bluuebunny/crossref_metadata_2025 huggingface dataset:
F-4 Functional Modernization
Authors: Poulin W. D.
Published: October 2009

Evolving aircraft and engine technologies, as well as advancements in avionics, have resulted in a new generation of fighter aircraft. In order for an air force to remain survivable in such an environment it must face the necessity of either acquiring new aircraft or upgrading its fleet. Today, acquisition of new aircraft may not be an economically or politically viable solution. The newest aircraft, those with a thrust-to-weight ratio exceeding 1 to 1, generally exceed $20 million, exclusive of support costs. Politically, sale of such state-of-the-art aircraft to friendly countries may not be possible given the current FX aircraft export policy, and the fiscal posture of the country. However, there is an alternative to new aircraft acquisition, and that is functional modernization: the modernization of potentially viable systems through the implementation of new and available technologies. The Boeing Military Airplane Company and Pratt & Whitney have teamed in the newest aircraft functional modernization proposal, the F-4 Super Phantom. The full modernization package includes a new centerline conformal fuel tank, new digital avionics, and re-engining with new PW1120 engines. This paper examines the initial feasibility study conducted by Pratt & Whitney and Boeing to determine the feasibility of a functionally modernized F-4.
Experimental Evaluation of Heavy Fan-High-Pressure Compressor Interaction in a Three-Shaft Engine: Part 1—Experimental Setup and Results
Authors: Scha¨ffler A. , Miatt D. C.
Published: October 2009

Severe aerodynamic interaction between the fan core stream section and the high-pressure compressor of a three-shaft low-bypass-ratio engine is described. At high fan running lines a heavy single-cell rotating stall was found in the fan core stream even at high aerodynamic speeds between 90–98%. The rotating circumferential distortion with 180–200 deg sector angle is swallowed by the intermediate pressure compressor but erodes the high-pressure compressor surge margin by about 22%, leading to steady-state surges. A remotely mounted transducer in a specific arrangement was used successfully for measurements in the hot environment behind intermediate and high-pressure compressor using a so-called “long-line” system with a closed end at the downstream pipe.
Design of Noninteracting Multivariable Feedback Control Systems Without Decoupling Filters
Authors: Baker D. A. , Maday C. J.
Published: October 2009

The design of multivariable control systems for modern applications is an important challenge to the control system engineer. Active control of metal machining operations, control of gas turbine operations, and chemical process control are current areas of interest. In precision machining operations where tolerances of a few microinches are required, in-process control with several servos will be required. These servos could control spindle axis location and tool position about several axes, thus forming a multi-input/multi-output system. Modern gas turbines, required to operate over more extended regimes, are provided with multiple controls, e.g., nozzle settings and fuel flows which must be implemented in some rational manner. In the chemical process industries, there are many examples of multivariable systems with several control variables and several desired or controlled outputs. One control approach considers a separate system for each of the controlled variables, so that a change in one input will produce an interaction effect that must be managed by another separate system. This approach is attractive and straightforward to implement, but current practice shows significant coupling effects. In order to reduce or eliminate interaction, a control algorithm, with strong integral compensation, for a sixth-order, two-input, two-output linear plant with dynamic coupling is proposed. Decoupling filters are not used. The primary goal is to realize a substantial reduction in the coupling effects when a step input is used for a single variable. A secondary goal is to achieve deadbeat response for the controlled variable to the step input. Moreover, these goals are to be attained in the presence of significant changes in the system parameters or in the presence of arbitrary external disturbances, i.e., robustness is required. The control strategy uses cascaded integral error compensation that permits conceptual division of the network so that two single-input/single-output systems result. Coupling effects are treated as arbitrary disturbances. Poles for each loop are placed on the real axis in the left-half plane. Numerical solutions to the system equations show that this approach produces a system that achieves effective decoupling and robustness simultaneously. It is significantly superior to Proportional-Integral-Derivative controllers which also are considered in detail.
A Cost-Effective Indirect Coal-Fired Gas Turbine Power and Water-From-Air Cycle
Authors: Trumpler P. R.
Published: October 2009

An ideal open gas turbine cycle with multiple-stage intercooled compression and multiple-stage reheat expansion theoretically approaches Carnot thermal efficiency. A proposed practicable process to utilize this cycle with indirect firing of coal as fuel, with an air heater in place of the boiler, a turbine inlet temperature of 1700°F (927°C) and top pressure of 788 psia (53.6 atm) gives promise of lowering power plant station heat rates (HHV) from 8970 Btu/kWh currently realized by the best scrubber-equipped coal fired steam plants to 7460, a reduction of 16.8% in fuel consumption and consequently the cost of flue gas scrubbers. In addition, a 316 MW plant delivers at rated output 130,000 gal per day water stripped from atmospheric air. Primarily because of an expensive air heater and regenerator the gas turbine plant is penalized by an estimated increase in initial cost from $1000/kW for a steam plant to $1433/kW. With coal priced at $3/million Btu, water selling at 2¢/gal, money at 8% interest, inflation at 5%, and an 81% plant capacity factor, the payback period is 17 years.
Comparison of Burning Rates in a Natural-Gas-Fueled Spark Ignition Engine
Authors: Jones A. L. , Evans R. L.
Published: October 2009

A series of tests was conducted on a Toyota, four-cylinder, spark ignition engine which was modified to run on either gasoline or natural gas. The aim of the experiment was to investigate the performance and combustion behavior of natural gas, with particular emphasis on its low burning velocity. A pressure transducer installed in the cylinder head was used to obtain pressure versus crank angle curves from which mass burn rates and burning velocities were calculated, using a heat release analysis program. Results indicate that the low laminar burning velocity of natural gas extends its ignition delay period (time to 1 percent burned) by up to 100 percent compared with gasoline. This contrasts with the remainder of the combustion period which is dominated by turbulence effects that produce very similar burning velocities for the two fuels.
A Procedure for Calculating Fuel Gas Blend Knock Rating for Large-Bore Gas Engines and Predicting Engine Operation
Authors: Schaub F. S. , Hubbard R. L.
Published: October 2009

This paper describes the procedure developed by Cooper-Bessemer for large-bore gas engines to calculate the knock rating of gas fuel blends and to predict with accuracy the required engine build to use that fuel with optimum detonation margin. Engine prototype test work has included fuel sensitivity tests mapped as a function of compression ratio, fuel air ratio, ignition advance, combustion air temperature, and engine rating. Success in predicting production engine operation for a given application involving a particular fuel blend has been gratifying. The basic reference method blend selected was normal butane in methane. Details are included in the paper to illustrate the problems in making sensitivity correlations between small-bore fuel research engines and large-bore production engines.
The Design, Performance and Analysis of a High Work Capacity Transonic Turbine
Authors: Bryce J. D. , Litchfield M. R. , Leversuch N. P.
Published: October 2009

This paper describes the design and testing of a high work capacity single-stage transonic turbine of aerodynamic duty tailored to the requirements of driving the high-pressure core of a low cost turbofan engine. Aerodynamic loading was high for this duty (ΔH/U2 = 2.1) and a major objective in the design was the control of the resulting transonic flow to achieve good turbine performance. Practical and coolable blading was a design requirement. At the design point (pressure ratio = 4.48), a turbine total to total efficiency of 87.0 percent was measured—this being based on measured shaft power and a tip clearance of 1.4 percent of blade height. In addition, the turbine was comprehensively instrumented to allow measurement of aerofoil surface static pressures on both stator and rotor—the latter being expedited via a rotating scanivalve system. Downstream area traverses were also conducted. Analysis of these measurements indicates that the turbine operates at overall reaction levels lower than design but the rotor blade performs efficiently.
Numerical Analysis of Fully Three-Dimensional Periodic Flows Through a Turbine Stage
Authors: Koya M. , Kotake S.
Published: October 2009

Fully three-dimensional periodic flows through a turbine stage of stator and rotor are studied numerically by solving time-dependent three-dimensional Euler equations with the finite-volume method. The phase relation of stator and rotor flows and the related blade-row interaction are accounted for in the time-space domain. The established method of numerical calculation makes a practical contribution to predict actual turbine flows through a turbine stage of stator and rotor which have an arbitrary number of blades.
Development and Application of Industrial Gas Turbines for Medium-Btu Gaseous Fuels
Authors: Meier J. G. , Hung W. S. Y. , Sood V. M.
Published: October 2009

This paper describes the successful development and application of industrial gas turbines using medium-Btu gaseous fuels, including those derived from biodegradation of organic matters found in sanitary landfills and liquid sewage. The effects on the gas turbine and its combustion system of burning these alternate fuels compared to burning high-Btu fuels, along with the gas turbine development required to use alternate fuels from the point of view of combustion process, control system, gas turbine durability, maintainability and safety, are discussed.
An Expression of Liquid Film Thickness Inside Prefilming Atomizers
Authors: Gan Xiao-Hua , Zhao Qi-Shou
Published: October 2009

In the present paper, the characteristics of liquid film thickness inside prefilming airblast atomizers are investigated. An expression of liquid film thickness in three-dimensional axisymmetric coordinates is presented. The film thickness of kerosene and water is measured by using special techniques. It is found that the predictions of liquid film thickness agree well with experiments.
End-Wall and Profile Losses in a Low-Speed Axial Flow Compressor Rotor
Authors: Lakshminarayana B. , Sitaram N. , Zhang J.
Published: October 2009

The blade-to-blade variation of relative stagnation pressure losses in the tip region inside the rotor of a single-stage, axial-flow compressor is presented and interpreted in this paper. The losses are measured at two flow coefficients (one at the design point and the other at the near peak pressure rise point) to discern the effect of blade loading on the end-wall losses. The tip clearance losses are found to increase with an increase in the pressure rise coefficient. The losses away from the tip region and near the hub regions are measured downstream. The losses are integrated and interpreted in this paper.
A Theory of Post-Stall Transients in Axial Compression Systems: Part I—Development of Equations
Authors: Moore F. K. , Greitzer E. M.
Published: October 2009

An approximate theory is presented for post-stall transients in multistage axial compression systems. The theory leads to a set of three simultaneous nonlinear third-order partial differential equations for pressure rise, and average and disturbed values of flow coefficient, as functions of time and angle around the compressor. By a Galerkin procedure, angular dependence is averaged, and the equations become first order in time. These final equations are capable of describing the growth and possible decay of a rotating-stall cell during a compressor mass-flow transient. It is shown how rotating-stall-like and surgelike motions are coupled through these equations, and also how the instantaneous compressor pumping characteristic changes during the transient stall process.
Influence of Coal Properties on Forward Combustion in Laminar Flow
Authors: Lockwood W. R. , Corlett R. C. , Mortazavi H. R. , Emery A. F.
Published: October 2009

Numerical results are presented for forward combustion in coal channels wherein the flow is laminar. The work is motivated by the need to describe deviations from ideal permeative flow characteristics in theoretical models of underground rubble gasification. For simplicity, the geometry is idealized to a straight circular channel of initially uniform diameter. Coal and inlet gas properties, as well as gas flow rate and initial channel diameter, are arbitrary. A baseline case, in which O2-steam is injected into a channel in virgin coal, is chosen to match laboratory work reported by other investigators. The results of independent variation of six major parameters are also shown. Finally, representative results are presented for injection of a hot mixture of steam and gasification products into hot char.
Combustion Gas Properties: Part II—Prediction of Partial Pressures of CO2 and H2O in Combustion Gases of Aviation and Diesel Fuels
Authors: Gu¨lder O¨. L.
Published: October 2009

Empirical formulae are presented by means of which the partial pressures of CO2 and H2O in the combustion gases of aviation fuel-air and diesel fuel-air systems can be calculated as functions of pressure, temperature, equivalence ratio, and hydrogen-to-carbon atomic ratio of the fuel. The formulae have been developed by fitting the data from a detailed chemical equilibrium code to a functional expression. Comparisons of the results from the proposed formulae with the results obtained from a chemical equilibrium code have shown that the mean absolute error in predicted partial pressures is around 0.8 percent. These formulae provide a very fast and easy means of predicting partial pressures of CO2 and H2O as compared to equilibrium calculations, and they are also applicable to gasolines, residual fuels, and pure alkanes and aromatics as well as aviation and diesel fuels.
Internal Flow Effects in Prefilming Airblast Atomizers: Mechanisms of Atomization and Droplet Spectra
Authors: Sattelmayer T. , Wittig S.
Published: October 2009

Fuel atomization with prefilming airblast nozzles has been investigated. The present analysis is directed toward a detailed investigation of the atomization processes and the clarification of the fundamental phenomena. Two-dimensional models were utilized. High-speed films, showing the deterioration of the liquid film close to the atomizing edge, reveal the dynamics of the liquid’s deterioration and show the motion of the film during the drop formation. The liquid separation is shown to be a periodic process with the drop formation caused by momentum transfer. The frequency spectrum of the liquid separation is determined by means of an optical technique. It is seen that the main frequencies depend only on the air velocity. They are always lower than the corresponding wave frequencies. The droplet size measurements obtained by a light scattering technique emphasize the dominant role of the air velocity at the atomizing edge. A decrease in the surface tension provides an improvement in atomization quality. Other parameters such as liquid flow rate, liquid viscosity, gap height, and length of the prefilming surface within the nozzle were found not to affect directly the droplet size distribution produced, if the air velocity in each of the two ducts of the nozzle is kept constant. The pressure drop of the air, however, rises. It is shown that the droplet size distribution can be easily determined, if the arithmetic mean value of the air velocity in both ducts is known, e.g., from a calculation of the internal flow. Due to the high liquid mass flow rates of airblast nozzles, the wavy film is partly atomized within the nozzle before the liquid separates at the atomizing edge. The measurements show that the portion of the liquid mass flow atomized remains relatively small and that the droplet sizes are equivalent to those produced at the atomizing edge.
Velocity and Turbulence Fields in Pipe Entrance Regions in the Presence of Cross Flows
Authors: Lloyd S. , Brown A.
Published: October 2009

This paper reports on an experimental investigation into the velocity and turbulence fields in the entrance region of a circular pipe with cross flow at the entry. The pipe entry is a sharp square-edged type with air as the working fluid and measurements are made over the region 0<X/D<21. Observations are presented for a range of cross flows with a maximum Reynolds number, based on pipe diameter, of 64,000. The hot-wire anemometer measurements show a separated nonaxisymmetric flow at entry followed by a skewed flow which progressively smooths out with distance along the pipe.
Improvement of a Cycle J Integral for CT Specimens
Authors: Liu Shao-Lun , Xie Ji-Zhou
Published: October 2009

The cycle J integral formula for CT specimens has been improved as follows: ΔJ=(2/Bb)(α1•U + α2•ΔP•Δδ) + (2/Bb)Ue−1.2025a/w + 0.6233 for 0.3≤a/w≤0.53; ΔJ=(2/Bb)(α1•U + α2•ΔP•Δδ) + (2/Bb)Ue−0.02 sin[(π/0.23)(a/w−0.53)] for 0.53<a/w<0.95. This formula is applicable to the fatigue crack propagation range of 0.3≤a/w<0.95. In comparison with other formulae of the cycle J integral, the application range of the above expression is enlarged and its accuracy is also increased to a certain extent.
Analytical and Experimental Investigation of the Coupled Bladed Disk/Shaft Whirl of a Cantilevered Turbofan
Authors: Crawley E. F. , Ducharme E. H. , Mokadam D. R.
Published: October 2009

The structural dynamics of a rotating flexible blade-rigid disk-flexible cantilevered shaft system is analytically and experimentally investigated. A simple analytical model yields the equations of motion expressed in the rotating frame, which show that the blade one nodal diameter modes dynamically couple to the rigid body whirling motion of the shaft-disk system. The blade modes higher than one nodal diameter are uncoupled from the shaft-disk dynamics. Nondimensionalization of the coupled equations of motion yield the criteria for the propensity and magnitude of the interaction between the bladed disk and shaft-disk modes. The analytical model was then correlated with the results of a structural dynamic experiment performed on the MIT Aeroelastic Rotor, a fan similar in design to a modern high bypass ratio shroudless turbofan. A special whirl excitation apparatus was used to excite both forward and backward asynchronous whirl, in order to determine the natural frequencies of the system. The agreement between the predicted and experimental natural frequencies is good and indicates the possibility of significant interaction of the one nodal diameter blade modes with the shaft-disk modes.
Thermodynamic Study of an Indirect Fired Air Turbine Cogeneration System With Reheat
Authors: Huang F. F. , Wang Ling
Published: October 2009

A previous study of an indirect fired air turbine cogeneration system has been extended to include the concept of reheat. The effects of the number of reheat stages and cycle pressure drops on system performance parameters (such as power and process heat production, fuel utilization efficiency, and second-law efficiency) are examined.
Steam-Injected Gas Turbines
Authors: Larson E. D. , Williams R. H.
Published: October 2009

Among cogeneration and central station power generating technologies, gas turbine systems are attractive largely because of their low capital cost and simplicity. However, poor part-load efficiencies have restricted simple-cycle gas turbines largely to base-load cogeneration applications, while relatively low efficiencies for the production of power only have restricted gas turbines largely to peaking central station applications. Steam-injected gas turbines overcome cogeneration part-load problems by providing for steam in excess of process requirements to be injected into the combustor to raise electrical output and generating efficiency. For central station applications, proposed steam-injected gas turbines would achieve higher efficiencies at smaller capacities than any existing commercial technology, including combined cycles. Their high efficiency and expected low capital cost would make them highly competitive for baseload power generation. This paper provides an overview of steam-injection technology, including performance calculations and an assessment of the economic significance of the technology for cogeneration and central station applications.
On the Premixed Combustion in a Direct-Injection Diesel Engine
Authors: Alkidas A. C.
Published: October 2009

The factors influencing premixed burning and the importance of premixed burning on the exhaust emissions from a small high-speed direct-injection diesel engine were investigated. The characteristics of premixed and diffusion burning were examined using a single-zone heat-release analysis. The mass of fuel burned in premixed combustion was found to be linearly related to the product of engine speed and ignition-delay time and to be essentially independent of the total amount of fuel injected. Accordingly, the premixed-burned fraction increased with increasing engine speed, with decreasing fuel-air ratio and with retarding injection timing. The hydrocarbon emissions did not correlate well with the premixed-burned fraction. In contrast, the oxides of nitrogen emissions were found to increase with decreasing premixed-burned fraction, indicating that diffusion burning, and not premixed burning, is the primary source of oxides of nitrogen emissions.
Fuel Oil Reburning Application for NOx Control to Firetube Package Boilers
Authors: Mulholland J. A. , Hall R. E.
Published: October 2009

Two pilot-scale (0.73 MW or 2.5 × 106 Btu/hr) firetube package boilers were retrofitted for fuel oil reburning application for NOx emission control. When firing distillate fuel oil (0.01 percent nitrogen content), an overall NOx reduction of 46 percent from an uncontrolled emission of 125 ppm (dry, at zero percent O2) was realized by diverting 20 percent of the total boiler load to a second stage burner; a 51 percent NOx reduction from 265 ppm was achieved in a distillate/residual fuel oil mixture (0.14 percent nitrogen content) reburning application. Nitrogen-free fuel oil reburning was found to be slightly more effective at reducing NOx than was natural gas reburning, although longer fuel-rich zone residence times were required to allow for evaporation and mixing of the fuel oil droplets. Key parameters investigated which impact the reburning process were: primary flame NOx, reburn zone stoichiometry, and reburn zone residence time. Reburning applied to firetube package boilers requires minimal facility modification. Reburning can be coupled with other NOx control techniques (e.g., distributed air low NOx burners) to achieve NOx emissions of less than 100 ppm. However, for very low primary flame NOx conditions (i.e., less than 200 ppm), reburning fuel nitrogen content is a limiting factor, and reburning with a low-nitrogen-content fuel, such as natural gas or nitrogen-free distillate oil, may be necessary to achieve 50 percent NOx reduction.
Performance Deterioration of a Turbofan and a Turbojet Engine Upon Exposure to a Dust Environment
Authors: Dunn M. G. , Padova C. , Moller J. E. , Adams R. M.
Published: October 2009

Results are reported for a measurement program designed to investigate the performance deterioration of a TF33 turbofan and a J57 turbojet engine upon exposure to a dust-laden environment. Engine parameters were measured in order to facilitate the recognition of incipient engine difficulties. In addition, a successful effort was made to operate the engines satisfactorily when they were severely damaged. Two TF33 engines have been operated in the same dust mixture but under different operating conditions and a J57 engine was operated at the same conditions as one of the TF33 engines. The JS7 is the core engine of the TF33 with some differences that will be described in the paper. A description of the experimental technique, the operating experiences, photographs of the components taken from the J57 engine in a post-test teardown, and a discussion of the results are presented.
Interpretation of Gas Turbine Response Due to Dust Ingestion
Authors: Batcho P. F. , Moller J. C. , Padova C. , Dunn M. G.
Published: October 2009

A measurement program currently underway at Arvin/Calspan Advanced Technology Center has been used in the evaluation of observed engine behavior during dust ingestion. The Pratt and Whitney TF33 turbofan and J57 turbojet were used in the investigation. Solid particle ingestion was found to erode the compressor blades and result in substantial performance deterioration. The engines were found to have increased susceptibility to surge at low power settings. The roles that anti-ice and intercompressor bleed airplay in surge avoidance are discussed. A discussion of the fuel controller behavior in a deteriorated engine and its effect during steady-state engine operation is also presented. Experimental data obtained during testing were compared to a predictive capability developed to describe deteriorated engine response. The effects of tip clearance, blade profile, and secondary flows were taken into account. The results show good agreement with experimentally observed engine behavior.
A Correlation for the Burning Velocity of Methane–Air Mixtures at High Pressures and Temperatures
Authors: Al-Himyary T. J. , Karim G. A.
Published: October 2009

A formulation for the burning velocity of methane–air mixtures was developed over a range of equivalence ratios at temperatures and pressures high enough to cover conditions encountered in a typical operating spark ignition engine using the experimental data of Babkin and Kozachenko [1]. An example involving the use of such data in a diagnostic program to yield information about the characteristics of flame propagation in an engine fueled with methane is shown.
Study of the Flow Pattern in Compact Manifold Type Junctions by LDA
Authors: Sierens R. , Snauwaert P.
Published: October 2009

In this paper pressure and velocity measurements on two theoretical compact manifold type junctions (compact pulse converters) under steady-state conditions are described. The velocity measurements are done with Laser-Doppler anemometry (LDA). The pressure distributions and the velocity profiles for different flow configurations and different mass flow rates are presented. These results are used for calculation of loss coefficients and for comparison with a numerical algorithm for simulating the three dimensional turbulent quasi-steady flow in compact manifold type junctions.
An Analysis of the Engine Blowdown Process Using Multidimensional Computations
Authors: Uzkan T.
Published: October 2009

The details of the blowdown period were studied for the EMD-710 diesel engine by using a multidimensional computational code for in-cylinder flows. Computed results are presented describing both global and detailed features of the flow field during the blowdown period. Global features include variations of cylinder pressure, mass, angular momentum, turbulence kinetic energy, and the exhaust mass. A parametric analysis has shown that the percent pressure drop and the percent mass exhausted are almost invariable with the initial cylinder pressure or mass. Details of the mass convection process within the cylinder are investigated through development of the line separating the downward and upward flowing gas regions. The location and speed of propagation of this separation line are also found to be independent of initial cylinder pressure and mass. The results show that the speed of the separation line is about twice the piston speed for an initial period of 15 deg crank angle. Then it starts to decrease and becomes equal to the piston speed at about 26 deg after the exhaust valve opening. Beyond this time the separation line is slower than the piston speed.
Prediction of Combustion Performance of Aviation Kerosines Using a Novel Premixed Flame Technique
Authors: Carrier D. M. , Wetton R. J.
Published: October 2009

A novel method for predicting aviation fuel combustion performance has been developed in which the sooting point of a premixed flame is detected automatically. Comparisons with full-scale combustor data confirm that the technique is a more realistic index of combustion quality than Smoke Point or hydrogen content.
Pilot-Scale Characterization of Dry Sorbent Injection for SO2 Control in a Low-NOx Tangential System
Authors: Martin R. J. , Kelly J. T. , Ohmine S. , Chu E. K.
Published: October 2009

A 380-kW (1.3 million Btu/hr) two-burner level, tangentially fired, pilot-scale facility was used to characterize a dry-calcium-based sorbent SO2 capture technique combined with an offset auxiliary air low-NOx burner. Baseline tests showed that the facility properly simulates full-scale temperatures and emission levels. Dry sorbent SO2 test results suggest that for enhanced sorbent SO2 capture, injection should take place away from the burner zone where temperatures are lower, and that the time sorbent particles spend in the optimal temperature range should be extended as much as possible through sorbent injection methods and temperature profile modification.
Numerical Model for Predicting Performance of Three-Dimensional Pulverized-Fuel Fired Furnaces
Authors: Fiveland W. A. , Wessel R. A.
Published: October 2009

A numerical furnace model (FURMO) was developed to model steady-state, three-dimensional pulverized-fuel combustion in practical furnace geometries. This model is based on a fundamental description of various interacting processes which occur during combustion: turbulent flow, heterogeneous and homogeneous chemical reaction, and heat transfer. The detailed analysis achieved by the method is useful for evaluating furnace performance and in the interpretation of laboratory, intermediate, and utility test data. In this paper, three-dimensional pulverized coal combustion is investigated for a 560 MW utility boiler. Numerical results for flow, heat transfer, and chemistry are presented. Contour maps are exhibited to describe these complex three-dimensional interactions. Model sensitivity is evaluated for changes in slag layer thickness, particle size distribution, and devolatilization and char oxidation rates.
The Effect of Disk Geometry on Heat Transfer in a Rotating Cavity With a Radial Outflow of Fluid
Authors: Farthing P. R. , Owen J. M.
Published: October 2009

Flow visualization and heat transfer measurements have been made in a cavity comprising two nonplane disks of 762 mm diameter and a peripheral shroud, all of which could be rotated up to 2000 rpm. “Cobs,” made from a lightweight foam material and shaped to model the geometry of turbine disks, were attached to the center of each disk. Cooling air at flow rates up to 0.1 kg/s entered the cavity through the center of the “upstream” disk and left via holes in the shroud. The flow structure was found to be similar to that observed in earlier tests for the plane-disk case: a source region, Ekman layers, sink layer, and interior core were observed by flow visualization. Providing the source region did not fill the entire cavity, solutions of the turbulent integral boundary-layer equations provided a reasonable approximation to the Nusselt numbers measured on the heated “downstream” disk.
Results From the Phase II Test Using the High-Temperature Developing Unit (HTDU)
Authors: Aoki S. , Teshima K. , Arai M. , Yamao H.
Published: October 2009

Phase II of the high-temperature turbine test was performed using the High-Temperature Developing Unit (HTDU). This unit has the same two stages as the high-pressure turbine of the AGTJ-100A reheat system. The purpose of the Phase II test was to investigate the potential of candidate technologies that may be applied to the advanced engine, the AGTJ-100B. Cooling characteristics of several cooling schemes for the first stage blades, and the performance of thermal barrier coating employed on the first stage nozzles and blades, were investigated. This paper presents the Phase II test results.
A Nonlinear Controller Design Method for Fuel-Injected Automotive Engines
Authors: Cho D. , Hedrick J. K.
Published: October 2009

A nonlinear, “sliding mode” fuel-injection controller is designed based on a physically motivated, mathematical engine model. The designed controller can achieve a commanded air-to-fuel ratio with excellent transient properties, which offers the potential for improving fuel economy, torque transients, and emission levels. The controller is robust to model errors as well as to rapidly changing maneuvers of throttle and spark advance. The sliding mode control method offers a great potential for future engine control problems, since: it results in a relatively simple control structure that requires little on-line computing and no table lookups; it is robust to model errors and disturbances; and it can be easily adapted to a family of engines.
A Rankine Bottoming Cycle System for Heavy-Duty Applications
Authors: Cemenska R. A.
Published: October 2009

Fuel costs represent a major portion of the total operating expense of a heavy-duty engine in continuous service. Many new technologies are being developed to lower engine fuel consumption, but a 10–15 percent reduction in fuel costs is now achievable using Rankine Bottoming Cycle (RBC) technology. System economics require integration of state-of-the-art technology in the turbine, heat exchangers, and automatic controls. This paper describes the design and initial test results of a project to demonstrate a diesel engine-RBC power plant. The system was constructed for a Caterpillar 3500 series 16-cylinder (3516) engine with a combined output of 1415 kW. Initial test results have demonstrated a 10.4 percent fuel savings at a thermal efficiency of 44.5 percent. The RBC module is a steam-based, stand-alone unit featuring unattended operation through the use of on-board water treatment, a once-through boiler, automatic control system, and a unique design three-stage-dual pressure steam turbine. The modular concept allows the system to be adapted to other engines and alternative heat sources.
Behavior of Band Spectra in Diesel Combustion Flames: A Study on Chemical Reactions in Diesel Combustion
Authors: Nagase K. , Funatsu K.
Published: October 2009

When a precombustion chamber type Diesel engine is operated under light loads and at low speeds, it is observed that the ignition flames in its main combustion chamber are generated in several stages under specific conditions of fuel injection. The authors, by observing the multistage ignition flames through an optical fiber probe inserted into the chamber, confirmed a number of band spectra emitted from some substances and CH radicals, existing in the flames, and have made clear some aspects of the chemical reactions taking place in Diesel combustion.
Experiments With Coal Fuels in a High-Temperature Diesel Engine
Authors: Likos W. E. , Ryan T. W.
Published: October 2009

The combustion of 50 wt percent coal slurries, using water, diesel fuel, and methanol as carrier liquids, was investigated in a single-cylinder research engine. High temperatures were achieved in the engine cylinder using low-heat-rejection engine technology, electrically heated glow plugs, and heated inlet air. Comparisons of the fuels and different methods of providing high cylinder temperature were made using cylinder pressure data and heat release calculations. Autoignition of the coal/water slurries was attained using auxiliary heat input. The burning rates of all the autoignited slurries were significantly enhanced by using a pilot injection of diesel fuel. Under some operating conditions the engine thermal efficiency was equal to diesel fuel performance. It was apparent that engines designed for coal slurry should maximize the prechamber volume.
The Effects of Engine Speed on the Scavenging Characteristics of a Two-Cycle Engine
Authors: Uzkan T.
Published: October 2009

The effects of engine speed on the fresh air breathing characteristics of a uniflow, two-cycle engine were studied by using a multidimensional computational code for in-cylinder flows. Computed results are presented describing both global and detailed features of the flow field during the air breathing and compression stroke, at four different engine speeds, namely, 400, 700, 900, and 1000 rpm. Global features are presented including the variations of cylinder pressure, mass, angular momentum, turbulence kinetic energy, and the exhaust mass as a function of crank angle. Detailed features of the flow field are presented in terms of the velocity vector plots, fresh air concentration contour plots, and swirl velocity contour plots at certain crank angles. The volumetric scavenging, and charging efficiency decreases, but the trapping efficiency increases with increasing engine speed. A simple scavenging model (correlating the fraction of fresh air in exhaust to the fraction of fresh air in cylinder) suitable for use in engine performance algorithms is presented. Predictions indicate that the effect of engine speed on such a model is not negligible. The use of similar models would be questionable and limited in range, if they are insensitive to engine speed. The residual gas concentration at TDC is shown to be relatively uniform at low engine speeds, but at high speeds, the residual gases are more concentrated at the squish region and the fresh air is more concentrated near the bowl center.
Mathematical Modeling of the Scavenging Process in a Two-Stroke Diesel Engine
Authors: Carapanayotis A. , Salcudean M.
Published: October 2009

A multidimensional investigation of the scavenging process in the GM6V53T General Motors diesel engine has been carried out. This six-cylinder two-stroke engine features uniflow scavenging with four exhaust valves per cylinder, direct fuel injection, and turbocharging. The conservative equations of mass, energy, concentration, turbulence kinetic energy, and energy dissipation rate have been written in finite difference form and solved explicitly in time. The scavenging process has been studied by using a configuration of two exhaust valves as compared with the actual configuration, which has four exhaust valves. The computed flow characteristics and scavenging efficiency are very similar if the exhaust areas of the two different configurations are equivalent.
Thermal Barrier Coating Life Prediction Model Development
Authors: Cruse T. A. , Stewart S. E. , Ortiz M.
Published: October 2009

Ceramic thermal barrier coating tests show that the coating fails by ceramic spallation. Analysis of life data indicates that cyclic thermal loading and thermal exposure play synergistic roles in controlling the spallation life of the coating. A life prediction algorithm has been developed, based on a damage accumulation algorithm that includes both cyclic and time-dependent damage. The cyclic damage is related to the calculated cyclic inelastic strain range in the ceramic coating; the time-dependent damage is related to the oxidation kinetics at the bond-ceramic interface. Cyclic inelastic strain range is calculated using a modified form of the Walker viscoplastic material model. Calculation of the oxidation kinetics is based on traditional oxidation algorithms using experimentally determined parameters. A relation between oxide growth and cycle parameters was derived from test data. The life prediction model was evaluated by predicting the lives of a set of thermal cyclic tests whose heating and cooling rates were significantly greater than those used to correlate the life parameters. Correlation between the actual and predicted spallation lives is within a factor of 3. This is judged to be satisfactory, relative to fatigue life prediction scatter in metals.
Design Experience in Minimizing Radiation Exposure to Personnel During Maintenance of BWR Power Plants
Authors: Punches J. R.
Published: October 2009

As nuclear power plants become older, in-vessel maintenance to high radiation components will become more common. This paper describes General Electric’s experience in making such repairs on Boiling Water Reactors and how the use of engineering and project management enhances the productivity of special maintenance projects. Design techniques employed to minimize personnel radiation exposure are discussed. Specialized remote, automatic, and semi-automatic equipment designs are presented. Included are sample descriptions of special tools developed, problems encountered, and lessons learned.
Computerized Dose Estimates for Maintenance
Authors: Lau F. L. , Sejvar J.
Published: October 2009

The minimization and control of radiation exposure usually starts with the determination of the total expected dose. Manual determination of an accurate value can require an extensive, error-prone amount of data manipulation. By computerizing the model for this determination the individual task and total dose values can be identified much more rapidly and accurately than by manual methods. Also, high-dose operations can be easily evaluated for ways to reduce exposure. The microcomputer also allows instantaneous updating of estimates as changes are made both in the planning stage and in the performance of the job.
Coal–Water Slurry Combustion in Gas Turbines
Authors: Staub F. W. , Kimura S. G. , Spiro C. L. , Horner M. W.
Published: October 2009

This paper presents preliminary results of a program to investigate the key technologies for burning coal-water slurries in gas turbines. Results are given for slurry atomization and combustion testing and analyses performed at conditions typical for gas turbine applications. Significant progress has been made toward the understanding of slurry combustion and ash deposition phenomena. Confidence has been gained to the extent where elimination of a supplementary pilot fuel can now be projected.
Effect of Molecular Structure on Soot Formation Characteristics of Aviation Turbine Fuels
Authors: Gu¨lder O¨. L. , Glavincˇevski B. , Das S.
Published: October 2009

The smoke point has been shown to be quantitatively related to the molecular structure of hydrocarbon fuels. A fast technique of determining the molecular composition of commercial and experimental fuels, in terms of carbon type structure, by using proton nuclear magnetic resonance (1H NMR) spectrometry, has been described. By measuring the smoke point soot yields of a laminar diffusion flame with a group of fuels—all having a constant hydrogen-to-carbon ratio—it has been shown that neither the smoke point nor the hydrogen-to-carbon ratio alone can describe the sooting propensity of turbine fuels. Obtained results indicate that smoke points and hydrogen-to-carbon ratio are complementary to each other in describing the sooting propensities of turbine fuels. This has been further tested using the available data in literature obtained from gas turbine combustors and diffusion flames.
Flame Speeds in Fuel Sprays With Hydrogen Addition
Authors: Richards G. A. , Sojka P. E. , Lefebvre A. H.
Published: October 2009

The influence of hydrogen addition on the burning rates of kerosine sprays in air is studied experimentally. Flame speeds are measured as a function of fuel drop size, equivalence ratio, and hydrogen concentration. The results obtained show that evaporation rates have a controlling effect on flame speeds over wide ranges of mean drop size. They also demonstrate that the burning rates of liquid kerosine-air mixtures are augmented appreciably by the addition of small quantities of hydrogen to the air flowing into the combustion zone.
XG40—Advanced Combat Engine Technology Demonstrator Program
Authors: Jarvis A. F.
Published: October 2009

Commenced in 1982, the XG40 program is central to the demonstration of Rolls-Royce technology appropriate to the requirements of the advanced combat engine for mid-1990s operation. At the same time, the technology in scaled form is viewed as having wider application than for the advanced combat engine alone. This program is jointly funded by UK MoD and Rolls-Royce. In the paper the concepts and scope of the program are described. Associations with previous research programs and other advanced technology demonstrator programs of Rolls-Royce are stated. To meet the multirole capabilities of the advanced fighter and taking the European requirements in particular, the combat engine must be designed to give enhanced dry thrust, retain good dry specific fuel consumption, and reduce reheated fuel consumption compared with current fighter engines. A thrust/weight ratio of 10:1 is targeted and at the same time, requirements for operating cost, reliability, and durability are stringent. As a demonstrator, XG40 has been designed to meet the foregoing performance requirements. At the same time, advanced materials, manufacturing technology, and design of structures have been incorporated to enable the required levels of reliability, durability, component cost, and weight to be demonstrated. Although a demonstrator, XG40 was designed at a scale judged to be appropriate to the likely next generation European fighter requirement. Thus, the engine is in the 90/95 kN nominal Sea Level Static Combat thrust class. Configuration and design are discussed. XG40 is a total technology demonstration program. Principal modules each have a full-scale aerothermal rig program and appropriate structure rig programs. Apart from rigs, the program, including durability testing, utilizes a number of cores and engines plus spares. Achievements and progress toward milestones are reviewed.
Design for the 145-MW Blast Furnace Gas Firing Gas Turbine Combined Cycle Plant
Authors: Takano H. , Kitauchi Y. , Hiura H.
Published: October 2009

A 145-MW blast furnace gas firing gas turbine combined cycle plant was designed and installed in a steel works in Japan as a repowering unit. A 124-MW large-scale gas turbine with turbine inlet temperature 1150°C (1423 K) was adopted as a core engine for the combined cycle plant. The fuel of this gas turbine is blast furnace gas mixed with coke oven gas. These are byproducts of steel works, and the calorific value of the mixed gas is controlled to be about 1000 kcal/Nm3 (4187 kJ/Nm3). A specially designed multicannular type combustor was developed to burn such a low Btu fuel. The gas turbine, generator, steam turbine, and fuel gas compressor are connected to make a single-shaft configuration. As a result of introducing the gas turbine combined cycle plant, the plant thermal efficiency was above 45 percent (at NET) and the total electricity generation in the works has increased from 243 MW to 317 MW. This paper describes the design features of this combined cycle plant.