bluuebunny/crossref_metadata_2025 huggingface dataset:
3-D Laser Anemometer Measurements in a Labyrinth Seal
Authors: Morrison G. L. , Johnson M. C. , Tatterson G. B.
Published: April 2008

The flow field inside a seven-cavity labyrinth seal with a 0.00127-m clearance was measured using a 3-D laser-Doppler anemometer system. Through the use of this system, the mean velocity vector and the entire Reynolds stress tensor distributions were measured for the first, third, fifth, and seventh cavities of the seal. There was one large recirculation region present in the cavity for the flow condition tested, Re = 28,000 and Ta = 7000. The axial and radial mean velocities as well as all of the Reynolds stress terms became cavity independent by the third cavity. The azimuthal mean velocity varied from cavity to cavity with its magnitude increasing as the flow progressed downstream.
Engine Performance Monitoring and Troubleshooting Techniques for the CF-18 Aircraft
Authors: Cue R. W. , Muir D. E.
Published: April 2008

The F404-GE-400 engines of the CF-18 aircraft are the first engines of the Canadian Forces to be maintained under a formal on-condition maintenance program. In support of this program, the Canadian Forces are developing advanced troubleshooting and performance monitoring procedures based on information recorded by the aircraft In-flight Engine Condition Monitoring System (IECMS). A suite of computer programs has been developed that enables maintenance personnel to access, display, and analyze in-flight event data recorded by the IECMS and to track the performance of individual engines based on “health indices” derived from the IECMS take-off ground roll recordings. The new techniques have been under evaluation at each of the CF-18 main operating bases for a period of approximately 14 months. Results to date indicate that the IECMS recordings provide a considerable amount of information of benefit to engine technicians and maintenance planners.
A Computer Code Using Exergy for Optimizing Thermal Plants
Authors: Bidini G. , Stecco S. S.
Published: April 2008

This paper presents an exergetic approach to reducing energy consumption in industrial plants. The minimum pinchpoint temperature difference is determined for several cases of heat exchange between hot and cold fluid streams with reduced thermal losses. The proposed method, designated TEXAS (Thermal and economic EXergetic Analysis of Systems), derives families of characteristic curves showing economic parameters versus exergetic efficiency in relation to factors such as heat transfer, surface, and scaling. As the method is highly affected by the economic parameter assumptions, the sensitivity of the variations in the parameters is also analyzed.
On the Leading Edge: Combining Maturity and Advanced Technology on the F404 Turbofan Engine
Authors: Powel S. F.
Published: April 2008

The overall design concept of the F404 afterburning turbofan engine is reviewed together with some of the lessons learned from over 2 million flight hours in service. GE Aircraft Engines’ derivative and growth plans for the F404 family are then reviewed including the “Building Block” component development approach. Examples of advanced technologies under development for introduction into new F404 derivative engine models are presented in the areas of materials, digital and fiber optic controls systems, and vectoring exhaust nozzles. The design concept and details of the F404-GE-402, F412-GE-400, and other derivative engines under full-scale development are described. Studies for future growth variants and the benefits of the F404 derivative approach to development of afterburning engines in the 18,000-24,000 lb (80-107 kN) thrust class and non-afterburning engines in the 12,000-19,000 lb (53-85 kN) class are discussed.
SNECMA M88 Engine Development Status
Authors: Corde J. C.
Published: April 2008

After describing the historical origins of the SNECMA M88 engine development program, the paper presents the general development planning until the production engine flight qualification at the end of 1995. Then the technical aspects of the program are emphasized: The main new technologies involved in the engine, the general arrangement, and the performance are described and the engine development, status is fully presented (development philosophy, main component tests, and complete engine tests).
Integrated Propulsion System Requirements for Control of STOVL Aircraft
Authors: Gallops G. W. , Weiss C. F. , Carlton R. A.
Published: April 2008

This paper describes an evaluation of propulsion system requirements and capability for a Short Take-Off/Vertical Landing (STOVL) aircraft employing modulation of the propulsive lift distribution for pitch and roll control in hover. The effects of propulsive lift nozzle configuration and propulsion system dynamic response were evaluated using a combined system simulation consisting of a six degree of freedom aircraft model, engine model, and integrated flight/propulsion control. The response and stability of propulsive lift control are compared with control by reaction jets supplied by engine bleed. Aircraft performance is demonstrated in simulated STOVL maneuvers using a dynamic pilot model. The conclusion of this study is that propulsive lift control of aircraft pitch and roll is feasible and can provide as much as a 10 percent increase in engine lift rating over systems that employ reaction control alone. The dynamic response of practical propulsive lift configurations, however, is less than that of reaction control configurations, which must be offset through integration of the propulsion system and its control.
Optimizing Aircraft Performance With Adaptive, Integrated Flight/Propulsion Control
Authors: Smith R. H. , Chisholm J. D. , Stewart J. F.
Published: April 2008

An adaptive, integrated flight/propulsion control algorithm called Performance Seeking Control (PSC) has been developed to optimize total aircraft performance during steady-state engine operation. The multimode algorithm will minimize fuel consumption at cruise conditions; maximize excess thrust (thrust minus drag) during aircraft accelerations, climbs, and dashes; and extend engine life by reducing Fan Turbine Inlet Temperature (FTIT) when the extended life mode is engaged. On-board models of the inlet, engine, and nozzle are optimized to compute a set of control trims, which are then applied as increments to the nominal engine and inlet control schedules. The on-board engine model is continually updated to match the operating characteristics of the actual engine cycle through the use of a Kalman filter, which accounts for anomalous engine operation. The PSC algorithm will be flight demonstrated on an F-15 test aircraft under the direction of the NASA Ames/Dryden Flight Research Facility. This paper discusses the PSC design strategy, describes the control algorithm, and presents results from high-fidelity, nonlinear aircraft/engine simulations. Simulation results indicate that thrust increases as high as 15 percent and specific fuel consumption reductions up to 3 percent are realizable by the PSC system.
Integration of a New Process Into an Existing Site: A Case Study in the Application of Pinch Technology
Authors: Linnhoff B. , Alanis F. J.
Published: April 2008

New production processes often need to be located in existing sites. Existing sites usually have existing utility systems providing electric power and steam in a limited number of existing mains. A site will have an overall power demand, be nearly balanced, or have a power surplus. Steam consumption, steam generation, power consumption, and power generation of a new process need to be economically assessed against the existing situation on site. Site average and site marginal costs help in this assessment. Changes in overall site production pattern, throughput, energy tariffs, etc., complicate the issue. This paper describes a specific situation. A new Nitric Acid plant is to be located in an existing site. Nitric Acid processes are net energy exporters and contractors tend to offer three basic options: steam export, power export, or a mixed option. The paper discusses how integration of each option affects the balance of the overall site utility system. Boiler feedwater needs to be supplied to the Nitric Acid plant, condensate is returned, the site fuel consumption changes, etc. The true marginal operating cost savings (Nitric Acid processes are energy exporters) are established for each option. The paper then proceeds to consider alternatives. First, it considers whether improvements can be made in the Nitric Acid process and in the existing site utility system separately. Objective targets are set using Pinch Technology and energy cost benefits are improved by 60 percent. Second, the question is posed whether a more fundamental approach would be appropriate. Rather than accepting optimized but separate designs for the Nitric Acid process and the site, could we integrate the Nitric Acid process and the site by allowing individual heat sources and heat sinks in the process to interact with the site utility system individually? This may sound complex and impractical. However, the paper demonstrates how the problem so defined can be tackled using Pinch Technology and how an alternative Nitric Acid process design emerges that is optimized specifically for the site. The design is practical and the energy cost benefits are approximately doubled. The paper is written with two objectives in mind. First, it is hoped to demonstrate the benefits of “site-specific optimization.” Second, it is hoped to demonstrate the benefits of Pinch Technology. The problem is totally defined (all data are given) before a solution is attempted. Realistic and clear assumptions are made so that the overall objective is clearly defined in terms of cost. While such black-and-white conditions are not usually given in practice, the benefit is that the reader is free to attempt his or her own solution using either technique or method and compare costs. It is hoped that, in particular, this will stimulate the use of the technique of Exergy Analysis and lead to a constructive dialogue in the literature concerning the relative merits of the techniques of Exergy Analysis and Pinch Technology.
Integration of a New Process Into an Existing Site: A Case Study in the Application of Exergy Analysis
Authors: Gaggioli R. A. , Sama D. A. , Qian Sanhong , El-Sayed Y. M.
Published: April 2008

This paper presents a case study that demonstrates how exergy analysis can help make intelligent process design decisions in a logical manner. A proposed, new nitric acid plant is to be intergrated into an existing facility wherein a steam system produces part of the facility’s power needs and all of the process steam, at three pressures. The objective is to minimize the expenditure for fuel and power under two scenarios: when the ratio R of power to fuel costs is 2.5, and when the ratio is 4. The procedure used was first to carry out exergy analyses of the three principal subsystems: (1) the process utilization, (2) the existing steam/power generation, and (3) the proposed HNO3 plant. Secondly, improvements of each of these subsystems were developed, independently, by systematically eliminating unnecessary thermodynamic inefficiencies. (For the steam plant and for the nitric acid plant, alone, improved reconfigurations have been presented earlier: Sama et al., 1988, 1989, respectively.) Finally, in this article, further opportunities for reducing inefficiencies, by integration of the three subsystems, were exploited. In the contractor’s original conceptual design with integration, the facility needs to purchase 77 MW of fuel and 2.2 MW of power. Improved designs developed here save equivalent fuel of over 45 MW when R=2.5 and over 60 MW when R=4 (i.e., 4.5 and 6.0 million dollars per year at a fuel cost of $100/kW-yr or $3.35/106 Btu).
A Computer Method for Thermal Power Cycle Calculation
Authors: Perz E.
Published: April 2008

This paper describes a highly flexible computer method for thermodynamic power cycle calculations (PCC). With this method the user can model any cycle scheme by selecting components from a library and connecting them in an appropriate way. The flexibility is not restricted by any predefined cycle schemes. A power cycle is mathematically represented by a system of algebraic equations. The structure of mathematical cycle models as well as different approaches to set up and solve the resulting equations with computer programs are discussed in the first section. The second section describes the developed method. The mass and energy balance equations are set up and solved with a semiparallel algorithm. As input only the cycle’s topology and component parameters must be entered. Information about the calculation sequence and the convergence method can be omitted completely. The example of two simple steam cycles demonstrates the applied technique. The method requires only a few, if any, iterations. Calculation time and storage requirements can be kept low enough to calculate even very complex cycles on personal computers. At the end of the paper input data and results for a complex cycle scheme as it may occur in reality are given to demonstrate the performance finally.
Combined Cycle Enhancement
Authors: Jericha H. , Hoeller F.
Published: April 2008

The Combined Cycle Plant (CCP) offers the best solutions to curb air pollution and the greenhouse effect, and it represents today the most effective heat engine ever created. At Graz University of Technology work is being conducted in close cooperation with industry to further enhancement of CC systems with regard to raising output and efficiency. Feasibility studies for intake air climatization, overload and part-load control, introduction of aeroderivate gas turbines in conjunction with high-temperature steam cycles, proposals for cooling, and the use of hydrogen as fuel are presented.
Options in Gas Turbine Power Augmentation Using Inlet Air Chilling
Authors: Ondryas I. S. , Wilson D. A. , Kawamoto M. , Haub G. L.
Published: April 2008

Gas turbine power augmentation in a cogeneration plant using inlet air chilling is investigated. Options include absorption chillers, mechanical (electric driven) chillers, thermal energy storage. Motive energy for the chillers is steam from the gas turbine exhaust or electrical energy for mechanical chillers. Chilled water distribution in the inlet air system is described. The overall economics of the power augmentation benefits is investigated.
Performance Curves for Single-Stage Vapor Compression Cycles With Solution Circuit
Authors: Amrane K. , Rane M. V. , Radermacher R.
Published: April 2008

The performance curves for a single-stage vapor compression heat pump with solution circuit (VCHSC) and for its modified version, the cycle using a subcooler and a preheater, are obtained and are compared for the same total UA value including all heat exchangers. The two cycles are simulated at low and high temperature lifts. The weak solution concentration and flow rate are varied. The parameters studied are the cooling COP, the solution heat exchanger (SHX) effectiveness, the pressure ratio, the solution temperature glides in the absorber and the desorber, the desorber load, and the distribution of the UA value. Changing the weak solution concentration from 20 to 90 wt% ammonia increased the desorber load ten times. The cooling COP improved by as much as 20 percent by incorporating the preheater and the subcooler, for both the low and the high temperature lifts. Compared to the conventional ammonia vapor compression cycle, the modified VCHSC showed a maximum improvement in cooling COP of 88 and 35 percent for the low and high temperature lifts, respectively. The results indicate that VCHSC is a very versatile heat pump and/or refrigeration system suitable for a wide range of applications and changing operating conditions.
A Method for the Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles
Authors: Murdock J. W. , Keyser D. R.
Published: April 2008

This paper describes a precise method for extrapolating the coefficient of discharge of PTC 6 throat tap nozzles using all or most of the calibration data. The theoretical basis for this method is described in a parallel paper [3]. Numerical examples are given using actual calibration data to describe this method. Because this method permits the use of all calibration data at or above Reynolds numbers of 1,000,000, it is a clear improvement over the PTC 6-1976 method, which permits only the highest single point.
Evaluating Thermographic Phosphors in an Operating Turbine Engine
Authors: Noel B. W. , Borella H. M. , Lewis W. , Turley W. D. , Beshears D. L. , Capps G. J. , Cates M. R. , Muhs J. D. , Tobin K. W.
Published: April 2008

The results of a field test in a commercial turbine engine showed that we can remotely measure the temperature of engine components in operating engines using thermographic phosphors. The remote-measurement method exploits the temperature dependence of the characteristic decay time of the laser-induced fluorescence of thermographic phosphors. This paper summarizes recent work leading up to and including a successful test of the thermographic-phosphor method in an operating turbine engine.
A Control System for a High-Quality Generating Set Equipped With a Two-Shaft Gas Turbine
Authors: Kumakura H. , Matsumura T. , Tsuruta E. , Watanabe A.
Published: April 2008

A control system has been developed for a high-quality generating set (150-kW) equipped with a two-shaft gas turbine featuring a variable power turbine nozzle. Because this generating set satisfies stringent frequency stability requirements, it can be employed as the direct electric power source for computer centers without using constant-voltage, constant-frequency power supply systems. Conventional generating sets of this kind have normally been powered by single-shaft gas turbines, which have a larger output shaft inertia than the two-shaft version. Good frequency characteristics have also been realized with the two-shaft gas turbine, which provides superior quick start ability and lower fuel consumption under partial loads.
Performance Deterioration in Industrial Gas Turbines
Authors: Diakunchak I. S.
Published: April 2008

This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.
Implanted Component Faults and Their Effects on Gas Turbine Engine Performance
Authors: MacLeod J. D. , Taylor V. , Laflamme J. C. G.
Published: April 2008

Under the sponsorship of the Canadian Department of National Defence, the Engine Laboratory of the National Research Council of Canada (NRCC) has established a program for the evaluation of component deterioration on gas turbine engine performance. The effect is aimed at investigating the effects of typical in-service faults on the performance characteristics of each individual engine component. The objective of the program is the development of a generalized fault library, which will be used with fault identification techniques in the field, to reduce unscheduled maintenance. To evaluate the effects of implanted faults on the performance of a single spool engine, such as an Allison T56 turboprop engine, a series of faulted parts were installed. For this paper the following faults were analyzed: (a) first-stage turbine nozzle erosion damage; (b) first-stage turbine rotor blade untwist; (c) compressor seal wear; (d) first and second-stage compressor blade tip clearance increase. This paper describes the project objectives, the experimental installation, and the results of the fault implantation on engine performance. Discussed are performance variations on both engine and component characteristics. As the performance changes were significant, a rigorous measurement uncertainty analysis is included.
Real-Time Estimation of Gas Turbine Engine Damage Using a Control-Based Kalman Filter Algorithm
Authors: Kerr L. J. , Nemec T. S. , Gallops G. W.
Published: April 2008

A second-generation Kalman filter algorithm is described that has sufficient accuracy and response for real-time detection and estimation of gas turbine engine gas path damage caused by normal wear, mechanical failures, and ingestion of foreign objects. The algorithm was developed for in-flight operation of aircraft engines but also has application for marine and industrial gas turbines. The control measurement and microcomputer requirements are described. The performance and sensitivity to engine transients and measurement errors is evaluated. The algorithm is demonstrated with actual engine data of ice and bird ingestion tests.
A Procedure for Automated Gas Turbine Blade Fault Identification Based on Spectral Pattern Analysis
Authors: Loukis E. , Mathioudakis K. , Papailiou K.
Published: April 2008

A method for diagnosing the existence and the kinds of faults in blades of a gas turbine compressor is presented in the present paper. The innovative feature of this method is that it performs the diagnosis automatically, that is, it gives a direct answer to whether a fault exists and what type of fault it is, without requiring the interpretation of results by a human expert. This is achieved by derivation of the values of discriminants calculated from spectral patterns of fast response measurement data. A decision about the corresponding engine status is then derived according to the values of the discriminants. In the paper, the procedure of examining the suitability of particular parameter discriminants and the constitution of a related knowledge base is described. The derivation of decisions by a computer, and on what engine condition a particular measurement data set corresponds, are then described.
Coating Effect on Particle Trajectories and Turbine Blade Erosion
Authors: Tabakoff W. , Metwally M.
Published: April 2008

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to improve the erosion resistance, nickel and cobalt superalloy blades and vanes are widely used in the hot section of gas turbines. Protective coatings have been used to enhance superalloy resistance to hot erosion. An investigation has been conducted to study coal ash particle dynamics and resulting blade erosion for both uncoated and coated blades of a two-stage axial flow gas turbine. A quasi-three-dimensional flow solution is obtained for each blade row for accurate computation of particle trajectories. The change in particle momentum due to collision with the turbine blades and casings is modeled using restitution parameters derived from three-component laser-Doppler velocimeter measurements. The erosion models for both blade superalloy and coatings are derived based on the erosion data obtained by testing the blade superalloy and coatings in a high-temperature erosion wind tunnel. The results show both the three-dimensional particle trajectories and the resulting blade impact locations for both uncoated and coated blade surfaces. In addition are shown the distribution of the erosion rate, impact frequency, impact velocity, and impact angle for the superalloy and the coating. The results indicate significant effects of the coating, especially on blade erosion and material deterioration.
High-Cycle Fatigue Design Evolution and Experience of Free-Standing Combustion Turbine Blades
Authors: Scalzo A. J.
Published: April 2008

Combustion turbine blade design criteria can generally be classified as either temperature or fatigue related. Since less is usually known about the factors influencing the fatigue phenomenon, it is considered the more challenging. In addition, as analytical and experimental techniques became more sophisticated and more accurate, the natural tendency was to replace archaic “guidelines” or “rules” with less conservative approaches that at times led to the discovery of new high-cycle fatigue “thresholds.” This paper presents the evolution of the combustion turbine blade high cycle fatigue design criteria for free-standing blades. It also presents the analysis and corrective actions taken to resolve several unique combustion turbine blade fatigue problems, all encountered over a 35-year period while the author has been employed at Westinghouse Electric Corporation. Included are high-cycle fatigue problems due to cooling air leakage, seal pin friction, and combustion temperature maldistribution, as well as flow-induced nonsynchronous vibration.
Analysis of Cracked Gas Turbine Blades
Authors: Bernstein H. L. , Allen J. M.
Published: April 2008

Results from an analysis of cracked first-stage blades (or buckets) from two General Electric MS7001E industrial/electric utility gas turbines are presented. Numerous cracks were observed along the leading-edge and midchord regions of the pressure and suction surfaces. In one unit cracks were found after 874 start-stop cycles, which included 218 trips from load and 11,000 service hours. Buckets in the sister engine were examined after 1800 cycles, which included 218 trips from load and 24,000 service hours. In both cases, cracks initiated in the platinum aluminide coating and propagated into the IN-738LC base metal. For the 11,000-hour bucket, 20-mil (0.5-mm) deep cracks were observed, and for the 24,000-hour bucket, the leading edge cracks had grown to the leading edge cooling hole, a distance of 0.2 in. (5 mm). The number of cycles to crack initiation was in good agreement with thermal mechanical fatigue (TMF) predictions from the REMLIF computer program, which is part of the Electric Power Research Institute’s (EPRI) Life Management System. The cracking was greatly accelerated by the large number of trips experienced. The extensive crack propagation that occurred is thought to have been strongly assisted by oxygen and sulfur penetration along the grain boundaries. The coating on the leading edge degraded from the original platinum-aluminide plus beta phases to a gamma prime phase after 24,000 hours of service, but it was still protective except where it was cracked. Where the coating was cracked, environmental attack of the interdiffusion zone and base metal occurred, resulting in spallation of the coating and preferential grain boundary attack. Operating and maintenance considerations for optimizing bucket life in demanding cyclic duty environments are also discussed.
TMFSLAM—Design Analysis Tool for Coated Structures
Authors: Bechtel G. S. , McKnight R. L. , Cook T. S.
Published: April 2008

Hot flowpath components in aircraft gas turbine engines are subject to a severe operating environment. The large thermal gradients can produce high thermal strains that, when combined with mechanical loads and a deleterious environment, can lead to premature failure. To combat this possibility, designers spend considerable time determining the stress and strain fields in these components as the parts undergo typical operating histories. These field quantities can then be used to determine failure parameters and determine life limiting locations. The field determinations can be difficult and, in combination with numerous potential failure mechanisms, the structural assurance process can take a considerable time to complete. To shorten this process, a personal computer (PC) based preliminary design system has been developed. This system, called Thermo-mechanical Fatigue—Structural Life Assessment Method (TMFSLAM), permits the user to rapidly evaluate the interactive effects of duty cycle, geometry, and materials on component life. The quantitative results determined by TMFSLAM will be available to make decisions on design changes, material substitution, etc.
Development Testing of Epicyclic Gearing
Authors: Yates D. E. , Lack G. J.
Published: April 2008

The increasing use of epicyclics for high-powered marine and industrial applications has resulted in world-wide interest in this type of gearing. The coaxial input and output, reduced losses, small size, and low weight are some of the advantages. The use of a full-size development test rig using the power circulation method has been fundamental to the evolution of double helical, flexible annulus epicyclics, and has led to a detailed understanding of their operating principles. This understanding has been essential for the analytical modeling and the development of innovative design concepts. The paper outlines some of the work that has been carried out in the test rig at NEI Allen Ltd.—Allen Gears. The method of measuring the dynamic load sharing is discussed and some of the results that have led to improvements in the design and manufacturing methods are given. Test rig work continues currently with the development of low-noise gears and vibration isolation.
A New Method for Calculating Burst Speed of Aeroengine Disks
Authors: Qilin Hong , Qixuan Zheng , Ping Wang , Guicang Hou
Published: April 2008

An approximate analytical large deformation method, based on the Nadai deformation theory, for calculating the burst speed of aeroengine disks, is presented in this paper. The basic equations are developed and the calculation procedures are illustrated. The burst speeds are calculated for some tested disks, and the calculation results are compared with the test results; the differences between two results are shown to be less than 8 percent. This shows that the new method is both simple and convenient. Therefore, it could be employed in the development of aeroengine disks.
The Transfer Number of Hydrocarbon Liquids
Authors: Odgers J. , Kretschmer D.
Published: April 2008

The transfer number (B) assumes considerable importance in the evaporation and diffusion of fuels prior to their combustion. Quite often the transfer number is assumed to be a constant for a given fuel. These notes examine the feasibility of this assumption. New correlations have been derived for the specific heats of the liquid fuels and their latent heats, over a wide range of temperatures and pressures, as also the effects of pressure upon the boiling characteristics. New prediction techniques are also proposed for critical temperatures and pressures. Taking note of the above correlations, it becomes possible to assess the values of B for a wide range of combustor operating conditions for any given fuel. The significance of these variations upon the probable combustion behavior of the fuels is then commented upon. The results show that the assumption of a constant value for B could lead to a significant misinterpretation of combustion behavior due to operating conditions and/or the use of different fuels.
Ceramic Candle Filter Performance at the Grimethorpe (UK) Pressurized Fluidized Bed Combustor
Authors: Stringer J. , Leitch A. J.
Published: April 2008

A pilot hot-gas particulate removal system, based on positive porous ceramic filters, has been tested on the Grimethorpe Pressurized Fluidized Bed Combustor facility. The filters are in the form of closed-ended tubes, 1.5 m long: These are generally called “candles.” The dust accumulates on the outside of the candles, and is periodically removed by a pulse of air into the candle interior, which then flows outward through the candle wall in the reverse direction to the normal flow of the combustion gas. The EPRI system contained a maximum of 130 candles, which is approximately equivalent to the requirement for 7 MW(e) capacity, depending on the filter-operating parameters. The filter unit operated for a total of 860 h under PFBC conditions, of which 790 h were at defined process conditions, typically 850°C and 10 bar. The amount of gas flowing through each filter element was varied, and the time between cleaning pulses also was varied. The pressure drop through each filter element rose as the dust accumulated on the outer wall, and recovered after the cleaning pulse. However, the post-cleaning pressure drop does not recover to the original clean candle value, but increases with time. It is believed that a steady-state value is attained, but the exposure in the Grimethorpe test series was insufficient to establish this unequivocally. During the test, five candles failed. This appears to have been due to mechanical shock, as a result of candles lifting because of excessive pressure differentials across their support plate, and dropping back. The failures are not believed to be intrinsic to the technology. However, in addition a reduction in the strength of the candles with time of exposure was observed. This might also attain a steady-state value, but this too could not be established on the basis of the tests reported in this paper. This is clearly a matter of importance, and further work will be required to determine the suitability of the clay-bonded silicon carbide medium used in these tests for this application. A number of deficiencies in the design of the unit emerged with the operating experience, and suggestions have been made for improvements. However, it is clear that further work on design optimization is required. The pulse-cleaning air usage in the tests was greater than would be economically acceptable in a practical system. Further work needs to be done to optimize the cleaning cycle. Overall, the test was very successful, and, when operating properly, the filters removed essentially all of the dust in the gas exiting from the combustor. Apart from the issues with the candle strength and the pulse-cleaning air usage, the other problems were not believed to be of major importance in the further development of the technology. This paper will summarize the test results, emphasizing the problems of candle durability and the pulse-cleaning system.
Development of an Innovative High-Temperature Gas Turbine Fuel Nozzle
Authors: Myers G. D. , Armstrong J. P. , White C. D. , Clouser S. , Harvey R. J.
Published: April 2008

The objective of the innovative high-temperature fuel nozzle program was to design, fabricate, and test propulsion engine fuel nozzles capable of performance despite extreme fuel and air inlet temperatures. Although a variety of both passive and active methods for reducing fuel wetted-surface temperatures were studied, simple thermal barriers were found to offer the best combination of operability, cycle flexibility, and performance. A separate nozzle material study examined several nonmetallics and coating schemes for evidence of passivating or catalytic tendencies. Two pilotless airblast nozzles were developed by employing finite-element modeling to optimize thermal barriers in the stem and tip. Operability of these prototypes was compared to a current state-of-the art piloted, prefliming airblast nozzle, both on the spray bench and through testing in a can-type combustor. The three nozzles were then equipped with internal thermocouples and operated at 1600°F air inlet temperature while injecting marine diesel fuel heated to 350°F. Measured and predicted internal temperatures as a function of fuel flow rate were compared. Results show that the thermal barrier systems dramatically reduced wetted-surface temperatures and the potential for coke fouling, even in an extreme environment.
Evaluation of NOx Mechanisms for Lean, Premixed Combustion
Authors: Corr R. A. , Malte P. C. , Marinov N. M.
Published: April 2008

The formation of the oxides of nitrogen, NOx, is examined through experiments and chemical kinetic modeling for lean, premixed combustion in a laboratory, atmospheric pressure, jet-stirred reactor. The experimental conditions are as follows: fuel-air equivalence ratio (φ) of 0.6, temperatures of 1460 to 1730 K, and reactor loadings of 20 to 150 kg/sec-m3 -atm2, which correspond to reactor mean residence times of 11.4 to 1.8 milliseconds. Two fuels are examined: ethylene, because of its importance as a combustion intermediate, and methane, because of its importance as a component of natural gas. Besides the premixed operation, the reactor also is operated nonpremixed. For both modes, the NOx increases with decreasing loading, from about 3–4 ppmv at the highest loading to about 11–21 ppmv at the lowest loading for the ethylene fuel. This increase in NOx occurs because a hot spot develops on centerline when the reactor is lightly loaded. Also for the lowest loading, the nonpremixed mode produces about twice as much NOx as the premixed mode, i.e., about 21 versus 11 ppmv. At the other reactor loadings, however, because of the intense mixing, the NOx levels are only slightly elevated for the nonpremixed mode compared to the premixed mode. Upon switching to methane fuel, the NOx decreases by about 25 percent. The major finding of this study is that prompt NO is the predominant mechanism for the NOx formed. The other mechanisms considered are the Zeldovich and nitrous oxide mechanisms. Furthermore, the amount of NOx measured and modeled agrees almost exactly with the extrapolation of Fenimore’s (1971) original prompt NO data to the present conditions of φ = 0.6. Although Fenimore conducted his experiments with porous plate and Meker-type burners for 0.8 ≤ φ ≤ 1.7, our findings show that his results apply well to high-intensity, lean combustion. In the gas turbine literature, e.g., see Shaw (1974) and Toof (1985), Fenimore’s results are expressed as: NO/(NO)equil=P1/2func(φ)(1) It is func (φ) that extrapolates well to our conditions. This finding indicates that func (φ) applies to laboratory burners of widely different mixing intensity, i.e., from Fenimore’s burners with structured flame fronts to our high-intensity burner with dispersed reaction. In our opinion, this finding strengthens the justification of using func (φ) for the prediction of NOx formation in practical combustors, including lean, premixed combustors.
Isothermal Flow Fields in a Research Combustor for Lean Blowout Studies
Authors: Sturgess G. J. , Heneghan S. P. , Vangsness M. D. , Ballal D. R. , Lesmerises A. L.
Published: April 2008

A propane-fueled research combustor has been designed and developed to investigate lean blowouts in a simulated primary zone of the combustors for aircraft gas turbine engines. To understand the flow development better and to ensure that the special provisions in the combustor for optical access did not introduce undue influence, measurements of the velocity fields inside the combustor were made using laser-Do¨ppler anemometry. These measurements were made in isothermal, constant density flow to relate the combustor flow field development to known jet behavior and to backward-facing step experimental data in the literature. The major features of the flow field appear to be consistent with the expected behavior, and there is no evidence that the provision of optical access adversely affected the flows measured.
1991 Soichiro Honda Lecture: Energy, Efficiency, and the Environment: Three Big Es of Transportation
Authors: Springer K. J.
Published: April 2008

The three big Es of transportation are Energy, Efficiency, and the Environment. As the clouds of global climate change and the desire to rely less on Mid-East crude builds, how do manufacturers and refiners reconcile the needs of consumer acceptance and governmental regulation? How can policies and practices be united so that everyone involved works to the common goal of personal mobility? This lecture traces recent events that have resulted in paradox on top of paradox. As industry continues to react to the latest round of air pollution regulations, where are we headed as far as new CAFE limits and the potential for additional longer term controls related to the greenhouse effect? These are issues that will affect those in the equipment and oil industry, as well as the consumer, in the days ahead.
Effects of Spark Plug Number and Location in Natural Gas Engines
Authors: Meyer R. C. , Meyers D. P. , King S. R. , Liss W. E.
Published: April 2008

Combustion experiments were conducted on a spark-ignited single-cylinder engine operating on natural gas. A special open chamber cylinder head was designed to accept as many as four spark plugs. Data were obtained to investigate the effects of spark plug quantity and location on NOx, HC, CO emissions, brake and indicated thermal efficiency, MBT timing, combustion duration, ignition delay, peak cylinder pressure, peak cylinder temperature, and heat release over a wide range of equivalence ratios.
The Effect of Injection Timing, Enhanced Aftercooling, and Low-Sulfur, Low-Aromatic Diesel Fuel on Locomotive Exhaust Emissions
Authors: Markworth V. O. , Fritz S. G. , Cataldi G. R.
Published: April 2008

An experimental study was performed to demonstrate the fuel economy and exhaust emissions implications of retarding fuel injection timing, enhancing charge air aftercooling, and using low-sulfur, low-aromatic diesel fuel for locomotive engines. Steady-state gaseous and particulate emissions data are presented from two 12-cylinder diesel locomotive engines. The two laboratory engines, an EMD 645E3B and a GE 7FDL, are each rated at 1860 kW (2500 hp) and represent the majority of the locomotive fleet in North America. Each engine was tested for total hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), and particulate. Emissions were measured at three steady-state operating conditions: rated speed and load, idle, and an intermediate speed and load. Test results on the EMD engine indicate that a 4 deg injection timing retard, along with a low-sulfur, low-aromatic fuel and enhanced aftercooling, was effective in reducing NOx from 10.5 g/hp-h to 7.2 g/hp-h; however, particulates increased from 0.15 g/hp-h to 0.19 g/hp-h, and fuel efficiency was 4.3 percent worse. Similar observations were made with the GE engine. This paper gives details on the test engines, the measurement procedures, and the emissions results.
Coal-Water Slurry Spray Characteristics of a Positive Displacement Fuel Injection System
Authors: Seshadri A. K. , Caton J. A. , Kihm K. D.
Published: April 2008

Experiments have been completed to characterize coal-water slurry sprays from a modified positive displacement fuel injection system of a diesel engine. The injection system includes an injection jerk pump driven by an electric motor, a specially designed diaphragm to separate the abrasive coal from the pump, and a single-hole fuel nozzle. The sprays were injected into a pressurized chamber equipped with windows. High speed movies and instantaneous fuel line pressures were obtained. For injection pressures of order 30 MPa or higher, the sprays were similar for coal-water slurry, diesel fuel, and water. The time until the center core of the spray broke up (break-up time) was determined both from the movies and from a model using the fuel line pressures. Results from these two independent procedures were in good agreement. For the base conditions, the break-up time was 0.58 and 0.50 ms for coal-water slurry and diesel fuel, respectively. The break-up times increased with increasing nozzle orifice size and with decreasing chamber density. The break-up time was not a function of coal loading for coal loadings up to 53 percent. Cone angles of the sprays were dependent on the operating conditions and fluid, as well as on the time and location of the measurement. For one set of cases studied, the time-averaged cone angle was 15.9 and 16.3 deg for coal-water slurry and diesel fuel, respectively.
Variable Geometry and Waste-Gated Automotive Turbochargers: Measurements and Comparison of Turbine Performance
Authors: Capobianco M. , Gambarotta A.
Published: April 2008

In turbocharging automotive Diesel engines, an effective method to extend the turbine flow range and control the boost level is the use of a variable geometry turbine (VGT): This technique can be very helpful to improve the transient response of the engine and reduce exhaust emissions. In order to compare the performance of variable geometry and conventional waste-gated turbines, a thorough experimental investigation was developed on a test facility at the Department of Energetic Engineering of the University of Genoa (DINE). Two VG turbines were considered: a variable area turbine (VAT) and a variable nozzle turbine (VNT). The VG turbines were compared with a fixed geometry waste-gated turbine in both steady and unsteady flow conditions, referring to mass flow and efficiency characteristics.
The Rational Efficiency of Power Plants and Their Components
Authors: Horlock J. H.
Published: April 2008

The use of a rational efficiency for a power plant (the work output divided by the maximum possible reversible work output) is well established for conventional and combined plants. However, there are in the literature several proposals for “second-law” efficiencies of power plant components and no universally agreed practice. The paper discusses these various proposals and recommends particular definitions for the efficiency of components. These definitions are consistent with the universally agreed definition for overall plant rational efficiency. The approach is illustrated by a numerical example.
Repowering Application Considerations
Authors: Brander J. A. , Chase D. L.
Published: April 2008

As utilities plan for load growth in the 1990s, they are faced with the difficulty of choosing the most economic generation while subject to a number of challenging constraints. These constraints include environmental regulations, particularly the new Clean Air Act, risk aversion, fuel availability and costs, etc. One of the options open to many utilities with existing steam units is repowering, which involves the installation of gas turbine(s) and heat recovery steam generator(s) (HRSG) to convert the steam plant to combined-cycle operation. This paper takes an overall look at the application considerations involved in the use of this generating option, beginning with a summary of the size ranges of existing steam turbines that can be repowered using the GE gas turbine product line. Other topics covered include performance estimates for repowered cycles, current emissions capabilities of GE gas turbines, approximate space requirements and repowering economics.
Shop Test Result of the V64.3 Gas Turbine
Authors: Jansen M. , Schulenberg T. , Waldinger D.
Published: April 2008

The V64.3 60-MW combustion turbine is the first of a new generation of high-temperature gas turbines, designed for 50 and 60 Hz simple cycle, combined cycle, and cogeneration applications. The prototype engine was tested in 1990 in the Berlin factories under the full range of operation conditions. It was equipped with various measurement systems to monitor pressures, gas and metal temperatures, clearances, strains, vibrations, and exhaust emissions. The paper describes the engine design, the test facility and instrumentation, and the engine performance. Results are given for turbine blade temperatures, compressor and turbine vibrations, exhaust gas temperature, and NOx emissions for combustion of natural gas and fuel oil.
Considerations on the Design Principles for a Binary Mixture Heat Recovery Boiler
Authors: Stecco S. S. , Desideri U.
Published: April 2008

The use of a binary mixture as a working fluid in bottoming cycles has in recent years been recognized as a means of improving combined cycle efficiency. There is, however, quite a number of studies dealing with components of plants that employ fluids other than water, and particularly binary mixtures. Due to different specific volume, viscosity, thermal conductivity, and Prandtl number, heat recovery boilers designed to work with water require certain modifications before they can be used with binary mixtures. Since a binary mixture is able to recover more heat from the exhaust fumes than water, the temperature difference between the hot and the cold fluids is generally lower over the whole recovery boiler; this necessitates greater care in sizing the tube bundles in order to avoid an excessive heat transfer surface per unit of thermal power exchanged. The aim of this paper is to provide some general criteria for the design of a heat recovery boiler for a binary mixture, by showing the influence of various dimensional parameters on the heat surface and pressure drop both in the cold and the hot side. Heat transfer coefficients and pressure drops in the hot side were computed by means of correlations found in the literature. A particular application was studied for an ammonia-water mixture, used in the Kalina cycles, which represents one of the most interesting binary cycles proposed so far.