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RESEARCH PAPERS

J. Eng. Gas Turbines Power. 1989;111(2):187-192. doi:10.1115/1.3240235.

The F100-PW-229 fighter aircraft engine is a higher thrust derivative of the F100-PW-220 and in the same frame size. The engine was developed from the F100 Engine Model Derivative (EMD) Program and parallel IR&D efforts. The increased thrust was achieved by increasing the flow and pressure ratio of the two-spool compression system accompanied by an increase in turbine temperature. The increased length compression system was offset by an innovative design intermediate case and a reduced length combustor to maintain overall engine axial length. The –229 engine has a thrust-to-weight ratio of 8.0 with a 20–30 percent performance increase over the –220 model across the flight map. Significant improvements in maintainability have been incorporated while retaining the proven durability and operability features of the –220 engine. The Government-industry partnership is working well, continually providing increased performance engines for our first-line fighters.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):193-199. doi:10.1115/1.3240236.

Commenced in 1982, the XG40 program is central to the demonstration of Rolls-Royce technology appropriate to the requirements of the advanced combat engine for mid-1990s operation. At the same time, the technology in scaled form is viewed as having wider application than for the advanced combat engine alone. This program is jointly funded by UK MoD and Rolls-Royce. In the paper the concepts and scope of the program are described. Associations with previous research programs and other advanced technology demonstrator programs of Rolls-Royce are stated. To meet the multirole capabilities of the advanced fighter and taking the European requirements in particular, the combat engine must be designed to give enhanced dry thrust, retain good dry specific fuel consumption, and reduce reheated fuel consumption compared with current fighter engines. A thrust/weight ratio of 10:1 is targeted and at the same time, requirements for operating cost, reliability, and durability are stringent. As a demonstrator, XG40 has been designed to meet the foregoing performance requirements. At the same time, advanced materials, manufacturing technology, and design of structures have been incorporated to enable the required levels of reliability, durability, component cost, and weight to be demonstrated. Although a demonstrator, XG40 was designed at a scale judged to be appropriate to the likely next generation European fighter requirement. Thus, the engine is in the 90/95 kN nominal Sea Level Static Combat thrust class. Configuration and design are discussed. XG40 is a total technology demonstration program. Principal modules each have a full-scale aerothermal rig program and appropriate structure rig programs. Apart from rigs, the program, including durability testing, utilizes a number of cores and engines plus spares. Achievements and progress toward milestones are reviewed.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):200-210. doi:10.1115/1.3240237.

In early 1988, Simpson Paper Company installed the world’s first GE LM5000 cogeneration plant with full high and low pressure steam injection. The full STIG LM5000 achieves a dramatic power increase (from 32.5 MW to 49.5 MW) and remarkable improvements in efficiency from 36 to 43 percent, while reducing NOx emissions from 225 to less than 25 ppmv before further reduction with SCR. The plant, installed at Ripon, CA, features: (1) 130,000 lb/hr (59,000 kg/h) of steam injection at three locations on the gas turbine; (2) the first-time use of SCR with the STIG LM5000 resulting in an ultimate NOx emission rate of 6-13 ppmv; (3) a unique feedwater heat exchanger arrangement to reduce boiler stack temperature to 250°F (121°C); and (4) an innovative submicron inlet air filtration system to minimize the need for compressor washing. The details of cycle selection, design, installation, performance, and economic benefits of this first full STIG installation provide a useful insight into the potential of a flexible new technology.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):211-217. doi:10.1115/1.3240238.

The 501F 60-Hz Combustion Turbine has been developed jointly by Westinghouse Electric Corporation and Mitsubishi Heavy Industries, Ltd. It continues a long line of large heavy-duty single-shaft combustion turbines by combining the proven efficient and reliable concepts of the W501D5 with the low NOx technology of the MW701D, together with the experience of the advanced cooled MF111. The new engine is described along with the improved evolutionary changes made from previous engines. Planned design and performance verification programs including model, full-scale component testing, and full-load engine tests are described. Mature output and efficiency in simple cycle mode will be 145 MW and 34 percent, respectively, with expected combined cycle efficiencies in excess of 50 percent.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):218-224. doi:10.1115/1.3240239.

A 145-MW blast furnace gas firing gas turbine combined cycle plant was designed and installed in a steel works in Japan as a repowering unit. A 124-MW large-scale gas turbine with turbine inlet temperature 1150°C (1423 K) was adopted as a core engine for the combined cycle plant. The fuel of this gas turbine is blast furnace gas mixed with coke oven gas. These are byproducts of steel works, and the calorific value of the mixed gas is controlled to be about 1000 kcal/Nm3 (4187 kJ/Nm3 ). A specially designed multicannular type combustor was developed to burn such a low Btu fuel. The gas turbine, generator, steam turbine, and fuel gas compressor are connected to make a single-shaft configuration. As a result of introducing the gas turbine combined cycle plant, the plant thermal efficiency was above 45 percent (at NET) and the total electricity generation in the works has increased from 243 MW to 317 MW. This paper describes the design features of this combined cycle plant.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):225-231. doi:10.1115/1.3240240.

Due to the recent popularity of small and medium-sized industrial gas turbines in many fields, gas turbines below 100 SHP have been employed as prime movers, a power range traditionally reserved for diesel and gasoline engines. Generally speaking, however, small gas turbines have many design difficulties in thermal efficiency, high rotational speed, compact auxiliary equipment, etc., derived from limitations of their dimensions. Small gas turbines S5A-01 and S5B-01, which have 32 PS output power at standard conditions, have been developed and are being produced. Presently, a 30 percent growth rated power producer for S5A-02 and S5B-02 gas turbines is under development. These engines’ configurations are as follows: single-stage centrifugal compressor; single-stage radial turbine; single can combustor; hybrid fuel nozzle with pressure atomizer and airblast atomizer; fuel control valve with pulse width modulation system; electric motor drive fuel pump. In this paper, the authors describe the design features and development history of the base engine and the experimental results with the growth rated version.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):232-236. doi:10.1115/1.3240241.

Methods to establish component reliability have been in existence for nearly forty years. However, these methods have not been applied to gas turbine systems, because of a lack of consistent definitions and methodology. This paper describes a systematic procedure for calculating control-system reliability, which also can be extended to calculations for mechanical equipment. This is accomplished by a computerized model. Using the results of this model, practical methods and configurations are described to improve gas turbine reliability, such as: redundancy of essential components; quality of components; environmental factors; sensing devices and actuators; and circuits and logic design. The paper also compares these methods and the resulting reliability improvements in system cost and complexity.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):237-243. doi:10.1115/1.3240242.

The desirability of being able to extract relevant fault diagnostic information from transient gas turbine data records is discussed. A method is outlined for estimating the effects of unmeasured fault parameters from input/output measurements. The resultant sensitivity of the technique depends on the sampling rate and the measurement noise.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):244-250. doi:10.1115/1.3240243.

The Canadian Department of National Defence has identified a need for improved Engine Health Monitoring procedures for the new Canadian Patrol Frigate (CPF). The CPF propulsion system includes two General Electric LM2500 gas turbines, a high-pressure-ratio engine with multiple stages of compressor variable geometry. A general method for predicting the thermodynamic performance of variable geometry axial compressors has been developed. The new modeling technique is based on a meanline stage-stacking analysis and relies only on the limited performance data typically made available by engine manufacturers. The method has been applied to the LM2500-30 marine gas turbine and the variations in engine performance that can result from a malfunction of the variable geometry system in service have been estimated.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):251-256. doi:10.1115/1.3240244.

Rolling element bearings require distinctly different techniques for monitoring and diagnostics from those used for fluid-film type bearings. A description of these techniques and the instrumentation used to acquire the necessary data is provided for comparison. Also included are some case studies to illustrate how these techniques are applied.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):257-263. doi:10.1115/1.3240245.

This paper presents a basis for selecting and justifying vibration monitoring equipment for power-generating gas turbines. Users of industrial gas turbines from utility and petrochemical companies are surveyed; a utility forced outage data base is analyzed; typical vibration limits are presented; and the current capabilities of commercial monitoring systems and vibration transducers are summarized. The industry survey by site visits and questionnaire develops common trends; it itemizes malfunctions that can be successfully identified with appropriate vibration monitoring; it summarizes current practices, benefits, limitations, and operating experience with various transducer types, as applied to harsh gas turbine environments. Vibration limits, trending, and sources of vibration are addressed. Operational factors are considered in planning and cost justifying vibration monitoring systems for a basic trip protection, periodic measurements, and on-line computerized continuous protection. Seventeen case histories and examples illustrate and support these findings. Analysis of the utility-generated data base complements the industry survey; it isolates the contribution of different vibration-related outages for base loaded and peaking units; graphic results break down these outages into duration, man-hours to repair, and frequency of occurrence.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):264-270. doi:10.1115/1.3240246.

Although considerable effort has been put into the study of steady-state vibration control, there are few methods applicable to transient vibration control of rotor-bearing systems. In this paper optimal control theory has been adopted to minimize rotor vibration due to sudden imbalance, e.g., blade loss. The system gain matrix is obtained by choosing the weighting matrices and solving the Riccati equation. Control forces are applied to the system via a feedback loop. A seven mass rotor system is simulated for illustration. A relationshp between the number of sensors and the number of modes used in the optimal control model is investigated. Comparisons of responses are made for various configurations of modes, sensors, and actuators. Furthermore, spillover effect is examined by comparing results from collocated and noncollocated sensor configurations. Results show that shaft vibration is significantly attenuated in the closed-loop system.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):271-278. doi:10.1115/1.3240248.

The programs in the structural analysis area of the HOST program emphasized the generation of computer codes for performing three-dimensional inelastic analysis with more accuracy and less manpower. This paper presents the application of that technology to Aircraft Gas Turbine Engine (AGTE) components: combustors, turbine blades, and vanes. Previous limitations will be reviewed and the breakthrough technology highlighted. The synergism and spillover of the program will be demonstrated by reviewing applications to thermal barrier coatings analysis and the SSME HPFTP turbine blade. These applications show that this technology has increased the ability of the AGTE designer to be more innovative, productive, and accurate.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):279-285. doi:10.1115/1.3240249.

This paper presents a summary of the life prediction methods developed under the NASA Lewis Research Center’s Hot Section Technology (HOST) program. A major objective of the fatigue and fracture efforts under the HOST program was to significantly improve the analytic life prediction tools used by the aeronautical gas turbine engine industry. This has been achieved in the areas of high-temperature thermal and mechanical fatigue of bare and coated high-temperature superalloys. Such technical improvements will eventually reduce life cycle costs. The cyclic crack initiation and propagation resistance of nominally isotropic polycrystalline alloys and highly anisotropic single crystal alloys have been addressed. A sizeable data base has been generated for three alloys [cast PWA 1455 (B–1900 + Hf), wrought Inconel 718, and cast single-crystal PWA 1480] in bare and coated conditions. Two coating systems, diffusion aluminide (PWA 273) and plasma-sprayed MCrAlY overlay (PWA 286), were employed. Life prediction modeling efforts were devoted to creep-fatigue interaction, oxidation, coatings interactions, multiaxially of stress-strain states, mean stress effects, cumulative damage, and thermomechanical fatigue. The fatigue crack initiation life models developed to date include the Cyclic Damage Accumulation (CDA) Model of Pratt & Whitney and the Total Strain Version of Strainrange Partitioning (TS-SRP) of NASA Lewis for nominally isotropic materials, and the Tensile Hysteretic Energy Model of Pratt & Whitney for anisotropic superalloys. The fatigue model being developed by the General Electric Company is based upon the concepts of Path-Independent Integrals (PII) for describing cyclic crack growth under complex non-linear response at the crack tip due to thermomechanical loading conditions. A micromechanistic oxidation crack extension model has been derived by researchers at Syracuse University. The models are described and discussed in the paper. Only limited verification has been achieved to date as several of the technical programs are still in progress and the verification tasks are scheduled, quite naturally, near the conclusion of the program. To date, efforts have concentrated on developement of independent models for cyclic constitutive behavior, cyclic crack initiation, and cyclic crack propagation. The transition between crack initiation and crack propagation has not been thoroughly researched as yet, and the integration of these models into a unified life prediction method has not been addressed.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):286-300. doi:10.1115/1.3240250.

This paper summarizes the structural analysis technologies and activities of the NASA Lewis Research Center’s gas turbine engine Hot Section Technology (HOST) program. The technologies synergistically developed and validated include: time-varying thermal/mechanical load models; component-specific automated geometric modeling and solution strategy capabilities; advanced inelastic analysis methods; inelastic constitutive models; high-temperature experimental techniques and experiments; and nonlinear structural analysis codes. Features of the program that incorporate the new technologies and their application to hot section component analysis and design are described. Improved and, in some cases, first-time three-dimensional nonlinear structural analyses of hot section components of isotropic and anisotropic nickel-base superalloys are presented.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):301-305. doi:10.1115/1.3240251.

Thermal barrier coating life models developed under the NASA Lewis Research Center’s Hot Section Technology (HOST) program are summarized. An initial laboratory model and three design-capable models are discussed. Current understanding of coating failure mechanisms is also summarized.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):306-309. doi:10.1115/1.3240252.

An augmenter viewing system employing a coherent fiber-optic array was developed for use in jet engine testing applications at AEDC. Real-time viewing of the test article afterburner was obtained in a severe environment under high temperature and vibration levels. The optical system consisted of a conventional front-end lens assembly coupled with the fiber-optic array, and a solid-state color video camera mounted inside the test cell. The advantages and problems associated with a fiber-optics-based viewing system will be discussed in comparison with more conventional viewing techniques for this application.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):310-317. doi:10.1115/1.3240253.

LDA measurements of the three mean velocity components and the corresponding turbulence intensities have been made to provide qualitative and quantitative information on the flow field in a water model of a can-type gas turbine combustion chamber. The combustor geometry comprised a swirl-driven primary zone, annulus-fed rows of primary and secondary jets, and an exit contraction. The effect of variation of the flow split between the swirler and the dilution holes on the flow pattern in the primary zone has been investigated in detail. Flow visualization studies revealed that significant changes occur in this region due to the interaction between the swirling flow and the radially directed primary jets. A large toroidal recirculation was formed and high levels of turbulence energy were generated in the core of the combustor at low levels of swirler flow rate. As the swirl level increases, the strength of this recirculation was observed to weaken. Beyond a critical level, the primary recirculation was pushed off center and the undesirable feature of a forward velocity on the combustor axis in the primary zone was observed. Despite the dramatic changes brought about in the primary zone, the flow pattern downstream of the secondary jets was practically the same for all flow splits due to the strong mixing caused by the two rows of jets.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):318-324. doi:10.1115/1.3240254.

A theory is presented for the calculation of rotordynamic coefficients for the fluid-rotor interaction in rotary atomizers, based on calculation of the fluid flow through a whirling atomizer wheel. The theory predicts potentially unstable rotor whirl in high-speed rotary atomizers. The whirl frequency can be that of the first critical forward or the first critical backward precession of the rotor, depending on atomizer wheel geometry, speed, fluid properties, and flow rate. The predicted whirl phenomena have been produced in an atomizer test stand. Both forward and backward precession have been observed to become unstable. The observed whirl directions and amplitudes are consistent with the calculated coefficients. Some design parameters are identified that can help control and suppress the whirl.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):327-334. doi:10.1115/1.3240257.

This paper discusses the theory of evaporative cooling and describes the application of wetted rigid media evaporative coolers to gas turbines. Calculations of parameters used to predict evaporative cooler performance are included. Also included are discussions of evaporative cooler design, installation, operation, feedwater quality, and the causes and prevention of water carry-over.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):335-342. doi:10.1115/1.3240258.

Investigations into the thermodynamic processes in labyrinth seal flow fields have been carried out using the nonintrusive optical technique of holographic interferometry. Labyrinth seals in the form of two-dimensional actual size models were used. The types of seal geometry tested reflected those in current use in aerogas turbines, their sizes being typically 10 mm × 20 mm in section with sealing constrictions as small as 0.25 mm. The tests provided a great deal of information that had not previously been available and confirmed several experimental and theoretical results that were not fully understood. The data were obtained in the form of isodensity contour maps. These full field density measurements of the test section flow were analyzed in several ways to provide an insight into the processes occurring within the labyrinth seal. The effects of kinetic energy carry-over upon seal stage performance were dramatically demonstrated in both straight-through and stepped seals. Useful qualitative, as well as quantitative, information regarding the flow field structure could be obtained from the isodensity maps. An indication of particular flow features was obtained at a glance. The optical technique was found to be ideally suited to the investigations and the expected difficulties associated with working in the very small test sections did not arise. The configuration of the optical system ensured that image aberrations were minimized and temporal flow instabilities did not adversely affect the isodensity contour maps. The paper reviews the optical technique and presents a selection of the holographic results along with their interpretation.

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1989;111(2):343-350. doi:10.1115/1.3240259.

As part of an ongoing investigation into the effects of compressor fouling on gas turbine performance, the stage stacking technique was used in conjunction with generalized turbine characteristics to simulate the performance of two common pipeline engines, the G. E. LM2500 and the Solar Centaur. A linear fouling model was introduced that simulates the progressive buildup of contaminants in the compressor by modifying the appropriate stage flow and efficiency characteristics in a stepwise fashion. This simulation of the onset and progressive nature of compressor fouling allows quantitative analysis of performance deterioration to be performed on the basis of trends noted in monitored parameters. A preliminary study into how severely a given level of fouling will affect engines of different size indicated that stage loading may be the more critical parameter.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster

TECHNICAL BRIEFS

Commentary by Dr. Valentin Fuster

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