bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomass-Gasifier Steam-Injected Gas Turbine Cogeneration
Authors: Larson E. D. , Williams R. H.
Published: April 2008

Steam injection for power and efficiency augmentation in aeroderivative gas turbines is now commercially established for natural gas-fired cogeneration. Steam-injected gas turbines fired with coal and biomass are being developed. In terms of efficiency, capital cost, and commercial viability, the most promising way to fuel steam-injected gas turbines with biomass is via the biomass-integrated gasifier/steam-injected gas turbine (BIG/STIG). The R&D effort required to commercialize the BIG/STIG is modest because it can build on extensive previous coal-integrated gasifier/gas turbine development efforts. An economic analysis of BIG/STIG cogeneration is presented here for cane sugar factories, where sugar cane residues would be the fuel. A BIG/STIG investment would be attractive for sugar producers, who could sell large quantities of electricity, or for the local electric utility, as a low-cost generating option. Worldwide, the cane sugar industry could support some 50,000 MW of BIG/STIG capacity, and there are many potential applications in the forest products and other biomass-based industries.
The Evolution of Marine Gas Turbine Controls
Authors: Sylvestre R. A. , Dupuis R. J.
Published: April 2008

The background and evolution of gas turbine fuel controls is examined in this paper from a Naval perspective. The initial application of aeroderivative gas turbines to Navy ships utilized the engine’s existing aircraft fuel controls, which were coupled to the ship’s hydropneumatic machinery control system. These engines were adapted to Naval requirements by including engine specific functions. The evolution of Naval gas turbine controllers first to analog electronic, and more recently, to distributed digital controls, has increased the system complexity and added a number of levels of machinery protection. The design of a specific electronic control module is used to illustrate the current state of the technology. The paper concludes with a discussion of the further need to address the issues of fuel handling, metering and control in Navy ships with particular emphasis on integration in the marine environment.
Practical Design Considerations for Integrating the Propulsion System With the Aircraft for Jetborne Flight
Authors: Groll D. B. , Bossart T. R.
Published: April 2008

Results of a pilot-in-the-loop simulator evaluation for engine and configuration variations to the AV-8B Harrier II aircraft are presented. Configurations were tested for various center of gravity locations, weights, pitching moments of inertia, and thrust center locations in jetborne flight. The effects of the propulsion system’s characteristics in relation to aircraft parameters are generalized with regard to pitch handling qualities such as control power, pitch sensitivity, disturbance susceptibility, and control margin. A proposed modification to improve pitch handling qualities also was evaluated and results for this modification are discussed.
Some Aerodynamic Aspects of Engine Secondary Air Systems
Authors: Zimmermann H.
Published: April 2008

Internal cooling air systems of turbomachines contain various fluid flow components, i.e., rotating holes, tapping configurations, coverplates, labyrinth seals, etc., for which only the basic aerodynamics are known. Numerical calculations for these elements are carried out and compared with test results showing fair agreement in general. For most of the components of internal air systems there is a serious lack of test data. It is shown that the situation can be relieved by applying numerical methods, which also should be used to improve and extend the empirical correlations in the air systems computer programs.
Threshold Performance Optimization of a Rotor-Bearing System Subjected to Leakage Excitation
Authors: Wang J. H. , Shih F. M.
Published: April 2008

Fluid leakage in blade tips in turbomachinery may induce instability and limit and output rating. In this work, the optimization technique has been used to find diameters of shaft elements and bearing supports so that the optimized rotor-bearing system can sustain a larger fluid leakage force. The results show that the threshold performance of rotor-bearing systems can be significantly improved by slight modifications of the shaft diameters. The results also indicate that the threshold performance can be improved more significantly by the combination of optimum bearing supports and optimum shaft diameters.
Noninteractive Macroscopic Reliability Model for Ceramic Matrix Composites With Orthotropic Material Symmetry
Authors: Duffy S. F. , Manderscheid J. M.
Published: April 2008

A macroscopic noninteractive reliability model for ceramic matrix composites is presented. The model is multiaxial and applicable to composites that can be characterized as orthotropic. Tensorial invariant theory is used to create an integrity basis with invariants that correspond to physical mechanisms related to fracture. This integrity basis is then used to construct a failure function per unit volume (or area) of material. It is assumed that the overall strength of the composite is governed by weakest link theory. This leads to a Weibull-type model similar in nature to the principle of independent action (PIA) model for isotropic monolithic ceramics. An experimental program to obtain model parameters is briefly discussed. In addition, qualitative features of the model are illustrated by presenting reliability surfaces for various model parameters.
Local-Global Analysis of Crack Growth in Continuously Reinforced Ceramic Matrix Composites
Authors: Ballarini R. , Ahmed S.
Published: April 2008

This paper describes the development of a mathematical model for predicting the strength and micromechanical failure characteristics of continuously reinforced ceramic matrix composites. The local-global analysis models the vicinity of a propagating crack tip as a local heterogeneous region (LHR) consisting of springlike representations of the matrix, fibers, and interfaces. This region is embedded in an anisotropic continuum (representing the bulk composite), which is modeled by conventional finite elements. Parametric studies are conducted to investigate the effects of LHR size, component properties, interface conditions, etc. on the strength and sequence of the failure processes in the unidirectional composite system. The results are compared with those predicted by the models developed by Marshall et al. (1985) and by Budiansky et al. (1986).
Mechanisms of Degradation and Failure in a Plasma-Deposited Thermal Barrier Coating
Authors: DeMasi-Marcin J. T. , Sheffler K. D. , Bose S.
Published: April 2008

Failure of a two-layer plasma-deposited thermal barrier coating is caused by cyclic thermal exposure and occurs by spallation of the outer ceramic layer. Spallation life is quantitatively predictable, based on the severity of cyclic thermal exposure. This paper describes and attempts to explain unusual constitutive behavior observed in the insulative ceramic coating layer, and presents details of the ceramic cracking damage accumulation process, which is responsible for spallation failure. Comments also are offered to rationalize the previously documented influence of interfacial oxidation on ceramic damage accumulation and spallation life.
Bond Coat Development for Thermal Barrier Coatings
Authors: Wortman D. J. , Duderstadt E. C. , Nelson W. A.
Published: April 2008

The use of thermal barrier coatings on high-pressure turbine components can improve gas turbine efficiency through reduction of cooling airflow. However, to reduce cooling airflow, a highly reliable thermal barrier coating is required. This increased reliability will be achievable through several complimentary approaches: material and process development, life prediction method development, and engine service experience. The results of bond coat material development, which has increased the thermal cycle life of plasma spray thermal barrier coatings, are presented. Improvements were achieved by two methods: (1) use of creep-resistant bond coat compositions, and (2) overaluminiding of the bond coat.
Tailoring Zirconia Coatings for Performance in a Marine Gas Turbine Environment
Authors: Strangman T. E. , Schienle J. L.
Published: April 2008

Zirconia coatings represent an advanced materials technology that offers significant durability and performance benefits for marine gas turbines. Thin zirconia coatings offer superior resistance to hot corrosion attack from fuel (sulfur, vanadium, and sodium) and air (sea salt) impurities present in marine engine environments. Thicker zirconia coatings reduce transient thermal stresses and heat transferred into air-cooled components. This paper describes the development of zirconia coatings, applied by the electron beam evaporation-physical vapor deposition process, that are tailored to provide superior durability in a marine engine environment.
Burner Rig Evaluation of Ceramic Coatings With Vanadium-Contaminated Fuels
Authors: Nagaraj B. A. , Wortman D. J.
Published: April 2008

The performance of yttria-stabilized zirconia (YSZ), ceria-stabilized zirconia (CSZ), and magnesia-stabilized zirconia (MSZ) coatings was evaluated using an atmospheric burner rig; test environment contained compounds of vanadium, sodium, and sulfur. The coatings were deposited by plasma spraying and electron beam physical vapor deposition (EB-PVD); sputtered sealant layers of hafnia, alumina, and platinum were deposited on the YSZ coating. The tests were performed for up to 500 hours at 1650°F and 1300°F. The tests were designed to simulate the deposit chemistry and sulfur trioxide partial pressures expected in a marine gas turbine engine operating on contaminated fuel. YSZ, CSZ, and MSZ coatings all underwent reaction in the burner rig environment; the reaction products and their effects on spallation were varied. MSZ was by far the most reactive, readily forming MgSO4 in both 1650°F and 1300°F tests. The observed reaction products provided a measure of “protection” for the bond coat by preventing molten salt infiltration for the duration of the test. The mechanism of ceramic spallation is discussed. Sputtered overlayers of platinum, hafnia, and alumina did not prevent salt infiltration and reaction with the underlying ceramic, although no reaction product between the overlayer and the salt was observed.
Metallurgical Characterization of a High-Pressure Rotor for Remaining Service Life Assessment After 26 Years of Service
Authors: Cheruvu N. S. , Malmfeldt L. R.
Published: April 2008

In-service material degradation of a high-pressure rotor steel has been investigated for remaining service life assessment. The samples for this study were taken from the cold and hot locations of a rotor that had operated for approximately 167,500 hours. The test results have indicated that the rotor steel is slightly softened and temper embrittled as a result of service exposure. Based on isostress creep rupture data of the rotor steel in the service-exposure. Based on isostress creep rupture data of the rotor steel in the service-exposed condition, it is concluded that crack initiation due to creep is not a concern in the near future. Considering the uncertainties associated with the extrapolation of short-time rupture data on remaining service life assessment, the rotor material should be re-evaluated for degradation of properties after the next 10 years of operation.
Prediction of Erosive-Corrosive Wear in Low-Carbon Steel Piping Conveying Water or Wet Steam
Authors: Keck R. G. , Griffith P.
Published: April 2008

Techniques to predict erosive-corrosive wear in pipes conveying single and two-phase water in low-carbon steel secondary power plant piping systems are presented. Model equations for two mechanisms, oxide dissolution and droplet impingement, are introduced and the terms in each theory are defined in detail. Parametric curves showing dissolution model results are presented and the effects of localized wear enhancement due to flow geometries are discussed.
Advanced Aircraft Gas Turbine Engine Controls
Authors: Wright W. E. , Hall J. C.
Published: April 2008

With the advent of vectored thrust, vertical lift, and fly-by-wire aircraft, the complexity of aircraft gas turbine control systems has evolved to the point wherein they must approach or equal the reliability of current quad redundant flight control systems. To advance the technology of high-reliability engine controls, one solution to the Byzantine General’s problem (Lamport et al., 1982) is presented as the foundation for fault tolerant engine control architecture. In addition to creating a control architecture, an approach to managing the architecture’s redundancy is addressed.
Simulation of Bird Strikes on Turbine Engines
Authors: Niering E.
Published: April 2008

External components of aeroengines, such as casings and intake blades, must be capable of withstanding bird strikes. Various methods of computer simulation that have been developed are presented in summary. The most accurate and meaningful results are obtained with finite element programs specifically developed for impact events. Bird and component are divided into finite elements. The component model must allow for great elastic-plastic deformation, where the yield strength is a function of the strain rate. A model shape and a homogeneous substitute material must be defined for the complicated and nonhomogeneous structure of the bird. Bird strikes on a rotating spinner and an intake blade are investigated with the finite element program DYNA3D.
The Impact of Atmospheric Conditions on Gas Turbine Performance
Authors: El Hadik A. A.
Published: April 2008

In a hot summer climate, as in Kuwait and other Arabian Gulf countries, the performance of a gas turbine deteriorates drastically during the high-temperature hours (up to 60°C in Kuwait). Power demand is the highest at these times. This necessitates an increase in installed gas turbine capacities to balance this deterioration. Gas turbines users are becoming aware of this problem as they depend more on gas turbines to satisfy their power needs and process heat for desalination due to the recent technical and economical development of gas turbines. This paper is devoted to studying the impact of atmospheric conditions, such as ambient temperature, pressure, and relative humidity on gas turbine performance. The reason for considering air pressures different from standard atmospheric pressure at the compressor inlet is the variation of this pressure with altitude. The results of this study can be generalized to include the cases of flights at high altitudes. A fully interactive computer program based on the derived governing equations is developed. The effects of typical variations of atmospheric conditions on power output and efficiency are considered. These include ambient temperature (range from −20 to 60°C), altitude (range from zero to 2000 m above sea level), and relative humidity (range from zero to 100 percent). The thermal efficiency and specific net work of a gas turbine were calculated at different values of maximum turbine inlet temperature (TIT) and variable environmental conditions. The value of TIT is a design factor that depends on the material specifications and the fuel/air ratio. Typical operating values of TIT in modern gas turbines were chosen for this study: 1000, 1200, 1400, and 1600 K. Both partial and full loads were considered in the analysis. Finally the calculated results were compared with actual gas turbine data supplied by manufacturers.
Convective Boiling in Narrow Concentric Annuli
Authors: Bankoff S. G. , Rehm T. E.
Published: April 2008

An experimental apparatus was used to simulate the annulus formed by a single tube passing through a tube support plate (TSP) in the steam generator of a PWR nuclear power plant. It was found that the extent of thin film evaporation, compared to nucleate boiling, is larger for smaller annuli, with a transition at 0.203 mm gap width to a local dryout/rewet condition. A model was developed that predicts an increasing extent of surface dryout/rewet prior to critical heat flux (CHF). A CHF correlation was developed by modification of a pool boiling CHF correlation, and the Chen (1966) correlation was modified to allow prediction of the two-phase heat transfer coefficient.
3500 SI Engine Application Flexibility
Authors: Havran R. L.
Published: April 2008

The 3500 Spark-Ignited Engine is a 170 mm bore by 190 mm stroke family including 8, 12, and 16-cylinder models rated at 54 bkW per cylinder. Initial production included low-emission versions of the 12 and 16 cylinder engines in 1986. This paper describes basic combustion and attachment developments that have broadened the product offering for improved performance in more varied fuel and high-temperature cogeneration applications.
Exhaust Gas Emissions of Butanol, Ethanol, and Methanol-Gasoline Blends
Authors: Rice R. W. , Sanyal A. K. , Elrod A. C. , Bata R. M.
Published: April 2008

Emissions levels for CO, NOx, and unburned fuel (UBF) from a stationary four-cylinder Chrysler engine were measured under a variety of operating conditions for gasoline and three different 20 vol percent alcohol-gasoline blends. In tests of separate isobutanol, ethanol, and methanol blends, lower CO and NOx emissions were observed for the alcohol blends relative to gasoline, particularly for fuel-rich operation. Generally, on a volume (mole) basis unburned fuel emissions were highest for methanol blends and lowest for gasoline, but on a mass or OMHCE basis only small differences were noted. For a given fuel, the separate effects of engine speed, load, and equivalence ratio were examined.
An Integrated Model of Ring Pack Performance
Authors: Keribar R. , Dursunkaya Z. , Flemming M. F.
Published: April 2008

This paper describes an integrated model developed for the detailed characterization and simulation of piston ring pack behavior in internal combustion engines and the prediction of ring pack performance. The model includes comprehensive and coupled treatments of (1) ring-liner hydrodynamic and boundary lubrication and friction; (2) ring axial, radial, and (toroidal) twist dynamics; (3) inter-ring gas dynamics and blowby. The physics of each of these highly inter-related phenomena are represented by submodels, which are intimately coupled to form a design-oriented predictive tool aimed at the calculation of ring film thicknesses, ring motions, land pressures, engine friction, and blowby. The paper also describes the results of a series of analytical studies investigating effects of engine speed and load and ring pack design parameters, on ring motions, film thicknesses, and inter-ring pressures, as well as ring friction and blowby.
On the Development of Modern Analysis Techniques for Single Cylinder Testing of Large-Bore Engines
Authors: Beshouri G. M.
Published: April 2008

The world-wide consolidation of many engine manufacturers, along with the relatively low production rate of new engines, has resulted in a significant reduction in the facilities, engines, and personnel available for conducting full-engine laboratory quality tests against calibrated dynamometers. Concurrently, the continued pressure for further reduction in exhaust emissions, along with improvements in fuel consumption, has created a growing aftermarket for the retrofit/upgrade of new technologies requiring further engine development. Regrettably, the prohibitive cost and capital investment associated with full engine tests, along with the lack of facilities, makes such tests prohibitive. Therefore, a number of new experimental techniques and associated analysis methods have been developed for conducting laboratory quality single-cylinder tests on commercial engines without interfering with their profitable operation. Such tests have been successfully conducted on both spark-ignited and dual fuel engines. Many details of the methods utilized, along with estimations of their accuracy and reliability, are described.
Study of the Nonsteady Flow in a Multipulse Converter
Authors: Flamang P. , Sierens R.
Published: April 2008

In a previous paper [1] a simplified model has been proposed to calculate the pressure loss coefficients of a multipulse converter under steady-state flow conditions. Therefore a special test rig has been built, which simulates the nonsteady but cyclic flow in the exhaust system of a real engine. Pressure and velocity measurements (with LDA) are compared with the results of the numerical simulation for the flow through the multipulse converter of the test rig. Finally, a comparison is made between measurements and calculations of the pressure history in the exhaust system of a real engine. This paper proves that this simplified model accurately predicts the behavior of the multipulse converter under nonstationary flow conditions.
Global Climate Change
Authors: Hammerle R. H. , Shiller J. W. , Schwarz M. J.
Published: April 2008

This paper reviews the validity of the greenhouse warming theory, its possible impact on the automotive industry, and what could be done. Currently there is very limited evidence that man’s activity has caused global warming. Mathematical models of the earth’s heat balance predict warming and associated climate changes, but their predictions have not been validated. Concern over possible warming has led to several evaluations of feasible CO2 control measures. Although cars and trucks contribute only a small fraction of the CO2 buildup, the automotive industry may be expected to reduce its share of the atmospheric CO2 loading if controls become necessary. Methods to reduce automotive CO2 emissions, including alternative fuels such as methanol, natural gas, and electricity, are discussed. Also, control of the other greenhouse gases, which may currently contribute about 45 percent of the greenhouse warming, is considered.
Fully Loaded Factory Test of the CW251B12 Gas Turbine Engine
Authors: Diakunchak I. S.
Published: April 2008

The fully loaded factory test of the CW251B12 45 MW class industrial gas turbine is described in this paper. This gas turbine is the latest uprating of the W251 series of engines. The main objectives of the factory test were the verification of the performance and the mechanical integrity of the new engine model. A brief description of the main features of the engine, the application of the first unit, the test facility, and the engine instrumentation used in the test is included. Details of the engine performance test results, telemetry test data results, and the hot end component metal temperature measurements are provided.
Power Performance of a Nonisentropic Brayton Cycle
Authors: Wu C. , Kiang R. L.
Published: April 2008

Work and power optimization of a Brayton cycle are analyzed with a finite-time heat transfer analysis. This work extends the recent flurry of publications in heat engine efficiency under the maximum power condition by incorporating nonisentropic compression and expansion. As expected, these nonisentropic processes lower the power output as well as the cycle efficiency when compared with an endoreversible Brayton cycle under the same conditions.
An Explanation for Observed Compression Ratios in Internal Combustion Engines
Authors: Klein S. A.
Published: April 2008

Comparisons of the compression ratios, efficiencies, and work of the ideal Otto and Diesel cycles are presented at conditions that yield maximum work per cycle. The compression ratios that maximize the work of the Diesel cycle are found always to be higher than those for the Otto cycle at the same operating conditions, although the thermal efficiencies are nearly identical. The compression ratios that maximize the work of the Otto and Diesel cycles compare well with the compression ratios employed in corresponding production engines.
Acoustic Design of Lightweight Gas Turbine Enclosures
Authors: Rawlinson R. D.
Published: April 2008

Acoustic enclosures for the gas turbine industry have to comply with a number of stringent safety requirements including structural strength, fire resistance, and sound insulation. This has led traditionally to heavy enclosure designs. Corrugated enclosure panels offer significant structural advantages because of their increased bending stiffness. Consequently, a corrugated panel of a given thickness can give the same structural strength as a flat panel of substantially greater weight and thickness. However, corrugated panels are intrinsically less effective as a sound insulator than flat panels of the same thickness. This paper examines the implications of corrugated, lightweight panels for acoustic enclosures. It illustrated that, by careful design, the inherent acoustical disadvantages of corrugated panels can be overcome so that thinner, lighter, and more cost-effective enclosures can be used without compromising the overall structural and acoustical design requirements.
Development of ODS Superalloy Technology in Japan for Turbine Blade Applications
Authors: Mino K.
Published: April 2008

The strength of ODS superalloys has not been so satisfactory as to attract much attention for application in turbine blades. As one of the advanced materials programs supported by MITI, cooperative works were undertaken to develop ODS superalloys superior to monocrystalline alloys. Mechanical properties of new ODS alloys developed in Japan were summarized to evaluate their potentials for turbine blade applications. The project tasks included isothermal forging and diffusion bonding studies for blade fabrication.
Analytical and Experimental Simulation of Fan Blade Behavior and Damage Under Bird Impact
Authors: Teichman H. C. , Tadros R. N.
Published: April 2008

An extensive analytical and experimental program has been undertaken to investigate the Foreign Object Damage resistance capabilities of external components for small gas turbofan engines. A transient nonlinear impact analysis has been used to predict the structural response of fan blades under bird ingestion conditions. This analysis is based on finite elements, a three-dimensional bird load model, and an interactive structure-to-bird contact algorithm. Experiments were designed and carried out to record large blade deformations during bird impact, and were used to validate and calibrate the analytical models. The analytical models and testing program are described, and dominant fan blade response and failure modes are presented. Predicted results demonstrate good correlation with tests. Analysis application to fan blade design and other engine components is recommended.
A Proposed Method for Assessing the Susceptibility of Axial Compressors to Fouling
Authors: Seddigh F. , Saravanamuttoo H. I. H.
Published: April 2008

Although the overall effect of compressor fouling on engine performance has been recognized for many years, remarkably little has been published on the quantifiable effects. Mathematical modeling of compressors using stage stacking methods has recently been used for a systematic study of compressor fouling and earlier investigations led to an interest in the effects of engine size and compressor stage loading. This paper presents a proposed index showing the susceptibility of compressors to fouling, which could be useful in helping operators to determine cleanup intervals. Three engines of widely differing performance were used in developing this index and additional operator experience would be useful in confirming its validity.
Effect of Particle Size Distribution on Particle Dynamics and Blade Erosion in Axial Flow Turbines
Authors: Tabakoff W. , Hamed A. , Metwally M.
Published: April 2008

This work presents the results of an investigation conducted to study the effect of coal ash particle size distribution on the particle dynamics, and the resulting blade erosion in axial flow gas turbines. The particle dynamics and their blade impacts are determined from a three-dimensional trajectory analysis within the turbine blade passages. The particle rebound conditions and the blade material erosion characteristics are simulated using empirical equations, derived from experimental measurements. For the typical ash particle size distribution considered in this investigation, the results demonstrate that the size distribution has a significant influence on the blade erosion intensity and pattern.
Potential Applications of Structural Ceramic Composites in Gas Turbines
Authors: Parks W. P. , Ramey R. R. , Rawlins D. C. , Price J. R. , Van Roode M.
Published: April 2008

A Babcock and Wilcox-Solar Turbines Team has completed a program to assess the potential for structural ceramic composites in turbines for direct coal-fired or coal gasification environments. A review is made of the existing processes in direct coal firing, pressurized fluid bed combustors, and coal gasification combined cycle systems. Material requirements in these areas were also discussed. The program examined state-of-the-art ceramic composite materials. Utilization of ceramic composites in the turbine rotor blades and nozzle vanes would provide the most benefit. A research program designed to introduce ceramic composite components to these turbines was recommended.
A Computational Fluid Dynamics and Chemistry Model for Jet Fuel Thermal Stability
Authors: Krazinski J. L. , Vanka S. P. , Pearce J. A. , Roquemore W. M.
Published: April 2008

This paper describes the development of a model for predicting the thermal decomposition rates of aviation fuels. A thermal deposition model was incorporated into FLANELS-2D, an existing computational fluid dynamics (CFD) code that solves the Reynolds-averaged conservation equations of mass, momentum, and energy. The decomposition chemistry is modeled by three global Arrhenius expressions in which the fuel decomposition was assumed to be due to an autoxidation reaction with dissolved oxygen. The deposition process was modeled by assuming that all deposit-forming species transported to the wall adhered and formed a deposit. Calibration of the model required the determination of the following parameters for a given fuel: (1) the pre-exponential constant and activation energy for the wall reaction, (2) the pre-exponential constant and activation energy for the bulk autoxidation reaction, and (3) the pre-exponential constant and activation energy for the precursor decomposition reaction. Values for these parameters were estimated using experimental data from published heated-tube experiments. Results show that the FLANELS-2D code performed well in estimating the fuel temperatures and that the three-equation chemistry model performed reasonably well in accounting for both the rate of deposition and the amount of dissolved oxygen present in the fuel at the end of the heated tube.
Chemical Composition of Exhaust From Aircraft Turbine Engines
Authors: Spicer C. W. , Holdren M. W. , Smith D. L. , Hughes D. P. , Smith M. D.
Published: April 2008

This paper reports measurements of the chemical composition of exhaust from two aircraft turbine engines. The two engines are the F101, used on the B-1B aircraft, and the F110, used on the F-16C and F-16D aircraft. Samples were collected from each engine using a probe positioned just behind the exhaust nozzle. The measurements reported here were made at four power settings from idle to intermediate power. Exhaust composition measurements included carbon monoxide, carbon dioxide, nitrogen oxides, total hydrocarbons, and individual organic species. The principal focus of this paper is on the detailed organic species results.
Status of Topping Combustor Development for Second-Generation Fluidized Bed Combined Cycles
Authors: Garland R. V. , Pillsbury P. W.
Published: April 2008

Addition of a fluidized bed combustor to a high-efficiency combined cycle plant enables direct firing of inexpensive run-of-the-mine coal in an environmentally acceptable manner. To attain high thermal efficiencies, coal pyrolysis is included. The low heating value fuel gas from the pyrolyzer is burned in a topping combustion system that boosts gas turbine inlet temperature to state of the art while the pyrolyzer-produced char is burned in the bed. The candidate topping combustor, the multi-annular swirl burner, based on a design by J. M. Bee´r, is presented and discussed. Design requirements differ from conventional gas turbine combustors. The use of hot, vitiated air for cooling and combustion, and the use of low heating value fuel containing ammonia, are two factors that make the design requirements unique. The multi-annular swirl burner contains rich-burn, quick-quench, and lean-burn zones formed aerodynamically rather than the physically separate volumes found in other rich-lean combustors. Although fuel is injected through a centrally located nozzle, the combustion air enters axially through a series of swirlers. Wall temperatures are controlled by relatively thick layers of air entering through the various swirler sections, which allows the combustor to be of all-metal construction rather than the ceramic often used in rich-lean concepts. This 12-in.-dia design utilizes some of the features of the previous 5-in. and 10-in. versions of the multi-annular swirl burner; test results from the previous projects were utilized in the formulation of the test for the present program. In the upcoming tests, vitiated air will be provided to simulate a pressurized fluidized bed effluent. Hot syngas seeded with ammonia will be used to simulate the low-Btu gas produced in the pyrolyzer.
Influence of Fuel Cost on the Operation of a Gas Turbine-Waste Heat Boiler Cogeneration Plant
Authors: Ito K. , Yokoyama R. , Akagi S. , Matsumoto Y.
Published: April 2008

The influence of fuel cost on the operation is investigated for a gas turbine-waste heat boiler cogeneration plant by an optimal operational planning method. A planning method is first presented by which the operational policy of each piece of constituent equipment is determined so as to minimize the operational cost. Then, a case study is performed for a cogeneration plant used for district heating and cooling. Through the study, it is made clear how the optimal operational policy and the economic or energy conservative properties are influenced by the costs of purchased electric power and natural gas. It is also shown that the optimal operational policy is superior in economy as compared with other conventional ones.
A Small Air Turbine Power Plant Fired With Coal in an Atmospheric Fluid Bed
Authors: Foster-Pegg R. W.
Published: April 2008

An efficient, indirectly heated, steam-injected air turbine power or cogeneration plant, fired with coal in an atmospheric fluid bed, is described. The plant will meet all environmental standards and will generate about 35 MW. The plant offers a high power-to-steam ratio without requiring a condensing steam turbine and can operate efficiently without any export steam. Eliminating a condensing steam turbine, cooling tower, etc., reduces the capital cost and produces a low $/kW installation. If necessary, most of the water injected into the air turbine can be recovered from the exhaust air and reused. All the equipment for the plant is commercially available.
Indianapolis Resource Recovery Facility: Community Efforts and Techology Required for a Successful Project
Authors: Stevens P. L. , Henderson J. S. , Tulli R.
Published: April 2008

There are many community needs. Refuse is an abundant byproduct of our civilization. The disposal of this byproduct has become a major problem for our cities. This paper describes one community’s efforts to turn a community problem, refuse disposal, into a community asset. The paper describes the many aspects of effort and technology required to develop the Indianapolis Resource Recovery Facility. This facility required the cooperation of the public and private sectors to blend technology into a successful project. Special efforts were required to match appropriate technology to specific community needs and produce a successful and economically sound project. Five basic activities are presented. The first four activities are essential steps for any community to assure the right project fit to community needs. The areas presented are: (1) defining community needs, (2) technology evaluation (approaches evaluated), (3) feasibility studies (economic studies), (4) project implementation (bids and contracts), and (5) a description of the Indianapolis Resource Recovery facility. A review of these five areas places a real world perspective on refuse as an alternative fuel and source of resource recovery.
Fuel Molecular Structure and Flame Temperature Effects on Soot Formation in Gas Turbine Combustors
Authors: Gu¨lder O¨. L. , Glavincˇevski B. , Baksh M. F.
Published: April 2008

A systematic study of soot formation along the centerlines of axisymmetric laminar diffusion flames of a large number of liquid hydrocarbons, hydrocarbon blends, and aviation turbine and diesel fuels was made. Measurements of the attenuation of a laser beam across the flame diameter were used to obtain the soot volume fraction, assuming Rayleigh extinction. Two sets of hydrocarbon blends were designed such that the molecular fuel composition varied considerably but the temperature fields in the flames were kept practically constant. Thus it was possible to separate the effects of molecular structure and the flame temperature on soot formation. It was quantitatively shown that the smoke point height is a lumped measure of fuel molecular constitution. The developed empirical relationship between soot volume fractions and fuel smoke point and hydrogen-to-carbon ratio was applied to five different combustor radiation data, and good agreement was obtained.
Crankshaft Stress Analysis—Combination of Finite Element and Classical Analysis Techniques
Authors: Heath A. R. , McNamara P. M.
Published: April 2008

The conflicting legislative and customer pressures on engine design, for example, combining low friction and a high level of refinement, require sophisticated tools if competitive designs are to be realized. This is particularly true of crankshafts, probably the most analyzed of all engine components. This paper describes the hierarchy of methods used for crankshaft stress analysis with case studies. A computer-based analysis system is described that combines FE and classical methods to allow optimized designs to be produced efficiently. At the lowest level simplified classical techniques are integrated into the CAD-based design process. These methods give the rapid feedback necessary to perform concept design iterations. Various levels of FE analysis are available to carry out more detailed analyses of the crankshaft. The FE studies may feed information to or take information from the classical methods. At the highest level a method for including the load sharing effects of the flexible crankshaft within a flexible block interconnected by nonlinear oil films is described. This method includes the FE modeling of the complete crankshaft and the consideration of its stress field throughout an engine cycle. Fatigue assessment is performed to calculate the distribution of fatigue safety factor on the surface of the crankshaft. This level of analysis can be used for failure investigation, or detailed design optimization and verification. The method is compatible with those used for vibration and oil film analysis.
Aerodynamic and Thermal Analysis of an Engine Cylinder Head Using Numerical Flow Simulation
Authors: Taghavi R. , Dupont A. , Dupont J. F.
Published: April 2008

A computational fluid dynamics code is used as a guide during the development stage of a passenger car spark ignition engine. The focus is on the flow properties of the inlet port as well as the heat transfer characteristics of the proposed cylinder head design. In the first part of this study, the aerodynamic characteristics of two slightly different inlet ports are considered and their effect on the development of in-cylinder flow is examined. The collected information is used to estimate geometric sensitivity and assess the effects of drifts between design and actual production specifications of inlet ports. In the second part, the same computational code is used to simulate in-cylinder combustion and determine the resulting temperature and heat flux distribution on the cylinder head walls. A comparison is then carried out between numerical results and experimental measurements and good agreement is obtained.
What Causes Slower Flame Propagation in the Lean-Combustion Engine?
Authors: Kuo T.-W.
Published: April 2008

Previous engine data suggest that slower flame propagation in lean-burn engines could be due to slower flame expansion velocity at lean conditions than at stoichiometric combustion. Two classes of model, a quasi-dimensional engine-simulation program and a multidimensional engine-flow and combustion code, were used to study this effect in detail and to assess the capabilities of the models to resolve combustion details. The computed flame-speed data from each program differed somewhat in magnitude, but the predicted trends at various equivalence ratios were quite similar. The trends include: (1) The peak in-cylinder burned-gas temperature decreases by about 300 K as the equivalence ratio is decreased from 0.98 to 0.70. (2) Both the laminar flame speed and the flame-propagation speed, the latter computed from the time derivative of flame radius, decrease with decreasing equivalence ratio. (3) The turbulent burning speed, defined as the ratio of specific fuel-burning rate to the product of the flame frontal area and unburned-mixture density, is relatively insensitive to equivalence-ratio variations at the same flame-radius position. The previous experimental finding that the reduction in flame-propagation speed with decreasing equivalence ratio is caused mainly by the lower thermal-expansion speed, calculated by subtracting the turbulent burning speed from the flame-propagation speed, was confirmed. This is a consequence of lower burned-gas temperature for the lean case. Regarding the reliability of the models to resolve the combustion details, limitations of the models are identified and discussed in detail.
Coal-Fueled Diesel Engine Progress at GE Transportation Systems
Authors: Flynn P. L. , Hsu B. D. , Leonard G. L.
Published: April 2008

A coal-fueled diesel engine holds the promise of a rugged, modular heat engine that uses cheap, abundant fuel. Economic studies have indicated attractive returns at moderate diesel fuel prices. The compositions of coal-water fuels are being expanded to cover the major coal sources. Combustion has been developed at 1000 rpm with mechanical and electronic fuel injection. Dual fuel operation can run the engine over the load range. Erosion of fuel nozzles has been controlled with diamond compacts. Wear of piston rings and cylinder liners can be controlled with tungsten carbide coatings. Emission measurements show higher particulates and SO2 and lower NOx, CO, and HC. Particulate and SO2 control measures are being investigated.
Coal-Fueled Diesel Cycle Simulation: The Role of Group Effects
Authors: Branyon D. P. , Caton J. A. , Annamalai K.
Published: April 2008

An existing coal-water slurry fueled diesel engine cycle simulation was modified to include particle-to-particle and droplet-to-droplet interactions during the combustion and vaporization processes. Two aspects of these interactions, known as group effects, were considered. Group Effect Number 1 (GE1) relates to the species concentrations and temperature profiles between particles during combustion and between droplets during vaporization. Group Effect Number 2 (GE2) relates to the blockage of air entrainment to the fuel region due to the large momentum flux of volatiles and CO during combustion or water vapor during vaporization. The major conclusions were that GE1 affected the detailed process characteristics and in-cylinder conditions, and moderately affected the overall engine performance for the cases studied. These results were largely due to suppression of the water vaporization process relative to the case with no group effects. GE2 did not significantly affect the in-cylinder processes or the overall performance of the engine for the cases studied.
Single Cylinder Testing of a High-Pressure Electronic Pilot Fuel Injector for Low NOx Emission Dual Fuel Engines: Part I—Baseline, Feasibility, and Comparative Testing
Authors: Workman J. , Beshouri G. M.
Published: April 2008

Current dual fuel engines utilizing standard mechanical (Bosch type) fuel injection systems set to 5–6 percent pilot delivery do not appear capable of reducing NOx emissions much below the current minimum of 4 g/bhp-h without incurring substantial penalties in efficiency and operability. A prototype Electronic Pilot Fuel Injector (EPFI) was designed that overcomes the shortcomings of the mechanical injection system, consistently delivering 3 percent or less pilot at pressures as high as 20,000 psi. The EPFI was installed and tested in one cylinder of a standard production dual fuel engine operating at a waste water treatment facility. A feasibility test confirmed that the engine would indeed operate satisfactorily at 2.9 percent pilot. Comparisons with baseline data revealed the EPFI yielded a 45 percent reduction in NOx emissions with a 3 percent or greater improvement in efficiency. Further optimization of the system, discussed in Part II, indicates that even greater reductions in NOx emissions can be obtained without incurring a penalty in fuel consumption.
Regeneration Analysis Under Different Exhaust Gas Thermal Conditions
Authors: Bella G. , Rocco V.
Published: April 2008

A refinement of the honeycomb trap model developed by the authors for analyzing the temperature history of the trap channels during the regeneration period is presented. The first results obtained, shown in previous papers [1, 2], encouraged the authors to improve the model in order to account for the heat transfer not only along the channel length, but also in the radial direction. In order to achieve this objective, a control volume approach was used to simulate the soot regeneration in all contiguous channels along the axial and radial directions of the monolith, and to determine the wall temperature and soot oxidation as a function of time. Different thermodynamic conditions of the exhaust gas at the trap inlet were considered in order to examine the effects of cold regeneration. For the same soot amount accumulated in the trap, the soot burnup time and temperature history depend on the inlet temperature. In addition to varying the gas initial conditions, the effects of the amount of soot collected and its radial distribution in the channels, before the regeneration process takes place, were also considered in order to predict the wall temperature rise and the soot oxidation rate. The results show the temperature peak values and their location inside the trap, and permit estimation of the conditions under which the trap temperature can reach unbearable values.
An Algorithm and Criteria for Compressor Characteristics Real Time Modeling and Approximation
Authors: El-Gammal A. M.
Published: April 2008

Numerous problems are encountered in realizing an adequate real time model for an aircraft engine. The purpose of this article is to propose a systematic approach for modeling and approximating the characteristics of an engine or engine component parts, and to apply this approach to the Viper compressor (VC) characteristics. The proposed approach introduces a set of quantitative model-performance measures. Monitoring these measures makes it possible to take care of the multiple objectives of the model simultaneously and individually, and to attach a guarantee level to the model behavior. A set of (66) models are considered, from which the adequate VC model for real time (RT) simulation purposes is determined.