bluuebunny/crossref_metadata_2025 huggingface dataset:
Engine Control Reliability and Durability Improvement Through Accelerated Mission Environmental Testing
Authors: Davies W. J. , Vizzini R. W.
Published: October 2009

The integration of aircraft control systems for future weapon systems will require the engine control system to meet the mission reliability of the flight control system. This will be accomplished through system redundancy and verified by accelerated environmental testing. Combined environment reliability testing (CERT) will assure control system structural integrity and reliability growth of engine-mounted digital electronic controls. Pratt & Whitney, under contract to the U.S. Navy, has recently completed a 10,000-hr CERT program. Dual full authority digital electronic controls (FADEC), connected by a fiber optic data link, were subjected to environmental tests simulating a composite F-14 mission profile. The FADEC units were also exposed to periodic high vibration levels which would be experienced after foreign object damage and salt spray testing to simulate aircraft carrier environment. The test results are reported herein providing insight not only into the reliability and durability of digital electronic controls but also into the equipment and procedures required for testing of future military and commercial engine control systems.
Maximum-Slew-Rate Control for Hydrogenerators
Authors: Jaeger J. , Wozniak L.
Published: October 2009

Traditionally, speed control of hydrogenerators has been implemented by analog proportional-plus-integral control of speed error. With digital controllers, nonlinear, adaptive control strategies may be implemented to achieve improved systems response. This paper develops a control scheme which responds to perturbations by moving wicket gates at their maximum slew rate. For a simulated 10 percent load rejection, the new controller reduced settling time by over 50 percent as compared to the equal-root-case PI controller. This was achieved while maintaining the same peak overshoot and keeping pressure within design limits. The deadbeat nature of the transient response promises decreased wear on mechanical components while substantially improving overall performance of hydrogenerators.
Periodic and Continuous Vibration Monitoring for Preventive/Predictive Maintenance of Rotating Machinery
Authors: Laws W. C. , Muszynska A.
Published: October 2009

The application of vibration monitoring as part of Preventive/Predictive Maintenance programs is discussed. Several alternative methods, including periodic and continuous monitoring techniques, are described. Emphasis is given to the importance of selecting vibration transducers with due regard for the specific machinery type. The equally important need to install monitoring systems which are cost effective and provide genuinely useful information for maintenance engineers and vibration analysts is also highlighted. It is argued that critical machinery should be monitored continuously, and in cases when more detailed investigation is required that high-quality Predictive Maintenance vibration analysis techniques be applied. The need is also emphasized for specialist interpretation of vibration data in order to identify specific machinery malfunctions, of which several examples are given.
Aeroelastic Behavior of Low-Aspect-Ratio Metal and Composite Blades
Authors: White J. F. , Bendiksen O. O.
Published: October 2009

The aeroelastic stability of titanium and composite blades of low aspect ratio is examined over a range of design parameters, using a Rayleigh-Ritz formulation. The blade modes include a plate-type mode to account for chordwise bending. Chord-wise flexibility is found to have a significant effect on the unstalled supersonic flutter of low-aspect-ratio blades, and also on the stability of tip sections of shrouded fan blades. For blades with a thickness of less than approximately 4 percent of chord, the chordwise, second bending, and first torsion branches are all unstable at moderately high supersonic Mach numbers. For composite blades, the important structural coupling between bending and torsion cannot be modeled properly unless chordwise bending is accounted for. Typically, aft fiber sweep produces beneficial bending-torsion coupling that is stabilizing, whereas forward fiber sweep has the opposite effect. By using crossed-ply laminate configurations, critical aeroelastic modes can be stabilized.
Quality Assurance in Manufacturing High-Performance Ceramics
Authors: Srinivasan M. , Earl M.
Published: October 2009

Quality assurance of ceramic components during various processing stages is an important ingredient in assuring the reliability in engineering applications. The current advances which are made in advanced nondestructive evaluation of finished components have been very useful. However, the importance of in-process quality control in closed-loop iterative process and product development has to be understood in terms of materials science aspects. This paper addresses some of the tools in nondestructive evaluation which are available in ceramic manufacture and gives illustrations of successful implementation of those techniques in two categories of ceramic applications, current and advanced. Further research and development needs in the NDE are also briefly addressed.
Adapting the Heat and Mass Transfer Analogy to Model Performance of Automotive Catalytic Converters
Authors: Mondt J. R.
Published: October 2009

Using theory for mass transfer of a diffusing specie with very low concentration, rate equations and a mass-balance equation can be combined to derive a differential equation for mass transfer in an automotive catalytic converter. A closed-form solution to this equation shows conversion efficiency to be a function of the dimensionless size of the converter, or the number of transfer units, Ntum. This mass-transfer-limited analysis does not include catalyst kinetics; hence it is limited to fully warm, fresh catalyst performance. However, a technique is developed to model lightoff of a catalytic converter by combining convective heat transfer when warming up with mass-transfer-limited conversion when fully warm. Realistic assessment of the merit of a catalytic converter must also include the influence of size and shape on flow pressure drop. Accordingly the size and shape of square-cell monoliths and packed-sphere bead beds are correlated with both conversion performance and pressure drop. Applications of these correlations are shown to compare realistically the size versus performance characteristic of monoliths with that for bead beds, in spite of drastically different flow patterns for the two converters. Model predictions are confirmed by engine-dynamometer and vehicle test results.
Effective Thermal Conductivity of Coal Ash Deposits at Moderate to High Temperatures
Authors: Anderson D. W. , Viskanta R. , Incropera F. P.
Published: October 2009

The effective thermal conductivity of coal ash deposits strongly influences heat transfer in pulverized coal-fired boilers. In this study thermal conductivity measurements were performed over a wide range of temperatures for fly ash, slagging deposits, and fouling deposits. The effects of ash particle size, thermal history, and physical structure of the deposit are discussed. Thermal history and deposit structure were observed to have the greatest influence on the local thermal conductivty, which increased by an order of magnitude with particle melting. Conductivities for solid-porous deposits were twice those of the same sample in particulate form.
Exergy Analysis of Combined Cycles: Part 2—Analysis and Optimization of Two-Pressure Steam Bottoming Cycles
Authors: Chin W. W. , El-Masri M. A.
Published: October 2009

Results of a study for selecting the optimum parameters of a dual-pressure bottoming cycle as a function of the gas turbine exhaust temperature are presented. Realistic constraints reflecting current technological practice are assumed. Exergy analysis is applied to quantify all loss sources in each cycle. Compared to a single pressure at typical exhaust gas temperatures the optimized dual-pressure configuration is found to increase steam cycle work output on the order of 3 percent, principally through the reduction of the heat transfer irreversibility from about 15 to 8 percent of the exhaust gas energy. Measures to further reduce the heat transfer irreversibility such as three-pressure systems or use of multicomponent mixtures can therefore only result in modest additional gains. The results for the efficiency of optimized dual-pressure bottoming cycles are correlated against turbine exit temperature by simple polynomial fits. Sensitivity of the results to variations in the constraint envelope are presented.
Development, Installation, and Operating Results of a Steam Injection System (STIG™) in a General Electric LM5000 Gas Generator
Authors: Burnham J. B. , Giuliani M. H. , Moeller D. J.
Published: October 2009

This paper describes the first full-scale field test of a steam injection system for a natural-gas-fired G.E. LM5000 gas generator for the purpose of: (a) decreased exhaust emissions, (b) increased power output, and (c) improved efficiency. It discusses the steam supply system, engine features, test results, and plant economics for steam injection into the combustor and compressor discharge sections of the LM5000 at rates up to 65,000 lb/hr (29,510 kg/hr).
Surface Flaw Reliability Analysis of Ceramic Components With the SCARE Finite Element Postprocessor Program
Authors: Gyekenyesi J. P. , Nemeth N. N.
Published: October 2009

The SCARE (Structural Ceramics Analysis and Reliability Evaluation) computer program on statistical fast fracture reliability analysis with quadratic elements for volume-distributed imperfections is enhanced to include the use of linear finite elements and the capability of designing against concurrent surface flaw-induced ceramic component failure. The SCARE code is presently coupled as a postprocessor to the MSC/NASTRAN general purpose, finite element analysis program. The improved version now includes the Weibull and Batdorf statistical failure theories for both surface and volume flaw-based reliability analysis. The program uses the two-parameter Weibull fracture strength cumulative failure probability distribution model with the principle of independent action for polyaxial stress states, and Batdorf’s shear-sensitive as well as shear-insensitive statistical theories. The shear-sensitive surface crack configurations include the Griffith crack and Griffith notch geometries, using the total critical coplanar strain energy release rate criterion to predict mixed-mode fracture. Weibull material parameters based on both surface and volume flaw-induced fracture can also be calculated from modulus of rupture bar tests, using the least-squares method with known specimen geometry and grouped fracture data. The surface flaw reliability prediction uses MSC/NASTRAN stress, temperature, and external boundary area output, obtained from the use of linear or quadratic shell and three-dimensional isoparametric finite elements. The statistical fast fracture theories for surface flaw-induced failure, along with selected input and output formats and options, are summarized. A sample problem to demonstrate various features of the program is included.
Hot Isostatic Pressing of Sintered Alpha Silicon Carbide Turbine Components
Authors: Ten Eyck M. O. , Ohnsorg R. W. , Groseclose L. E.
Published: October 2009

Hot isostatic pressing (HIPing) without encapsulation has been investigated with sintered alpha silicon carbide plates and Modulus of Rupture (MOR) bars made by dry pressing and with MOR bars and gas turbine rotors made by injection molding. Early HIPing trials indicated that substantial density increases up to 99.5 percent of theoretical could be achieved. At least 98 percent densification was consistently attainable on components initially having greater than 95 percent density and less than about 1 percent open porosity. Several HIPing cycles were investigated by varying maximum temperature, maximum pressure, and their respective rates. Analysis of densities, MOR bar strength and Weibull modulus, and microstructures were used to assess the influence of HIPing parameters on material properties. Vacuum spin test results and room temperature flexural strength data on MOR bars cut from HIPed rotors were compared with results from pressureless sintered rotors. Although densities and flexural strength showed improvement, data on rotor spin-test performance were inconclusive. Emphasis is now being placed on optimizing the HIPing cycle for gas turbine rotors.
Ash Behavior During Combustion and Deposition in Coal-Fueled Gas Turbines
Authors: Spiro C. L. , Kimura S. G. , Chen C. C.
Published: October 2009

Chemical and physical transformations of coal ash during combustion and deposition in gas turbine environments have been studied. Extensive characterization of the coal-water mixture fuel and deposits obtained on deposition pins and turbine nozzle vanes has been performed. The behavior of alkali metals has been found to be much different from that for petroleum fuels, resulting in lower than expected deposition and probable reduced corrosion rates.
Engine Valves—Design and Material Evolution
Authors: Larson J. M. , Jenkins L. F. , Narasimhan S. L. , Belmore J. E.
Published: October 2009

This paper reviews the design and material evolution of poppet valves used in reciprocating internal combustion engines in the United States. Driving forces which led to the current state-of-the-art technology, such as needs for improved durability and cost effectiveness, are described. This paper also endeavors to predict how valve materials, design, and construction will change over the next two decades in response to continual engine performance improvement demands in a worldwide competitive environment. As a basis for understanding the past evolution and future trends in valve design, the key operating parameters that affect valve function are detailed.
Caterpillar’s 3600 PEEC Locomotive Governor (Programmable Electronic Engine Control)
Authors: Burns S. R. , Evans R. G.
Published: October 2009

Caterpillar Inc. recently introduced the 3600 Series medium speed, 280 kW/cylinder diesel engine to its product line. Offered in 6 and 8 cylinder inline and 12 and 16 cylinder vee configurations, the 3600 Series engines will be used for marine, electrical power generation, industrial, and locomotive applications. Caterpillar has also developed a microprocessor-based digital electronic control to meet the applications of these engines. The control system can be tailored for many applications; however, this system was developed primarily for locomotive use. The PEEC (Programmable Electronic Engine Control) locomotive speed and load control governor provides minimum fuel consumption and increases productivity of locomotives in both mainline and switch yard service. This paper describes the PEEC locomotive system as applicable to 3600 Series engines.
Combustion Characteristics of a Single-Cylinder Open-Chamber Diesel Engine
Authors: Alkidas A. C.
Published: October 2009

The combustion characteristics of an open-chamber diesel engine were examined by means of heat-release analysis and flame luminosity measurements. Increasing the load was found to decrease premixed burning and correspondingly to increase diffusion burning. During most of the diffusion combustion the burning rate of the fuel appeared to be directly proportional to the amount of unburned fuel present in the cylinder. The duration of heat release in crank-angle degrees increased linearly with load and, in general, increased with decreasing engine speed and retarded injection timing. The measured duration of flame luminosity was significantly longer than the calculated duration of heat release, which suggested that emission of radiation continued long after the heat-release reactions ceased.
Reduction of NOx and Particulate Emissions in the Diesel Combustion Process
Authors: Wade W. R. , Hunter C. E. , Trinker F. H. , Cikanek H. A.
Published: October 2009

A model of the combustion and emission formation processes was formulated to identify modifications to combustion process parameters with potential for reducing NOx and particulate emissions in a diesel engine. The model was calibrated using data from an experimental, single-cylinder, direct injection diesel engine. Several combustion system modifications were made to the engine that reduced NOx and particulate emissions. The model was used to estimate the changes in the combustion process parameters responsible for the reductions observed. After calibration, the model was used to evaluate the effects of a wide range of modifications to the combustion process parameters on NOx and particulate emissions. These results were used to estimate changes in the combustion process parameters required to approach the objectives assumed for the 1991 Federal emission regulations for heavy-duty diesel engines. A reduction in the lubricating oil contribution to the particulate emissions was also projected to be required to approach the 1991 objectives.
Dual Fuel Engine Control Systems for Transportation Applications
Authors: Gettel L. E. , Perry G. C. , Boisvert J. , O’Sullivan P. J.
Published: October 2009

Microprocessor control systems have been developed for dual fuel diesel engines intended for transportation applications. Control system requirements for transportation engines are more demanding than for stationary engines, as the system must be able to cope with variable speed and load. Detailed fuel maps were determined for both normally aspirated and turbocharged diesel engines based on the criterion that the engine did not operate in the regimes where knock or incomplete combustion occurred. The control system was developed so that the engine would follow the detailed fuel map. The input variables to the control system are engine speed and load. Based on this, the system then controls the amount of natural gas and diesel fuel supplied to the engine. The performance of the system will be briefly summarized.
Operation of a Caterpillar 3516 Spark-Ignited Engine on Low-Btu Fuel
Authors: Macari N. C. , Richardson R. D.
Published: October 2009

The use of an engine-generator package, fueled by landfill gas, to produce usable electrical power has generated considerable interest among both landfill operators and engine manufacturers. Landfill gas operation presents some unusual technical challenges that require preparation of the gas prior to engine consumption as well as modifications to the spark-ignited engine. The primary obstacles to landfill gas operation are the low-Btu content of the gas, its poor combustion characteristics, and fluctuations in the heating value of the gas. Even so, the engine was not derated from the standard natural gas generator set rating of 762 kW net electrical output. In addition, the engine performance was optimized to meet the EPA site laws for stationary gas engines while still maintaining very low brake specific fuel consumption (BSFC). Finally, 90 days of continuous operation demonstrated engine durability.
Continued Development of a Coal/Water Slurry-Fired Slow-Speed Diesel Engine: A Review of Recent Test Results
Authors: Nydick S. E. , Porchet F. , Steiger H. A.
Published: October 2009

The results of tests performed on a slow-speed, two-stroke single-cylinder diesel engine show that thermal efficiency is approximately the same when fired with coal/water slurry fuels and diesel oil and that exhaust pollutant emissions, most notably NOx, are lower with the coal/water slurry fuels. Engine wear, particularly at the piston ring/cylinder liner interface, is considerably greater than that which occurs with liquid fuels. However, it is concluded that by means of technological advances regarding piston ring/cylinder liner materials, new designs, and new concepts in lubrication, a reliable and economical coal/water slurry-fired slow-speed engine can be developed.
Calculation of Integral Compressor Misalignments From Measured Web Deflections
Authors: James R. W. , Bishop L. E.
Published: October 2009

Exxon’s South Texas Division operates approximately 100 engine/compressors ranging from 1000 to 3400 hp (746–2535 kW) each. Traditionally, engine frame realignment procedures for these units have been basically trial and error. This paper presents an analytical procedure that eliminates much of the trial and error associated with engine frame realignment efforts by converting crankshaft web deflection readings to a profile of the main bearing shells. The program output indicates both the magnitude and direction of corrections that are needed to reduce any excessive web deflection readings. Raw field data are mathematically smoothed by a curve-fitting routine to provide insight on possible errors which could be easily overlooked in a visual examination of a web deflection survey. This paper addresses the key aspects of applying this approach in both routine evaluation and in major realignment work. Several examples are presented, including one case history showing how computer modeling of a 3400 hp (2535 kW) engine/compressor crankshaft profile permitted new chocks to be custom made before shutdown of the unit for realignment. This reduced downtime for the complete rechocking and realignment from 4 days to 14 h.
Induction System Effects on Small-Scale Turbulence in a High-Speed Diesel Engine
Authors: Catania A. E. , Mittica A.
Published: October 2009

The influence of the induction system on small-scale turbulence in a high-speed, automotive diesel engine was investigated under variable swirl conditions. The induction system was made up of two equiverse swirl tangential ducts, and valves of the same size and lift. Variable swirl conditions were obtained by keeping one of the inlet valves either closed or functioning, and by changing engine speed. The investigation was carried out for two induction system configurations: with both ducts operating and with only one of them operating. Two different engine speeds were considered, one relatively low (1600 rpm) and the other quite high (3000 rpm), the latter being the highest speed at which engine turbulence has been measured up to now. Cycle-resolved hot-wire anemometry measurements of air velocity were performed throughout the induction and compression strokes, under motored conditions, along a radial direction at an axial level that was virtually in the middle of the combustion chamber at top dead center. The velocity data were analyzed using the nonstationary time-averaging procedure previously developed by the authors. Correlation and spectral analysis of the small-scale turbulence so determined was also performed. The turbulence intensity and its degree of nonhomogeneity and anisotropy were sensibly influenced by the variable swirl conditions, depending on both the intake system configuration and engine speed; they generally showed an increase with increasing swirl intensity, at the end of the compression stroke. A similar trend was observed in the cyclic fluctuation of both the mean velocity and turbulence intensity. The micro time scale of turbulence was found to be almost uniform during induction and compression, showing a slight dependence on the measurement point and on the intake system configuration, but a more sensible dependence on the engine speed. No effect of the cylinder wall on turbulence was apparent.
Field Evaluation of Gas Turbine Protective Coatings
Authors: McMinn A. , Viswanathan R. , Knauf C. L.
Published: October 2009

The hot corrosion resistance of several protective coatings that had been applied to MAR-M-509 nozzle guide vanes and exposed in a utility gas turbine has been evaluated. The coatings included basic aluminide, rhodium-aluminide, platinum-rhodium-aluminide, and palladium-aluminide diffusion coatings, and cobalt-chromium-aluminum-yttrium (CoCrAlY) and ceramic overlay coatings. A combination of metallographic examination of vane cross sections and energy dispersive X-ray analysis (EDS) was employed in the evaluation. The results showed that none of the coatings was totally resistant to corrosive attack. The CoCrAlY and platinum-rhodium-aluminide coatings exhibited the greatest resistance to hot corrosion. The CoCrAlY coated vanes were, however, susceptible to thermal fatigue cracking. Except for the poor performance of the palladium-aluminide coating, the precious metal aluminides offered the best protection against corrosion. Hot isostatically pressing coatings was not found to be beneficial, and in one case appeared detrimental.
An Equation of State for Steam for Turbomachinery and Other Flow Calculations
Authors: Young J. B.
Published: October 2009

Large-scale equations of state for steam used for generating tables are unsuitable for inclusion infinite difference flow calculation computer codes. Such codes, which are in common use in the turbomachinery industry, may require 106 property evaluations before convergence is achieved. This paper describes a simple equation of state for superheated and two-phase property calculations for use in these circumstances. Computational efficiency is excellent and accuracy over the range of application is comparable to that of the large-scale equations. Further advantages are that complete thermodynamic consistency is maintained and the equation can be differentiated analytically for direct substitution into the gas dynamic equations where required. A truncated virial form is used to represent superheated properties and a new empirical correlation for the third virial coefficient of steam is presented.
Optimum Design Technique for Rotating Wheels
Authors: Hattori T. , Ohnishi H. , Taneda M.
Published: October 2009

Compressor rotors and turbine rotors are subject to centrifugal and thermal loads. These loads increase proportionally with tip speed, pressure ratio, and gas temperature. On the other hand, the rotor weight must be lessened to improve rotor dynamics and restrict bearing load. Thus, an optimum design technique is required, which offers the lightest possible wheel shape under the stress limit restriction. This paper introduces an optimum design system developed for turbomachinery rotors, and discusses several application results. The sequential linear programming method is used in the optimizing process, and centrifugal and thermal stress analyses of variable thickness rotating wheels are performed using Donath’s method. This system’s validity is confirmed by application to uniform-strength rotating disk problems and comparison with analytical results. This optimum design program is then applied to the design of axial flow compressor wheels.
On Predicting the Resonant Response of Bladed Disk Assemblies
Authors: Griffin J. H.
Published: October 2009

The vibratory responses of blades in gas turbine engines vary because of mistuning. An approach is developed for calculating the statistical distribution of peak resonant stresses in engine blading. It is used to predict the vibratory response of an un-shrouded fan stage. The results of the calculation compare favorably with test data for the lower frequency modes. The procedure can be used to predict fleet durability and offers a practical engineering approach for dealing with stage mistuning.
Effect of Fluid Inertia on the Performance of Squeeze Film Damper Supported Rotors
Authors: San Andres L. A. , Vance J. M.
Published: October 2009

The effect of fluid inertia on the synchronous steady-state operation of a centrally preloaded single mass flexible rotor supported in squeeze film bearing dampers is examined theoretically. For a model representative of some aircraft engine applications, frequency response curves are presented exhibiting the effect of fluid inertia on rotor excursion amplitudes and imbalance transmissibilities for both pressurized and unpressurized short open-ended squeeze film damper supports. It is shown that a significant reduction in amplitude response and transmitted force is possible for dampers operating at moderately large squeeze film Reynolds numbers. Furthermore, for unpressurized dampers the possibilities of bistable operation and jump phenomena are shown to be reduced and virtually disappear at sufficiently large operating Reynolds numbers.
Flow Losses in Stirling Engine Heat Exchangers
Authors: Jones J. D.
Published: October 2009

Closed-form expressions are sought which will allow the rapid and accurate calculation of pressure variation, flow velocities, and flow friction losses in crank-driven Stirling cycle machines. The compression and expansion spaces of the Stirling machine are assumed to be isothermal and their volumes are assumed to vary sinusoidally. It is further assumed that the cyclic pressure variation of the working fluid and the flow velocities within the passages of the machine can be represented by sinusoids. Closed-form expressions are deduced for the amplitude and phase of these variations. Using the expressions so deduced, formulae are derived for frictional losses in the three heat exchangers, taking into account the variation in mass flow rate over the cycle and the difference in amplitude of mass flow between the two ends of the regenerator. By comparing these expressions with calculations based on the assumption of an average flow rate over the cycle, it is shown that the latter method leads to flow losses being underestimated by more than 50 percent. It is recommended that the formulae deduced here be used for first-stage design work.
Steam-Injected Gas Turbine Integrated With a Self-Production Demineralized Water Thermal Plant
Authors: Cerri G. , Arsuffi G.
Published: October 2009

A simple steam-injected gas turbine cycle equipped with an exhaust heat recovery section is analyzed. The heat recovery section consists of a waste heat boiler, which produces the steam to be injected into the combustion chamber, and a self-production demineralized water plant based on a distillation process. This plant supplies the pure water needed in the mixed steam-gas cycle. Desalination plant requirements are investigated and heat consumption for producing distilled water is given. Overall steam-gas turbine cycle performance and feasibility of desalting plants are investigated in a firing temperature range from 1000.°C to 1400.°C for various compressor pressure and steam-to-air injection ratios. An example is reported.
Off-Design Exergy Audit of a Thermal Power Station
Authors: Yasni E. , Carrington C. G.
Published: October 2009

A second-law state analysis procedure, having on-line capability, has been implemented at a fossil-fueled power station at Huntly, N.Z. The analysis fully integrates the combustion and steam processes in order to provide a viable understanding of the influence of operating parameters on the distribution of losses within the plant. The procedures do not rely significantly on manufacturer’s performance data and the validity of the audit is substantially verifiable. Examples of audit data are presented, including operation with and without the top heater and a comparison of throttle and sliding pressure control.
Refinery Process Heater NOx Control by Staged Combustion Air Lances
Authors: Hunter S. C. , Hall R. E.
Published: October 2009

A vertically fired natural-draft petroleum-refinery crude-oil process heater was modified to reduce oxides of nitrogen (NOx) emissions by installing staged combustion air lances. Baseline NO emissions firing refinery gas before modification were measured to be 100 to 125 parts per million by volume, dry, corrected to 3 percent oxygen. Staged combustion air lances were installed to bypass combustion air around the burners to achieve staged combustion. With the modification, an average reduction of 64 percent in NO emissions was observed over a 30-day test period, with NO emissions of 25 to 50 ppm, dependent on the excess air. This method of combustion modification can be applied to most vertically fired process heaters where flame length increased by a factor of 2 to 4 would not cause flame impingement.
GASCAN—An Interactive Code for Thermal Analysis of Gas Turbine Systems
Authors: El-Masri M. A.
Published: October 2009

A general, dimensionless formulation of the thermodynamic, heat transfer, and fluid-dynamic processes in a cooled gas turbine is used to construct a compact, flexible, interactive system-analysis program. A variety of multishaft systems using surface or evaporative intercoolers, surface recuperators, or rotary regenerators, and incorporating gas turbine reheat combustors, can be analyzed. Different types of turbine cooling methods at various levels of technology parameters, including thermal barrier coatings, may be represented. The system configuration is flexible, allowing the number of turbine stages, shaft/spool arrangement, number and selection of coolant bleed points, and coolant routing scheme to be varied at will. Interactive iterations between system thermodynamic performance and simplified quasi-three-dimensional models of the turbine stages allow exploration of realistic turbine-design opportunities within the system/thermodynamic parameter space. The code performs exergy-balance analysis to break down and trace system inefficiencies to their source components and source processes within the components, thereby providing insight into the interactions between the components and the system optimization tradeoffs.
Gas Turbine Safety Improvement Through Risk Analysis
Authors: Crosby T. M. , Reinman G. L.
Published: October 2009

This paper is intended to provide the engineer with the information necessary to understand certain statistical methods that are used to improve system safety. It will provide an understanding of Weibull analysis, in that it describes when the Weibull distribution is appropriate, how to construct a Weibull plot, and how to use the parameters of the Weibull distribution to calculate risk. The paper will also provide the engineer with a comprehension of Monte Carlo simulation as it relates to quantifying safety risk. The basic components of Monte Carlo simulation are discussed as well as the formulation of a system model and its application in the gas turbine industry.
Solar Receiver for the Space Station Brayton Engine
Authors: Strumpf H. J. , Coombs M. G.
Published: October 2009

A study has been conducted on the preliminary design and development of a solar receiver to be used for electrical power production in a closed Brayton cycle engine on the NASA Space Station. The receiver incorporates integral thermal storage, using a eutectic mixture of LiF and CaF2 as the thermal storage solid-to-liquid phase change material (PCM). The thermal storage is required to enable power production during the substantial eclipse period which accompanies low-earth orbits. The design comprises a cylindrical receiver cavity. The walls of the cavity are lined with a series of tubes running the length of the cavity. The Brayton cycle working fluid flows through the tubes. The PCM is enclosed in individual, sealed metallic containment canisters which are stacked and thermally connected to the working fluid tube. The material for the working fluid tubes and containment canisters is the cobalt superalloy Haynes 188.
Improvement of Emissions From Diesel Engines
Authors: Morimatsu T. , Okazaki T. , Furuya T. , Furukawa H.
Published: October 2009

It is important to reduce emissions from diesel engines, which are used in the cogeneration systems. The mass transfer to the fuel spray plays various roles in fuel consumption rate and in trace species emission. High injection pressure and a re-entrant combustion chamber were used to make the mass transfer larger. The need for high injection pressure and controlled injection timing for NOx led the authors to use the new Komatsu fuel injection pump. This pump, which has a re-entrant combustion chamber, resulted in clean engine emissions and confirmed the importance of air entrainment to the spray.
Efficient and Low-Smoke Combustion of Various Low-Grade Fuels in High-Speed Small Diesel Engines
Authors: Murayama T. , Miyamoto N. , Chikahisa T. , Tosaka S.
Published: October 2009

In low-speed large diesel engines, low-grade or heavy petroleum fuels have long been used as an economy measure. Efficient use of various low-grade fuels has recently become a topic of great concern also for high-speed small diesel engines. This paper describes and analyzes improvements of the thermal efficiency and smoke emissions by fuel heating and blending with low-viscosity fuels in high-speed diesel engines with a range of low-grade or high-viscosity fuels.
Self-Ignition of Diesel Sprays and Its Dependence on Fuel Properties and Injection Parameters
Authors: Pischinger F. , Reuter U. , Scheid E.
Published: October 2009

The self-ignition process in diesel engines is influenced by many parameters, which are partially interrelated. In order to separate the influence of basic parameters, a special high-pressure, high-temperature vessel has been designed that allows injection in short intervals under defined and repeatable conditions. The evaluated parameters include: cetane number, viscosity and volatility, vaporization behavior, and ignition improving additives. In addition to other factors, the investigations showed that the cetane number itself is not sufficient to characterize the self-ignition properties especially of heavy fuels and fuels containing ignition improvers. Additionally, the influence of injection parameters was evaluated, including injection quantity, pressure level, and nozzle design.
A Dynamic Model of a Locomotive Diesel Engine and Electrohydraulic Governor
Authors: Rackmil C. I. , Blumberg P. N. , Becker D. A. , Schuller R. R. , Garvey D. C.
Published: October 2009

As part of a comprehensive simulation of a prototype locomotive propulsion system, a detailed model has been developed that predicts the dynamic response of an experimental two-stroke, turbocharged and intercooled diesel engine. Engine fueling and brake torque are computed from regression equations derived from an extensive data base. Corrections are applied to the calculated steady-state torque to account for dynamic deviations of in-cylinder trapped air-fuel ratio from the steady-state value. The engine simulation accurately represents the operation of the turbocharger, which is gear-driven at low turbocharger speeds, and freewheels through an overrunning clutch when exhaust energy accelerates the turbocharger beyond its geared speed. Engine fueling level, i.e., rack, is determined from a dynamic simulation of an electrohydraulic governor, which responds to the difference between the desired and the actual engine speeds. The governor representation includes: (1) finite rate of change of engine set speed; (2) load regulator feedback for control of applied engine loads; and (3) fuel limiting under conditions of excessively high load demand. The fundamentals of the engine/governor model are given in the paper along with examples that emphasize the dynamic operation of these particular components.
Progress on the Investigation of Coal-Water Slurry Fuel Combustion in a Medium Speed Diesel Engine: Part 2—Preliminary Full Load Test
Authors: Hsu B. D.
Published: October 2009

Full load (186 kW/cyl) operation using CWS fuel at 1050 rpm has been achieved on a single-cylinder GE-7FDL test engine. No major changes in engine parameters were made. With normal inlet air conditions, 3–5 percent pilot diesel fuel, separately injected or stratified into the main coal charge, was used. Inlet air temperature had to be raised about 40°C if no pilot diesel fuel was used. The coal burnout was about 95 percent and the cycle efficiency was comparable to using diesel fuel. The NOx and CO emissions were about 1/2 of those obtained normally with diesel fuel. The maximum heat release rate was higher than diesel fuel operation which resulted in higher maximum cylinder firing pressure. The combustion characteristic and its dependence on some fuel characteristics and inlet air parameters are discussed. Increasing coal burnout while limiting maximum cylinder firing pressure is the main objective of near future studies.
Operating Results of the Cooper-Bessemer JS-1 Engine on Coal–Water Slurry
Authors: Rao A. K. , Melcher C. H. , Wilson R. P. , Balles E. N. , Schaub F. S. , Kimberley J. A.
Published: October 2009

Successful operation of the Cooper-Bessemer JS-1 engine on coal–water slurry (CWS) fuel has been achieved at full power output, part load, and part speed conditions with varying degrees of diesel pilot fuel including zero pilot (auto-ignition of CWS). Selected results of the effect of pilot fuel quantity, pilot fuel timing, and manifold air temperature on engine performance are presented. Also, the influence of injector nozzle hole size and CWS mean particle size on engine performance is studied. High injection pressures resulted in good atomization of CWS and in combination with heated combustion air resulted in short ignition delays and very acceptable fuel consumption. Low CO/CO2 ratios in exhaust gas analysis confirmed good combustion efficiency. NOx emissions are compared for CWS and diesel fuel operation of the engine. Effect of injector nozzle hole size and manifold air temperature on NOx emissions is studied.
Coal–Water Slurry Operation in an EMD Diesel Engine
Authors: Urban C. M. , Mecredy H. E. , Ryan T. W. , Ingalls M. N. , Jett B. T.
Published: October 2009

The U.S. Department of Energy, Morgantown Energy Technology Center has assumed a leadership role in the development of coal-burning diesel engines. The motivation for this work is obvious when one considers the magnitude of the domestic reserves of coal and the widespread use of diesel engines. The work reported in this paper represents the preliminary engine experiments leading to the development of a coal-burning, medium-speed diesel engine. The basis of this development effort is a two-stroke, 900 rpm, 216-mm (8.5-in.) bore engine manufactured by Electro-Motive Division of General Motors Corporation. The engine, in a minimally modified form, has been operated for several hours on a slurry of 50 percent (by mass) coal in water. Engine operation was achieved in this configuration using a pilot injection of diesel fuel to ignite the main charge of slurry. A standard unit injector, slightly modified by increasing diametric clearances in the injector pump and nozzle tip, was used to inject the slurry. Under the engine operating conditions evaluated, the combustion efficiency of the coal and the NOx emissions were lower than, and the particulate emissions were higher than, corresponding diesel fuel results. These initial results, achieved without optimizing the system on the coal slurry, demonstrate the potential for utilizing coal slurry fuels.
Effects of Fuel Overpenetration and Overmixing During Ignition-Delay Period on Hydrocarbon Emissions From a Small Open-Chamber Diesel Engine
Authors: Kuo T.-W. , Wu K.-J. , Henningsen S.
Published: October 2009

A quasi-steady gas-jet model was applied to examine the spray trajectory in swirling flow during the ignition-delay period in an open-chamber diesel engine timed to start combustion at top dead center. Spray penetration, deflection, and the fractions of too-lean-mixed, burnable, and overpenetrated fuel at the start of combustion were calculated by employing the measured ignition delay and mean fuel-injection velocity. The calculated parameters were applied to correlate the measured exhaust hydrocarbon (HC) emissions. The engine parameters examined were bowl geometry, compression ratio, overall air-fuel ratio, and speed. Both the ignition delay and the relative spray-penetration parameter, defined as the ratio of the spray-penetration distances at the moments of start of combustion and wall impingement, gave good correlations for some of the engine parameters examined but could not explain all the measured trends. However, good correlation of the measured exhaust HC emissions was obtained by using the calculated too-lean-mixed and overpenetrated fuel fractions at the start of combustion. Correlation of the overpenetrated fuel with the measured HC indicated that approximately 2 percent of the fuel mass that overpenetrated before start of combustion emitted from the engine as unburned HC. This could account for 0 to 65 percent of the total HC emission from this engine. Additionally, it was found that the too-lean-mixed fuel could contribute 10 to 30 percent of the total HC emission, as found in a previous study on a somewhat similar engine. The remaining HC emission is caused by other sources such as bulk quenching.
The Application of Availability and Energy Balances to a Diesel Engine
Authors: Alkidas A. C.
Published: October 2009

The maximum power that can be extracted from an engine operating at a given condition was determined by means of analyses based on the first and second laws of thermodynamics. These analyses were applied to a heavy-duty single-cylinder open-chamber diesel engine operated at constant speed. Over the range of operating conditions investigated, the second-law efficiency (ratio of brake power to maximum extractable power) of the engine, which increased with engine load, was found to vary from 22 to 50 percent. It was concluded that besides heat transfer, the combustion process was the most important source of irreversibility and accounted for 25 to 43 percent of the lost power.
Heat Transfer With Insulated Combustion Chamber Walls and Its Influence on the Performance of Diesel Engines
Authors: Woschni G. , Spindler W.
Published: October 2009

Recently great expectations were put into the insulation of combustion chamber walls. A considerable reduction in fuel consumption, a marked reduction of the heat flow to the cooling water, and a significant increase of exhaust gas energy were predicted. In the meantime there exists an increasing number of publications reporting on significant increase of fuel consumption with total or partial insulation of the combustion chamber walls. In [1] a physical explanation of this effect is given: Simultaneously with the decrease of the temperature difference between gas and wall as a result of insulation, the heat transfer coefficient between gas and wall increases rapidly due to increasing wall temperature, thus overcompensating for the decrease in temperature difference between gas and wall. Hence a modified equation for calculation of the heat transfer coefficient was presented [1]. In the paper to be presented here, recent experimental results are reported that confirm the effects demonstrated in [1], including the influence of the heat transfer coefficient, which depends on the wall temperature, on the performance of naturally aspirated and turbocharged engines.
Study of the Steady-State Flow Pattern in a Multipulse Converter by LDA
Authors: Flamang P. , Sierens R.
Published: October 2009

This paper describes pressure and velocity measurements on a multipulse converter under steady-state conditions. Pressure loss coefficients were measured on this four-entry pulse converter system for a large number of flow configurations. Three-dimensional velocity measurements were done (with Laser-Doppler anemometry) for several flow configurations and at different cross sections in the converter. The normal flow situation (incoming flow at the four entries) and back flow situations were examined. For each cross section the axial velocity profiles, the secondary flow patterns, and the turbulent velocities are presented. From the pressure measurements mixing losses are derived. These are compared with the results of a one-dimensional calculation, which is based on the impulse law for incompressible flow. Taking into account the velocity measurements, this simplified model gives a remarkable agreement with the measured mixing losses.