but could fail due to unforeseen circumstances, are also discussed.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A017. doi:10.1115/79-GT-117.
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Advanced high-temperature gas-cooled reactor (HTGR) design concepts for energy production using gas turbine applications depend on cores capable of generating helium coolant outlet temperatures up to 900 C (1652 F). This paper describes a preliminary analysis of a large HTGR [4000 MW (t)] core using a prismatic fuel with coolant gas core outlet temperatures of 850 C (1562 F). This study provides core design considerations in the areas of radial fuel zoning, power distribution, fuel performance, fuel temperatures, and fission product release for a large HTGR core operating under high-temperature conditions. Though the work was performed on a 4000-MW(t) core, all design considerations developed are equally applicable to a 3000-MW(t) core. Potentials for upgrading the core performance and suggested improvements for implementation in future design work are cited.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A018. doi:10.1115/79-GT-118.
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Gas turbines under 5000 hp in size used for nain propulsion in smaller vessels (under 200 ft), eventually find themselves installed in a variety of craft: pleasure craft, commercial craft, and military craft. Although the engines, and sometimes the propulsion, are the same, they will enjoy (or suffer) considerable differences in installation features due to the use or owner of the vessel. The similarity of a 100-ft yacht, ferry or gunboat as regards the installation priorities of the turbine propulsion system generally ends at the length of the ship. This paper will use several recently delivered vessels, under construction programs and newly designed craft as examples to provide installation background data which might guide in future considerations of turbines for these different vessel types.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A019. doi:10.1115/79-GT-120.
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Base pressure data were systematically collected at VKI during recent years on a great variety of cascades operated over a wide range of outlet March numbers. An attempt is made to correlate these data by relating the base pressure to important cascade and flow parameters. Details about the trailing edge flow are obtained by using an enlarged model simulating the overhang section of convergent turbine cascades. The experimental cascade and model test results are compared with theoretical calculations using base pressure calculation methods.

Topics: Pressure , Turbines
Commentary by Dr. Valentin Fuster
1979;():V01BT02A020. doi:10.1115/79-GT-121.
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A 2.25 sq ft (0.21 sq m) atmospheric fluidized bed combustor (AFBC), using Illinois No. 6 coal and Quincy limestone is being used to test the in-bed corrosion resistance of selected austenitic alloys with a maximum metal temperature of 870 C (1600 F). This paper describes the combustor test facility, test parameters, materials selection and summarizes the results after 1500 hr of testing.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A021. doi:10.1115/79-GT-122.
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Firmly based on the well established Olympus “A” and “B” gas generators, the successful design and development of a 30 percent more powerful version, the Olympus “O,” specifically for industrial and marine operation, represents a significant milestone in the use of compact gas turbines in these fields. Producing 33 EGMW, the re-design of the gas generator turbines and combustion system to introduce more advanced technology permitted the raising of the maximum cycle temperature by 140 K. The engineering program from project concept through basic development and launch to successful commercial service operation is described with particular emphasis on problem identification, analysis, and solution.

Topics: Generators
Commentary by Dr. Valentin Fuster
1979;():V01BT02A022. doi:10.1115/79-GT-123.
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The new relationships of partial admission losses which account for influence of all major geometric parameters of concern to the turbine designer are presented, based on fluid dynamic analysis of the losses. The performance maps are presented showing the trends in efficiencies that are attainable in turbine designed over a wide range of loading, axial velocity/blade speed ratio, Reynolds number, and aspect ratio. Finally, the question of partial admission versus low aspect ratio is discussed.

Topics: Turbines
Commentary by Dr. Valentin Fuster
1979;():V01BT02A026. doi:10.1115/79-GT-127.
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Ceramic gas turbines are being studied in many countries for future use as automobile engines. Ceramic turbines were also examined here to determine their potential as engines for passenger cars. Initially, it was found that in the Japanese 10-mode driving cycle and at a turbine inlet temperature (TIT) of 1350 C, the turbine fuel economy was not better than current gasoline engines. On the other hand, it was also found that fuel economy is greatly improved if the air flow at idle conditions is reduced to 1/2 by using, for example, variable geometry components. It is pointed out that a simulation technique is available for estimating the dynamic characteristics of regenerative gas turbine engines, including consideration of variable geometry components. However, satisfactory regenerator models were not readily available. Hence, an experimental regenerator model was made. Where compared with test values, comparatively good results were obtained. Part II of this paper will report in the future on how these models were applied to an engine and what results were obtained from the dynamic simulation of the regenerative, high temperature gas turbine.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A027. doi:10.1115/79-GT-128.
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Instationary afflux conditions as they exist in a turbomachine can be realized by means of a rotating spoke cylinder interposed ahead of the test section. Measurements of instationary boundary layers confirm the idea that when the wake regions impinge on the plate surface for the duration of the disturbance, the boundary layer becomes turbulent. As a consequence of the transition zones being formed in this way, intermittently laminar and turbulent states of the boundary layer are observed.

Topics: Boundary layers
Commentary by Dr. Valentin Fuster
1979;():V01BT02A028. doi:10.1115/79-GT-129.
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A low turbulence high-speed wind tunnel, using anti-turbulence screening and a 100:1 contraction ratio, has been found suitable for high-speed smoke flow visualization. The location and strength of normal, oblique, and curved shock waves generated by transonic or supersonic wind tunnel flow over airfoils or through axial compressor cascades is determined by combined shadowgraph and smokelines visualization techniques without the interference effects caused by intrusive probes. The Reynolds number based on chord varied between 50,000 and 106. Preliminary results are compared with the relevant theory and data gathered using a total pressure probe.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A029. doi:10.1115/79-GT-130.
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The pitchwise distribution of the components of the Reynolds stress tensor downstream of a rotating blade row can be obtained with a single slanted hot-wire and the technique of periodic sampling and averaging. The requirements imposed on the hot-wire and the sensitivity coefficients to the six stresses are given. Information concerning the electronic set-up and the problems associated with measuring the Reynolds stresses are discussed. It is shown that the sampling technique does not modify the mean square value of the sampled signal if the correlation time of the turbulence is smaller than half the sampling rate, or when the frequency bandwidth of the turbulence is higher than twice the sampling frequency. Typical results, including the 3D-mean flow data obtained downstream of a low-speed axial compressor rotor at different radii are presented. The results show typical modifications of the stresses in the rotor wake region and the regions influenced by secondary flow or tip-leakage flow.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A030. doi:10.1115/79-GT-131.
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The author dedicates his contribution to the position occupied by the gas turbine in the present production of electric energy from the point of view of possibilities for better utilization of the thermal energy (fuel) used, i.e., of increasing the cycle efficiency. The influence of the fuel type, which becomes important for the economic viability of the plant as well as for comparison with different power plant systems, is considered in detail. Due to the fact that the predominant reserves of energy are to be found in the gas turbine’s waste heat, the design basis for a system utilizing this available energy source is discussed. The heavy-duty KWU gas turbines are used to provide an introduction to the GUD waste heat recovery system. The system which has been developed is described on the basis of European as well as Middle Eastern experience. The basic scheme is stated, and the influence which the specific site conditions have on its extension is mentioned. A special section is dedicated to the operation of the GUD plant, especially the start-up and emergency shutdown devices. In the final section of the paper, conclusions are drawn regarding the further development of the unfired combined cycle.

Topics: Combined cycles
Commentary by Dr. Valentin Fuster
1979;():V01BT02A031. doi:10.1115/79-GT-132.
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A major advantage of the two-shaft gas turbine as a prime mover is the steep torque-speed characteristic, so that the stall torque is typically twice the design torque. The co-turboshaft engine has a torque-speed curve which can be more than twice as steep as the conventional engine, so that only a rudimentary transmission would be required for normal operations. The co-turboshaft gas turbine engine has a co-rotating compressor case which is geared, together with the free power turbine, to the output shaft. As load increases and output shaft speed decreases, the effective gas generator speed increases, with no increase in rotor speed, and the power output rises. The engine has a torque-speed curve with up to four times the slope of a conventional free shaft turbine engine torque curve. This paper reviews results of testing a compressor with a co-rotating casing, and presents the results of simulating a typical engine using a hybrid computer to predict engine steady state performance. Effects of different design choices of compressor casing speed ratio are shown on engine torque, power and turbine inlet temperature characteristics. Control strategies for some possible applications, such as off-road vehicles and construction equipment, are discussed in relation to their likely duty cycles.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A032. doi:10.1115/79-GT-133.
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Theoretical analysis and experiments were carried out on cylindrical oil squeeze film dampers. The finite element method (FEM) was applied for calculating pressure distribution in the dampers with end seals and oil grooves. Measurements of the viscous damping coefficient of several dampers were conducted and compared with theoretical values. The effects of the dampers on the vibrational characteristics of engines were reviewed through theoretical analysis and experiments on an engine model. Then, the effects of squeeze film dampers on an actual engine were evaluated for design information.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A033. doi:10.1115/79-GT-134.
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An empirical description of fatigue crack propagation (FCP) under complex loadings, typical of those experienced by gas turbine disks, is presented. This approach uses a three coefficient sigmoidal curve (SINH) to model the macroscopic effects on FCP of service overloads, dwells, and load sequencing, as well as basic influences of frequency, stress ratio, and temperature. The coefficients are then related to these growth-controlling parameters through simple, linear, empirical functions. Comparisons are made of this approach with more conventional methods, and the results of laboratory verification tests are presented.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A034. doi:10.1115/79-GT-135.
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This paper deals with the influence of disk skew on the synchronous unbalance of flexible rotors in damped bearings. A simple overhung rotor 1E treated to illustrate the effects of various combinations of unbalance and disk skew on the amplitude and phase angle response at the disk and bearings. The paper shows that it is impossible to balance the rotor at all speeds by single plane balancing even if three correction planes are employed. The presence of disk skew may be best detected by monitoring the far bearing for a rapid phase angle decrease after passing through the first critical speed.

Topics: Rotors , Disks
Commentary by Dr. Valentin Fuster
1979;():V01BT02A035. doi:10.1115/79-GT-136.
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The EPA aircraft emission regulations were promulgated in 1973 and resulted in urgent investigations of many approaches aimed at reducing gas turbine emissions with minimum penalties to normal combustion performance. The impact of this work on small aircraft gas turbine engines is discussed, and emission reduction techniques and data are presented. Unique problems experienced with smaller gas turbine combustion systems are reviewed as are the potential difficulties of developing higher performance small combustors in the future, without the benefit of the complex and costly mechanical approaches which are applicable to the larger engines. The impact of relaxed fuel specifications and alternate-source gas turbine fuels is discussed in terms of altered fuel properties and development of fuel injection technology.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A036. doi:10.1115/79-GT-137.
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Comparative tests have been made in combustion turbine burners between six coal derived liquid (CDL) fuels and No. 2 distillate oil. All CDL fuels were evaluated in a half-scale (by diameter) combustor test rig, while one CDL fuel was also evaluated in a full scale high pressure combustion rig. The effects of these fuels on emissions of smoke and oxides of nitrogen, and on combustor metal temperature are discussed. Also observed in the testing were flame radiation, post-test combustor cleanliness, and emissions of carbon monoxide and hydrocarbons. Two of the CDLs do appear to be within the tolerance band which present combustion turbines can accept, with the exception of elevated NOx emissions. This work is part of an Electric Power Research Institute program to develop burners for coal derived liquids.

Topics: Combustion , Fuels , Coal , Turbines
Commentary by Dr. Valentin Fuster
1979;():V01BT02A037. doi:10.1115/79-GT-138.
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Ten fuels were burned in a GT-225 diffusion-flame combustor and the performance, durability, and emissions evaluated. These fuels were: reference kerosene, three petroleum distillales, two alcohols, one coal-derived fuel, a fuel made from far sands, and two fuels made from oil shale. All of the fuels were burned without modifying either combustor or fuel nozzle. The more volatile petroleum distillates burned more efficiently than kerosene. The alcohols and the more viscous synthetic fuels exhibited combustion efficiencies slightly lower than that of kerosene, possibly as a result of pooper initial atomization. The synthetic fuels having high aromatic contents produced higher flame-tube-wall temperatures than did kerosene, but not sufficiently high to reduce durability. The emissions from the combustion of all petroleum distillates were comparable to those of kerosene. The alcohols gave 60 to 80 percent lower oxides of nitrogen emissions, up to 650 percent higher carbon monoxide emissions and up to 300 percent higher total hydrocarbon emissions than kerosene, but these emissions were considerably reduced by increasing atomizing-air differental pressure to the injector. Some of the synthetic fuels contained large amounts of nitrogen and substantial oxidation of it was evidenced. The most viscous synthetic fuels exhibited carbon monixide and total hydrocarbon emissions 100 percent higher than kerosene.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A038. doi:10.1115/79-GT-139.
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Methane/air volumetric mixtures (gob-gas) ranging from 10 to 40 percent methane have been experimentally evaluated in the Solar Low Calorific Value Gas Combustor Facility. The majority of data was taken at ambient atmospheric conditions at the inlet to the combustor with some testing to 200 C (400 F) inlet temperature and two atmospheres pressure. Operational fuel-air ranges for 99 percent combustion efficiency were defined as well as the lean extinction limits for the above mentioned range of gob gas mixtures. This latter reduced data has been correlated so as to provide approximate combustor design functions.

Topics: Methane
Commentary by Dr. Valentin Fuster
1979;():V01BT02A039. doi:10.1115/79-GT-140.
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A previously tested 30-kw shaft output engine has been fitted with a closed-loop gas management system for power control. The closed-cycle engine operates at essentially constant speed and turbine inlet temperature, and power capability is a function of pressure level. The gas management system compresses and stores excess argon working fluid during load removal and injects on demand in response to load application. The system consists of a low, medium and high pressure storage accumulator, piston-type motor-driven compressor, valving and electronic control unit for sequencing the accumulators. Peak storage pressures at minimum power (10kw) are 765, 1076, and 1517 kPa (111, 156, and 220 psia). The engine and control system were run for a total of 57 hr over numerous transients of varying duration and range. Operation was characterized by quick response, smooth switching, and effective control. During load removal, the compressor required up to 3 min. to reduce full inventory to minimum power while turbine bypass valves allowed immediate engine response without excessive overspeed. Manually adjustable inject orifices allowed system response to closely follow load applications of 15 sec to 3 min. Compression heating in the accumulators during charging tended to elevate the switch points slightly, altering the storage capacities after repeated transients.

Topics: Engines
Commentary by Dr. Valentin Fuster
1979;():V01BT02A041. doi:10.1115/79-GT-142.
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Inasmuch as conventional gas turbine combustors often produce soot even with the present low aromatic content fuels, the production of acceptable liquid turbine fuels from hydrogen deficient raw materials such as coal and tar sands requires large quantities of high cost hydrogen if conventional combustors are to be used. The economics of producing alternate turbine fuels would be improved if high aromatic content fuels could be burned in gas turbines without soot formation. Gas turbines using the catalytic combustor not only can efficiently burn highly aromatic fuels without soot formation but can meet all existing or proposed regulations on emissions of hydrocarbons, carbon monoxide, and nitrogen oxides. Under certain conditions, high fuels can be burned with as little as 10 to 15 percent conversion of the fuel nitrogen to nitrogen oxides. In view of the potential savings, any program for alternate fuels should take into account the opportunities offered by the catalytic combustor.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A042. doi:10.1115/79-GT-143.
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During transients of axial-flow gas turbines, the characteristics of the compressor are altered. The changes in these characteristics (excluding surge line changes) have been related to transient heat transfer parameters, and these relations have been incorporated in a program for predicting the transient response of a single-shaft aero gas turbine. The effect of the change in compressor characteristics has been examined in accelerations using two alternative acceleration fuel schedules. When the fuel is scheduled on compressor delivery pressure alone. there is no increase in predicted acceleration times. When the fuel is scheduled on shaft speed alone, the predicted acceleration times are increased by about 5 to 6 percent.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A043. doi:10.1115/79-GT-144.
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Measurements have been made of the normal component of the radiative heat flux to the wall of a model gas turbine combustor with and without a mirrored background. Measurements have also been made of the centerline soot concentration. The data show that the heat flux correlated with the soot concentration but not universally, since JET A fuel yielded a different curve 1han DIESEL fuel. A theoretical analysis of the heat flux from a soot suspension was formulated. A criterion was established for the use of a small particle analysis. Finally, it is shown that there is no correspondence between theory and these experiments. It is speculated that turbulent fluctuations need to be modeled.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A044. doi:10.1115/79-GT-145.
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The relationships between the performance coefficients for flow, kinetic energy, and thrust are developed for the irreversible adiabatic flow through a choked nozzle. The basis of the development is maximum flowrate per unit area and an exit pressure greater than or equal to the exhaust pressure. The relationships cannot be presented in explicit mathematical form. However, from the application of linearizing techniques, linear relationships have been developed, which are accurate to within 0.1 percent. The relationships allow one to determine two performance coefficients from empirical data for a single coefficient. The relationships also allow one to predict difficult to measure flow properties such as the exit plane pressure for a choked nozzle. The applicability of the development to supersonic and unchoked nozzles is discussed.

Topics: Nozzles
Commentary by Dr. Valentin Fuster
1979;():V01BT02A045. doi:10.1115/79-GT-146.
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A flexible shaft is prone to a number of vibration phenomena which occur at frequencies other than synchronous with rotational speed Nonsynchronous vibrations from several sources were observed while running a test rig designed to simulate the operation of a supercritical power tranmission shaft The test rig was run first with very light external damping and then with a higher level of external damping, for comparison. As a result, the effect of external damping on the nonsynchronous vibrations of the test rig was observed. All of these nonsynchronous vibrations were of significant amplitude. Their presence in the vibrations spectra for a supercritical power transmission shaft at various speeds in the operating range indicates that very careful attention to all of the vibration spectra should be made in any supercritical power transmission shafting. This paper presents a review of the analysis performed and a comparison with experimental data. A thorough discussion of the observed nonsynchronous whirl is also provided.

Topics: Vibration
Commentary by Dr. Valentin Fuster
1979;():V01BT02A046. doi:10.1115/79-GT-147.
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Over ocean, salt aerosols ingested in the combustion air of a marine gas turbine cause engine compressor fouling and are a primary factor in engine hot section corrosion. To minimize salt ingestion effects on engine performance and life, a high performance salt filtration system is required. The U.S. Navy is currently conducting the Gas Turbine Inlet Development Program. The program consists of work elements including salt filter tests, at-sea salt-in-air measurements, ship aerodynamic studies, inlet duct design, etc. To complete the assigned work tasks, Navy facilities had to develop state-of-the-art instrumentation and test procedures. Based on these work tasks, the U.S. Navy will publish a Gas Turbine Inlet System Design Handbook. The handbook will provide design guidance for the ship builder and inlet duct designer for optimizing shipboard salt filtration perfmance.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A048. doi:10.1115/79-GT-149.
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This paper describes the design of elastomeric bearing supports for a rotor built to simulate the power turbine of an advanced gas turbine engine which traverses two bending critical speeds. The elastomer dampers were constructed so as to minimize rotor dynamic response at the critical speeds. Results are presented of unbalance response tests performed with two different elastomer materials. These results showed that the resonances on the elastomer-mounted rotor were well damped for both elastomer materials and showed linear response to the unbalance weights used for response testing. Additional tests were performed using solid steel supports at either end (hard-mounted), which resulted in drastically increased sensitivity and nonlinear response, and with steel supports in one end of the rotor and the elastomer at the other, which yielded results which were between the soft- and hard-mounted cases. It is concluded that elastomeric supports are a viable alternative to other methods of mounting flexible rotors, that damping was well in excess of predictions and that elastomeric supports are tolerant of small rotor misalignments.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A049. doi:10.1115/79-GT-150.
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Investigations contributing to the development and design of the low emission catalytic reactor to be used in large industrial combustion turbine applications are considered. Experimental results on the behavior of catalytically supported combustion under typical operating conditions are presented. They were obtained by burning No. 2 oil in a flow passage containing an Engelhard catalyst. Temperature measurements are made by specially designed thermocouples along the axial direction of the monolithic substrate. These measurements, at steady-state conditions, include axial variation through the substrate for different conditions of inlet temperature, fuel concentration, and mass flow conditions. In addition, the effect of catalyst length on the temperature profile is illustrated. Emissions measurements are made for the evaluation of the performance of the catalytic reactor under different operating conditions. The conditions required to achieve combustion efficiencies ≥99.5 percent have been experimentally determined. The thermo-mechanical analysis of the support structure of a catalyst element using transpiration cooling has been performed for steady-state conditions. Results show improvements in stress and amount of cooling air required compared to film cooling.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A050. doi:10.1115/79-GT-151.
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Most cogeneration facilities considered since the Arab oil embargo have been limited to study activity. These studies are based primarily on regulatory and economic constraints. Important factors to be considered include site, fuel, and capital requirements for various options. This paper examines several studies and their findings and comments on the advantages and disadvantages of various systems including combustion turbines, coal fired steam boilers and turbine generators.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A054. doi:10.1115/79-GT-155.
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Liquid synthetic fuels derived from non-petroleum resources will play a major role in meeting future national energy demands. In the case of gas turbine applications, it is known that the different properties of these fuels can rusult in substantially altered combustion performance. Most importantly, decreased fuel hydrogen content resulting from an increased aromatic content has been observed to result in increased exhaust smoke and particulates as well as greater flame luminosity. This paper contributes empirical information and insight which allows the greater soot formation tendencies of low hydrogen content fuels to be better understood. A small scale laboratory device which simulates the strongly backmixed conditions present in the primary zone of a gas turbine combustor is utilized. The Jet Stirred Combustor provides for very rapid mixing between a premixture of vaporized fuel and air and the combustion products within a 5.08-cm-dia hemispherical reactor. Results to be presented are gaseous combustion product distributions, incipient soot limits, and soot production (mg) for a variety of fuels. The influences of combustor inlet temperature and reactor mass loading have been evaluated and the sooting characteristics of fuel blends have been studied. These results have been analyzed to develop useful correlation which are in general agreement with existing mechanistic concepts of the soot formation process.

Topics: Combustion , Fuels , Soot
Commentary by Dr. Valentin Fuster
1979;():V01BT02A056. doi:10.1115/79-GT-157.
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Experimental and theoretical studies are made of the factors governing the weak extinction limits of stabilized flames supplied with flowing mixtures of liquid fuel drops and air. The test program includes wide variations in inlet air pressure, velocity and turbulence level, and also covers wide ranges of fuel volatility and mean drop size. The influence of flameholder size and blockage is also examined. An equation is derived for predicting weak extinction limits which shows good agreement with the corresponding experimental values.

Topics: Fuels , Turbulence
Commentary by Dr. Valentin Fuster
1979;():V01BT02A057. doi:10.1115/79-GT-158.
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A study has recently been completed for the Department of Energy on the conceptual design of coal-fired, closed-cycle, gas-turbine power plants that operate at high turbine-inlet temperatures and use air as the cycle fluid. This paper describes the design of one type of heater system for such a power plant — a pulverized coal furnace. Designs are presented for a 1550 F (843 C) turbine inlet temperature cycle that utilizes metallic superalloy heat exchanger tubes and a 1750 F (954 C) turbine inlet temperature cycle that utilizes ceramic heat exchanger tubes. The heaters consist of two sections — a radiant section where heat is transferred primarily by radiation from the pulverized coal luminous flame, and a convective section where heat is transferred primarily by forced convection from the nonluminous combustion gas. To maintain flame stability in the furnace, a minimum power density criterion must be met. This requires modularization of the radiant heaters.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A058. doi:10.1115/79-GT-159.
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The DD-963 Class ships are the first U.S. Navy vessels to utilize a waste heat recovery system on a gas turbine engine. This paper will present the experience gained from the three years of shipboard operation with the system. The experience will be used to develop areas for consideration that can improve the probability of success in future system procurements. The areas to be considered are: (a) the need for definitive military specifications; (b) the need to test at Navy laboratories and (c) the need to test complete systems under simulated shipboard conditions.

Topics: Heat recovery
Commentary by Dr. Valentin Fuster
1979;():V01BT02A059. doi:10.1115/79-GT-160.
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This paper reports a DOE-sponsored program to evaluate the effect of the combustion products of coal-derived fuels on current and potential materials used in gas turbine hot-section components and on the plugging of cooling holes in air-cooled airfoils. Atmospheric-pressure small burner rigs and a combustor operating at elevated pressures and design air flows, equipped with a segment of a first-stage nozzle (turbine simulator), were used in these evaluations.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A060. doi:10.1115/79-GT-161.
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Several successful methods for balancing flexible rotating shells have been developed in recent years. The methods can apparently be subdivided into a group which is based on modal characteristics and another set which employs influence coefficients. The relative merits of these two approaches have been the subject of much discussion and argument — most of it inconclusive and rather fruitless. The authors consider that in practice many of the differences are more apparent than real and that they seem to occur because the various techniques are normally presented in relatively simple and ideal, theoretical terms. This paper represents the start of a joint project which hopes to resolve the apparent differences and, eventually, develop a unified approach to such balancing. A discussion of the theoretical basis for this unified approach is presented along with a description of a test program conducted to explore the possibilities of such an approach.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A061. doi:10.1115/79-GT-162.
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Combined cycles for pipeline-booster stations using waste heat from gas turbines exhaust can improve the overall efficiency of such stations remarkably. Several working fluids are suitable. Due to existing criteria for selecting a working medium under mentioned conditions, water, ammonia, propane and butane can be considered as practical working fluids. The investigations have shown that: (a) ammonia is advantageous at low exhaust gas and ambient temperatures, (b) water is most effective at high exhaust gas and ambient temperatures, and (c), additionally, hydrocarbons are suitable in a medium range for exhaust gas and condensing temperatures. Not only thermodynamic but also operational features have to be considered. There is not one optimum working fluid but a best one suitable according to the prevailing site conditions.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A062. doi:10.1115/79-GT-163.
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Welded titanium inlet guide vanes in an Air Force turbojet engine, have been experiencing a high rate of vibration induced cracking after very short service The cause of this cracking has been identified as resonant vibration excited by pressure fluctuations occurring when the first-stage fan blades pass the inlet guide vanes A bonded vibration damping wrap has provided a cost effective fix which can be applied on a retrofit basis for major cost savings The damping wrap, which consists of multiple layers of energy dissipating adhesives separated by constraining layers of aluminum foil, is bonded to the vanes under high temperature and pressure in an autoclave. This paper describes the results of engine test-cell tests and the comparison of these results with actual service experience obtained under operational conditions Measured effects on engine performance, distortion tolerance, and anti-icing performance are presented along with measured stress reductions, as compared with increases in modal damping. Durability design considerations are discussed, along with the results of durability tests in an engine test stand and actual service experience.

Topics: Engines , Damping , Vibration
Commentary by Dr. Valentin Fuster
1979;():V01BT02A063. doi:10.1115/79-GT-164.
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This paper describes the evolution of the Garrett-AiResearch TPE331 turboprop engine. It discusses the reasoning behind the original design and describes the subsequent growth of the engine from 575 to 1040 hp within the same engine frame size. The performance of the various models and the design features that provided minimum fuel consumption and maximum reliability are also discussed.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A064. doi:10.1115/79-GT-165.
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A single small gas turbine engine, containing an annular combustor producing nearly conventional emission levels, was sampled for gaseous emissions and smoke a total of 20 times in a one month period. Five samples each of two fuel injector designs were tested in random order, and the combustor angular orientation was varied with respect to the compressor. In addition to the basic tests with aviation kerosene fuel, emission measurements were also made with Avgas and diesel fuel with each injector design. Fuel spray drop size distributions were estimated from sample test data. The result of changing the fuel injectors was the production of a significant variation in hydrocarbon and carbon monoxide emissions, with limited variation in oxides of nitrogen and smoke. After correction for ambient and operating conditions. the standard deviation in the EPA parameter for hydrocarbons was about 30 percent of the average value and 15 percent of the average value for carbon monoxide. It was postulated that the variation was caused by fuel injector manufacturing tolerances which resulted in large variations in the maximum drop size in individual sprays causing variable entrapment of unvaporized drops in the wall cooling film. The conclusion is that small and perhaps non-detectable variations in injectors can cause changes in emissions from gas turbines, and, in particular, from small gas turbines.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A065. doi:10.1115/79-GT-166.
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The Exxon Research pressurized fluidized bed coal combustion pilot plant, known as the miniplant, has been in operation since 1974. Constructed under EPA contract, this facility operates at pressures to 10 atm, bed velocities to 10 ft/sec and temperatures to 1800 F. It can burn 400 lb of coal per hour and has operated for over 2500 test hours. Under a program sponsored by the U. S. Department of Energy, the Exxon pressurized fluidized bed coal combustion miniplant provided a test site and environment for the exposure of specimens of potential PFBCC fireside heat exchanger alloys and gas turbine materials. The intent of these PFBCC exposure tests is to compile a suitable engineering data base for the characterization of the corrosion/erosion behavior of a number of commercially available alloys when exposed to a pressurized fluidized bed coal combustion environment. These PFBCC exposures will provide corrosion/erosion data and comparisons of materials for application to advanced gas turbine/combined cycle type power systems using coal.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A066. doi:10.1115/79-GT-167.
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This paper discusses the application of a power recovery system to recover waste heat from the exhaust gases of gas turbines and convert this energy into shaft horsepower. Also discussed are power cycles, selection of power fluid, equipment selection, and application of the power recovery system to various gas turbines. Several charts and tables are included: process flow diagram, cycle efficiencies, curve for estimating recoverable horsepower.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A068. doi:10.1115/79-GT-169.
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A concept is described for using a very fuel-rich partial oxidation process as the first stage of a two-stage combustion system for onboard processing of broadened specification fuels to improve their combustion characteristics. Results of an initial step in the experimental verification of the concept are presented, where the basic benefits of H2 enrichment are shown to provide extended lean-combustion limits and permit simultaneous achievement of ultralow levels of NOx, CO, and HC emissions. The H2 required to obtain these results is within the range available from a partial oxidation precombustion stage. Operation of a catalytic partial oxidation reactor using a conventional aviation turbine fuel (JP5) and an unconventional fuel (blend of JP5/xylene) is shown to produce a “fuel gas” stream with near-theoretical equilibrium H2 content. However, a number of design considerations indicate that the precombustion stage should be incorporated as a thermal reaction.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A069. doi:10.1115/79-GT-170.
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Axial and swirling airflows were used to break up water jets and sheets into sprays of droplets to determine the overall effects of orifice diameter, weight flow of air, and the use of an air swirler on fineness of atomization as characterized by mean drop size. A scanning radiometer was used to determine the mean drop diameter of each spray. Swirling airflows were produced with an axial combustor, 70-deg brake angle, air swirler. Water jets were injected axially upstream, axially downstream and cross stream into the airflow. In addition, pressure atomizing fuel nozzles which produced a sheet and ligament type of breakup were investigated. Increasing the weight flow rate of air or the use of an air swiler markedly reduced the spray mean drop size. Test conditions included a water flow rate of 68.0 liter per hour and airflow rates (per unit area) of 3.7 to 25.7 g per square cm per sec, at 293 K and inlet-air static pressures of 1.01 × 105 to 1.98 × 105 N/m2.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A070. doi:10.1115/79-GT-171.
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The use of transient temperature measurements to determine convective heat transfer coefficients is extended to the more complex environment of the gas turbine combustion chamber. Numerical solutions to a transient liner wall heat balance demonstrate that the rate of metal temperature with time is exponential and that the rate is only a function of the convective heat transfer coefficients. Data taken during a snap acceleration of a gas turbine confirms the exponential temperature response. The combination of numerical analysis and transient temperature measurements provides an approximate method of determining linear heat transfer coefficients.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A071. doi:10.1115/79-GT-172.
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An industrial gas turbine combustor has been developed which is capable of operating over the gas turbine load range on a variety of coal-derived low Btu gases as well as No. 2 distillate fuel. At gas turbine cycle conditions using simulated coal-derived low Btu gas, CO emissions and combustor blowout characteristics are comparable to those obtained with current product line combustors burning No. 2 distillate. The results of laboratory single burner combustion tests with simulated low Btu gases, ranging in heating value from 809 to 1369 kcal/NM3 (91–154 Btu/scf), are described. Parametric studies were also conducted in which the moisture content of the fuel (at constant volumetric lower heating value) and heating value were varied. The results of these tests are compared with those obtained with a conventional constant cross-sectional area combustor and those of other investigators.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A072. doi:10.1115/79-GT-174.
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Validation tests were carried out based upon tests specified in Military Specification MIL-F-8901. The Electrocoalescer has demonstrated excellent performance, has passed the validation test, and showed an improved performance over that of the Military Standard Filter Separator. When tested with diesel fuel, the improvement was on the order of a factor of 10 or more. Moreover, it demonstrated a lower overall pressure drop. Use of the Electrocoalescer in fuels decontamination service is expected to result in cleaner fuels and longer filter life.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A073. doi:10.1115/79-GT-175.
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A compact engine configuration is obtained on small gas turbine engines by the use of a reverse flow annular combustion system. Such combustion systems are usually of narrow width and of relatively large flame tube surface area/volume ratio. In consequence, there is a tendency for excessive concentrations of fuel near to the flame tube internal surfaces and fuel impingement on the flame tube which can give rise to performance deficiencies, such as carbon build, loss of efficiency at low load conditions, smoke, and metal overheating particularly with fuels similar to ASTM D 975 Type 2-D diesel. Since there is an increasing requirement for engines to operate with such heavier fuels, research and development programs were initiated to evolve an improved combustion system. The paper briefly describes the main features of these work programs and outlines the configuration evolved and the performance achieved. An arrangement has been obtained which gives a high standard of performance with fuels ranging from aviation kerosene fuel to gas oil and marine diesel.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A074. doi:10.1115/79-GT-176.
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The thermal efficiency of a gas turbine engine depends on the cycle pressure and temperature ratio and on the aerodynamic efficiencies of the gas path components. Maintaining and/or improving structural integrity and aerodynamic efficiency in this high pressure, high temperature environment is the preeminent problem of the turbine designer. High gas temperatures require at least some of the metal structures to be cooled, yet cooling air is a loss to the cycle and its consumption must be kept to a minimum. Research into cooling techniques and boundary layer behavior on airfoils and endwalls and into test procedures for obtaining heat transfer data are providing some of the answers the designer needs. Increased operating pressures generate increased mechanical stresses. Finite element analyses and automated design procedures are proving to be powerful aids to the designer. Improving aerodynamic efficiency requires careful control of the flow in three dimensions, particularly in low aspect ratio machines. The first practical computation method for three-dimensional, viscous, transonic flows became available in late 1977 and has made this one of the most exciting areas of turbine technology. Additional gains in aerodynamic efficiency can be realized by controlling leakages, especially those over the rotor tip, by accounting for the transient interactions between rotor and stator and by careful control of discharged coolant flow. This paper briefly describes the turbine cooling research conducted by the Air Force Aero Propulsion Laboratory and describes mor extensively the AFAPL programs in turbine aerodynamics, including applications of three-dimensional flow analysis.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A075. doi:10.1115/79-GT-177.
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Direct coal-fired gas turbines need efficient high temperature particulate control in order to be an attractive option for the efficient conversion of coal to electrical energy. Particulates in the range of three to ten microns are very difficult to remove and it is, therefore, proposed that they be fragmented into particulates below the threshold size for turbine blade erosion using pulsed CO2 lasers. Beam interaction with combustion products is considered. A 1000-MW(e) conceptual plant is presented to demonstrate costs and recirculating power requirements.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A076. doi:10.1115/79-GT-178.
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Two combustor rigs have been used to study the sensitivities of combustor operation to the physical and chemical properties of fuels. Nineteen fuels including synfuels were used to accentuate the properties of concern: composition, viscosity, and boiling-point distribution. Flame radiation and smoke were best correlated by hydrogen content rather than hydrocarbon structure; the soot formation was due to gas-phase reactions. Lean-blowout conditions were about the same for all fuels except that gasoline could be burned leaner at idle conditions. Ignition limits were more sensitive to volatility than viscosity. Gaseous emissions and combustion efficiency were not significantly affected by fuel properties although some sensitivity to boiling point distribution was evident. In all performance areas, the syncrude fuels correlated in the same ways as the petroleum-derived fuels except for the NOx emissions from the nitrogen containing shale oil fuel.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A078. doi:10.1115/79-GT-180.
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A combustor of the gas turbine type, employing acoustic control of the dilution-air jet flows, was designed and successfully tested. Temperature measurements showed that acoustic modulation of the dilution-air flows can be used to selectively and progressively control the exit plane temperature distribution. The effectiveness of the process was found to depend on the excitation frequency and power of the loudspeaker drivers. Reductions in the exit plane temperature profile, by as much as 545 C, were observed. The mechanism of interaction between the modulated dilution-air flow and combustor main gas flow appears to depend on the combined effect of pulsed flow with superimposed toroidal vortex. The increase in pressure drop across the combustor, associated with the operation of the acoustic drive, was found to be negligible. The work contributes to the design of combustors such that a desired exit plane temperature distribution may be achieved.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A079. doi:10.1115/79-GT-181.
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With the widespread use of microprocessors, new applications are being accepted into gas turbine control and monitoring systems where their capabilities are being tested and proved while in the most arduous physical location — “on the engine.” Some practical guidelines and arguments are given in establishing the criteria for use in these applications and environments.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A080. doi:10.1115/79-GT-182.
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A lifting-surface analysis is presented for the steady, three-dimensional, compressible flow through an annular blade row. A kernel-function procedure is used to solve the linearized integral equation which relates the unknown blade loading to a specified camber line. The unknown loading is expanded in a finite series of prescribed loading functions which allows the required integrations to be performed analytically, leading to a great savings in computer time. Numerical results are reported for a range of solidities and hub-to-tip ratios; comparisons are made with both two-dimensional strip theory and other three-dimensional results.

Topics: Blades
Commentary by Dr. Valentin Fuster
1979;():V01BT02A082. doi:10.1115/79-GT-184.
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A small perturbation theory is presented for the prediction of the decay of steady circumferential pressure, temperature and velocity distortions in multistage axial flow compressors. The mathematical model which is employed replaces the blade rows of the compressor by actuator discs. A closed solution for the linearized equations describing the two-dimensional, inviscid and compressible flow between the discs is derived and appropriate matching conditions at the discs (assuming a quasi-steady blade response) are determined. An efficient calculation procedure is presented which allows the rapid computation of the distortion development through any compressor configuration, i.e., through any combination of rotors, stators, and axial clearances including the core engine compression system. The theory can be applied to the mean section of the compressor or separately from stream surface to stream surface. Due to the assumption of a two-dimensional flow, however, it is restricted to purely circumferential distortions in compressors with sufficiently high hub-to-tip ratios where radial flow redistributions can be expected to be small. The validity of the small perturbation theory is demonstrated by comparing the theoretical results with experimental data. In addition, the theory is used to study the effect of Mach-number and flow rate on the decay of the distortions through two compressor configurations. Suggestions are made on how to utilize the theory for the design of distortion-tolerant compressors.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A084. doi:10.1115/79-GT-186.
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This paper presents the results of a wind tunnel model study to determine temperatures at various locations generated by the hot exhaust air from the Compressor Research Facility [CRF] which is being built at Wright-Patterson Air Force Base, Ohio. The study was designed to provide data at the inlet to the CRF and at other nearby locations where pedestrians, building ventilation systems, and vegetation might be affected. The test program, which was conducted in the Calspan Atmospheric Simulation Facility, included flow visualization studies and quantitative concentration measurements of a tracer gas from which full-scale temperature could be calculated. The concentration measurements were performed for a number of wind speeds at each of twelve different wind directions. Two exhaust flows and two exhaust stack configurations were studied.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A085. doi:10.1115/79-GT-187.
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The potential environmental problems associated with unrecuperated and recuperated advanced open-cycle gas turbine power plants were analyzed. Such plants, operated with improved high temperature technology (1478 K turbine inlet temperature), achieve 30 to 40 percent cycle efficiencies. The major environmental concerns are associated with NOx emissions resulting from combustor operating practice. Uncontrolled systems were determined to greatly exceed the proposed gas turbine NOx emission standard of 75 cm3/m3 at 15 percent O2 (dry), even when corrected for improved efficiency. Consideration is given to control options which include water injection, catalytic combustion, and combustion modifications (staging). Results indicate the limitations of water injection in comparison with the other control approaches. It was found that uncontrolled NOx emissions could be reduced by about 80 percent with water addition, and in excess of 98 percent with catalytic combustion.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A086. doi:10.1115/79-GT-188.
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Developments in catalytic combustion have shown increasing potential for application in gas turbine combustors. Significant advantages in reducing combustor emissions, particularly nitrogen oxides (NOx), can be realized. Both thermal and fuel NOx control were demonstrated for a developed graded cell catalyst concept. Other criteria for catalyst scaleup and high pressure operation have been developed. The concepts have been demonstrated in a catalytic model gas turbine combustor and a catalytic staged combustor. The staged combustor shows great potential for control of fuel NOx. New concepts in turbine combustors are required to implement catalytic combustion technology. Gas turbine manufacturers were surveyed to identify design criteria. The established criteria were prioritized and incorporated into several conceptual designs for the combustor. Ongoing development will advance the concepts to prototype demonstration.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A087. doi:10.1115/79-GT-189.
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Early field tests on 25- and 33-MW combustion turbines indicated that, with modest controls on fuel sulfur content, compliance with strict regulations on particulate emissions, such as the 10 lb (4.5 kg) per hour Rule 67 of the Los Angeles Air Pollution Control District, was feasible. This paper describes the field development program to demonstrate Rule 67 compliance on an 80-MW combustion turbine for which the 10-lb/hr (4.5-kg/hr) limit is approximately 4 psm by weight. Particulate controls were implemented by installing improved-smoke combustors, and using water injection and low sulfur fuel. Meticulous sampling and analytical procedures were developed, using a specially designed and equipped environmental test laboratory trailer, to study the properties of particulate collection filters, and to improve the precision of measurements from each portion of the particulate sampling system: probe, filter, and water impingers. The test results clearly indicate that with proper attention to the details of sample system preconditioning, sample collection and analysis, the large combustion turbine can comply with the stringent 10-lb/hr (4.5-kg/hr) particulate limit of Rule 67.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A088. doi:10.1115/79-GT-190.
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The commercial operation of coal-fired pressurized fluid-bed combustion-gas turbine plants for central station electric power generation or for industrial cogeneration applications depends on the reliable operation of the gas turbine. Reliable operation of the turbine is related to the particulate and chemical composition of the gases that it expands. This study is limited to an evaluation of particulates as they limit turbine life by erosion. Pressurized fluid-bed combustor design and operation trade-offs exist that affect the particle concentration and size ranges presented to the gas cleaning equipment. Gas cleaning equipment choices will subsequently effect the particulates going to the turbine. The development of a particle profile model permits an assessment of the effect of these decisions on the particles that enter the turbine. Turbine tolerance models previously developed by Westinghouse are then used to estimate turbine life and the incremental energy cost penalty. The scope of the evaluation procedure is presented and selected parametric cases presented to illustrate available trade-offs for design, operation, and cost.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A089. doi:10.1115/79-GT-191.
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To assess the improvements in starting reliability obtainable from the use of programmable controllers for sequence control, governing and fuel management of gas turbine powered generating sets, the CEGB installed controllers on two 17 1/2-MW Olympus powered units. This report looks at the performance achieved and the problems encountered from their use on power station plant.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A090. doi:10.1115/79-GT-192.
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The Advanced Low-Emissions Catalytic-Combustor Program ia an ongoing three-phase contract contract effort with the primary objective of evolving the technology required for incorporating catalytic combustors into advanced aircraft gas-turbine engines. Phase I is corrently in progress. At the present time, analytical evaluation is being conducted on advanced catalytic combustor concepts — including variable geometry — with their known inherent potential advantages of low level pollutant emission, widened combustion at ability limits, and reduced pattern factor for longer turbine life. Phases II and III will consist of experimental evaluation of the most promising concepts.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A091. doi:10.1115/79-GT-194.
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The continuing development of a characteristic time model for gaseous pollutant emissions from conventional gas turbine engines is described. The now engine studied here is the Pratt and Whitney JT9D, and it is shown that universal correlations can be obtained by comparison with previous results. Current limitations of the modeling approach are detailed.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A093. doi:10.1115/79-GT-196.
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British Gas have experienced problems at some installations from low frequency turbine noise. The paper describes how the low frequency noise problems were investigated and then resolved by aerodynamic modifications and a silencer extension.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A095. doi:10.1115/79-GT-198.
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An MS5000 gas turbine is now being redesigned for integrated operation on low Btu Lurgi coal gas in the Powerton Gasification Combined Cycle Test Facility. Air is extracted from the machine to provide process air for the gasifiers, and a heat recovery steam generator provides steam for the gas plant. This paper describes the design modifications to the gas turbine and its control system to accommodate such operation. Since the facility will demonstrate operation in a variety of control modes using gas produced from a wide range of domestic coals, the gas turbine control system emphasizes flexibility and incorporates several functions unique to low Btu gas applications. Major modifications to the fuel and combustion systems are also required. Test results on the resulting new combustor design are reported in a companion paper (1).

Topics: Coal , Design , Gas turbines
Commentary by Dr. Valentin Fuster
1979;():V01BT02A097. doi:10.1115/79-GT-200.
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The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A098. doi:10.1115/79-GT-201.
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The General Electric Company is carrying out a design study and evaluation of bottoming cycles for gas pipeline compressor prime movers. Three sites were chosen for the study of demonstration organic bottoming cycles of about 5000 hp applied to three aircraft derivative gas turbines of approximately the same size. The purpose of the study is to design and evaluate all important aspects of installing organic bottoming cycle systems on a selected group of gas turbine prime movers driving gas compressors. As a result of the study, it was found that pipeline bottoming cycles applied to gas turbine prime movers could reduce the heat rate 35 percent more than the Department of Energy target value of 20 percent. Installation designs for three sites are described.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A099. doi:10.1115/79-GT-202.
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This paper reports the experimental study of the three-dimensional characteristics of the mean velocity in the wake of a moderately loaded compressor rotor blade. The measurements were taken with a three-sensor hot-wire probe rotating with the rotor. The wake was surveyed at several radial and axial stations. The loading was found to have substantial effect and this was reflected not only in the axial and tangential components, but also in the radial component. The radial velocities were found to be high very near the trailing-edge and this exhibits the characteristics prevalent in a trailing vortex system. The static pressures across the wake were measured using a direction insensitive spherical head static-stagnation pressure probe. The static pressure was found to be higher inside the wake. These and other measurements are reported and correlated in this paper.

Topics: Compressors , Wakes , Rotors , Blades
Commentary by Dr. Valentin Fuster
1979;():V01BT02A101. doi:10.1115/79-GT-204.
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This paper presents a discussion of the significant results of a study program conducted for the Department of Energy to evaluate the potential for closed cycle gas turbines and the associated combustion heater systems for use in coal fired public utility power plants. Two specific problem areas were addressed: (a) the identification and analysis of system concepts which offer high overall plant efficiency consistent with low cost of electricity (COE) from coal-pile-to-bus-bar, and (b) the identification and conceptual design of combustor/heat exchanger concepts compatible for use as the cycle gas primary heater for those plant systems. The study guidelines were based directly upon the ground rules established for the ECAS studies to facilitate comparison of study results. Included is a discussion of a unique computer model approach to accomplish the system analysis and parametric studies performed to evaluate entire closed cycle gas turbine utility power plants with and without Rankine bottoming cycles. Both atmospheric fluidized bed and radiant/convective combustor /heat exchanger systems were addressed. Each incorporated metallic or ceramic heat exchanger technology. The work culminated in conceptual designs of complete coal fired, closed cycle gas turbine power plants. Critical component technology assessment and cost and performance estimates for the plants are also discussed.

Commentary by Dr. Valentin Fuster
1979;():V01BT02A102. doi:10.1115/79-GT-205.
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This paper describes the newly introduced Ruston TA2500 gas turbine. The design is based on that of the well proven TA1750 and retains its outstanding features of reliability, long life, and ease of maintenance. Component efficiencies have been improved to increase the overall thermal performance and the Ruston designed solid-state control system with its Rustronic solid-state governor has been incorporated to give greater operating flexibility. Other changes include a compressor driven auxiliary gearbox which obviates the necessity for motor driven auxiliary pumps and a new design of frame similar to that of the Ruston TB5000 gas turbine.

Commentary by Dr. Valentin Fuster

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