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Aircraft Engine

1998;():V002T02A001. doi:10.1115/98-GT-080.
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A preliminary comparison of the installed performance of three variable cycle jet engine concepts for future Supersonic Transports is outlined in this paper. These engines, are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine.

The comparison of the uninstalled performance, variable geometry, cycle changes, the effect of variable compressor stators on the running lines of the compressors and sizing assessments for each engine were carried out in Reference 4.

An estimate is now made of the installed performance by calculating the air friction, the pre-entry and the afterbody drags, plus the wave drag. A sizing calculation was carried out for the nacelles of all the engines. The uninstalled and installed fuel bills, for two standard missions, are also estimated.

These preliminary results indicate that the Turbofan-Turbojet and the Mid Tandem Fan engines are quite similar in terms of general suitability. The Mid Tandem Fan appears to be an attractive proposition from the point of view of sizing, however this comes with a small penalty in fuel consumption. The Double Bypass engine was found to be the least attractive of the powerplants investigated. The differences, however appear to be small.

Topics: Cycles
Commentary by Dr. Valentin Fuster
1998;():V002T02A002. doi:10.1115/98-GT-145.
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The U.S. Navy in cooperation with the Ministries of Defense of Germany and Sweden are initiating a 3-year demonstration program in 1998 to evaluate and define the benefits of thrust vectoring beyond those already understood for Close-in-Combat (CiC). The VECTOR (Vectoring ESTOL Control and Tailless Operational Research) program will capitalize on the X-31 airframe and a contractor team that includes Boeing, G.E., DASA, Volvo, and SAAB to demonstrate the following technologies:

• AVEN® Nozzle - a G.E. designed vectoring nozzle applicable to the F404 family of engines

• Extremely Short Takeoff and Landing (ESTOL) - employ thrust vectoring and precision control for poststall flight in approach to landing and during take off

• Reduced Tail/Tailless - rely on thrust vectoring for primary aircraft stability and control

• Advanced Air Data System (AADS) - flush air data ports or optical air data system integrated with the control system to handle the extensive angle-of-attack and sideslip envelope.

The flight test activity will be conducted in the United States. However, technical development activities will be conducted in all three countries. Germany and Sweden will contribute technical expertise primarily related to flight control and propulsion system integration, respectively.

Commentary by Dr. Valentin Fuster
1998;():V002T02A003. doi:10.1115/98-GT-182.
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At GE Aircraft Engines (GEAE), during the preliminary design process for aircraft propulsion systems, the designer has always been concerned about the cost implications of engine architecture and material requirements, which are driven by design specified engine thermodynamic operating conditions. The concern was not only about initial acquisition economics, but about maintenance costs associated with the propulsion life cycle as well as the development costs associated with design and certification of the power plant. The difficulty has been that there was no rapid, accurate cost estimating process to allow the designers ready access to the cost implications of design choices. High cycle pressure ratios and bypass ratios were thermodynamically attractive in reducing SFC. Technology, whether in the form of complex aerodynamic blade shapes to increase efficiency or higher temperature materials to reduce undesirable effects of cooling flows on SFC, was considered without in depth quantitative cost impacts of these design choices.

Commentary by Dr. Valentin Fuster
1998;():V002T02A004. doi:10.1115/98-GT-262.
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Digital mockups have become an integral part of the design of aircraft engines and their environment (nacelle, pylon). In this paper, we show that the conventional physical mockup is not a necessity any more. In fact, the experience of the CFM56-7 design shows that the adjustments required to compensate for the absence of a physical mockup have brought with them a considerable amount of flexibility and reactivity. Thus the deletion of tile physical mockup means a lot more than the corresponding direct savings it generates. Relying solely on the digital mockup is a major change in the design process, and greatly contributes to the global quality of the product.

Commentary by Dr. Valentin Fuster
1998;():V002T02A005. doi:10.1115/98-GT-306.
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Power generating gas turbines employ an inlet duct or contraction to accelerate air to the operating inlet velocity of the compressor. Multiple passages of this kind are necessary in gas turbines with cycle modifications such as intercooling. An experimental investigation was carried out to obtain flow characteristics of a curved wall annular contraction. The results are described in terms of the velocity vectors, surface pressure coefficients, static and stagnation pressure distributions, and profiles of mean velocities, turbulence intensity, and Reynolds shear stress. The upstream flow conditions were changed to evaluate how they affected the flow development in the passage. Results show that the static pressure and axial velocity profiles at the contraction exit were uniform. Higher inlet turbulence increased the Reynolds shear stress although the effect on the static and total pressure fields was negligible. The overall stagnation pressure loss was approximately 2 to 3 percent of the dynamic head at the contraction exit.

Topics: Flow (Dynamics)
Commentary by Dr. Valentin Fuster
1998;():V002T02A006. doi:10.1115/98-GT-311.
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ABB has designed a new family of industrial gasturbines for power generation using a Sequential Combustion Cycle (SCC) on a large single shaft engine. This concept allows considerable increase in power density and efficiency by only increasing pressure without raising the maximum hot gas temperature of the cycle. Instead a second combustion after an HP-turbine is used to reheat the gas before the final expansion in an LP-turbine.

This concept is applied to the analysis of a high bypass ratio jet engine. In an engine with a single combustor, thrust is a function of bypass ratio and the combination of maximum pressure and temperature in the cycle. The proposed SCC allows increased thrust without pushing technology on materials and cooling. A modern twin spool engine is taken as reference. When total inlet massflow is kept constant, increasing bypass ratio decreases core mass flow. This limits the fuel flow for the HP-spool and hence total energy input to the engine. Introduction of the SCC gives another parameter of freedom to the cycle design. However the twin spool concept is now a disadvantage. The low fuel flow for the HP-spool due to high bypass ratio means there is not enough energy available to build up the necessary pressure for an economical expansion in the LP-turbine after the second combustion. Specific fuel consumption will be unacceptable.

It is proposed to apply the SCC concept in a single spool engine with a geared fan. Both turbines can now support the compression. The fan is operated as a constant speed propeller with variable blade pitch. This engine concept allows for a given inlet massflow a substantially higher bypass ratio and hence decreases specific fuel consumption while specific thrust can be kept on a level which will be considerably higher than it would be in todays engines with comparable bypass ratio.

Commentary by Dr. Valentin Fuster
1998;():V002T02A007. doi:10.1115/98-GT-342.
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A dynamic combustor model is developed for inclusion into a one-dimensional full gas turbine engine simulation code. A flux-difference splitting algorithm is used to numerically integrate the quasi-one-dimensional Euler equations, supplemented with species mass conservation equations. The combustion model involves a single-step, global finite-rate chemistry scheme with a temperature-dependent activation energy. Source terms are used to account for mass bleed and mass injection, with additional capabilities to handle momentum and energy sources and sinks. Numerical results for cold and reacting flow for a can-type gas turbine combustor are presented. Comparisons with experimental data from this combustor are also made.

Commentary by Dr. Valentin Fuster
1998;():V002T02A008. doi:10.1115/98-GT-343.
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In gas turbine performance simulations often the question arises: What is the best thermodynamic cycle design point? This is an optimization task which can be attacked in two ways: One can do a series of parameter variations and pick from the resulting graphs the best solution or one can employ numerical optimization algorithms that produce a single cycle which fulfills all constraints.

The conventional parameter study builds strongly on the engineering judgement and gives useful information over a range of parameter selections. However, when values for more than a few variables have to be determined while several constraints are existing, then numerical optimization routines can help to find the mathematical optimum faster and more accurately. Sometimes even an outstanding solution is found which was overlooked while doing a preliminary parameter study.

For any simulation task a sophisticated graphical user interface is of great benefit. This is especially true for automated numerical optimizations. It is quite helpful to see on the screen of a PC how the variables are changing and which constraints are limiting the design. A quick and clear graphical representation of trade studies is also of great advantage. The paper describes how numerical optimization and parameter studies are implemented in a Windows-based PC program.

As an example, the cycle selection of a derivative turbofan engine with a given core shows the merits of numerical optimization. The parameter variation is best suited for presenting the sensitivity of the result in the neighborhood of the optimum cycle design point.

Commentary by Dr. Valentin Fuster
1998;():V002T02A009. doi:10.1115/98-GT-354.
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This paper describes the status and potential for a fast time-to-market concurrent engineering process. The principles have been developed by the author over a 25 year learning process and used effectively on a variety of programs. Fast CE™ is fundamentally predicated on integration of the manufacturing and engineering processes at the conceptual design phase. Commencement at this early date is critical — 80 to 90% of the inherent production unit cost is locked in place during this process. Subsequent to development of an integrated design strategy, both producibility and functional product development evolve in parallel using a “model-centric” approach to maintain the integrity of all elements of the program. Fast CE™ not only eliminates the use of drawings, it requires that they not be used in any capacity except as a convenience reference. This provides tight control over a common data base that directly links all of the activities necessary to design and produce a product. The result is a significant reduction in cost and schedule, with gains in all of the processes required to bring a product to market. Drawing elimination in itself can amount to a savings of as much as one third of the total design cost. The activities previously supported by drawings — quality assurance, for example — are managed through simpler, more functionally oriented processes.

The author describes the elements of Fast CE™ and the radical changes required in certain areas. Historical background traces development of the processes, providing perspective on the strategies and the issues faced and overcome, and leading to the issues currently faced in attainment of its full potential. The cost and schedule gains identified require cultural as well as operational changes. The more radical of these changes present a management challenge to any organization intent on gaining the full spectrum of benefits.

Commentary by Dr. Valentin Fuster
1998;():V002T02A010. doi:10.1115/98-GT-355.
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Fixed aperture (FA) nozzles offer the potential to significantly reduce the complexity and cost of afterburning turbine engine exhaust nozzles. This is accomplished by utilizing secondary air from an ejector system to control primary jet expansion at low nozzle pressure ratios and thereby eliminating the variable position divergent flaps and associated actuators, linkages, and hydraulics. The relatively cool ejector air flowing over the hot nozzle surfaces, combined with the gapless external airframe interfaces enabled by the fixed divergent section, offer the possibility for concurrent reductions in infrared and radar signatures. The installed aerodynamic performance of FA-based ejector nozzles has been analyzed with several engine cycles to explore these potential benefits.

Topics: Design , Nozzles
Commentary by Dr. Valentin Fuster
1998;():V002T02A011. doi:10.1115/98-GT-470.
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A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six kg/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over the range of test conditions of interest. These conditions included both assisted (with a starter motor) and unassisted (altitude windmill) starts. The model was then exercised to study a variety of engine configuration modifications designed to improve its starting characteristics and thus quantify potential starting improvements for the next generation of gas turbine engines. This paper discusses the model development and describes the test facilities used to obtain the calibration data. The test matrix for the ground level testing is also presented. A companion paper presents the model calibration results and the results of the trade-off study.

Commentary by Dr. Valentin Fuster
1998;():V002T02A012. doi:10.1115/98-GT-471.
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A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six-kg/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over the range of test conditions of interest. These conditions included both assisted (with a starter motor) and unassisted (altitude windmill) starts. The model was then exercised to study a variety of engine configuration modifications designed to improve its starting characteristics and thus quantify potential starting improvements for the next generation of gas turbine engines. This paper presents the model calibration results and the results of the trade-off study. A companion paper discusses the model development and describes the test facilities used to obtain the calibration data.

Commentary by Dr. Valentin Fuster
1998;():V002T02A013. doi:10.1115/98-GT-486.
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Dimensional analysis has been used in experimental fluid mechanics for over a hundred years. Controllable and uncontrollable variables in an experiment can be efficiently organized into nondimensional groups or parameters. Such nondimensional parameters are used for geometric scaling, and for developing dynamic similitude in experimental processes. Commonly used nondimensional parameters in fluid mechanics include Reynold’s No., Mach No., Froude No., Weber No., Strouhal No., etc. Most modern text books and technical papers discuss the use of Buckingham Pi Theorem for developing the nondimensionalization process. An often ignored and somewhat older technique is the Rayleigh Method. Both the Pi Theorem and the Rayleigh Method are founded on the Principle of Dimensional Homogeneity, and require some experience in the grouping of physical variables. The present paper uses the Rayleigh method to develop two new nondimensional parameters. A discussion is presented about the use of the parameters in the application of turbine flowmeter calibration and test data analysis. It is shown that data analysis for turbine flowmeters is considerably simplified by the use of the new parameters.

Commentary by Dr. Valentin Fuster
1998;():V002T02A014. doi:10.1115/98-GT-512.
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This paper presents the technology of searching for the most effective (optimal) engineering solutions for gas-turbine engines and their components at the stages of their designing, development and modernization. The distinctive feature of the technology is the possibility to solve optimization problems with large dimensionality (tens and hundreds of variables), with single or multiple criteria (search of Pareto-optimal solutions set), with minimal number of researched object mathematical simulator direct calls.

Commentary by Dr. Valentin Fuster
1998;():V002T02A015. doi:10.1115/98-GT-555.
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As part of the DoD Base Realignment and Closure process, the unique Navy capability to test aircraft engines under various environmental conditions is being transitioned to the Air Force. A new facility, using two modified sea-level Air Force T-9 test cells as building blocks, formed the basis of the new design. The structural design of the test cells and test control building was based on the aerodynamic and acoustic requirements for testing large afterburning turbojet/turbofan engines. Major construction has passed the 90-percent completion milestone. Aerodynamic criteria were defined in 1/12th-scale model tests of an engine installation using an F110 engine simulator. Modifications were then made to the basic T-9 test cells to allow ram air duct direct-connect capability. Following construction, activation/validation of the test facility will be conducted with an actual F110 engine, run in both direct-connect and bellmouth inlet configurations. Initial Operational Capability is scheduled for September 1998. Technical aspects of the facility design, construction, and ram air duct are described. Final system capabilities are airflow of 249.48 kg/sec; inlet air temperature range of 219 to 503 K; and inlet air pressures up to 206.85 kPa (1.1 Mach number). Environmental conditions of high and low temperature, water and ice ingestion, sand ingestion, and salt air corrosion can be duplicated. Engine transient operation, and mission profile endurance tests with simulated inlet conditions of forward flight velocities will be available to both government and industry users.

Topics: Test facilities
Commentary by Dr. Valentin Fuster
1998;():V002T02A016. doi:10.1115/98-GT-556.
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Within the initiative of the German Aerospace Research Programme - Engine 3E Project - the altitude test facility at the University of Stuttgart has been successfully adapted and commissioned as a new facility for BR700 core demonstrator engine tests.

A core demonstrator consists of high pressure components of the engine. The low pressure system, which is not part of the core engine, must be simulated by the test facility itself. This paper describes the technical concept of the computer control system and the procedure in which the core demonstrator, altitude test facility and sub-systems were integrated and tested. The concept consists of:

1. A Master Control System to run the measurement process and to control and monitor the overall test activity.

2. A modified FADEC of a BR700-710 engine with modified control laws to control the core demonstrator.

3. A Facility Controller to control the air conditioning process of the facility-air station and to provide the required core inlet pressure and temperature profiles for the running of the core demonstrator.

4. Various sub-systems for supplying the core engine with lubricating oil, fuel, etc.

The test programme was focussed on evaluating the interaction between the various control systems. It was found that the test facility fulfills the requirements of providing the transient pressure and temperature profiles for rapid accelerations and decelerations during core engine test.

Commentary by Dr. Valentin Fuster
1998;():V002T02A017. doi:10.1115/98-GT-557.
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A high pressure hot test facility for cooled gas turbine components has been developed for use in turbine cooling research. In this facility, heat transfer tests for a sector of real turbine vanes can be performed under continuous operation. The heat transfer tests are performed at an operating point that is scaled down from the real engine operating point. The compressor can deliver air at the rate of up to 10 kg/s at 20 bars. Air temperatures of up to 1170 K can be achieved by using an oil-fired combustor. Besides conventional instrumentation such as thermocouples and pressure probes, the facility is equipped with an IR-camera to map two-dimensional wall temperature fields. Hot wire anemometry and an LDV system are used to determine mean and fluctuating velocity components.

This paper describes design and performance of the test facility as well as the control and measurement equipment. The test and evaluation procedures used for testing of cooled gas turbine vanes are also presented.

Commentary by Dr. Valentin Fuster
1998;():V002T02A018. doi:10.1115/98-GT-558.
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While it is known that the occurrence of flutter is dominated by aerodynamics, it also depends on such parameters as inlet distortion and acoustics, aerodynamic and mechanical mistuning, and structural damping. It is shown in this paper that recent developments in predictive methods are showing considerable promise and leading to an improved understanding of the controlling parameters. A non-linear coupled structural-fluid approach is described and applied at engine representative conditions. This involves 3D unsteady CFD calculations of the fan and intake flows. Particular emphasis is placed on the influence of intake acoustics. Earlier work on flutter prediction has focused on either the fan assembly without a proper representation of the intake, or the calculation of the acoustic properties of the intake without properly representing the interaction with the fan. The present study includes a combined fan plus intake calculation, the latter being represented via an axisymmetric approximation. With an initial prescribed velocity disturbance of the blades in a 2 nodal diameter mode, the calculations showed a strong response in a 4 nodal diameter mode. Considerable acoustic activity within the duct was also noted. This result was compared with CFD calculations for the full 3D intake geometry. It was concluded that a realistic representation of intake acoustics is required for a full description of the problem.

Commentary by Dr. Valentin Fuster

Marine

1998;():V002T03A001. doi:10.1115/98-GT-041.
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The propulsion configurations of current gas turbine powered military and commercial vessels have been established based upon available power ratings of existing engines, relative to the performance requirements of ship builders and operators. Development of the LM2500+ engine has extended power capability with minimal changes to the physical parameters of the current LM2500 marine packages. This paper explores the extended possibilities of gas turbine based propulsion in both military and commercial vessels through application of increased gas turbine power in packages of essentially current size and weight such as the LM2500+.

Commentary by Dr. Valentin Fuster
1998;():V002T03A002. doi:10.1115/98-GT-078.
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The useful life of gas turbines and the availability of power after start-up depend on their transient response. For this reason, several articles have been written on the dynamic simulation of gas turbine systems in electrical generation, cogeneration, and marine applications. The simulations typically rely on performance maps and time lags extracted from manufacturer’s specifications. This work was undertaken to increase the generality of turbine models over what can be obtained from performance maps. The paper describes a mathematical computer model developed to investigate the dynamic response of a simple single-shaft gas turbine system. The model uses design parameters normally incorporated in gas turbine design (e.g. load coefficient, flow coefficient, and deHaller Number) as well as compressor and turbine stage geometry and compressor and turbine material properties. A dynamic combustion chamber model is also incorporated. Other input parameters are included to enable the model to be adaptable to various system sizes and environments.

The model was formulated in a graphical interface, and the results of several trials are displayed. The influence of important parameters (e.g. fuel-air ratio, IGVs, load, efficiencies) on turbine response from a “cold” start and from steady-state is studied. To gain further insights into the response, a start-up procedure similar to that reported in the literature for an industrial gas turbine system is simulated. Because of the approach used, the computer model is easily adaptable to further improvements and combined simulation of turbines and control systems.

Commentary by Dr. Valentin Fuster
1998;():V002T03A003. doi:10.1115/98-GT-135.
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The LM2500 gas turbine has been used in Italian Navy (ITN) ships for more than twenty years, as the first engines were installed on board the “Lupo” class Frigates during the second half of the 1970s.

The LM2500 during its service has proven to be reliable in both the “Combined Diesel or Gas” (CODOG) and the “Combined Gas and Gas” (COGAG) propulsion plant, with Controllable Pitch Propeller (CPP) and Fixed Pitch Propeller (FPP) as the ITN marine operational experience demonstrates. The last application was in the DURAND DE LA PENNE Class DDG with a CODOG arrangement and two shaft lines with Feathered Controllable Pitch Propellers (FCPP), produced by FINCANTIERI shipyard, which may range from a forward to an astern direction till the blades reach a flag position. This type of propeller allows a considerable drop in the absorbed power and therefore in fuel consumption and noise when using a single shaft.

Based on the ITN experience with the DDG class, the use of FCPP achieves remarkable fuel savings with the gas turbine since, due to the high specific consumption of the engine at low speeds, it is cheaper to have a single shaft running.

The maintenance approach to the engines installed on board ITN ships, based on the “on condition” concept, has been developed by the ITN and Fiat Avio to maximise the availability of the vessels. This covers both on-board corrective maintenance (inspection, special maintenance and / or introduction of improvements) and the substitution maintenance, with successive overhaul and application of decided updating of gas generators and power turbines.

Commentary by Dr. Valentin Fuster
1998;():V002T03A004. doi:10.1115/98-GT-147.
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This paper covers 35 years of operation with the ROLLS-ROYCE Marine PROTEUS Gas Turbine in the Swedish Navy SPICA class Torpedo Boats and the NORRKÖPING class Missile Boats.

54 installed PROTEUS Gas Turbines in 18 boats have accumulated nearly 300 000 running hours. The service is intended to continue until year 2010.

The paper describes:

• Experience from operation.

• Technical problems and their solutions.

• Major modifications.

• Life extension program.

• Problem areas.

• The future of the PROTEUS within Swedish Navy.

The Swedish Navy operation of PROTEUS engines in fast surface attack ships is demanding and the environment is harsh. This causes great strain to the entire machinery.

With the Gas Turbine Propulsion new Ship maneuvering technique had to be developed and adopted.

Initial installation and engine problems had to be cured.

Throughout the years several technical problems have turned up and been solved.

The largest number or serious engine damages has been Power degradation and broken Compressor or burnt Turbine Blades and Vanes. Mainly as a result of a fouled Compressor, incorrect Bleed Valve setting or corrosion.

Next largest engine problem has been vibration. In the early days engine related but nowadays generated by the installation or other equipment in the ship.

All efforts laid down by involved personnel has greatly contributed to improve the reliability of the engine and its installation.

New problems will certainly show up by age and changed operational procedures, thus calling for a continued improvement work.

Spare parts accessibility will be the limiting factor for future PROTEUS operation. Therefore cooperation with ROLLS-ROYCE and the remaining operators in Spare Parts production and for exchange of Spare Parts is essential.

Topics: Gas turbines , Navy , Ships
Commentary by Dr. Valentin Fuster
1998;():V002T03A005. doi:10.1115/98-GT-148.
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This paper is a summary of 35 years experience from maintenance, overhaul and repair of the ROLLS-ROYCE Marine PROTEUS Gas Turbine in the Swedish Navy.

The 54 installed PROTEUS Gas Turbines in 18 ships have accumulated nearly 300 000 running hours. The reliability has steadily improved thanks to careful monitoring and intensive improvement programs.

The initial, less than 500 hours average between engine removals has been extended to nearly 3000 hours as of today. Also the number of catastrophic engine failures has decreased.

Although the Spare Parts prices and the Labor Costs per hour have increased over the years the maintenance cost per fired Gas Turbine hour has decreased.

The paper describes the technical and economical aspects together with the cost reducing efforts. The information derives from the Swedish Navy Maintenance and Failure Reporting System, named “MARIS”, and from the VOLVO overhaul workshop annual technical and economical activity report.

Commentary by Dr. Valentin Fuster
1998;():V002T03A006. doi:10.1115/98-GT-273.
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The U.S. Navy and Allison Engine Company successfully completed a second round of testing which integrated a new Woodward Governor Full Authority Digital Control (FADC) system for gas turbine control and a Redundant Independent Mechanical Start System (RIMSS). This integrated system will be installed on Allison Model AG9140 Ship Service Gas Turbine Generators (SSGTGs) on hull numbers DDG-86 and follow of the U.S. Navy’s Arleigh Burke (DDG-51) class destroyers.

The Full Authority Digital Control (FADC) Local Operating Panel (LOCOP) will be a direct replacement of the original AG9140 LOCOP and will control both the Allison 501-K34 gas turbine and the RIMSS unit. RIMSS is a gas turbine powered, mechanically coupled start system for the SSGTGs and is designed to replace the high pressure start air system on DDG-51 class ships.

This paper describes the FADC and RIMSS systems and details Phase II testing that was conducted on the AG9140 SSGTG located at the Naval Surface Warfare Center, Carderock Division - Ship Systems Engineering Station (NSWCCD-SSES) DDG-51 Land Based Engineering Site (LBES), Figure 1. The test program embodied the second portion of RIMSS testing which included the addition of the final prototype FADC control system. The test agenda included electric plant operations with the FADC and a second 500 start endurance test of RIMSS. The primary objective of Phase II testing was to evaluate the FADC control system and to further validate engine life predictions for the RIMSS engine.

Commentary by Dr. Valentin Fuster
1998;():V002T03A007. doi:10.1115/98-GT-277.
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Application of gas turbines for power generation services aboard special classed floater vessels for mobile oil and gas exploration platforms has been demonstrated and certified by classification societies. A floating platform, designed by Kerr McGee UK PLC, in operation in the North Sea on purpose-built vessel, Tentech 850, has incorporated a pair of Mars T-12,000 gas turbine generator sets designed and supplied by Solar Turbines. The system has been registration classed and certified by Det Norske Veritas in mid 1993 for all of the power generating services required for extended oil extraction and pre-production processing, as well as, auxiliary electric power required for operations.

This paper presents the selection and certification process required for this application and an update of the operating experience during the first years of operation.

Commentary by Dr. Valentin Fuster
1998;():V002T03A008. doi:10.1115/98-GT-278.
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To support the propulsion and electrical requirements of an all-electric CVX, the use of heavy-duty power generation gas turbines could be considered as a viable alternative to conventional steam propulsion. A 300 MWe total plant baseload capacity is needed for an all-electric ship requiring 200 MWe for propulsion and a peak electric catapult power requirement of 200 MWe.

Applications of advanced marine gas turbines to provide electric power to an all-electric CVX have a major advantage in that the gas turbines do not have to be located in the same area as the electric propulsion motors. The possibility of locating the turbine-generators topside to minimize the ship impacts associated with long runs of large intake and exhaust ducts was briefly studied and is discussed herein.

Topics: Gas turbines
Commentary by Dr. Valentin Fuster
1998;():V002T03A009. doi:10.1115/98-GT-280.
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A new generation of auxiliary ships to enter the U.S. Navy (USN) fleet is the AOE-6 SUPPLY CLASS. These fast combat support ships conduct operations at sea as part of a Carrier Battle group to provide oil, aviation fuel, and ammunition to the carrier and her escorts. The SUPPLY CLASS is the first ship in the entire USN fleet to use a combined gas turbine and diesel generator cooling air intake system to cool its respective engine modules. The cooling air intake was designed this way to save on costs. As the ships in this class continued with operations and problems of insufficient supply of cooling air for the gas turbines modules started surfacing, the entire intake system required investigation and analysis. Since the gas turbines and diesel generators share a common cooling air trunk, they were competing for air. This paper will outline the tests that were performed to determine the problems, the recommended solutions, and the lessons learned from the investigations.

Commentary by Dr. Valentin Fuster
1998;():V002T03A010. doi:10.1115/98-GT-281.
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The U. S. Navy uses the Allison 501-K series engines as the prime mover of the Ship Service Gas Turbine Generators (SSGTGs) on DD-963, DDG-993, CG-47 and DDG-51 Class Ships. Historical data shows the engine’s most unreliable component to be the Accessory GearBox (AGB). This paper describes an intensive effort to identify and correct the root cause of the AGB failures and improve overall engine reliability and operational availability.

Commentary by Dr. Valentin Fuster
1998;():V002T03A011. doi:10.1115/98-GT-284.
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A field test was conducted on a three splitter diffuser and a vaneless diffuser (no splitters) to determine, the pressure recovery coefficient, effects on engine performance, exhaust collector temperature distribution, and exhaust gas noise.

This paper presents the cause of the mechanical failure of the three splitter diffuser, basic diffuser design, field test instrumentation, and the test results. The test results found the vaneless diffuser had a higher pressure recovery, created a lower back pressure, and did not raise the exhaust gas temperature (EGT) nor fuel consumption of the engine, as compared to the three splitter diffuser.

Commentary by Dr. Valentin Fuster
1998;():V002T03A012. doi:10.1115/98-GT-298.
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Land-based water injection into the combustor of gas turbines is a state-of-the-art technology, which is a low-risk, low-cost option for reduction of gas-turbine emissions. A controller for a water-injected combustor (WIC) system was designed for automatic control of water injection. Steady-state tests of the WIC system in an LM2500 propulsion-engine facility yielded basic engine-interactive data for the WIC’s unique automatic software logic. The steady-state tests demonstrated anticipated NOx reductions in conformity with proposed (but not implemented) California Air Resources Board (CARB) mandates. The controller automatically compensates for the effects of humidity, temperature and engine load.

This automatic response was expressly designed to deliver acceptable water rates even during the abrupt power excursions encountered in emergencies, including collision-avoidance crashback maneuvers. The transient test data indicated unacceptable flameout in the engine during engine deceleration to idle speed. Detailed analyses of the flameouts show that the controller can reduce water flow within two deciseconds of a change in power demand. However, the residence time of water in the manifolds can be about a second for some operating conditions. Several fixes for this problem are described.

Commentary by Dr. Valentin Fuster
1998;():V002T03A013. doi:10.1115/98-GT-299.
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The US Navy utilizes Gas Turbine Engines in a variety of propulsion and power generation applications. Despite dramatic shifts in the world defense posture, the basic application requirements for this equipment has not changed. Each ship and her crew operate in potentially hazardous environments, either by threat from man or nature. Because US Navy ships operate around the world, each ship must be self-supported and continue to function in her mission far from repair and maintenance activities. Due to the unique nature of this application, the configuration of the 501-K17 Gas Turbine Generators is constantly under technical review to provide critical technical upgrades. Included in the engineering review process is the requirement to provide integrated logistics support at installation. Interim support packages provide interim logistics products which fulfill the support requirements and maintain configuration control of the Gas Turbine Engines across hull applications without impeding the installation schedule.

Commentary by Dr. Valentin Fuster
1998;():V002T03A014. doi:10.1115/98-GT-330.
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Application of gas turbines in the off-shore oil and gas market has been successful for many years, utilizing both industrial gas turbines, as well as, aeroderivative types. Today, many operators in this market are pursuing the use of converted oil tankers and purpose-built barges — called Floating Production Storage and Off-Loading vessels (FPSO) — and semi-submersible or tension-leg platforms as alternative means of drilling for and production of oil and gas in much deeper waters than before, gaining flexibility of operation and reduced overall costs.

Due to the special requirements of extreme conditions experienced on board a FPSO vessel, each application involves a considerable amount of pre-design to determine the gas turbine package required capability to satisfy needed reliability. Additionally, international and local maritime regulatory bodies and classification societies concurrence/approval generally are required to authorize vessel operation. The intent of the “Code of Construction and Equipment of Offshore Drilling Units” is to recommend design criteria, construction standards, and other safety measures in order to minimize risk to the vessels, platforms, personnel and to the environment.

To incorporate these requirements into a standardized cost effective gas turbine system, this paper outlines the design features of such a package for installation on FPSO vessels.

Commentary by Dr. Valentin Fuster
1998;():V002T03A015. doi:10.1115/98-GT-332.
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Water, in the liquid or vapor phase, injected at various locations into the gas turbine cycle has frequently been employed to improve engine performance while simultaneously reducing NOx emissions. Commercial steam injected gas turbines have been designed to inject small amounts of steam (less than 15% of air flow), generated in a heat recovery boiler, into or downstream of the combustor. Recently, it has been proposed to inject larger amounts of water (as high as 50% of air flow) and operate combustors near stoichiometric conditions. All these methods increase turbine mass flow rate without increasing air flow rate and consequently increase specific power. The increase in specific power for naval applications means smaller intake and exhaust stacks and therefore less impact on topside space.

The present paper presents a new concept, in naval propulsion plants, to decrease NOx production and increase specific power with a water fog (droplet spray) injected (WFI) directly into the inlet of the engine compressor. The simulated performance of a simple-cycle gas turbine engine using WFI is reported. The paper describes the computer model developed to predict compressor performance resulting from the evaporation of water passing through the stages of an axial flow compressor. The resulting effects are similar to those of an intercooled compressor, without the complications due to the addition of piping, heat exchangers, and the requirement for a dual spool compressor. The effects of evaporative cooling on compressor characteristics are presented. These results include compressor maps modified for various water flow rates as well as estimates of the reductions in compression work and compressor discharge temperature.

These modified compressor performance characteristics are used in the engine simulation to predict how a WFI engine would perform under various water injection flow rates. Estimates of increased output power and decreased air flow rates are presented.

Commentary by Dr. Valentin Fuster
1998;():V002T03A016. doi:10.1115/98-GT-333.
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Epicyclic gearboxes of star configuration running at partial loads were found to induce non-synchronous (not related to speed) low-frequency vibrations, besides low level sub-synchronous (speed related) which were transmitted to other parts of a turbogenerator power train. At certain loads, the amplitudes of the non-synchronous vibrations were high enough to cause potential damage to sleeve bearings used in the power train system if a generator set would run for any considerable length of time at these loads. It was also observed that a very small increase in load above a certain limit (about 18% of full load) resulted in almost total elimination of these vibrations. Analysis of test data showed the non-synchronous vibrations were due to ‘backward whirl’ motion of gearbox output shaft in its sleeve bearings. Higher damping in the bearings was considered to be one of the most effective methods to suppress backward whirl of a shaft and hence, the non-synchronous vibrations. Accordingly, a new set of gearbox output shaft sleeve bearings was designed for higher damping that would allow these types of generator sets to run at partial and full loads without any detrimental vibration.

Commentary by Dr. Valentin Fuster
1998;():V002T03A017. doi:10.1115/98-GT-437.
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The Visby Class Corvette will enjoy the advantages of a Combined Diesel or Gas (CODOG) turbine arrangement in which the diesel engines are used for low-speed mine hunting and ASW missions, while the four turbines can be operated either individually or in pairs to provide cruise or high-speed dash capability. The integration of these features into a single gearbox, the design of the Allied Signal model TF50A turbine engine, and the integration of the CODOG system into the ship is discussed herein. Attention is focused on the unique design features which provide the “stealth” capabilities of this ship.

Commentary by Dr. Valentin Fuster

Microturbines and Small Turbomachinery

1998;():V002T04A001. doi:10.1115/98-GT-084.
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Main powerplants for aircraft in the US Navy inventory typically require a source of pneumatic power in order to initiate the engine start sequence. The equipment which is used as the source for this power is termed “UNIJASU”, or Universal Jet Aircraft Start Unit.

UNIJASU is a fully self-contained, transportable source of ground power which may be adapted to both land or carrier-based operations. At the nucleus of this unit is a modified T53 aircraft gas turbine, originally developed and fielded by the Lycoming Turbine Engine Division of Stratford Conn. In the current application, the T53 has been re-configured as a gas generator with specific provisions for extensive operation in a marine environment. Using the bleed machine concept, up to 30% of the engine massflow (equating to roughly 420 air horsepower) can be delivered to an aircraft starter upon demand. The present production source for the T53 engine is the AlliedSignal Engine Company, located at Phoenix, Az.

As of the writing date (mid-1997), the US Navy is in the process of procuring its next generation air start units via contract to AlliedSignal. This paper describes the salient features of a rigorous two-phase development program starting with the initial adaptation of the aircraft turbine engine to a naval ground power unit, and culminating with over 6000hrs of system level testing, inclusive of actual field evaluations.

Topics: Gas turbines , Navy
Commentary by Dr. Valentin Fuster
1998;():V002T04A002. doi:10.1115/98-GT-209.
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This paper describes on/off design performance of a 50KW turbogenerator gas turbine engine for hybrid vehicle application. For optimum design point selection, a relevant pa4rameter study is carried out. The turbogenerator gas turbine engine for a hybrid vehicle is expected to be designed for maximum fuel economy, ultra low emissions, and very low cost. A compressor, combustor, turbine, and a permanent-magnet generator will be mounted on a single high speed (80,000 rpm) shaft that will be supported on air bearings. As the generator is built into the shaft, gearbox and other moving parts become unnecessary and thus will increase the system’s reliability and reduce the manufacturing cost. The engine has a radial compressor and turbine with design point pressure ratio of 4.0. This pressure ratio was set based on calculation of specific fuel consumption and specific power variation with pressure ratio. For the turbine inlet temperature, a rather conservative value of 1100K was selected. Designed mass flow rate was 0.5 kg/sec. Parametric study of the cycle indicates that specific work and efficiency increase at a given pressure ratio and turbine inlet temperature. Off design analysis shows that the gas turbine system reaches self operating condition at about N/NDP = 0.48. Bleeding air for a turbine stator cooling is omitted considering the low TIT in the present engine and to enable the simple geometric configuration for manufacturing purpose. Various engine performance simulations including ambient temperature influence, surging at part load condition; transient analysis were performed to secure the optimum engine operating characteristics. Surge margin throughout the performance analysis were maintained to be over 50% approximately. Present analysis will be compared with performance test result which is scheduled at the end of 1998.

Commentary by Dr. Valentin Fuster
1998;():V002T04A003. doi:10.1115/98-GT-288.
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CGT301 ceramic gas turbine is being developed under a contract from NEDO as a part of the New Sunshine Program of MITI to improve the performance of gas turbine for co-generation through the replacement of the hot section components with ceramic parts.

CGT301 is a recuperated, single-shaft ceramic gas turbine. We have been developing some unique technologies, such as the “hybrid” rotor, composed of a metal disk and inserted ceramic blades, considering the future applicability to larger gas turbines.

We could attain the good engine performance with the primary type CGT at a TIT of 1,200°C. The reliability of the hybrid rotor was confirmed at a TIT of 1,350°C on the test rig.

We conducted preliminary tests using the primary type CGT to extract the possible problems derived from the higher TIT. Some modifications were made and the engine operation at a TIT of 1,280°C was conducted successfully.

On the basis of those experiences we finished the design and fabrication of the pilot CGT.

This paper presents the progress in the development of CGT301.

Commentary by Dr. Valentin Fuster
1998;():V002T04A004. doi:10.1115/98-GT-309.
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Micro gas turbine units are becoming popular for on-site combined heat and power production (CHP). CHP units based on gas turbines have several advantages; low emissions, compactness, low maintenance costs and fuel flexibility. The successful development of a small high-speed turbogenerator gives major opportunities to meet the customers’ demands in a deregulated and competitive market.

Vattenfall, together with Volvo Aero Turbines and ABB, has actively participated in development of a future concept of micro gas turbines. The first demonstration plant in Northern Europe for small scale heat and power co-generation, a 40 kWe turbogenerator was installed by Vattenfall at Pappersgruppen in Gothenburg, Sweden.

A first evaluation phase of the demonstration plant has been performed. The electricity and heat output showed to be 38 kWe and 70 kW respectively at full load. The net plant efficiency was 28.2% and the overall efficiency was 80%, based on the lower heating value. The emissions from the unit were very low due to low emission combustion chamber. The evaluation period will continue during 97/98. The influence of outdoor temperature, degree of loading, as well as the required maintenance and manned operation will be investigated.

Commentary by Dr. Valentin Fuster
1998;():V002T04A005. doi:10.1115/98-GT-358.
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Small single or twin entry radial turbines are mostly used to drive compressors of the turbocharged internal combustion engines. There are two general possibilities to feed the turbine of a four-stroke, 4-cylinder turbocharged Diesel engine: 1) by preserving most of the available exhaust kinetic energy, or 2) by mixing exhaust pulses from all cylinders in one common manifold. In the first case, better utilization of the dynamic pulse energy increases efficiency of the turbine; highly unsteady mass flow of the exhaust gasses, on the other hand, and thus periods of partial exhaust flow admission at the turbine inlet simultaneously reduces this gain in the turbine efficiency. More steady mass-flow of the exhaust gasses is created in the case of the exhaust system 2), however some kinetic energy is lost during the mixing phase in the common exhaust manifold. Calculation of the overall turbocharger and turbine efficiency is normally based on average values of the measured pressures and temperatures. As the result apparent efficiencies are obtained; the more the flow is pulsating, the bigger is the difference between the real and the apparent efficiency. The ratio between these two efficiencies is known as the energy pulsation factor β. It depends generally on the “pulse intensity”-pressure deviation from its mean value, shape of the pressure pulse, number of the individual pulses feeding separate gas turbine inlets, turbocharger, and can be successfully used to determine real efficiency of a turbocharger and to define some working parameters of the engine.

A field of β factors for different engine running conditions and for the 4-cylinder engine with 2-cylinder group pulse system (rarely applied), and the commonly applied exhaust system with 4-cylinder group and moderate pressure fluctuation is presented in the paper. Influence of the dynamic exhaust temperatures on the β value is discussed as well.

Commentary by Dr. Valentin Fuster
1998;():V002T04A006. doi:10.1115/98-GT-392.
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The European Gas Turbine Program “AGATA” which started in 1993 now has reached its verification phase. The objective of the program is to develop three critical ceramic components aimed at a 60 kW turbogenerator in a hybrid electric vehicle — a catalytic combustor, a radial turbine wheel and a static heat exchanger. The AGATA partners represent car manufacturers as well as companies and research institutes in the turbine, catalyst and ceramic material fields in both France and Sweden. Each of the three ceramic components is validated separately during steady state and transient conditions in separate test rigs at ONERA, France, where the high pressure/temperature conditions can be achieved. A separate test rig for laser measurements downstream of the catalytic combustor is set up at Volvo Aero Turbines, Sweden.

The catalytic combustor design which includes preheater, premix duct and catalytic section operates at temperatures up to 1623 K. Due to this high temperature, the catalyst initially has undergone pilot tests including ageing, activity and strength tests. The premix duct flow field also has been evaluated by LDV measurements. The full scale combustion tests are ongoing.

The turbine wheel design is completed and the first wheels have been manufactured. FEM calculations have indicated that stress levels are below 300 MPa. The material used is a silicon nitride manufactured by AC Cerama (Grade CSN 101). Cold spin tests with complete wheels have started. Hot spin tests at TTT 1623 K will be performed in a modified turbo charger rig and are expected to start in February 1998.

The heat exchanger is of a high efficiency plate recuperator design using Cordierite material. Hot side inlet temperature is 1286 K. Therefore initial tests with test samples have been run to evaluate the thermomechanical properties at high temperatures. Tests are now proceeding with a 1/4 scale recuperator prototype to evaluate performance at steady state conditions. Manufacturing of the full scale heat exchanger is now in progress.

Topics: Gas turbines
Commentary by Dr. Valentin Fuster
1998;():V002T04A007. doi:10.1115/98-GT-398.
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The 300kW Industrial Ceramic Gas Turbine (CGT) Research and Development Project is going on as a part of New Sunshine project under the contract of Japanese Ministry of International Trade and Industry (MITI). The objective of this project is to achieve higher efficiency and lower pollutant emissions for small sized gas turbine engines used in co-generation systems.

Under this project, Kyocera has been developing various ceramic components for the CGT302 engine designed by Kawasaki Heavy Industries (KHI). This engine has set a thermal efficiency of over 42% at a turbine inlet temperature (TIT) of 1350°C as a final target. For such operations, we have developed the new silicon nitride materials, SN281 and SN282, which have excellent stress rupture strength and superior oxidation resistance at elevated temperatures up to 1500°C.

We have also developed improved fabrication technologies for the use of SN281 and SN282 as engine components. In 1997 fiscal year, all ceramic components for the CGT302 were successfully fabricated by using these new materials. Especially, the large sized monolithic power turbine (PT) rotor, which has a 192mm outer diameter, was manufactured by SN282, and exhibited fracture rotating speeds greater than 120% of the design rotating speed in cold spin tests.

This paper discusses the mechanical properties of these new materials and the results of ceramic components evaluated under engine test conditions.

Commentary by Dr. Valentin Fuster
1998;():V002T04A008. doi:10.1115/98-GT-399.
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A new high quality turbine system using monolithic silicon-nitride ceramic is under development. In this study particle impact tests of the silicon-nitride have been tried at room and elevated temperatures with and without tensile load, which simulates centrifugal force of blade rotation. In the experiment 1 mm diameter particle is impacted at velocities up to 900 m s−1. In this paper, critical velocities for bending fracture and Hertzian cracks are examined. Moreover, strength degradation at elevated temperature and spall fracture of the blade are discussed. The main results are: 1) The bending fracture mode critical impact velocity for soft particles is higher than that for hard particles. 2)The impact parameter ϕ for initiation of Hertzian cracks ranges 1.08×10−5 – 1.56×10−5 for the materials tested. 3)Strength degradation at elevated temperature was clearly observed. 4) In the impact tests on blades spall fracture, which was caused by interaction of stress waves, appeared.

Commentary by Dr. Valentin Fuster
1998;():V002T04A009. doi:10.1115/98-GT-400.
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This paper describes the development of a low-emission, 50-kW turbine-driven generator called a turbogenerator. It gives a detailed description of the key design features that benefit hybrid electric vehicles driven in various driving cycles. Although the turbogenerator is designed for hybrid electric vehicles, other applications such as standby and primary electric power generation will benefit from its characteristics. These include very-low-exhaust emissions, low cost, high reliability, high fuel efficiency, compact design, and low noise levels. The turbogenerator is relatively unique in that the turbine wheel, compressor impeller, and electrical generator are all mounted on a single, common shaft which is supported on air bearings. These features eliminate the need for both the gearbox and oil lubrication commonly found on conventional automotive and gas turbine engines. AlliedSignal developed the 50-kW turbogenerator for Ford Motor Company under the DOE Hybrid Electric Vehicle Propulsion Program. The turbogenerator is designed to fit into the engine compartment of a Mercury Sable. AlliedSignal originally proved this innovative concept in an APU development program for the U.S. Army. The unit developed for that program has accumulated over 600 hours of operation in laboratory and Army vehicle tests.

Commentary by Dr. Valentin Fuster
1998;():V002T04A010. doi:10.1115/98-GT-451.
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The purpose of this program has been the development of advanced gas turbine engine technologies in support of U.S. Department of Energy (DoE) programs for use in generator sets for hybrid-electric automotive propulsion systems.

Initially the objective of this program had been the development of four key technologies to be applied 10 advanced turbogenerators:

• structural ceramic materials and processes

• low emissions combustion systems

• regenerator and seal systems

• insulation systems and processes.

Of these four, the lack of full program funding has limited 1997 activities to two technologies, i.e.: continued development of ceramics applications and continued regenerator and seal system development.

In late 1997, DoE Office of Transportation Technologies discontinued active sponsorship of this effort, and therefore, the potential application to automotive systems now appears to be delayed. However, the application to stationary engines is very relevant and will proceed.

Commentary by Dr. Valentin Fuster
1998;():V002T04A011. doi:10.1115/98-GT-498.
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NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles.

In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1350 °C in accordance with the project goals, we developed two silicon nitride materials with further improved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles.

On applying these silicon nitride ceramics to CGT engine, we evaluated various properties of silicon nitride materials considering the environment in CGT engine. Particle impact testing is one of those evaluations. Materials used in CGT engine are exposed in high speed gas flow, and impact damage of these materials is considered to be a concern. We tested ST-1 in the particle impact test. In this test, we observed fracture modes, and estimated the critical impact velocity.

This paper summarizes the development of silicon nitride components, and the result of evaluations of these silicon nitride materials.

Commentary by Dr. Valentin Fuster
1998;():V002T04A012. doi:10.1115/98-GT-501.
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In Japan, from the point of view of energy saving and environmental protection, a 300kW Ceramic Gas Turbine (CGT) Research and Development program started in 1988 and is still continuing as a part of “the New Sunshine Project” promoted by the Ministry of International Trade and Industry (MITT).

The final target of the program is to achieve 42% thermal efficiency at 1350°C of turbine inlet temperature (TIT) and to keep NOx emissions below present national regulations. Under contract to the New Energy and Industrial Technology Development Organization (NEDO), Kawasaki Heavy Industries, Ltd. (KHI) has been developing the CGT302 with Kyocera Corporation and Sumitomo Precision Products Co., Ltd.

By the end of the fiscal year 1996, the CGT302 achieved 37.0% thermal efficiency at 1280°C of TIT. In 1997, TIT reached 1350°C and a durability operation for 20 hours at 1350°C was conducted successfully. Also fairly low NOx was proved at 1300°C of TIT. In January 1998, the CGT302 has achieved 37.4% thermal efficiency at 1250°C TIT.

In this paper, we will describe our approaches to the target performance of the CGT302 and current status.

Commentary by Dr. Valentin Fuster
1998;():V002T04A013. doi:10.1115/98-GT-554.
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AlliedSignal Engines is addressing critical concerns slowing commercialization of structural ceramics in gas turbines. The AlliedSignal 331-200[CT] APU test bed features ceramic first-stage nozzles and blades. Fabrication of ceramic components provides manufacturing process demonstration scale-up to minimum levels for commercial viability. Endurance tests and field testing in commercial aircraft will demonstrate component reliability.

Manufacturing scale-up activities showed significant progress in 1997. Subcontractors AlliedSignal Ceramic Components (CC, Torrance, CA) and Kyocera Industrial Ceramics Corporation (KICC, Vancouver, WA), transitioned process refinements to demonstration. CC initiated trial production of 100 nozzles/month. These suppliers are also developing fixed processes to fabricate ceramic integrally-bladed turbine rotors (“blisks”).

Ceramic design technology advanced with carbon particle impact testing supporting impact model verification, and 300 hours successful engine testing of longer-life inserted blade attachment compliant layers. Ceramic turbine nozzles were readied for planned field demonstrations with 473 hours of engine testing.

This work was funded as part of the Turbine Engine Technologies Program by the DoE Office of Transportation Technologies under Contract No. DE-AC02-96EE50454.

Commentary by Dr. Valentin Fuster
1998;():V002T04A014. doi:10.1115/98-GT-566.
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The European EUREKA project, EU 209, otherwise known as AGATA (Advanced Gas Turbine for Automobiles), is a programme dedicated to the development of three critical ceramic components — a catalytic combustor, a radial turbine wheel and a static heat exchanger — for a 60 kW turbogenerator in an hybrid electric vehicle. These three components, which are of critical importance to the achievement of low emissions and high efficiency, have been designed, developed, manufactured and tested as part of a full scale feasibility study. AGATA is a joint project conducted by eight commercial companies and four research institutes in France and Sweden. Silicon nitride ceramics play an important role both in the development of the catalytic combustor and for the radial turbine wheel. This paper outlines the main results of the AGATA project with special emphasis to the development of HIPed Si3N4 combustor and turbine wheel. AC Cerama has developed a HIPed Si3N4 material designated CSN 101. This material has been selected for the catalytic combustor afterburner as well as for the radial turbine wheel. Mechanical properties of the CSN 101 Si3N4 have been found to be at the level of the best available high temperature Si3N4 materials. A new glass encapsulation technique using an interlayer between the glass and the silicon nitride has been shown to give material with excellent strength, oxidation resistance and creep resistance with as-HIPed surface finish.

Commentary by Dr. Valentin Fuster

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