bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction Kinetics at the Triple-Phase Boundary in PEM Fuel Cells
Authors: Berg P. , Novruzi A. , Volkov O.
Published: April 2008

A mathematical model is developed to describe the reaction dynamics in the vicinity of the triple-phase boundary (TPB), which is an important part of the pore scale structure of the catalyst layer in proton exchange membrane fuel cells. The model incorporates coupled diffusion, migration, and reaction phenomena of the chemical components in an undersaturated air pore and ionomer. One challenging feature of the work is the description of the TPB by a system of nonlinear partial differential equations (PDEs), coupling bulk, and surface-diffusion phenomena, which offers an approach to study the rarely investigated proton surface diffusion along the air pore surface. A numerical technique is implemented, taking into account the particular form of the domain, in order to solve the nonlinear PDE system efficiently. Several numerical results are discussed, including a sensitivity analysis with respect to the physical reference case and geometric parameters. The results indicate that surface diffusion might play a major role for the reaction kinetics, but only if the air pore is void of liquid water. In contrast, the formation of liquid water in the gas pores will turn surface diffusion into bulk diffusion, with the latter resembling the Grotthus mechanism.
Adaptive Simulation of Gas Turbine Performance
Authors: Stamatis A. , Mathioudakis K. , Papailiou K. D.
Published: April 2008

A method is presented allowing the simulation of gas turbine performance with the possibility of adapting to engine particularities. Measurements along the gas path are used, in order to adapt a given performance model by appropriate modification of the component maps. The proposed method can provide accurate simulation for engines of the same type, differing due to manufacturing or assembly tolerances. It doesn’t require accurate component maps, as they are derived during the adaptation process. It also can be used for health monitoring purposes, introducing thus a novel approach for component condition assessment. The effectiveness of the proposed method is demonstrated by application to an industrial gas turbine.
Casing Vibration and Gas Turbine Operating Conditions
Authors: Mathioudakis K. , Loukis E. , Papailiou K. D.
Published: April 2008

The results from an experimental investigation of the compressor casing vibration of an industrial gas turbine are presented. It is demonstrated that statistical properties of acceleration signals can be linked with engine operating conditions. The power content of such signals is dominated by contributions originating from the stages of the compressor, while the contribution of the shaft excitation is secondary. Using nonparametric identification methods, accelerometer outputs are correlated to unsteady pressure measurements taken by fast response transducers at the inner surface of the compressor casing. The transfer functions allow reconstruction of unsteady pressure signal features from the accelerometer readings. A possibility is thus provided for “seeing” the unsteady pressure field of the rotor blades without actually penetrating through the casing, but by simply observing its external surface vibrations.
Conversion of Sulfur Dioxide to Sulfur Trioxide in Gas Turbine Exhaust
Authors: Harris B. W.
Published: April 2008

Acid dewpoints were calculated from SO2-to-SO3 conversion in gas turbine exhaust. These data can be used as guidelines in setting feedwater temperatures in combined-cycle systems. Accurate settings can prevent corrosion of heat-exchanger (boiler) tubes, thus extending their life time. This study was done using gas turbine engines and a laboratory generator set. The units burned marine diesel or diesel No. 2 fuel with sulfur contents up to 1.3 percent. The exhaust from these systems contained an excess of 20 percent oxygen, and 3–10 percent water vapor. Exhaust temperatures ranged from 728 to 893 K (455 to 620°C).
On-Line Determination of Unburned Carbon in Airborne Fly Ash
Authors: Brown R. C. , Dona A. R.
Published: April 2008

Knowledge of the carbon content of fly ash is important for calculating combustion efficiency in coal-fired boilers. However, present methods of measuring carbon content of fly ash are tedious and time consuming. Thus, we are investigating photoacoustic absorption spectroscopy (PAS) as a method for on-line monitoring of carbon in fly ash. Photoacustic absorption spectroscopy is capable of detecting very weak absorptions and is unaffected by light scattering in a particulate-laden gas flow. Accordingly, PAS has good potential for distinguishing small amounts of carbon from mineral matter suspended in flue gas. Experiments have been performed on fly ash samples of variable carbon content suspended in a gas flow. A 35-mW HeNe laser was able to detect carbon loadings of 0.75 g/m3. Order-of-magnitude improvements in detection sensitivity are expected with higher power lasers or improved PAS cell design.
A Comparison of Analog and Digital Controls for Rotor Dynamic Vibration Reduction Through Active Magnetic Bearings
Authors: Williams R. D. , Keith F. J. , Allaire P. E.
Published: April 2008

Active magnetic bearings are implemented using analog and digital controllers to achieve vibration reduction for multimass flexible rotors. Various models are developed for the rotor-bearing system, and the first three critical speeds (resonant frequencies) are shown to be unaffected by inclusion of the higher order shaft dynamics in the model. Higher order rotor-bearing models reveal the presence of “shaft modes,” the excitation of which is a function of the position of the magnetic bearing proximity probe (these modes are effectively damped by the flexible coupling employed in the test apparatus). Rotor dynamic behavior is investigated for various analog and digital controllers. Rotor response in the presence of proportional-derivative control is similar for both analog and digital control. Higher order digital control algorithms (second derivative and integral) affect the rotor response in a frequency dependent manner: Second derivative feedback is effective at reducing third mode vibration, and integral feedback, while rejecting any steady-state rotor position error, slightly accentuates the vibration at the first critical speed. Increasing the sampling rate of the digital controller has a similar effect to increasing the amount of second derivative feedback employed.
Limit Cycle Vibration Analysis of a Long Rotating Cylinder Partially Filled With Liquid
Authors: Colding-Jorgensen J.
Published: April 2008

The dynamics of a long, stiff cylinder, flexibly suspended at the ends, partially filled with liquid, is analyzed for varying rotating speed. It appears from the analysis that in the absence of external damping, two distinct speed ranges with unstable whirl are present, as opposed to one instability region for the short cylinder, which has been analyzed by a number of authors (Kuipers, 1964; Wolf, 1968). This is in agreement with field experience with centrifuges, where several regions of instability are often encountered, each corresponding to a particular vibration mode. The results should also apply to a jet engine with oil accidentally trapped in the rotor, or any hollow rotor with liquid trapped in the cavity. When external damping is applied the linear theory predicts the rotor to be unstable at all speeds (Kuipers, 1964). This is clearly not in accordance with field experience, and other authors have suggested different types of nonlinear analysis that can give finite amplitude stable whirl or pulsating whirl (Berman et al., 1985). In the present analysis a simplified nonlinear analysis known as the hydraulic jump approximation is applied in the two unstable speed ranges predicted by the linear theory, and a stable whirl finite amplitude, dependent on the external damping, follows. It is argued that the amplitudes found this way should always be higher than those predicted by a more sophisticated analysis, and also higher than the amplitudes measured by other authors, so that the procedure described should give a safe worst case prediction of rotor whirl amplitudes for a given external damping. Finally, an experimental setup intended to verify the analysis in a quantitative way is presented.
Integrity Assessments of Components in the Creep Range
Authors: Penny R. K. , Weber M. A.
Published: April 2008

Robust methods for the predictions of deformations and lifetimes of components operating in the creep range are presented. The ingredients used for this are well-tried numerical techniques, combined with the concepts of continuum damage and so-called reference stresses. The methods described are derived in order to obtain the maximum benefit during the early stages of design where broad assessments of the influences of material choice, loadings, and geometry need to be made quickly and with economical use of computers. It is also intended that the same methods will be of value during operation if estimates of damage or if exercises in life extension are required. Results of the suggested method are amenable to tabular or graphic representation. To illustrate the use of these in parametric studies, three brief case studies are included. These involve a notched rod, a perforated plate, and a pipe for which lifetime estimates based upon failure criteria involving different degrees of conservatism are calculated. In addition, an illustration is given of the use of the charts presented in deciding inspection intervals and lifetime extensions. Finally, a brief excursion into the possibility for using the suggested methods for the mapping of designs within given regional constraints is given.
Fabrication and Development of Axial Silicon Nitride Gas Turbine Rotors
Authors: Bandyopadhyay G. , French K. W. , Sordelet D. J. , Moergenthaler K. D.
Published: April 2008

Since 1984, GTE Laboratories Inc. has performed research to develop net shape fabrication technology for axial silicon nitride rotors for the Daimler-Benz research gas turbine engine. The initial effort was focused on the fabrication of injection-molded profile disks. Subsequently, efforts were shifted to develop injection molding and slip casting technology for the bladed gasifier rotors. This joint activity has demonstrated that the ceramics technology has improved significantly over the last five years, as is evidenced by a major improvement in properties and performance of silicon nitride components. The evolution of the ceramics fabrication technology at GTE and the role of improved process and NDE methods on components fabricated in recent years are described in this paper.
Experimental Evaluation of Sorbents for Sulfur Control in a Coal-Fueled Gas Turbine Slagging Combustor
Authors: Cowell L. H. , Wen C. S. , LeCren R. T.
Published: April 2008

A slagging combustor has been used to evaluate three calcium-based sorbents for sulfur capture efficiency in order to assess their applicability for use in a coal-fueled gas turbine. Testing is completed in a bench-scale combustor with one-tenth the heat input needed for the full-scale gas turbine. The bench-scale rig is a two-stage combustor featuring a fuel-rich primary zone and a fuel-lean secondary zone. The combustor is operated at 6.5 bars with inlet air preheated to 600 K. Gas temperatures of 1840 K are generated in the primary zone and 1280 K in the secondary zone. Sorbents are either fed into the secondary zone or mixed with the coal-water mixture and fed into the primary zone. Dry powdered sorbents are fed into the secondary zone by an auger into one of six secondary air inlet ports. The three sorbents tested in the secondary zone include dolomite, pressure-hydrated dolomitic lime, and hydrated lime. Sorbents have been tested while burning coal-water mixtures with coal sulfur loadings of 0.56 to 3.13 weight percent sulfur. Sorbents are injected into the secondary zone at varying flow rates such that the calcium/sulfur ratio varies from 0.5 to 10.0. Hydrated lime exhibits the highest sulfur dioxide reductions in the exhaust of 90 percent. Pressure-hydrated dolomitic lime and dolomite reduce SO2 concentrations by 82 and 55 percent, respectively. Coal sulfur loading is found to have a small influence on sorbent sulfur capture efficiency. Pressure-hydrated dolomitic lime ground with the coal during coal-water mixture preparation and injected into the primary zone is found to lower the sulfur dioxide concentration by an insignificant amount.
A Computational Procedure for Diffuser-Combustor Flow Interaction Analysis
Authors: Karki K. C. , Oechsle V. L. , Mongia H. C.
Published: April 2008

This paper describes a diffuser-combustor flow interaction analysis procedure for gas turbine combustion systems. The method is based on the solution of the Navier–Stokes equations in a generalized nonorthogonal coordinate system. The turbulence effects are modeled via the standard two-equation (k-ε) model. The method has been applied to a practical gas turbine combustor-diffuser system that includes support struts and fuel nozzles. Results have been presented for a three-dimensional simulation, as well as for a simplified axisymmetric simulation. The flow exhibits significant three-dimensional behavior. The axisymmetric simulation is shown to predict the static pressure recovery and the total pressure losses reasonably well.
A New Heat Transfer Correlation and Flow Regime Map for Tube Bundles
Authors: Hassan Y. A. , Blanchat T. K.
Published: April 2008

A RELAP5/MOD2 computer code model for a once-through steam generator has been developed. The calculated heat transfer in the nucleate boiling flow was underpredicted as shown by a predicted superheat of only 11°C (20°F), whereas plant values range from 22–30°C (40–60°F). Existing heat transfer correlations used in thermal-hydraulic computer codes do not provide accurate predictions of the measurement-derived secondary convective heat transfer coefficients for steam generators because they were developed for flow inside tubes, not tube bundles. The RELAP5/MOD2 flow regime map was modified to account for flow across bundles. This modified flow regime map predicts better transition criteria between bubbly-to-slug and slug-to-annular flow. Consequently, improved saturated conditions for the fluid flow at the entrance to the boiler were obtained. A modified Chen-type heat transfer correlation was developed to predict the boiling heat transfer for steam generator tube bundle geometries. This correlation predicts better superheat.
Design of an Articulated Piston for Caterpillar® 3500 Engines Utilizing Computer-Aided Design and Analysis
Authors: Heitzman R. C.
Published: April 2008

The purpose of this paper is to describe the concept, design, and analysis of a two-piece articulated piston for the Caterpillar 3500 diesel engine. Utilization of computer design and analysis enabled the piston to be optimized for structural capability, weight, and performance. Extensive analysis was performed on the steel upper structure. Models generated in two and three dimensions evaluated mechanical, thermal, and combined load cases. The result of this design and analysis is a piston that meets the engine’s objectives and provides additional value to the engine product.
Progress in Electronic Control of Large Diesel Engines
Authors: Gant G. C. , Alves G. J.
Published: April 2008

The general theme of the growing use of electronic systems for the control and monitoring of large diesel engines is discussed. Central to the theme is a new digital governing system for industrial, traction, and marine diesels. This new governing system is capable also of being a marine propulsion controller or engine management/protection system and thus can be a very cost-effective package. In wider use it can work under the overall control of a power management host computer and interface with engine health monitoring equipment. Experience to date with the new governor is reported and plans for its future use outlined.
Effects of Physical Properties of Fuels on Diesel Injection
Authors: Henein N. A. , Jawad B. , Gulari E.
Published: April 2008

The physical properties of the fuel, such as density, viscosity, surface tension, and bulk modulus of elasticity, affect many aspects of the diesel injection process. The effects of these fuel properties on the fuel pressure in the high-pressure line, rate of injection, leakage, spray penetration, and droplet size distribution were determined experimentally. The mechanism of spray development was investigated by injecting the fuel into a high-pressure chamber. A pulsed Malvern drop-size analyzer, based on Fraunhofer diffraction, was utilized to determine droplet size ranges for various fuels.
Gasoline and Diesel Fuel Qualification: A National Need
Authors: Springer K. J.
Published: April 2008

Periodically, there is discussion between engine and vehicle manufacturers and petroleum companies regarding fuels with new and different characteristics to match the needs of spark and compression-ignited engines. The most recent discussions are related to legislation and regulations that will possibly require fuels to be reformulated in the future. The objective will be to make fuels that, when burned in IC engines, emit pollution no greater than alternatives such as methanol or natural gas. The thesis of this paper is that a national fuel qualification could result in motor fuels that, when used in cars and trucks, would be environmentally acceptable. A speculated series of tests to qualify the fuel, one unleaded grade of gasoline, one type 2-D fuel for on-highway diesel trucks and buses, and one type 1-D fuel for city bases, is described. Once qualified, the refiner would certify that the fuel dispensed is in all material respects identical to the prototype fuel qualified. The industry qualification would be good for, say, five years or until the fuel was reformulated. Such a procedure would be industry regulated through periodic audit as well as self-audit provisions to assure fuel quality is maintained at the dispensing pump. Most of the needed procedures are available for such qualification. It remains for the manufacturers and refiners to agree on the need to reformulate gasoline and diesel fuel, develop pass/fail limits for acceptance, and establish a qualification approval protocol. An approach to demonstrate improved performance and emissions is suggested.
Test Procedures for Measuring Exhaust Emissions From Natural Gas Transmission Engines
Authors: Fanick E. R.
Published: April 2008

The measurement of exhaust components from large natural gas transmission engines involves collection of the exhaust sample, transfer of the sample to the analytical instrumentation, measurement of individual component concentrations, and calculations of emission results in terms of mass, fuel specific, and brake specific rates. The major exhaust components measured include nitrogen oxides (NOx), total hydrocarbons (THC), carbon dioxide (CO2), carbon monoxide (CO), and oxygen (O2). Collection of the exhaust sample requires proper probe design and placement in the exhaust system. Transfer of the sample to the analytical instruments must maintain sample integrity from the point where the sample is removed from the exhaust stream to the point at which the sample enters the instrument for analysis. Various analytical techniques are used to measure the exhaust emission concentrations. These techniques include chemiluminescence for NOx, flame ionization for THC, nondispersive infrared (NDIR) for CO2 and CO, and polarography for O2. Calculation of the emission results in terms of mass fuel specific, and brake specific rates utilizes the measured emission concentrations, the engine operating parameters, and the “total carbon” method for data reduction and presentation.
Determination of Cycle Configuration of Gas Turbines and Aircraft Engines by an Optimization Procedure
Authors: Tsujikawa Y. , Nagaoka M.
Published: April 2008

This paper is devoted to the analyses and optimization of simple and sophisticated cycles, particularly for various gas turbine engines and aero-engines (including the scramjet engine) to achieve maximum performance. The optimization of such criteria as thermal efficiency, specific output, and total performance for gas turbine engines, and overall efficiency, nondimensional thrust, and specific impulse for aero-engines has been performed by the optimization procedure with the multiplier method. Comparison of results with analytical solutions establishes the validity of the optimization procedure.
Advanced Technology Programs for Small Turboshaft Engines: Past, Present, Future
Authors: Johnson E. T. , Lindsay H.
Published: April 2008

This paper addresses approximately 15 years of advanced technology programs sponsored by the United States Army Aviation Applied Technology Directorate and its predecessor organizations and conducted by GE Aircraft Engines (GEAE). Included in these programs is the accomplishment of (1) the 1500 shp demonstrator (GE12), which led to the 1700, and (2) the 5000 shp Modern Technology Demonstrator Engine (MTDE/GE27). Also included are several advanced technology component programs that have been completed or are ongoing through the early 1990s. The goals for the next generation of tri-service small advanced gas generator demonstration programs are shown. A prediction is thus made of the advancements required to fulfill the aircraft propulsion system established by the DoD/NASA Integrated High-Performance Turbine Engine Technology (IHPTET) initiative through the year 2000.
STOVL Hot Gas Ingestion Control Technology
Authors: Amuedo K. C. , Williams B. R. , Flood J. D. , Johns A. L.
Published: April 2008

A comprehensive wind tunnel test program was conducted to evaluate control of Hot Gas Ingestion (HGI) on a 9.2 percent scale model of the McDonnell Aircraft Company model 279-3C advanced Short Takeoff and Vertical Landing (STOVL) configuration. The test was conducted in the NASA-Lewis Research Center 9 ft by 15 ft Low Speed Wind Tunnel during the summer of 1987. Initial tests defined baseline HGI levels as determined by engine face temperature rise and temperature distortion. Subsequent testing was conducted to evaluate HGI control parametrically using Lift Improvement Devices (LIDs), forward nozzle splay angle, a combination of LIDs and forward nozzle splay angle, and main inlet blocking. The results from this test program demonstrate that HGI can be effectively controlled and that HGI is not a barrier to STOVL aircraft development.
Cogenerative, Direct Exhaust Integration of Gas Turbines in Ethylene Production
Authors: Cooke D. H. , Parizot W. D.
Published: April 2008

Within the past few years, gas turbines have been integrated into several new world-class ethylene production plants, for the first time using the exhaust as a source of preheated combustible oxygen for the cracking furnaces. The economic inducements and technical impact of such integration on the process are discussed. The general ethylene cracking and recovery process is described, and the various ways of integrating gas turbines are compared, culminating in the current leading designs. Means of providing ambient air backup to protect furnace operation from gas turbine trips are discussed. Furnace group sizing and oxygen demand for the major feedstocks, including naphtha and ethane/propane, are compared with the current range of oxygen and power available from single and dual gas turbines on the world market. Methods of partial integration, where gas turbine integration of the entire ethylene plant would produce more power than can be economically utilized or consume more premium fuel than available, are discussed. Fuel savings relative to ambient air operation are parametrized with percent exhaust oxygen and exhaust temperature. Aeroderivative and industrial gas turbine types are compared. Comparative economics with another means of gas turbine cogeneration, that of auxiliary boiler replacement with a combined cycle in a central utility, are presented.
The Use of Semi-Conductor Sensors for Blade Surface Pressure Measurement in a Model Turbine Stage
Authors: Ainsworth R. W. , Dietz A. J. , Nunn T. A.
Published: April 2008

The development of semi-conductor sensors particularly aimed at gas turbine technology applications is outlined. Methods of manufacture and means of utilizing some of the inherent advantages of this type of sensor are discussed. A novel technique, where miniature sensors are attached directly to the surface where the measurement is required, is described. This technique combines a high surface density of measurement points with a high frequency response capability. Detailed tests of the sensor’s performance have been conducted and results obtained using this technology are presented. The performance tests include frequency response, base strain sensitivity, g sensitivity, and software temperature compensation schemes. Finally, possible future applications for these techniques in gas turbine technology are outlined.
Dynamic Simulation of Compressor Station Operation Including Centrifugal Compressor and Gas Turbine
Authors: Botros K. K. , Campbell P. J. , Mah D. B.
Published: April 2008

Dynamic simulation of the operation of a compressor station requires mathematical modeling of the dynamic behavior of the compressor unit and various piping elements. Such models consist of large systems of nonlinear partial differential equations describing the pipe flow together with nonlinear algebraic equations describing the quasi-steady flow through various valves, constrictions, and compressors. In addition, the models also include mathematical descriptions of the control system, which consists of mixed algebraic and ordinary differential (mad) equations with some inequalities representing controllers’ limits. In this paper a numerical technique for the solution of the gas dynamics equations is described, based on the transfer matrix formulation relating the state vector time difference at one side of an element to that on the other side. This approach facilitates incorporation of all element transfer matrices into an overall transfer matrix according to the system geometric connectivity. The paper also presents simulation results and comparison with actual field measurements of three case histories: (1) simulation of a compressor surge protection control process; (2) unit startup; and (3) slow transient of a compressor station responding to changes in the discharge pressure set point. Good agreement between simulation results and field measurements is demonstrated.
An Investigation in the Variance in Particle Surface Interactions and Their Effects in Gas Turbines
Authors: Hamed A.
Published: April 2008

This work presents the results of a study conducted to investigate particle surface interaction characteristics and their effects on the particle dynamics and blade erosion in axial flow gas turbines. The particle restitution velocities measured experimentally using Laser Doppler Velocimetry in a special tunnel are analyzed using statistical methods. The resulting distribution functions of the rebounding particle velocities after surface impacts are introduced in the particle trajectory simulations through the turbine blade passages, using a methodology that combines particle dynamics computations in a probabilistic model. The presented results for the simulated ash particle dynamics demonstrate the effect of the experimentally measured variance in the particle restitution characteristics on the particle surface impacts, and the associated blade erosion in an axial flow turbine.
The Utilization of Computer-Aided Drafting (CAD) in Quality Control of Gas Turbine Component Repairs
Authors: Baldwin D. J.
Published: April 2008

In order to maintain a proper standard of excellence in any company, a quality control program must be implemented. This program must be designed to ensure that adequate quality is being provided to the customer. A thorough inspection department is of utmost importance in establishing a proper quality control system where every step of the repair process is monitored and recorded. All documentation produced should be of the highest quality standards possible, which can be obtained through the use of Computer-Aided Drafting (CAD). It is the intent of this paper to demonstrate how CAD can be utilized throughout the quality control process in order to provide clear, accurate, and concise information for the customers as well as the company.
Separating Hydrogen From Coal Gasification Gases With Alumina Membranes
Authors: Egan B. Z. , Fain D. E. , Roettger G. E. , White D. E.
Published: April 2008

Synthesis gas produced in coal gasification processes contains hydrogen, along with carbon monoxide, carbon dioxide, hydrogen sulfide, water, nitrogen, and other gases, depending on the particular gasification process. Development of membrane technology to separate the hydrogen from the raw gas at the high operating temperatures and pressures near exit gas conditions would improve the efficiency of the process. Tubular porous alumina membranes with mean pore radii ranging from about 9-22 Å have been fabricated and characterized. Based on the results of hydrostatic tests, the burst strength of the membranes ranged from 800-1600 psig, with a mean value of about 1300 psig. These membranes were evaluated for separating hydrogen and other gases. Tests of membrane permeabilities were made with helium, nitrogen, and carbon dioxide. Measurements were made at room temperature in the pressure range of 15-589 psi. In general, the relative gas permeabilities correlated qualitatively with a Knudsen flow mechanism; however, other gas transport mechanisms such as surface adsorption also may be involved. Efforts are under way to fabricate membranes having still smaller pores. At smaller pore sizes, higher separation factors are expected from molecular sieving effects.
Calculation Approach Validation for Airblast Atomizers
Authors: Rizk N. K. , Mongia H. C.
Published: April 2008

In order to formulate a common approach that could provide the spray parameters of airblast atomizers, various processes of liquid preparation, breakup, and secondary atomization have been included in a semi-analytical calculation procedure. The air velocity components in the atomizer flow field are provided by mathematical expressions, and the spray droplets are considered to form at ligament breakup through a disturbance wave growth concept. The validation of the developed approach included the application to six atomizers that significantly varied in concept, design, and size. They represented both prefilming and plain-jet types, and the data utilized in the present effort were obtained with six different liquids. Satisfactory agreement between the measurements and the predictions has been achieved under wide ranges of air/fuel ratio and air pressure drop for various test liquids. The results of this investigation indicate the potential of using such an approach in the early phases of airblast atomizer design, and may be followed by more detailed calculations using analytical tools.
Electrically Heated Catalysts for Cold-Start Emission Control on Gasoline- and Methanol-Fueled Vehicles
Authors: Heimrich M. J. , Albu S. , Ahuja M.
Published: April 2008

Cold-start emissions from current technology vehicles equipped with catalytic converters can account for over 80 percent of the emissions produced during the Federal Test Procedure (FTP). Excessive pollutants can be emitted for a period of one to two minutes following cold engine starting, partially because the catalyst has not reached an efficient operating temperature. Electrically heated catalysts, which are heated prior to engine starting, have been identified as a potential strategy for controlling cold-start emissions. This paper summarizes the emission results of three gasoline-fueled and three methanol-fueled vehicles equipped with electrically heated catalyst systems. Results from these vehicles demonstrate that heated catalyst technology can provide FTP emission levels of nonmethane organic gases (NMOG), carbon monoxide (CO), and oxides of nitrogen (NOx) that show promise of meeting the Ultra-Low Emission Vehicle (ULEV) standards established by the California Air Resources Board.
Coal-Fueled Diesel Engine Development Update at GE Transportation Systems
Authors: Hsu B. D.
Published: April 2008

The U.S. Department of Energy is sponsoring a General Electric Company development program for using coal-water slurry (CWS) to power a diesel engine and to test it in a locomotive. The first locomotive system test was successfully completed in 1991 on GE/TS test track. The first-phase coal-fueled 12-cylinder diesel engine used in the locomotive test employed a modified positive displacement fuel injection system and developed 2500 hp in the engine laboratory. The final phase all electric controlled fuel injection equipment (FIE) diesel engine has completed individual component development phases. Combustion research evaluated a broad range of CWS fuels with different source coals, particle sizes, and ash contents. The electronic controlled FIE single cylinder test engine yielded 99.5 percent combustion efficiency. Envelop filters and copper oxide sorbent have been chosen to clean up the engine emissions after extensive evaluation of various hot gas cleaning methods. The projected removal rate of particulate is 99.5 percent and that of SO2 is 90 percent. Over ten diamond insert injector nozzles performed well on the test engines. A bench test of one nozzle has been run for over 500 engine equivalent hours without significant wear. Tungsten carbide (WC) coated piston rings and cylinder liners were identified to be effective in overcoming power assembly wear. A matrix of WC spray parameters were investigated, and the best process was used to apply coatings onto full scale rings and liners. These and other test parts are currently running in two coal fuel operated cylinders on a converted eight-cylinder endurance test engine. All of these developed technologies will be applied onto the second phase engine and be used in the final phase locomotive test. An economic analysis was also completed on a concept locomotive design. Additional equipment cost and the level of diesel fuel price to repay the investment were analyzed. Thus the economic environment for the commercialization of the modern coal fueled locomotive is defined.
Injection Characteristics of Coal-Water Slurries in Medium-Speed Diesel Equipment
Authors: Dodge L. G. , Callahan T. J. , Ryan T. W. , Schwalb J. A. , Benson C. E. , Wilson R. P.
Published: April 2008

The injection characteristics of several micronized coal-water slurries (CWSs, where “s” implies plural) were investigated at high injection pressures (40 to 140 MPa, or 6,000 to 20,000 psi). Detailed spray characteristics including drop-size distributions and cone angles were measured using a continuous, high-pressure injection system spraying through various hole shapes and sizes into a continuous, elevated-pressure air flow. Penetration and cone angle were also measured using intermittent injection into an elevated-pressure quiescent chamber. Cone angles and fuel-air mixing increased rapidly with the relatively constant cone angles of diesel fuel. However, even at high injection pressures the CWSs mixed with air more slowly than diesel fuel at the same pressure. The narrower CWS sprays penetrated more rapidly than diesel fuel at the same injection pressures. Increasing injection pressure dramatically reduced drop sizes in the CWS sprays, while increasing injection pressure reduced drop sizes in the diesel fuel sprays more gradually. The CWSs produced larger average drop sizes than the diesel fuel at all conditions, except for some hole shapes at the highest injection pressures where the average sizes were about the same. Varying the hole shape using converging and diverging holes had a minimal impact on the spray characteristics. A turbulent jet mixing model was used to predict the penetration rate of the CWS fuel jets through different orifice sizes and into different air densities. The jet model also computes the liquid fuel-air ratio through the jet. The work reported here was abstracted from the more complete report by Schwalb et al. (1991).
Emissions From Heavy-Duty Trucks Converted to CNG
Authors: Fritz S. G. , Egbuonu R. I.
Published: April 2008

Emissions are reported for four heavy-duty trucks, which were converted to operate on compressed natural gas fuel. Two 1988 model year Ford F700 Series trucks equipped with 7.0 L gasoline engines and two 1986 model year GMC trucks equipped with DDC 8.2 L diesel engines were tested on a heavy-duty chassis dynamometer in a baseline condition and again after conversion to natural gas. The vehicles were tested over the EPA Urban Dynamometer Driving Schedule for Heavy-Duty Vehicles and at no-load curb idle. Regulated emissions of NOx, CO, HC, and diesel particulate, along with nonmethane hydrocarbons, are reported in grams/mile. Fuel economy is reported in energy-equivalent miles per gallon of gasoline or diesel fuel.
Progress in Diesel Engine Emissions Control
Authors: Khair M. K.
Published: April 2008

A considerable amount of work was carried out in the mid-1980s to develop heavy-duty diesel engines that could meet limits on particulate emissions. These limits, although high by today’s standards, were considered very restrictive. Some manufacturers struggled to achieve the 0.6 g/bhp-h particulate matter limit with enough margin for production variabilities and to account for the deterioration factor. Significant progress was achieved in diesel emissions control through engine and fuel system design changes. This eventually made it possible to meet a particulate level of 0.25 g/bhp-h for 1991. The next target level for particulate emissions is 0.1 g/bhp-h for the 1994 heavy-duty engine. To meet the challenge, engine developers are not only considering engine and injection system design changes but also fuel improvements and exhaust aftertreatment. This paper includes a review of past and current strategies used to control emissions in the modern diesel engine.
Condensing the Dumped Steam During a Turbine Bypass
Authors: Kals W.
Published: April 2008

The reaction of water-cooled and wet-surface air-cooled condensers to a bypass of the steam turbine is analyzed by the introduction of an indicant. Gas dynamics considerations for designing the breakdown of the steam pressure are included. SI metric units are compared with gravitational metric units in order to clarify the fundamental difference between these two systems of measure. Conditioning the steam before admission to the condenser involves desuperheating, which is analyzed on the basis of a heat balance.
Effect of Drift Eliminator Design on Cooling Tower Performance
Authors: Becker B. R. , Burdick L. F.
Published: April 2008

In the use of wet cooling towers, drift refers to small droplets of circulating water that are carried out of the cooling tower by the saturated exhaust air. Inertial impaction separators, known as drift eliminators, are used to strip the water droplets from the exhaust air. To achieve peak cooling tower operating efficiency, it is desirable that losses in fan system performance due to the drift eliminators be minimized. Therefore, an experimental program was developed and executed to evaluate the effect of drift eliminator design on cooling tower fan system performance. Flow visualization studies were used to gain insight into the flow patterns within the cooling tower plenum as influenced by drift eliminator design. A fully instrumented fan test cell was used to investigate the effects upon fan system performance resulting from two different styles of drift eliminators. The effect of drift eliminator discharge angle upon fan system total efficiency was investigated and the optimal discharge angle determined.
The Design, Fabrication, and Installation of a Quiet Compressor Station
Authors: Humphries E. , Schulz D. , Binek J.
Published: April 2008

Stringent environmental constraints are usually associated with or applied to the siting and installation of new pipeline facilities. This has resulted in the dedication of a significant portion of the design effort and ultimate cost of the facility to the mitigation of these environmental concerns. This paper describes how a compressor station can be designed and built such that stringent silencing requirements can be satisfied. The paper also references specific aspects of design that were successfully applied to the Parkway Compressor Station, Canada.
Aerodynamics of Bluff-Body Stabilized Confined Turbulent Premixed Flames
Authors: Pan J. C. , Vangsness M. D. , Ballal D. R.
Published: April 2008

Detailed information on the influence of geometric and flow parameters on the structure and properties of recirculation zone in confined combusting flows is not available. In this paper, recirculation zone structure and turbulence properties of methane-air mixtures downstream of several conical flameholders were measured using LDA. These tests employed different blockage ratios (13 and 25 percent), cone angles (30, 45, 60, and 90 deg), equivalence ratios (0.56, 0.65, 0.8, and 0.9), mean annular velocities (10, 15, and 20 m/s), and approach turbulence levels (2, 17, and 22 percent). It was found that increasing the blockage ratio and cone angle affected the recirculation zone size and shape only slightly. Also, these parameters increased the shear stress and turbulent kinetic energy (TKE) moderately. Increasing the equivalence ratio or approach turbulence intensity produced a recirculation zone shape very similar to that found in the cold flow. TKE decreased due to turbulent dilatation produced by increased heat release. These observations are discussed from the viewpoint of their importance to practical design and combustion modeling.
Wave Engine Aerothermodynamic Design
Authors: Weber H. E.
Published: April 2008

A method for aerothermodynamic preliminary design of a wave engine is presented. The engine has a centrifugal precompressor for the wave rotor, which feeds high and low-pressure turbines. Three specific wave engine designs are presented. Wave rotor blades are naturally cooled by the ingested air; thus combustion temperatures can be as high as 1900 K. Engine pressure ratios of over 25 are obtained in compact designs. It is shown that placing no nozzles at the end of the rotor blade passages yields the highest cycle efficiencies, which can be over 50 percent. Rotor blades are straight and easily milled, cast, or fabricated.
Advanced Ducted Engine Nacelle Aerodynamics and Integration Testing
Authors: McCall J. E. , Tracksdorf P. , Heinig K.
Published: April 2008

Future aircraft engine development may lead to Advanced Ducted Engines (ADE), which have a bypass ratio significantly higher than present turbofans. The increases in bypass ratio will dictate larger diameter nacelles and an increasing importance of the nacelle aerodynamics and wing integration aerodynamics. A series of isolated wind tunnel tests was therefore designed and conducted by PWA and MTU to investigate inlet, nozzle, and reverser aerodynamics. Additional installed testing was done in cooperation with MBB and BAe. Key features of the tests are noted and significant results are discussed.
Nickel-Base Alloy GTD-222, a New Gas Turbine Nozzle Alloy
Authors: Seaver D. W. , Beltran A. M.
Published: April 2008

This paper summarizes the key properties of GTD-222 (Wood and Haydon, 1989), a new cast nickel-base nozzle alloy developed by GE for use in land-based gas turbines. GTD-222 is being introduced as a replacement for FSX-414 in second and third-stage nozzles of certain machines. Presented in this paper are comparisons of the tensile, creep-rupture, and fatigue properties of GTD-222 versus FSX-414. In addition, the results of a long-term thermal stability study, high-temperature oxidation, and hot corrosion evaluation as well as weldability results will be discussed.
Developments in Magnesium-Based Materials and Processes
Authors: Lyon P. , King J. F. , Fowler G. A.
Published: April 2008

Recent developments in magnesium alloys, processing techniques, and corrosion protection schemes are reviewed. The casting alloy WE43 is detailed, data being presented showing that it compares favorably with aluminum-based casting alloys on a strength-to-weight basis. In addition its intrinsic corrosion characteristics are shown to be similar to those of aluminum-base alloys. A countergravity casting process, specifically designed to make higher quality, thin-walled magnesium alloy components, is described, together with property data indicating the improvements obtained. Also discussed are the ongoing developments in metal matrix composites and rapid solidification technologies, showing the benefits offered by these processing routes. Finally current corrosion protection schemes are reviewed and their overall cost effectiveness discussed.
The In-Process Dressing Characteristics of Vitrified Bonded CBN Grinding Wheels
Authors: Williams J. , Yazdzik H.
Published: April 2008

When grinding carbon steels, creep-resistant materials, and other metals such a titanium, cubic boron nitride (CBN) has become recognized as the preferred choice over Al2O3 and SiC. The succes or failure of the grinding process with CBN lies in the mechanical dressing of the wheel because mechanical dressing is accompanied by very large stresses that distort the grinding wheel and deflect the grinding machine. One recent approach is to true the CBN wheel mechanically and then dress the wheel during the actual grinding manufacturing process. This work observes the dressing of vitrified bonded CBN during the actual like cycle in the production process of steel bearings. Scanning electron micrographs of CBN wheel surfaces are related to surface topography measurements of both wheel and bearing using a Tallysurf machine. In addition, the compositions of the wheel surfaces were checked using the SEM x-ray spectrography facilities. In-process dressing was determined to comprise three distinct stages: the primary or initial dressing, the secondary occurring during steady-state grinding, and finally the tertiary stage after which dimensional tolerance is lost. It was found that the life characteristics of the CBN wheel are quite different than current theories predict. Instead of the limitation of grinding being due to work material loading of the wheel and subsequent dulling of the grains, it was found that the CBN grains remain unchanged and a wear process occurs in the matrix material until the grains fall out and the wheels lose their dimensional tolerance.
Development of Ceramic Turbocharger Rotors for High-Temperature Use
Authors: Kawase H. , Kato K. , Matsuhisa T. , Mizuno T.
Published: April 2008

A ceramic turbocharger rotor (CTR) for high-temperature use has been developed. The features of this rotor are the use of silicon nitride, which maintains high mechanical strength up to 1200°C, and a new joining technique between the ceramic rotor and its metal shaft. The CTR is expected to cope with stoichiometric mixture burning engines, which produce a higher exhaust gas temperature for fuel economy, and the impact resistance of the rotor against foreign object damage (FOD) has been markedly increased, over that of earlier rotors, resulting in higher reliability. This paper describes the development of ceramic turbocharger rotors for high-temperature use, focusing on the mechanical strength of silicon nitride and the joining of the ceramic rotor and its metal shaft.