bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Performance of a Heat Flux Microsensor
Authors: Hager J. M. , Simmons S. , Smith D. , Onishi S. , Langley L. W. , Diller T. E.
Published: April 2008

The performance characteristics of a heat flux microsensor have been measured and analyzed. This is a new heat flux gage system that is made using microfabrication techniques. The gages are small, have high frequency response, can measure very high heat flux, and output a voltage directly proportional to the heat flux. Each gage consists of a thin thermal resistance layer sandwiched between many thermocouple pairs forming a differential thermopile. Because the gage is made directly on the measurement surface and the total thickness is less than 2 μm, the presence of the gage contributes negligible flow and thermal disruption. The active surface area of the gage is 3 mm by 4 mm, with the leads attached outside this area to relay the surface heat flux and temperature signals. Gages were made and tested on glass and silicon substrates. The steady and unsteady response was measured experimentally and compared with analytical predictions. The analysis was performed using a one-dimensional, transient, finite-difference model of the six layers comprising the gage plus the substrate. Steady-state calibrations were done on a convection heat transfer apparatus and the transient response was measured to step changes of the imposed radiative flux. As an example of the potential capabilities, the time-resolved heat flux was measured at a stagnation point with imposed free-stream turbulence. A hot-film probe placed outside the boundary layer was used to provide a simultaneous signal showing the corresponding turbulent velocity fluctuations.
Service Temperature Estimation of Turbine Blades Based on Microstructural Observations
Authors: Aurrecoechea J. M. , Brentnall W. D. , Gast J. R.
Published: April 2008

Optical and electron metallographic (SEM) examination was performed on MARM-421 samples subjected to controlled furnace exposures, to quantify the microstructural changes associated with the prolonged high-temperature exposures. Gamma prime size measurements were used to generate a mathematical model, based on diffusion-controlled kinetics, designed to estimate temperatures. This computational technique was utilized to estimate exposure temperatures of turbine blades that had seen service in land-based gas turbine engines. The engines had accumulated from 1200 to more than 98,000 hours, operating under a variety of conditions. The procedure is generally applicable to commonly used gamma prime strengthened nickel-base superalloys.
Fast Response Wall Pressure Measurement as a Means of Gas Turbine Blade Fault Identification
Authors: Mathioudakis K. , Papathanasiou A. , Loukis E. , Papailiou K.
Published: April 2008

The distortions of the pressure field around rotating blades of turbomachinery components due to alterations of their shape can be utilized for the identification of faults related to the blading. Measurement of the unsteady pressure field near the wall provides information on such flow and pressure distortions and can thus be used for diagnostic purposes. An experimental investigation of the compressor rotating blade pressure field of an industrial gas turbine has been undertaken, in order to demonstrate the feasibility of the abovementioned principle. Various realistic gas turbine blade faults have been examined. Application of the appropriate processing techniques demonstrates that unsteady pressure measurements can be used to identify the occurrence of minor blade faults (not traceable by standard techniques) as well as the kind of fault. The proposed methodology has the potential for being incorporated in a computerized engine health monitoring system.
Engineering Design of Tough Ceramic Matrix Composites for Turbine Components
Authors: Tan T. M. , Pastore C. M. , Ko F. K.
Published: April 2008

This paper provides a review of the material design concepts for the toughening of ceramic matrix composites by three-dimensional fiber architecture. To establish a communication link between the structural and the materials engineers, an integrated design methodology is presented with an example. Through a Fabric Geometry Model (FGM), the contribution of three-dimensional fiber architecture is translated into a stiffness matrix for finite element structural analysis. With the feedback from the structural analysis, this design methodology provides an effective means to screen reinforcement materials systems for three-dimensional fabric-reinforced composite components.
Marine Gas Turbine Evaluation and Research at the Admiralty Test House, RAE Pyestock
Authors: Bruce C. J. , Cartwright R. A.
Published: April 2008

The Admiralty Test House (ATH) at the Royal Aerospace Establishment Pyestock has provided test bed facilities for evaluation of marine gas turbines and ancillary equipments for Royal Naval use since 1952. While the ATH is presently undergoing an extensive refurbishment program in preparation for trials of the Rolls-Royce 20MW Spey SM1C, research continues on a number of innovative gas turbine condition monitoring techniques. This paper presents a brief history of the Marine Gas Turbine Section and describes the facilities of the ATH following major refurbishment. The capabilities of the steady-state and transient data gathering facilities are outlined, together with the automated engine and test control systems, which provide cost-effective engine evaluation in both endurance and minor equipment trials.
Simulation of an Advanced Twin-Spool Industrial Gas Turbine
Authors: Zhu Ping , Saravanamuttoo H. I. H.
Published: April 2008

A full-range mathematical model of the LM-1600 gas turbine has been developed, for future use in EHM studies. No data were available from the manufacturer other than sales brochures giving some design and off-design performance. The model was developed using generalized component characteristics and shows excellent agreement with field data from a pipeline operator. A new method has been developed for doing the matching calculations, starting from the turbine (hot) end rather than from the compressor operating point. This method permits solution on a PC, and can be used for studying the full range of operating conditions and the development of fault matrices.
Analytical Condition Inspection and Extension of Time Between Overhaul of F3-30 Engine
Authors: Nakao M. , Ikeyama M. , Abe S.
Published: April 2008

F3-30 is the low-bypass-ratio turbofan engine developed to power the T-4 intermediate trainer for the Japan Air Self Defense Force (JASDF). The actual field service was started in Sept., 1988. The program to extend time between overhaul (TBO) of the F3-30 has been running. Analytical condition inspection (ACI) and accelerated mission testing (AMT) were conducted to confirm sufficient durability to extend TBO. Most deteriorations of parts and performance due to AMT were also found by ACI after field operation with approximately the same deterioration rate. On the other hand, some deteriorations were found by ACI only. These results show that ACI after field operation is also necessary to confirm the TBO extension, although AMT simulates the deterioration in field operations very well. The deteriorations that would be caused by the field operation during one extended-TBO were estimated with the results of ACI and AMT, and it was concluded that the F3-30 has sufficient durability for TBO extension to the next step.
Optimal Measurement and Health Index Selection for Gas Turbine Performance Status and Fault Diagnosis
Authors: Stamatis A. , Mathioudakis K. , Papailiou K.
Published: April 2008

In this paper, we present a method for defining the health estimation parameters and the measurements that must be used when a monitoring system for an engine is being set up. The particular engine layout, the available measuring instruments, and the accuracy by which data can be collected are the factors taken into account. The particular health condition estimation factors that have to be used are defined as a function of this information and the desired depth of fault identification. A fast selection procedure based on the method of singular value decomposition is presented. The uncertainty in the estimations is also derived, thus giving an additional element of information useful for decision making. The proposed method, together with adaptive performance modeling, provides a self-sufficient tool, which can be applied for setting up and subsequent exploitation of a health monitoring expert system. The advantage of the procedure is that it provides a frame of application, allowing quick implementation in a new engine of interest, other than the ones previously considered.
Optimizing Instrumentation When Measuring Jet Engine Blade Vibration
Authors: Griffin J. H.
Published: April 2008

An analytical model of bladed disk vibration is used to calculate the statistical variations in blade amplitudes that can occur in mistuned turbomachinery blading. The results provide a basis for evaluating alternative strategies for instrumenting the stage. This approach is illustrated by applying it to an unshrouded fan stage. It is found for this stage that the best strategy is to instrument blades that have frequencies near the tuned system frequency. A procedure is proposed for establishing how gages should be allocated from stage to stage throughout the engine.
Optimization of LM2500 Gas Generator and Power Turbine Trim-Balance Techniques
Authors: Thompson B. D.
Published: April 2008

A procedure has been developed by the U.S. Navy to trim-balance, in-place, the gas generator and power turbine rotor of the LM2500 Marine Gas Turbine Engine. This paper presents the theoretical background and the techniques necessary to optimize the procedure to balance the gas generator rotor. Additionally, a method was developed to trim balance LM2500 power turbines. To expand the implementation of both gas generator and power turbine trim-balancing, a capability has to be developed to minimize the effort required (trial weight runs, etc.). The objective was to be able to perform consistently what are called “First-Shot” trim balances. First-Shot trim balances require only one weight placement to bring the engine vibration levels to within the specified goals (less than 0.002 of an in. maximum amplitude) and that being the final trim weight. It was realized that the Least-Squares Influence-Coefficient Method, even with a good set of averaged influence coefficients, can lead to a number of trial weight experiments before the final trim weights can be placed. The method used to maximize the possibility of obtaining a First-Shot trim balance was to use modal information to tailor the influence coefficient sets to correct the most predominant and correctable imbalance problem. Since the influence coefficients were tailored, it became necessary to be able to identify, in the initial vibration survey, the type of response a particular LM2500 has. Using modal information obtained from a LM2500 rotor dynamics model and from the early trim-balance efforts, it was possible to identify the modal response of a given LM2500 and optimize the trim balance of that engine. With these improved techniques a 70 percent success rate for First-Shot trim balance has been achieved and the success rate of the trim balance procedure, as a whole, has been near 100 percent.
High-Temperature Erosion Resistance of Coatings for Gas Turbine
Authors: Tabakoff W. , Hamed A. , Metwally M. , Pasin M.
Published: April 2008

An experimental investigation was conducted to study the ash particle rebound characteristics and the associated erosion behavior of superalloys and aluminide coatings subjected to gas-particle flows at elevated temperature. A three-component LDV system was used to measure the restitution parameters of 15 micron mean diameter coal-ash particles impacting some widely used superalloys and coatings at different angles. The presented results show the variation of the particle restitution ratios with the impingement angle for the coated and uncoated superalloys. The erosion behaviors of INCO-738, MAR 246 and X40 superalloys and protective coatings C, N, RT22 and RT22B also have been investigated experimentally at high temperature using a specially designed erosion tunnel. The erosion results show the effect of velocity, temperature and the impact angle on the erosion rate (weight loss per unit weight of particles). Based on the experimental results of the particle mass effect on both weight losses and erosion rates, the coating lives have been estimated for different particle concentrations.
Thermal Barrier Coating Life Prediction Model Development
Authors: Meier S. M. , Nissley D. M. , Sheffler K. D. , Cruse T. A.
Published: April 2008

A thermal barrier coated (TBC) turbine component design system, including an accurate TBC life prediction model, is needed to realize the full potential of available TBC engine performance and/or durability benefits. The objective of this work, which was sponsored in part by NASA under the Hot Section Technology (HOST) Program (Contract NAS3-23944), was to generate a life prediction model for electron beam-physical vapor deposited (EB-PVD) zirconia TBC. Specific results include EB-PVD zirconia mechanical and physical properties, coating adherence strength measurements, interfacial oxide growth characteristics, quantitative cyclic thermal spallation life data, and a spallation life model.
Thermal Strain-Tolerant Abradable Thermal Barrier Coatings
Authors: Strangman T. E.
Published: April 2008

Thermal barrier coatings (TBCs) are applied to hot gas path surfaces to reduce metal temperatures and thermal stresses for improved turbine component durability. Improvements in engine performance are achieved when TBCs enable reductions in cooling air usage and turbine blade tip-shroud clearances. This paper describes the development of thick TBCs with superior strain tolerance. A pattern of grooves or slant steps incorporated into the surface to be coated enables the development of shadow gaps in the ceramic layer during plasma spray deposition. These gaps segment the TBC, permitting ceramic-metal thermal expansion mismatch and thermal strains to be accommodated by free expansion.
Self-Induced Flow in a Stepped Rotating Tube
Authors: Gilham S. , Ivey P. C. , Owen J. M.
Published: April 2008

Self-induced flow occurs when a tube, open at one end and sealed at the other, is rotated about its central axis: Fluid flows along the axis from the open end toward the sealed end and returns in a layer adjacent to the inner surface of the tube. This mechanism, which can occur under isothermal or nonisothermal conditions, is believed to be responsible for the so-called “hot-poker effect” that was observed during anti-icing tests on the nose bullet of an aeroengine. This paper describes a combined theoretical and experimental study of self-induced flow. It is shown that, for the length-to-diameter (L/D) ratios and rotational Reynolds numbers associated with the anti-icing tubes of aeroengines, the laminar flow near the sealed end of the tube is similar to that of the so-called free disk. Swirl in the air outside the open end reduces the self-induced flow, but flow can reach the sealed end of a stepped tube that has either a sudden contraction or a sudden enlargement.
Fracture Mechanics Approach to Creep Growth in Welded IN738LC Gas Turbine Blades
Authors: Foo W. P. , Castillo R.
Published: April 2008

Microcracks caused by hot cracking or strain age cracking mechanisms are very likely to be discovered in the weld repair zone of precision-cast IN738LC gas turbine blades. The possibility of crack propagation under the operating conditions of the gas turbine thereby becomes a crucial issue for gas turbine designers. The creep crack growth rate in air of the hipped and fully heat-treated IN738LC was measured at the service temperature experienced by the first-stage turbine blade tip. The corresponding growth behavior was also studied. The creep crack growth rate, da/dt, versus crack tip stress intensity factor, KI, a relation that exhibits the typical primary, secondary, and tertiary behavior, supports the applicability of KI, as an appropriate correlating parameter for the creep crack growth of this Ni-based superalloy under the loading conditions used in this study. Microstructural examination illustrated that the creep crack growth of IN738LC principally takes place by the nucleation, growth, coalescence, and link-up of grain boundary microvoids and microcracks. An excellent approximation of the stress intensity factor under service loading conditions in the vicinity of the crack tip was obtained by using the Westinghouse WECAN finite element analysis. It is shown that the crack tip stress intensity factor under normal loading conditions will not be able to drive the transverse through-the-wall-thickness blade tip crack in this study.
HITCAN for Actively Cooled Hot-Composite Thermostructural Analysis
Authors: Chamis C. C. , Murthy P. L. N. , Singhal S. N. , Lackney J. J.
Published: April 2008

A computer code, HITCAN (High Temperature Composite Analyzer) has been developed to analyze/design hot metal matrix composite structures. HITCAN is a general purpose code for predicting the global structural and local stress-strain response of multilayered (arbitrarily oriented) metal matrix structures both at the constituent (fiber, matrix, and interphase) and the structure level and including the fabrication process effects. The thermomechanical properties of the constituents are considered to be nonlinearly dependent on several parameters, including temperature, stress, and stress rate. The computational procedure employs an incremental iterative nonlinear approach utilizing a multifactor-interaction material behavior model, i.e., the material properties are expressed in terms of a product of several factors that affect the properties. HITCAN structural analysis capabilities (static, load stepping—a multistep static analysis with material properties updated at each step, modal, and buckling) for cooled hot structures are demonstrated through a specific example problem.
Morphology of Globules and Cenospheres in Heavy Fuel Oil Burner Experiments
Authors: Kwack E. Y. , Shakkottai P. , Massier P. F. , Back L. H.
Published: April 2008

Number 6 fuel oil was heated, sprayed, and burned in an enclosure using a small commercial oil burner. Samples of residues that emerged from the flame were collected at various locations outside the flame and observed by a scanning electron microscope. Porous cenospheres, larger globules (of size 80 μm to 200 μm) that resemble soap bubbles formed from the very viscous liquid residue, and unburned oil drops were the types of particle collected. Qualitative relationships of the morphology of these particles to the temperature history to which they were subjected were made.
Temperature Effects on Fuel Thermal Stability
Authors: Chin J. S. , Lefebvre A. H. , Sun F. T.-Y.
Published: April 2008

The thermal stability characteristics of four kerosine-type fuels are examined using a heated-tube apparatus that allows independent control of fuel pressure, fuel temperature, tube-wall temperature, and fuel flow rate. It is a closed loop system, and fuel flows through the heated tube for periods ranging from 6 to 22 h. The deposition rates of carbon on the tube walls are measured by weighing the tube before and after each test. The results obtained show that tube-wall and fuel temperatures both have a marked influence on deposition rates, the impact of fuel temperature being stronger than that of wall temperature. It is also found that deposition rates increase continuously with increases in tube-wall temperature. This finding contradicts the results of previous studies, which had led to the conclusion that deposition rates increase with increase in wall temperature up to a certain value, beyond which any further increase in wall temperature causes the deposition rate to decline.
Two-Stage Slagging Combustor Design for a Coal-Fueled Industrial Gas Turbine
Authors: Cowell L. H. , LeCren R. T. , Tenbrook C. E.
Published: April 2008

A full-size combustor for a coal-fueled industrial gas turbine engine has been designed and fabricated. The design is based on extensive work completed through one-tenth scale combustion tests. Testing of the combustion hardware will be completed with a high pressure air supply in a combustion test facility before the components are integrated with the gas turbine engine. The combustor is a two-staged, rich-lean design. Fuel and air are introduced in the primary combustion zone where the combustion process is initiated. The primary zone operates in a slagging mode inertially removing coal ash from the gas stream. Four injectors designed for coal water mixture (CWM) atomization are used to introduce the fuel and primary air. In the secondary combustion zone, additional air is injected to complete the combustion process at fuel lean conditions. The secondary zone also serves to reduce the gas temperatures exiting the combustor. Between the primary and secondary zones is a Particulate Rejection Impact Separator (PRIS). In this device much of the coal ash that passes from the primary zone is inertially separated from the gas stream. The two-staged combustor along with the PRIS have been designated as the combustor island. All of the combustor island components are refractory-lined to minimize heat loss. Fabrication of the combustor has been completed. The PRIS is still under construction. The combustor hardware is being installed at the Caterpillar Technical Center for high pressure test evaluation. The design, test installation, and test plan of the full-size combustor island are discussed.
Prediction of Gas Turbine On- and Off-Design Performance When Firing Coal-Derived Syngas
Authors: Johnson M. S.
Published: April 2008

This paper describes a procedure used to model the performance of gas turbines designed to fire natural gas (or distillate oil) when fired on medium-Btu fuel, such as coal-derived syngas. Results from such performance studies can be used in the design or analysis of Gasification Combined Cycle (GCC) power plants. The primary difficulty when firing syngas in a gas turbine designed for natural gas is the tendency to drive the compressor toward surge. If the gas turbine has sufficient surge margin and mechanical durability, Gas Turbine Evaluation code (GATE) simulations indicate that net output power can be increased on the order of 15 percent when firing syngas due to the advantageous increase in the ratio of the expander-to-compressor mass flow rates. Three classes of single-spool utility gas turbines are investigated spanning firing temperatures from 1985°F-2500°F (1358 K-1644 K). Performance simulations at a variety of part-load and ambient temperature conditions are described; the resulting performance curves are useful in GCC power plant studies.
Motion and Evaporation of Shear-Driven Liquid Films in Turbulent Gases
Authors: Wittig S. , Himmelsbach J. , Noll B. , Feld H. J. , Samenfink W.
Published: April 2008

Detailed measurements of wavy liquid films driven by the shear stress of turbulent air flow are obtained for different air temperatures, air velocities, and flow rates of the liquid. The experimental conditions are chosen from characteristic data of liquid film flow in prefilming airblast atomizers and film vaporization employing combustors. For the measurement of the local film thickness and film velocity a new optical instrument—based on the light absorption of the liquid—has been developed, which can be used at high temperatures with evaporation. The measured data of the gas phase and the liquid film are compared with the results of a numerical code using a laminar as well as a turbulent model for the film flow and a standard numerical finite volume code for the gas phase. The results utilizing the two models for the liquid film show that the film exhibits laminar rather than turbulent characteristics under a wide range of flow conditions. This is of considerable interest when heat is transferred across the film by heating or cooling of the wall. With this information the optical instrument can also be used to determine the local shear stress of the gas phase at the phase interface. Using time-averaged values for the thickness, the velocity, and the roughness of the film, the code leads to relatively accurate predictions of the interaction of the liquid film with the gas phase.
Measurements of the Entrainment Coefficient of Acoustically Pulsed Axisymmetric Free Air Jets
Authors: Vermeulen P. J. , Rainville P. , Ramesh V.
Published: April 2008

Novel direct measurements of the entrainment coefficient in the initial zone of a pulsating air jet have been successfully accomplished. A series of pulsating air jets flowing from different nozzle orifice sizes into surrounding air were investigated for the effects of jet axial length, excitation power, and Strouhal number. The entrainment coefficient of the excited jet varied strongly with axial distance downstream of the orifice exit plane and with pulsation strength. The acoustic drive considerably increased the entrainment coefficient by up to 4.6 times at 10 diameters downstream of the nozzle. There was only a tendency for the entrainment coefficient to increase with the Strouhal number and hence an optimum Strouhal number for jet response was not found.
CFD Analysis of Jet Mixing in Low NOx Flametube Combustors
Authors: Talpallikar M. V. , Smith C. E. , Lai M. C. , Holdeman J. D.
Published: April 2008

The Rich-burn/Quick-mix/Lean-burn (RQL) combustor has been identified as a potential gas turbine combustor concept to reduce NOx emissions in High Speed Civil Transport (HSCT) aircraft. To demonstrate reduced NOx levels, cylindrical flametube versions of RQL combustors are being tested at NASA Lewis Research Center. A critical technology needed for the RQL combustor is a method of quickly mixing bypass combustion air with rich-burn gases. In this study, jet mixing in a cylindrical quick-mix section was numerically analyzed. The quick-mix configuration was five inches in diameter and employed 12 radial-inflow slots. The numerical analyses were performed with an advanced, validated 3-D Computational Fluid Dynamics (CFD) code named REFLEQS. Parametric varation of jet-to-mainstream momentum flux ratio (J) and slot aspect ratio was investigated. Both nonreacting and reacting analyses were performed. Results showed mixing and NOx emissions to be highly sensitive to J and slot aspect ratio. Lowest NOx emissions occurred when the dilution jet penetrated to approximately midradius. The viability of using 3-D CFD analyses for optimizing jet mixing was demonstrated.
Natural Gas Fueling of a Caterpillar 3406 Diesel Engine
Authors: Doughty G. E. , Bell S. R. , Midkiff K. C.
Published: April 2008

A Caterpillar 3406 turbocharged diesel engine was converted to operate in a natural gas with diesel pilot ignition mode and was evaluated for performance and emission characteristics for both diesel and natural gas operation. Full-load power was achieved with natural gas fueling without knock. Similar fuel efficiencies were obtained with natural gas fueling at high loads, but efficiencies were lower for low loads. Bosch smoke numbers were reduced by over 50 percent with natural gas fueling for all cases investigated. NOx emissions were found to be lower at low loads and at high speeds under high load. CO emissions were significantly increased for natural gas fueling while CO2 concentrations in the exhaust were reduced for natural gas fueling.
Emission Reductions Through Precombustion Chamber Design in a Natural Gas, Lean Burn Engine
Authors: Crane M. E. , King S. R.
Published: April 2008

A study was conducted to evaluate the effects of various precombustion chamber design, operating, and control parameters on the exhaust emissions of a natural gas engine. Analysis of the results showed that engine-out total hydrocarbons and oxides of nitrogen (NOx) can be reduced, relative to conventional methods, through prechamber design. More specifically, a novel staged prechamber yielded significant reductions in NOx and total hydrocarbon emissions by promoting stable prechamber and main chamber ignition under fuel-lean conditions. Precise fuel control was also critical when balancing low emissions and engine efficiency (i.e., fuel economy). The purpose of this paper is to identify and explain positive and deleterious effects of natural gas prechamber design on exhaust emissions.
Development of the Cooper-Bessemer CleanBurn™ Gas-Diesel (Dual-Fuel) Engine
Authors: Blizzard D. T. , Schaub F. S. , Smith J. G.
Published: April 2008

NOx emission legislation requirements for large-bore internal combustion engines have required engine manufacturers to continue to develop and improve techniques for exhaust emission reduction. This paper describes the development of the Cooper-Bessemer Clean Burn™ gas-diesel (dual-fuel) engine that results in NOx reductions of up to 92 percent as compared with an uncontrolled gas-diesel engine. Historically, the gas-diesel and diesel engine combustion systems have not responded to similar techniques of NOx reduction that have been successful on straight spark-ignited natural gas burning engines. NOx levels of a nominal 1.0 g/BHP-h, equal to the spark-ignited natural gas fueled engine, have been achieved for the gas-diesel and are described. In addition, the higher opacity exhaust plume characteristic of gas-diesel combustion is significantly reduced or eliminated. This achievement is considered to be a major breakthrough, and the concept can be applied to both new and retrofit applications.
Features and Performance Data of Cooper-Bessemer Coal-Fueled Six-Cylinder LSB Engine
Authors: Rao A. K. , Balles E. N. , Wilson R. P.
Published: April 2008

The six-cylinder Cooper-Bessemer LSB engine has been converted to operate with one cylinder on coal-water slurry (CWS) fuel and with five cylinders operating on diesel fuel. This development followed the successful operation of the single-cylinder JS engine on CWS for over 600 hours to date. The CWS injection system was scaled up about a factor of two in fuel volume from the JS system. A new cam box drive was fabricated for the LSB single-cylinder operation. The engine was operated and full power output was achieved from the CWS cylinder. Preliminary test results indicate good operate efficiency. An exhaust emission control system is in place for the proposed operation of all the six cylinders on CWS and major engine components are on hand. These results mark a significant milestone in the progress toward commercial readiness of the coal-fueled diesel engine system.
Implicit Numerical Model of a High-Pressure Injection System
Authors: Catania A. E. , Dongiovanni C. , Mittica A.
Published: April 2008

An implicit finite-difference numerical method has been developed and applied to the simulation of unsteady flow phenomena in a high-pressure injection system. A first-order one-step BSBT (backward space, backward time) scheme was used to obtain the difference analogue of the one-dimensional, elemental-volume averaged, partial differential equations governing the pressure-pipe flow. Second and higher-order implicit difference representations were employed for the ordinary differential equations simulating the pump and injector dynamics. The resultant nonlinear algebraic equations were solved by the Newton-Raphson method and a fast modified version of the Gaussian elimination procedure was used to solve the linearized equations. This was an extension of the Thomas solver to a multidiagonal system of algebraic equations. A compact, efficient and stable numerical algorithm was so obtained. The mathematical model takes into account the compressibility of the liquid fuel, the boundary shear, and also includes the simulation of possible cavitation occurrence at one or multiple locations in the injection system. No artificial viscosity has to be added to the solution in the vicinity of discontinuities induced by cavitation in the flow properties. The cavitation simulation is based on a simple mixture model of transient two-phase flow in pipes and can incorporate the effects of gaseous cavitation occurrence. Experimental values of the flow coefficients were used for the pump and injector and, for the latter, the dependence of the discharge coefficients on the needle lift and injection pressure was also taken into account. The model was tested and validated by comparing the numerical results with those of experiments carried out at the Fiat Research Center on a diesel-engine inline injection system, with a jerk-pump and an orifice type nozzle-injector.
Optimization of Injection Law for Direct Injection Diesel Engine
Authors: Feola M. , Pelloni P. , Cantore G. , Bella G. , Casoli P. , Toderi G.
Published: April 2008

This paper describes how different timing and shape of the injection law can influence pollutant emission of a direct injection diesel engine. The study was carried out making use of a “multizone” thermodynamic model as regards the closed valve phase, and a “filling-emptying” one as regards the open valve phase. After being calibrated by comparison with experimental data, the abovementioned model was used for injection law optimization as regards minimum pollutant concentration (NOx and soot) in the exhaust gases with the smallest engine performance reduction possible.
Application of Methods for Determining Total Organic Contribution to Diesel Particulates
Authors: Newkirk M. S.
Published: April 2008

This paper describes the laboratory effort to relate quantities of diesel particulate volatile organics obtained by DFI/GC™ to those obtained by traditional methods of organic analysis. Experiments were designed to investigate the potential usefulness of DFI/GC for determining the organic fraction and unburned lubricating oil contributions of diesel particulate emissions for future technology engines. A 1991 Caterpillar 3176 was used to generate samples during several heavy-duty engine test cycles, including the cold- and hot-start transient FTP and several steady-state conditions. Particulate-laden filter samples were then analyzed for organics by DFI/GC, solvent extraction, and vacuum volatilization. Results obtained using the three techniques were compared using statistical analysis techniques. Results showed that DFI/GC is extremely useful for directly determining the organic fraction of diesel particulate, and provides a better estimation of unburned lubricating oil contribution to the organic fraction than the other methods evaluated.
Development of the Long-Stroke Version of the Mitsubishi SU Diesel Engine
Authors: Nakamura Y. , Ito M. , Arakawa H.
Published: April 2008

A Mitsubishi S6U2 six-cylinder, in line diesel engine has been developed as a long-stroke version of the SU engine with a bore of 240 mm. This SU engine has a production record of more than 300 units. The stroke of this long-stroke version is 300 mm, compared with 260 mm for present SU engines. This paper introduces the S6U2 engine, which has now been put into regular production and describes research that has been conducted through the period of development. In the aspect of performance in particular, this paper explains reduction in fuel consumption by optimizing inlet and exhaust valve timings and improving turbocharger performance, and the reduction of NOx by modifying the fuel injection system. In the aspect of reliability, this paper explains FEM calculation with a three-dimensional model and a stress measurement under real operation for the crankshaft. The results of stress measurement on the crankcase are also described.
Catalytic Control of NOx, CO, and NMHC Emissions From Stationary Diesel and Dual-Fuel Engines
Authors: Bittner R. W. , Aboujaoude F. W.
Published: April 2008

Selective Catalytic Reduction (SCR) and oxidation catalyst technology have been applied to a stationary diesel and dual-fuel (natural gas and #2 diesel) engine for catalytic control of nitrogen oxides (NOx), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions. At rated conditions, NOx emissions have been effectively reduced by up to 90 percent, with little loss of SCR catalyst performance after 850 hours of operation. Using adequate control of the ammonia (NH3) feed, the SCR system was capable of maintaining NH3 slip to 10 ppm or less. CO and NMHC were reduced by 93 and 85 percent, respectively. Little soot was observed on the surface of the catalyst due to the use of a catalyst system that minimizes the buildup of heavy hydrocarbons on the catalyst surface. In addition, the catalyst structure effectively resisted the buildup of sulfur compounds that could cause premature deactivation of the catalyst.
Optimization of Advanced Steam Condition Power Plants
Authors: Silvestri G. J. , Bannister R. L. , Fujikawa T. , Hizume A.
Published: April 2008

The modern pulverized-coal power plant is the product of continuous design experience and component improvement in the 20th century. In recent years, studies of the effect of high temperatures on turbine materials have led to major worldwide research and development programs on improving the thermal cycle by raising turbine-inlet pressure and temperature. This paper reviews the importance of various parameters in trying to optimize a turbine cycle designed for advanced steam conditions. Combinations of throttle pressure (between 3500 psi [24.1 MPa] and 10,000 psi [70MPa]), throttle and reheat temperature(1000°F [538°C] to 1400°F [760°C]), and number of reheats are explored to establish a realistic turbine cycle design. Assessments and trade-offs are discussed, as applicable. Critical cycle components, feedwater cycle arrangements, and reheat pressure selections are analyzed in establishing an optimized steam turbine-boiler cycle for a 1000 MW turbine-generator. Applicability of results to smaller advanced steam turbines is given. A brief update on the high-temperature Wakamatsu turbine project in Japan is also given.
Development Potential of Combined-Cycle (GUD) Power Plants With and Without Supplementary Firing
Authors: Finckh H. H. , Pfost H.
Published: April 2008

Unfired combined cycles achieve superior efficiencies at low emission levels. The potential and efficiency limits are investigated and the possibilities for enhancing efficiency are described. It is demonstrated that limited supplementary firing of the heat recovery steam generator can be an interesting alternative and that this allows efficiency and plant size to be increased. The effects of supplementary firing on NOx emissions are also shown.
Gas Turbines Above 150 MW for Integrated Coal Gasification Combined Cycles (IGCC)
Authors: Becker B. , Schetter B.
Published: April 2008

Commercial IGCC power plants need gas turbines with high efficiency and high power output in order to reduce specific installation costs and fuel consumption. Therefore the well-proven 154 MW V94.2 and the new 211 MW V94.3 high-temperature gas turbines are well suited for this kind of application. A high degree of integration of the gas turbine, steam turbine, oxygen production, gasifier, and raw gas heat recovery improves the cycle efficiency. The air use for oxygen production is taken from the gas turbine compressor. The N2 fraction is recompressed and mixed with the cleaned gas prior to combustion. Both features require modifications of the gas turbine casing and the burners. Newly designed burners using the coal gas with its very low heating value and a mixture of natural gas and steam as a second fuel are developed for low NOx and CO emissions. These special design features are described and burner test results presented.
Biomass-Gasifier/Gas Turbine Cogeneration in the Pulp and Paper Industry
Authors: Larson E. D.
Published: April 2008

Increasing atmospheric carbon dioxide from fossil fuel combustion is raising new interest in using renewable biomass for energy. Modest-scale cogeneration systems using air-blown gasifiers coupled to aeroderivative gas turbines are expected to have high efficiencies and low unit capital costs, making them well-suited for use with biomass. Biomass-gasifier/gas turbine (BIG/GT) technology is not commercial, but efforts aimed at near-term commercialization are ongoing worldwide. Estimated performance and cost and prospects for commercial development of two BIG/GT systems are described, one using solid biomass fuel (e.g., wood chips), the other using kraft black liquor. At an energy-efficient kraft pulp mill, a BIG/GT cogeneration system could produce over three times as much electricity as is typically produced today. The mill’s on-site energy needs could be met and a large surplus of electricity would be available for export. Using in addition currently unutilized forest residues for fuel, electricity production would be nearly five times today’s level. The total cost to produce the electricity in excess of on-site needs is estimated to be below 4 cents per kWh in most cases. At projected growth rates for kraft pulp production, the associated biomass residue fuels could support up to 100 GW of BIG/GT capacity at kraft pulp mills worldwide in 2020 (30 GW in the US). The excess electricity production worldwide in 2020 would be equivalent to 10 percent of today’s electricity production from fossil fuels.
Status of Steam-Injected Gas Turbines
Authors: Tuzson J.
Published: April 2008

The injection of exhaust-heat-generated steam into gas turbines for power augmentation has been proven to provide exceptional flexibility of operation in cogeneration applications. The chronology of development of this technology is presented, including a list of available turbines. A description is then given of the design process for converting existing gas turbines to steam injection. Finally, the water purification issue, which is perceived by some as a barrier to cost-effective implementation of such installations, is addressed. It is shown that water purification cost is of the order of 5 percent of the fuel cost and is therefore not a decisive factor.
Optimal Operation of a Diesel Engine Cogeneration Plant Including a Heat Storage Tank
Authors: Ito K. , Yokoyama R. , Shiba T.
Published: April 2008

The effect of heat storage on a cogeneration plant is investigated using a mathematical programming approach. For a diesel engine plant, an optimal planning method is presented by which the operational policy of constituent equipment is determined together with the charging history of a heat storage tank so as to minimize the daily operational cost. An algorithm is designed to solve this optimization problem efficiently by combining the dynamic programming method with the mixed-integer programming one. Through a case study, it is made clear how the volume of the heat storage tank influences the daily operational policy and the long-term economy of the total plant.
Design Stage Acoustic Analysis of Natural Gas Piping Systems in Centrifugal Compressor Stations
Authors: Rogers L. E.
Published: April 2008

This paper presents design stage methods to analyze centrifugal compressor station piping acoustically. The methods have been successfully applied to the design of 26 stations since 1988. Full details of the calculation procedures are given, as well as guidelines for interpreting predicted results. Finally, the relationships between acoustic and mechanical response are described.
Integrated Flight/Propulsion Control for Flight Critical Applications: A Propulsion System Perspective
Authors: Tillman K. D. , Ikeler T. J.
Published: April 2008

The Pratt & Whitney and Northrop companies together, under the Air Force Wright Research and Development Center (WRDC) sponsored Integrated Reliable Fault-Tolerant Control for Large Engines (INTERFACE II) Program [1, 2], designed and demonstrated an advanced real-time Integrated Flight and Propulsion Control (IFPC) system. This IFPC system was based upon the development of physically distinctive, functionally integrated, flight and propulsion controls that managed the Northrop twin engine, statically unstable, P700 airplane. Digital flight control and digital engine control hardware were combined with cockpit control hardware and computer simulations of the airplane and engines to provide a real-time, closed-loop, piloted IFPC system. As part of a follow-on effort, lessons learned during the INTERFACE II program are being applied to the design of a flight critical propulsion control system. This paper will present both the results of the INTERFACE II IFPC program and approaches toward definition and development of an integrated propulsion control system for flight critical applications.
Future Trends in Turboshaft Engines up to the 5000 Horsepower Class
Authors: Vogt R. L.
Published: April 2008

Advanced technology now being demonstrated in the test cell will provide growth in existing engine ratings in the near term and substantially improve new technology engines early in the twenty-first century. The benefits these advancements provide, to the engines, to the salient characteristics important to users and designers, and to the vehicles they will power, are discussed.
Interference Effects of Very High Bypass Ratio Nacelle Installations on a Low-Wing Transport
Authors: Ingraldi A. M. , Kariya T. T. , Re R. J. , Pendergraft O. C.
Published: April 2008

A twin-engine, low-wing transport model, with a supercritical wing designed for a cruise Mach number of0.77 and a lift coefficient of 0.55, was tested in the 16-Foot Transonic Tunnel at NASA Langley Research Center. The purpose of this test was to compare the wing/nacelle interference effects of superfans (very high bypass ratio turbofans, BPR ≈ 18) with the interference effects of advanced turbofans (BPR ≈ 6). Flow-through nacelles were used in this study. Forces and moments on the complete model were measured using a strain gage balance and extensive surface static pressure measuements (383 orifice locations) were made on the model’s wing, nacelles, and pylons. Data were taken at Mach numbers from 0.50 to 0.80 and model angle-of-attack was varied from −4 to +8 deg. Results of the investigation indicate that superfan nacelles can be installed with approximately the same drag penalty as conventional turbofan nacelles.
Ceramic Oxide Coatings for the Corrosion Protection of Silicon Carbide
Authors: van Roode M. , Price J. R. , Stala C.
Published: April 2008

Silicon carbide is currently used as a structural material for heat exchanger tubes and related applications because of its excellent thermal properties and oxidation resistance. Silicon carbide suffers corrosion degradation, however, in the aggressive furnace environments of industrial processes for aluminum remelting, advanced glass melting, and waste incineration. Adherent ceramic oxide coatings developed at Solar Turbines Incorporated, with the support of the Gas Research Institute, have been shown to afford corrosion protection to silicon carbide in a simulated aluminum remelt furnace environment as well as in laboratory-type corrosion testing. The coatings are also protective to silicon carbide-based ceramic matrix composites.
Multikilowatt Lasers in Manufacturing
Authors: Banas C. M.
Published: April 2008

The fundamentals of laser beam interactions with materials are discussed briefly and unique laser processing capabilities are noted. Introduction of this processing capability to manufacturing is reviewed. Typical high-volume production application requirements are identified and representative performance and production experience are described. Specific multikilowatt laser welding, piercing, and hardfacing applications in aerospace production are described. The evolution of production processes is discussed against the background of required processing capability. Also discussed are the unique laser processing capabilities that resulted in selection of the laser for production. Production experience is reviewed and cost saving factors are noted.