bluuebunny/crossref_metadata_2025 huggingface dataset:
Air-Breathing Hypersonic Cruise: Prospects for Mach 4–7 Waverider Aircraft
Authors: Blankson I. M.
Published: April 2008

There is currently a renewal of world-wide interest in hypersonic flight. Vehicle concepts being considered range from cruise missiles to SSTO and TSTO vehicles. The new characteristics of these vehicles are that they will be powered by air-breathing engines and have long residence times in the air-breathing corridor. In the Mach 4–7 regime, waverider aircraft are being considered as candidates for both long-range and short-range cruise missions, as hypersonic missiles, and as high-L/D highly maneuverable vehicles. This paper will discuss the potential for near-term and far-term application of air-breathing engines to the above-mentioned waverider vehicle concepts and missions. In particular, the cruise mission is discussed in detail and attempts are made to compare and contrast it with the accelerator mission. Past criticisms levied against waveriders alleging low volumetric efficiency, lack of engine/airframe integration studies, poor off-design performance, poor take-off and landing capability, have been shown by ongoing research to be unfounded. A discussion is presented of some of the technical challenges and ongoing research aimed at realizing such vehicles: from turboramjet and scramjet technology development, propulsion-airframe integration effects on vehicle performance, aeroservothermoelastic systems analysis, hypersonic stability and control with aeroservothermoelastic and propulsion effects, etc. A unique and very strong aspect of hypersonic vehicle design is the integration and interaction of the propulsion system, aerodynamics, aerodynamic heating, stability and control, and materials and structures. This first-order multidisciplinary situation demands the ability to integrate highly coupled and interacting elements in a fundamental and optimal fashion to achieve the desired performance. Some crucial technology needs are found in propulsion-airframe integration and its role in configuration definition, hypersonic boundary-layer transition and its impact on vehicle gross-weight and mission success, scramjet combustor mixing length and its impact on engine weight and, CFD (turbulence modeling, transition modeling, etc) as a principal tool for the design of hypersonic vehicles. Key technology implications in thermal management, structures, materials, and flight control systems will also be briefly discussed. It is concluded that most of the technology requirements in the Mach 4–7 regime are relatively conventional, making cited applications near-term, yet offering very significant advancements in aircraft technology.
Numerical Simulation of the Flow Field Around Supersonic Air-Intakes
Authors: Freskos G. , Penanhoat O.
Published: April 2008

The demand for efficiency in today’s and in future civil aircraft is such that experimental studies alone do not suffice to optimize aircraft aerodynamics. In this context, much effort has been spent in the past decade to develop numerical methods capable of reproducing the phenomena that occur in the engine flow field. This paper presents some studies in Computational Fluid Dynamics related to supersonic inlets. Two approaches are considered. First, there is a need for a code capable of calculating in a cost-efficient way the entire flow field around a two-dimensional or three-dimensional inlet, e.g., to perform parametric studies. To this effect, a computing method based on grid construction by mesh generator dedicated to inlet shapes and on the discretization of the unsteady Euler equations with an explicit upwind scheme was developed. The treatment of complex geometries led us to adopt a multiblock grid approach. Therefore particular attention was paid to the treatment of the boundary conditions between the different domains. Second, there is a need for a code that can capture local phenomena in order to get a better understanding of inlet behavior (shock/shock, shock/boundary layer interactions, etc.). To this effect a two-dimensional turbulent Navier-Stokes code is used. The two-equation k-ε turbulence model included in the program seems to be one of the most successful models for calculating flow realistically. Correction of the near-wall influence extends its capability to complex flow configurations, e.g., those with separated zones.
Thrust Vectoring/Reversing Tactics in Air-to-Air Combat
Authors: Boppe C. W. , Martorella R. P.
Published: April 2008

Considerable effort is now under way to develop technologies for enhancing fighter maneuvering limits. This has in part been motivated by the capabilities of advanced air-to-air missiles. One approach to enhanced combat effectiveness involves flight envelope expansion and improved controllability via engine thrust-vectoring and thrust-reversing. The complexity of fighter combat, however, makes it difficult to perform engineering analyses for assessing potential technological enhancements and risks. This paper describes a digital simulation that has been used to identify benefits associated with improved maneuverability. The Navy/Grumman F-14 aircraft provides the flight characteristics database. Combat tactics are developed as part of the solution process and are based solely on characteristics of the combatants and weapons employed. Head-on and codirectional neutral start combat engagements are used to illustrate study results.
Foothills Decompression/Recompression Facilities—Unique Power Recovery Application in Gas Pipelines
Authors: Kitt S. R. , Rose B. D.
Published: April 2008

Foothills Pipe Lines Ltd. is the Canadian sponsor of the Alaska Natural Gas Transportation System (ANGTS), a pipeline project selected in Canada and the United States as the means for transporting Alaskan gas reserves to the lower 48 United States. Currently, certain Prebuild portions of the ANGTS are in operation delivering Canadian gas to U. S. markets. A recent system expansion of the Eastern Leg Prebuild to accommodate increased Canadian gas exports entailed the construction of Decompression/Recompression facilities at Empress, Alberta to enable high-pressure operation of the Foothills pipeline while maintaining gas stripping at existing lowpressure extraction plants. The general process of the Decompression/Recompression facilities involves the expansion of high-pressure pipeline gas to conditions acceptable to the low-pressure extraction plants, then the recompression of the residue gas for return to the pipeline at original pressure. By directing the inlet gas through turbo expanders coupled to brake compressors, a substantial portion of the expansion energy is captured and used in providing the first stage of gas recompression. Including supplemental conventional compression, the Decompression/Recompression facilities are capable of providing approximately 37MW (50,000 HP) for continuous gas recompression. Although power recovery with turbo expanders is relatively common in the gas processing industry, such an application for gas recompression in large gas pipelines is unique. This technical paper describes the Foothills Decompression/Recompression facilities with their utilization of turbo expanders for pipeline recompression service, emphasizing the process design as well as the characteristics of the rotating equipment.
Axial Inlet Conversion to a Centrifugal Compressor With Magnetic Bearings
Authors: Novecosky T.
Published: April 2008

NOVA’s Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, United States, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).
Optimizing Automated Gas Turbine Fault Detection Using Statistical Pattern Recognition
Authors: Loukis E. , Mathioudakis K. , Papailiou K.
Published: April 2008

A method enabling the automated diagnosis of gas turbine compressor blade faults, based on the principles of statistical pattern recognition, is initially presented. The decision making is based on the derivation of spectral patterns from dynamic measurement data and then the calculation of discriminants with respect to reference spectral patterns of the faults while it takes into account their statistical properties. A method of optimizing the selection of discriminants using dynamic measurement data is also presented. A few scalar discriminants are derived, in such a way that the maximum available discrimination potential is exploited. In this way the success rate of automated decision making is further improved, while the need for intuitive discriminant selection is eliminated. The effectiveness of the proposed methods is demonstrated by application to data coming from an industrial gas turbine while extension to other aspects of fault diagnosis is discussed.
Fault Signatures Obtained From Fault Implant Tests on an F404 Engine
Authors: Eustace R. W. , Woodyatt B. A. , Merrington G. L. , Runacres A.
Published: April 2008

The fault diagnostic process for gas turbine engines can be improved if data acquired by an on-board engine monitoring system (EMS) are utilized effectively. In the commercial transport field, techniques are available to extract engine condition assessment information from steady-state EMS data. In a military environment, steady-state data are not always available, and therefore it is desirable to exact at least some of the information from transient data, such as during take-off. Fault signatures are presented for an F404 engine based on fault implant tests in a sea-level-static (SLS) test cell. A comparison is then made between the fault coverage capabilities of fault diagnostic techniques based on the use of steady-state engine data with those using transient data. The important conclusions to emerge from this work are that for the range of faults examined, not only is there similar fault information contained within the transient data, but the faults can be detected with increased sensitivity using these data.
Analysis of General Electric Model 7001 First-Stage Nozzle Cracking
Authors: Bernstein H. L. , McClung R. C. , Sharron T. R. , Allen J. M.
Published: April 2008

Analyses of first-stage nozzle cracking in General Electric Model 7001B and 7001E industrial gas turbines are presented. Empirical algorithms are developed to predict the maximum extent of cracking that is visible on these nozzles as a function of engine cyclic history and the number of fired hours. It is shown that the algorithms predict this cracking to within a factor of two. Metallurgical analyses of nozzles show that crack growth follows the carbide-matrix interface, environmental attack occurs at the crack tip, and that the microstructure changes by increasing the amount of carbide precipitation, which increases the hardness. These metallurgical results, along with mechanical test data and stress analyses from the literature, are used to understand the nature of nozzle cracking. The maximum extent of cracking coincides with locations of maximum thermal stresses as determined by finite element analyses of similar nozzle designs. This location is at the airfoil-shroud junction on the middle vanes of multivane castings. The use of these algorithms as a predictive maintenance tool and the ability to inspect nozzles visually in the engine also are discussed.
Detonation-Wave Technique for On-Load Deposit Removal From Surfaces Exposed to Fouling: Part I—Experimental Investigation and Development of the Method
Authors: Hanjalic´ K. , Smajevic´ I.
Published: April 2008

The paper presents a description and results of the experimental research, development, and full-scale testing of a new technique for cleaning gas-swept surfaces exposed to fouling, such as found in boilers, furnaces, heat exchangers, reactors, and gas ducts, by means of detonation waves. Part I describes the principles and reports on experimental investigations and optimization of the technique. Part II reports on several years of experience in applying the technique in full-scale operation in two large coal-fired boilers. Experiments involved detailed measurements of the pressure wave characteristics at a laboratory-scale model of a boiler furnace at a range of operating conditions and produced necessary information for optimum design and operation of the detonation wave generator. The investigation enabled a close insight into the detonation and shock wave generation, their behavior during propagation through the connecting ducts, and attenuation in the inner space of the model furnace. A good indication has also been obtained of the wave impact and effects on deposit-removal from different packages of tube bundles, which were placed in the model boiler in order to mimic boiler heating surfaces.
Microstructural Investigations of Plasma-Sprayed Yttria Partially Stabilized Zirconia TBC (In Relation to Thermomechanical Resistance and High-Temperature Oxidation Mechanisms)
Authors: Alpe´rine S. , Lelait L.
Published: April 2008

This study deals with microstructural investigations of plasma-sprayed yttria partially stabilized zirconia thermal barrier coatings, performed by classical and analytical transmission electron microscopy. The aim of the study was to determine eventual relationships between coating microstructure and toughness. The ceramic/metal interface, which plays an important role during TBC thermomechanical solicitation, has also been studied. In the 6–8 wt. percent Y2O3 range, the metastable tetragonal t′ phase is observed, showing special faulted microstructural features, such as grain twinning and antiphase boundary planes. Moreover, after high-temperature annealing in air, a very fine and stable precipitation of the equilibrium cubic phase appears. It is believed that these microstructural elements could act as crack deviation sites and enhance the coatings’ intrinsic toughness. Microstructural investigations of the alumina scales grown during high-temperature annealing reveal yttrium segregation at oxide grain boundaries as well as significant quantities of zirconium inside the alumina grains. The oxide growth seems to be dominated by a classical grain boundary oxygen diffusion mechanism. The presence of zirconium inside the alumina grains suggests that Al2O3 also partially forms by chemical reduction of ZrO2 by Al.
Thermal Fracture of Multilayer Ceramic Thermal Barrier Coatings
Authors: Takeuchi Y. R. , Kokini K.
Published: April 2008

Controlled experiments and a corresponding analytical model were developed to investigate the reasons for crack initiation in multilayer ceramic thermal barrier coatings. The experiments and model determined that surface cracks form as a result of tensile stresses created following stress relaxation in the ceramic at steady-state high temperatures (about 900°C–1100°C). Interface cracks generated by out-of-plane stresses are affected by the presence of these surface cracks and thermal transients and, possibly, edge effects.
Evaluation of Brayton and Rankine Alternatives for Diesel Waste Heat Exploitation
Authors: Woodward J. B.
Published: April 2008

A diesel engine may produce exhaust-gas thermal energy in excess of that needed for turbocharging. Alternatives for exploitation of the energy by producing work may be direct expansion through a gas turbine (completing a Brayton cycle that begins with the engine’s compression and combustion), or transfer of heat into a Rankine cycle. It is demonstrated that either alternative may have a domain in which it is superior in work done, or in exhaust volume per unit mass of diesel exhaust. Computation models are developed and demonstrated for finding the boundaries along which the Rankine and Brayton alternatives have equal merit in either work or exhaust volume.
Modeling and Analysis of Gas Turbine Performance Deterioration
Authors: Lakshminarasimha A. N. , Boyce M. P. , Meher-Homji C. B.
Published: April 2008

The effects of performance deterioration in both land and aircraft gas turbines are presented in this paper. Models for two of the most common causes of deterioration, viz., fouling and erosion, are presented. A stage-stacking procedure, which uses new installed engine field data for compressor map development, is described. The results of the effect of fouling in a powerplant gas turbine and that of erosion in a aircraft gas turbine are presented. Also described are methods of fault threshold quantification and fault matrix simulation. Results of the analyses were found to be consistent with field observations.
The Effectiveness of Heat Transfer From Flue Gases to Ammonia-Water Mixtures
Authors: Kusˇtrin I. , Tuma M.
Published: April 2008

The paper deals with the theoretical comparison of the heat transfer process from the exhaust gases of a gas turbine to pure water or to an ammonia-water mixture in the single-pressure, nonreheat, heat recovery boiler. The main difference is the variable-temperature boiling of the mixture, which improves the match of the temperature profiles in comparison to the match obtained by the use of pure water. The result is smaller loss of energy and exergy. Thermal and exergetic efficiencies are improved, which means better use of the primary heat source, i.e., the fuel of the gas turbine. At the end of the paper the usefulness of the ammonia-water mixture at higher inlet (above 500°C) and outlet (above 180°C) gas temperatures is analyzed. The main advantages of the mixture disappear under such conditions.
TEMPER—A Gas-Path Analysis Tool for Commercial Jet Engines
Authors: Doel D. L.
Published: April 2008

Almost from the inception of the gas turbine engine, airlines and engine manufacturers have sought an effective technique to determine the health of the gas-path components (fan, compressors, combustor, turbines) based on available gas-path measurements. The potential of such tools to save money by anticipating the need for overhaul and providing help in work scope definition is substantial, provided they produce reliable results. This paper describes a modern gas-path analysis tool (GE’s TEMPER program), discusses the benefits and problems experienced by current TEMPER users, and suggests promising research areas that may lead to an improved algorithm.
Integration of Turbo-Expander and Turbo-Ramjet Engines in Hypersonic Vehicles
Authors: Zellner B. , Sterr W. , Herrmann O.
Published: April 2008

Turbo-expander-ramjet and turbo-ramjet are two engine concepts considered for hypersonic aircraft designs with a flight regime between Mach 0 and 7. To establish any performance or integration aspects for these two combined-cycle engine types, an extended study of a variety of influence parameters is necessary, because the interaction between aircraft and propulsion system is even stronger than on conventional aircraft. In fact, the propulsion system is very sensitive to intake and nozzle/afterbody design at these high speeds. This paper presents the engine configurations chosen for comparison and describes the computer program used for the propulsion system performance simulation, including all relevant integration aspects. Furthermore, some results of propulsion system performance for a generic hypersonic aircraft and a typical ascent profile will be compared to indicate the special characteristics of the engines. Finally, some thoughts concerning the suitability and relevant technological requirements of the two engine types—seen from an aircraft manufacturer’s view—are included. The paper includes the results of two diploma theses, written by W. Sterr [1] and B. Zellner [2] at the Technical University of Munich, supervised by Prof. H. Rick (LFA) and O. Herrmann (MBB).
Analysis of a Basic Chemically Recuperated Gas Turbine Power Plant
Authors: Kesser K. F. , Hoffman M. A. , Baughn J. W.
Published: April 2008

This paper investigates a “basic” Chemically Recuperated Gas Turbine (a “basic” CRGT is defined here to be one without intercooling or reheat). The CRGT is of interest due to its potential for ultralow NOx emissions. A computer code has been developed to evaluate the performance characteristics (thermal efficiency and specific work) of the Basic CRGT, and to compare it to the steam-injected gas turbine (STIG), the combined cycle (CC) and the simple cycle gas turbine (SC) using consistent assumptions. The CRGT model includes a methane-steam reformer (MSR), which converts a methane-steam mixture into a hydrogen-rich fuel using the “waste” heat in the turbine exhaust. Models for the effects of turbine cooling air, variable specific heats, and the real gas effects of steam are included. The calculated results show that the Basic CRGT has a thermal efficiency higher than the STIG and simple cycles but not quite as high as the combined cycle.
Exergetic Comparison of Two KRW-Based IGCC Power Plants
Authors: Tsatsaronis G. , Tawfik T. , Lin L. , Gallaspy D. T.
Published: April 2008

In studies supported by the U.S. Department of Energy and the Electric Power Research Institute, several design configurations of Kellogg-Rust-Westinghouse (KRW)-based Integrated Gasification-Combined-Cycle (IGCC) power plants were developed. Two of these configurations are compared here from the exergetic viewpoint. The first design configuration (case 1) uses an air-blown KRW gasifier and hot gas cleanup while the second configuration (reference case) uses an oxygen-blown KRW gasifier and cold gas cleanup. Each case uses two General Electric MS7001F advanced combustion turbines. The exergetic comparison identifies the causes of performance difference between the two cases: differences in the exergy destruction of the gasification system, the gas turbine system, and the gas cooling process, as well as differences in the exergy loss accompanying the solids to disposal stream. The potential for using (a) oxygen-blown versus air-blown-KRW gasifiers, and (b) hot gas versus cold gas cleanup processes was evaluated. The results indicate that, among the available options, an oxygen-blown KRW gasifier using in-bed desulfurization combined with an optimized hot gas cleanup process has the largest potential for providing performance improvements.
Exergoeconomic Evaluation of a KRW-Based IGCC Power Plant
Authors: Tsatsaronis G. , Lin L. , Tawfik T. , Gallaspy D. T.
Published: April 2008

In a study supported by the U. S. Department of Energy, several design configurations of Kellogg-Rust-Westinghouse (KRW)-based Integrated Gasification-Combined-Cycle (IGCC) power plants were developed. One of these configurations was analyzed from the exergoeconomic (thermoeconomic) viewpoint. This design configuration uses an air-blown KRW gasifier, hot gas cleanup, and two General Electric MS7001F advanced combustion turbines. Operation at three different gasification temperatures was considered. The detailed exergoeconomic evaluation identified several changes for improving the cost effectiveness of this IGCC design configuration. These changes include the following: decreasing the gasifier operating temperature, enhancing the high-pressure steam generation in the gasification island, improving the efficiency of the steam cycle, and redesigning the entire heat exchanger network. Based on the cost information supplied by the M. W. Kellogg Company, an attempt was made to calculate the economically optimal exergetic efficiency for some of the most important plant components.
Working Group Activities of AGARD Propulsion and Energetics Panel
Authors: Ucer A. S.
Published: April 2008

One of the major activities of AGARD panels is to form working groups, which assemble experts who work on the particular subject for two or three years. As a result of the work, an advisory report is published, which compiles the state-of-the-art knowledge on the chosen specific topic. This paper explains the philosophy and procedures adopted during the formation of working groups of the Propulsion and Energetics Panel. Working groups concerning gas turbine technologies are presented. The selected working groups aim to improve the computational and experimental knowledge that would lead to the design of advanced aero gas turbine engines. Objective, scope, procedure, and important results of each working group will be explained. Working groups that were active during the 1980s and which were presently active are covered.
The PT6 Engine: 30 Years of Gas Turbine Technology Evolution
Authors: Badger M. , Julien A. , LeBlanc A. D. , Moustapha S. H. , Prabhu A. , Smailys A. A.
Published: April 2008

The PT6 engine entered service in the mid-1960s. Since then, application of new technology has enabled low-cost development of engines approaching 1500 kW, the introduction of electronic controls, improved power-to-weight ratio, higher cycle temperature, and reduced specific fuel consumption. At the same time, PT6 field experience in business, commuter, helicopter, and trainer applications has resulted in engines with low Direct Operating Cost and a reputation for rugged design and a high standard of engine reliability. This paper will highlight some interesting examples of this technical evolution, including the development of electronic controls and the application of the latest three-dimensional aerodynamic and stress analysis to both compressor and turbine components.
Advanced Hot Gas Cleaning System for Coal Gasification Processes
Authors: Newby R. A. , Bannister R. L.
Published: April 2008

The United States electric industry is entering a period where growth and the aging of existing plants will mandate a decision on whether to repower, add capacity, or do both. The power generation cycle of choice, today, is the combined cycle that utilizes the Brayton and Rankine cycles. The combustion turbine in a combined cycle can be used in a repowering mode or in a greenfield plant installation. Today’s fuel of choice for new combined cycle power generation is natural gas. However, due to a 300-year supply of coal within the United States, the fuel of the future will include coal. Westinghouse has supported the development of coal-fueled gas turbine technology over the past thirty years. Working with the U.S. Department of Energy and other organizations, Westinghouse is actively pursuing the development and commercialization of several coal-fueled processes. To protect the combustion turbine and environment from emissions generated during coal conversion (gasification/combustion) a gas cleanup system must be used. This paper reports on the status of fuel gas cleaning technology and describes the Westinghouse approach to developing an advanced hot gas cleaning system that contains component systems that remove particulate, sulfur, and alkali vapors. The basic process uses ceramic barrier filters for multiple cleaning functions.
Criteria for Design With Structural Materials in Combined-Cycle Applications Above 815°F
Authors: Swindeman R. W. , Marriott D. L.
Published: April 2008

A number of materials issues related to the design of piping and support components in high-temperature fluidized bed combustor systems were examined. These issues included the availability of long-time design data on structural materials, the general character of the creep and stress rupture behavior, the performance of weldments, and the assessment of damage accumulation. Emphasis was placed on alloy 800H, but several other alloys were briefly examined for use at temperatures above 816°C (1500°F). It was concluded that the character of the creep curve ranged significantly with chemistry, processing variables, and environment, and that the specification of design allowable stresses and life estimation techniques must be approached with caution for service above 816°C (1500°F).
Performance and Economic Enhancement of Cogeneration Gas Turbines Through Compressor Inlet Air Cooling
Authors: De Lucia M. , Bronconi R. , Carnevale E.
Published: April 2008

Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine’s power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.
Models for Predicting the Performance of Brayton-Cycle Engines
Authors: Korakianitis T. , Wilson D. G.
Published: April 2008

Gas turbine performance is the result of choices of type of cycle, cycle temperature ratio, pressure ratio, cooling flows, and component losses. The output is usually given as efficiency (thermal, propulsive, specific thrust, overall efficiency) versus specific power. This paper presents a set of computer programs for the performance prediction of shaft-power and jet-propulsion cycles: simple, regenerative, intercooled-regenerative, turbojet, and turbofan. Each cycle is constructed using individual component modules. Realistic assumptions are specified for component efficiencies as functions of pressure ratio, cooling mass-flow rate as a function of cooling technology levels, and various other cycle losses. The programs can be used to predict design point and off-design point operation using appropriate component efficiencies. The effects of various cycle choices on overall performance are discussed.
A New High-Efficiency Heavy-Duty Combustion Turbine 701F
Authors: Fukue I. , Aoki S. , Aoyama K. , Umemura S. , Merola A. , Noceto M. , Rosso M.
Published: April 2008

The 701F is a high-temperature 50 Hz industrial grade 220 MW size engine based on a scaling of the 501F 150 MW class 60 Hz machine, and incorporates a higher compressor pressure ratio to increase the thermal efficiency. The prototype engine is under a two-year performance and reliability verification testing program at MHI’s Yokohama Plant and was initially fired in June of 1992. This paper describes the 701F design features design changes made from 501F. The associated performance and reliability verification test program will also be presented.
Electric Drives on the LV100 Gas Turbine Engine
Authors: Jones W. D. , Fletcher A. R.
Published: April 2008

The LV100 gas turbine engine is being developed for U.S. Army ground vehicle use. A unique approach for controls and accessories is being used whereby the engine has no accessory gearbox. Instead a high-speed starter/generator is mounted directly on the compressor shaft and powers all engine accessories as well as supplies the basic electrical power needs of the vehicle. This paper discusses the evolution of the electrically driven LV100 accessory system starting with the Advanced Integrated Propulsion System (AIPS) demonstrator program, through the current system to future possibilities with electric vehicle propulsion. Issues in electrical vehicle propulsion are discussed including machine type, electrical power type, and operation with a gas turbine.
Investigation of the Part-Load Performance of Two 1.12 MW Regenerative Marine Gas Turbines
Authors: Korakianitis T. , Beier K. J.
Published: April 2008

Regenerative and intercooled-regenerative gas turbine engines with low pressure ratio have significant efficiency advantages over traditional aero-derivative engines of higher pressure ratios, and can compete with modern diesel engines for marine propulsion. Their performance is extremely sensitive to thermodynamic-cycle parameter choices and the type of components. The performances of two 1.12 MW (1500 hp) regenerative gas turbines are predicted with computer simulations. One engine has a single-shaft configuration, and the other has a gas-generator/power-turbine combination. The latter arrangement is essential for wide off-design operating regime. The performance of each engine driving fixed-pitch and controllable-pitch propellers, or an AC electric bus (for electric-motor-driven propellers) is investigated. For commercial applications the controllable-pitch propeller may have efficiency advantages (depending on engine type and shaft arrangements). For military applications the electric drive provides better operational flexibility.
Application of an Expert System to the Design of Furnace of a Circulating Fluidized Bed Boiler
Authors: Basu P. , Mitra S.
Published: April 2008

The design of a boiler using a new technology, i.e., circulating fluidized bed combustion, requires a considerable amount of expertise, which is a combination of experience, knowledge of the subject, and intuition. Boiler vendors, who are required to prepare a large number of proposals, rely heavily on the the skill and judgment of their senior (expert) designers. An artificial intelligence based expert system can greatly simplify this task. This system can assist expert designers to store their experience and decision-making skill through the code of a computer program, which remains intact and ready to apply their skill uniformly and rapidly to all designs when required. This may allow novice designers to carry out routine proposal designs, freeing the experts to improve current designs. The present paper gives an illustration of the use of expert systems to the design of only one aspect of the furnace, which is furnace cross section. It shows that in addition to the standard method of determining the furnace area from the fluidization, the design can take advantage of previous experience, which lists grate heat release rate and other relevant parameters. The expert system also modifies the calculated value to meet different concerns of the boiler purchaser and/or his consultants. Finally the expert develops a compromise of different considerations and requirements with importance attached to them. The paper also shows how the design will change when the importance attached to a particular constraint is relaxed.
GETRAN: A Generic, Modularly Structured Computer Code for Simulation of Dynamic Behavior of Aero- and Power Generation Gas Turbine Engines
Authors: Schobeiri M. T. , Attia M. , Lippke C.
Published: April 2008

The design concept, the theoretical background essential for the development of the modularly structured simulation code GETRAN, and several critical simulation cases are presented in this paper. The code being developed under contract with NASA Lewis Research Center is capable of simulating the nonlinear dynamic behavior of single- and multispool core engines, turbofan engines, and power generation gas turbine engines under adverse dynamic operating conditions. The modules implemented into GETRAN correspond to components of existing and new-generation aero- and stationary gas turbine engines with arbitrary configuration and arrangement. For precise simulation of turbine and compressor components, row-by-row diabatic and adiabatic calculation procedures are implemented that account for the specific turbine and compressor cascade, blade geometry, and characteristics. The nonlinear, dynamic behavior of the subject engine is calculated solving a number of systems of partial differential equations, which describe the unsteady behavior of each component individually. To identify each differential equation system unambiguously, special attention is paid to the addressing of each component. The code is capable of executing the simulation procedure at four levels, which increase with the degree of complexity of the system and dynamic event. As representative simulations, four different transient cases with single- and multispool thrust and power generation engines were simulated. These transient cases vary from throttling the exit nozzle area, operation with fuel schedule, rotor speed control, to rotating stall and surge.
Flex Cycle Combustor Development and Demonstration
Authors: Harris M. M. , Marsh D. N. , Vos E. A. , Durkin E.
Published: April 2008

An innovative, “flex-cycle” combustion system has been developed for the Garrett Model 400-1 Integrated Power Unit (IPU), a 425 shp (317 kW) gas turbine engine designed for use on future fighter aircraft. Demonstration of this system required real-time transient operation of the combustor in a full-scale test rig. The transient testing was unique, having been performed with an electronic control, which modulated all combustor operating parameters according to programmed engine component maps, drag curves, fuel schedules, and selected ambient test conditions. The axially injected annular combustor is capable of engine starts in two seconds, as well as producing 200 shp (149 kW) for emergency use at all altitudes up to 50,000 ft (15,240 m). The combustion system is capable of switching operation from the emergency power stored energy (SE) mode to the normal-air breathing (NAB) auxiliary power mode without loss of engine power. The flex-cycle combustor supplies emergency power in the SE mode with a temperature rise of 2200°F (1222°C) and in the NAB mode with a temperature rise of 1600°F (889°C). Specific features that make these requirements possible include air-assisted simplex airblast fuel atomizers with integral check valves, and effusion-cooled combustor liner walls. This paper describes the flex-cycle combustion system design, test methods used, and significant test results. Steady-state performance, in both the SE and NAB operating modes, and real-time transient test results are discussed. The transient testing included rapid starts as well as transitions from the SE to NAB operating regimes.
Experimental Investigation of GTE-115 Combustor With Premixed Burner Unit
Authors: Sokolov K. Y. , Tumanovsky A. G. , Gutnik M. N. , Mechanikov A. I. , Reshitko V. P. , Grinshtein M. I.
Published: April 2008

The results of experimental investigation of the basic parameters of one-burner, 1/18 sector of a full-scale annular combustor of the “Turboatom” GTE-115 gas turbine unit are presented. Specifics of fuel burnup and formation of toxic pollutants in premixed combustion using a pilot diffusion burner are presented. Generalized dependences of combustor characteristics versus flow parameters and an optimized algorithm of combustor loading are illustrated.
Low Emissions Combustor Development for an Industrial Gas Turbine to Utilize LCV Fuel Gas
Authors: Kelsall G. J. , Smith M. A. , Cannon M. F.
Published: April 2008

Advanced coal-based power generation systems such as the British Coal Topping Cycle offer the potential for high-efficiency electricity generation with minimum environmental impact. An important component of the Topping Cycle program is the gas turbine, for which development of a combustion system to burn low calorific value coal derived fuel gas, at a turbine inlet temperature of 1260°C (2300°F), with minimum pollutant emissions, is a key R&D issue. A phased combustor development program is underway burning low calorific value fuel gas (3.6-4.1 MJ/m3) with low emissions, particularly NOx derived from fuel-bound nitrogen. The first phase of the combustor development program has now been completed using a generic tubo-annular, prototype combustor design. Tests were carried out at combustor loading and Mach numbers considerably greater than the initial design values. Combustor performance at these conditions was encouraging. The second phase of the program is currently in progress. This will assess, initially, an improved variant of the prototype combustor operating at conditions selected to represent a particular medium sized industrial gas turbine. This combustor will also be capable of operating using natural gas as an auxiliary fuel, to suit the start-up procedure for the Topping Cycle. The paper presents the Phase 1 test program results for the prototype combustor. Design of the modified combustor for Phase 2 of the development program is discussed, together with preliminary combustion performance results.
Pressure and Temperature Distortion Testing of a Two-Stage Centrifugal Compressor
Authors: Cousins W. T. , Dalton K. K. , Andersen T. T. , Bobula G. A.
Published: April 2008

Altitude pressure and temperature inlet distortion testing of the two-stage centrifugal compressor in the T800-LHT-800 engine is described. The test setup and the testing techniques are reviewed and the results of the test are presented. The generation of classical 180 deg patterns of both pressure and temperature distortion is discussed. Temperature distortion was created using a hydrogen burner system while pressure distortion was created in the classical manner, using screens. Results of both individual and combined temperature and pressure distortions in both opposed and concurrent patterns are shown.
The Effect of Seal Width on Regenerator Effectiveness
Authors: Beck D. S.
Published: April 2008

The effect of axial conduction on regenerator effectiveness has been studied in the past under the assumption of zero seal width. The effect of axial conduction coupled with finite seal width is presented in this paper. A method for calculating effectiveness assuming axial conduction and finite seal width is presented. Results of sample calculations are presented to give the designer a feel for the dependence of seal-width effects on system-parameter values. It is shown that for typical regenerator designs, reductions in effectiveness due to axial conduction coupled with finite seal width can be twice as great as those due to axial conduction under the assumption of zero seal width. Also, it is shown that the required regenerator size to achieve a given effectiveness can increase dramatically when finite seal width is considered in design procedures. It is concluded that consideration of axial conduction should include finite seal width.
Full-Coverage Discrete Hole Film Cooling: Investigation of the Effect of Variable Density Ratio
Authors: Bazdidi-Tehrani F. , Andrews G. E.
Published: April 2008

Experimental results of the overall and adiabatic cooling effectiveness for full-coverage discrete hole film cooling are presented for a range of practical geometries. The results are reported for various hot gas mainstream-to-coolant temperature (density) ratios, in the realistic range of 1.0–3.2. The variation of this ratio was achieved by increasing the crossflow mainstream temperature, over the range 300–930 K. For combustor wall film cooling applications, the overall cooling effectiveness increased significantly with the number of holes per unit wall surface area, over the range of 4306–26910 m−2 and with the hole size, in the range of 1.0–2.2 mm, due to the improvement in film cooling. The effect of varying the mainstream-to-coolant temperature ratio, in the present range of 1.0–3.2, on the film cooling performance was shown to be small and no consistent trends were established for various configurations, for the coolant mass flow rates per unit wall surface area, less than 0.4 kg/sm2. At a higher value of 0.89 kg/sm2, an increase in the temperature ratio improved the film cooling performance slightly.
Study on the Turbine Vane and Blade for a 1500°C Class Industrial Gas Turbine
Authors: Amagasa S. , Shimomura K. , Kadowaki M. , Takeishi K. , Kawai H. , Aoki S. , Aoyama K.
Published: April 2008

This paper describes the summary of a three-year development program for the first-stage stationary vane and rotating blade for the next generation, 1500°C class, high-efficiency gas turbine. In such a high-temperature gas turbine, the first turbine vane and blade are the most important hot parts. Full-coverage film cooling (FCFC) is adopted for the cooling scheme, and directionally solidified (DS) nickel base superalloy and thermal barrier coating (TBC) will be used to prolong the creep and thermal fatigue life. The concept of the cooling configuration, fundamental cascade test results, and material test results will be presented.
Measurement of Residual Stresses in Metal Matrix Composites
Authors: Wright P. K.
Published: April 2008

Metal matrix composites (MMC) are expected to develop internal residual stresses on cooling from fabrication due to the large thermal expansion mismatch between reinforcing fibers and the matrix. This work was undertaken to measure experimentally these residual stresses and compare them with analytical calculations in order to establish clearly their levels and dependence on material parameters. Two techniques for residual stress measurement were investigated: (1) X-ray diffraction (sin2-psi method) and (2) neutron diffraction. Both techniques gave results in good agreement with analytical predictions for several systems (SCS-6/Ti-24Al-11Nb, W/NiAl, and Al2O3NiAl). The results obtained showed a dependence of residual stresses on thermal expansion coefficients, elastic moduli, volume fraction fibers, and matrix yield strengths. The fibers showed compressive stress states, and the matrix, tension. Average stresses were higher in the fiber direction than transverse to fibers.
Ceramic Composite Attachments for Transmission of High-Torque Loads
Authors: Brockmeyer J. W. , Straub A. C. , Krieg E. J.
Published: April 2008

The use of fiber-reinforced ceramic matrix composites (FRCMC) for advanced turbopump (T/P) hot-section components offers a number of potential advantages relative to the use of “conventional” materials. Among these advantages are reduced weight, enhanced life with reduced maintenance, and improved performance achievable by increasing the turbine inlet temperature. FRCMC are, however, emerging materials, and their design and analysis present unique challenges. These composites have relatively low thermal expansion coefficients and low strain-to-failure characteristics, and they have nonlinear, anisotropic properties. These characteristics particularly complicate the design of attachments to mating metallic components within a T/P. In an ongoing program, an FRCMC stator and rotor for a rocket engine T/P are being developed for eventual ground test demonstration. The rotor attachment is designed to transmit high-torque loads and provides an example of a design methodology that is compatible with current analytical capabilities. The approach used and described herein applies an empirically derived materials properties data base in combination with macromechanical analysis to reach a solution to this design challenge. This example demonstrates both the capabilities and the limitations of current design and analysis practices and provides direction for future development. A curvic coupling was chosen to meet the specific design goals and will be fabricated and tested to verify the design.
Stiffness Degradation in Metal Matrix Composites Caused by Thermomechanical Fatigue Loading
Authors: Aksoy S.
Published: April 2008

Damage during thermomechanical fatigue loading of a metal matrix composite is represented by a vector. The undamaged material is characterized by the generalized Hooke’s law for transversely isotropic materials. The residual elastic properties of metal matrix composite are related to the initial elastic properties by the damage vector. The residual stiffness properties are then correlated with the number of fatigue cycles to failure. The ability to use this concept to determine the safe strength requirement for a given cyclic life is discussed.