bluuebunny/crossref_metadata_2025 huggingface dataset:
Transonic Cascade Flow Solved by Separate Supersonic and Subsonic Computations With Shock Fitting
Authors: Wu Wenquan , Wu Chung-Hua , Yu Dabang
Published: October 2009

A new method to solve the transonic flow past a plane cascade with inlet bow wave and a passage shock extending from the leading edge all the way across the flow channel is presented. In this method, different algorithms are used for supersonic and subsonic flow regions, respectively, and the aerothermodynamic relations of a connecting passage shock are satisfied. Within the supersonic region, the method of characteristics is used. For calculation of the subsonic flow, the stream function equation expressed with respect to nonorthogonal curvilinear coordinates and nonorthogonal velocity components is solved with a matrix method. By the use of Rankine-Hugoniot relations, the passage shock can be accurately determined and a definite jump of the aerothermodynamic quantities across the passage shock is obtained. All calculations involved are programmed and incorporated into a single code. The computational procedure is straightforward and simple, and the computational time is short. Some results of typical applications of this method are given in this paper. Agreement of the numerical results with the experimental data, including the location and shape of the passage shock wave, is very good.
Measurements of Wake-Generated Unsteadiness in the Rotor Passages of Axial Flow Turbines
Authors: Hodson H. P.
Published: October 2009

This paper describes an investigation into the free-stream unsteadiness which is found in the rotor passages of axial flow turbines and which is caused by the interaction of the stator wakes with the rotor blades. The major part of this investigation was conducted at the midspan of the rotor of a large-scale, single-stage air turbine. Measurements are presented of the unsteady free-stream velocities and blade surface pressures. These are supplemented by further results which were obtained during a flow visualization experiment in a small-scale water turbine. It is shown that the unsteadiness is dominated by the convected phenomena associated with the passage of the wakes through the rotor.
Balancing Pulverized Coal Flows in Parallel Piping
Authors: Vetter A. A. , Vetter R. S.
Published: October 2009

The distributions of the two-phase (pulverized coal in air) fuel inputs through the 24 parallel coal transport pipes of a coal-fired power plant are determined with a computer code. The orificing which would provide balanced fuel inputs through these coal transport pipes under nominal load conditions is also calculated with the code. Over the entire range of loading, the orificing determined with the code provides much smaller fuel imbalances than the imbalances which result with the previously installed orificings.
Viscosity Measurements of Slags From Western Canadian Coals
Authors: Quon D. H. H. , Wang S. S. B. , Chen T. T.
Published: October 2009

The flow characteristics of slags formed by burning of western Canadian coals were characterized by means of high-temperature viscosity measurements. The results show that there is a general linear relationship between viscosities and SiO2/Al2O3, SiO2/(Al2O3 + Fe2O3) mass ratios and base/acid ratio of the slags. It can be concluded that the viscosities of the slags are sensitive to compositional variation. Attempts were made to correlate the viscosities calculated by Watt and Fereday and Bomkamp’s modified methods with the measured viscosities. The correlation is unsatisfactory. The computed viscosities are higher than the measured values.
Heat Transfer and Fluid Mechanics Measurements in Transitional Boundary Layer Flows
Authors: Wang T. , Simon T. W. , Buddhavarapu J.
Published: October 2009

Experimental results are presented to document hydrodynamic and thermal development of flat-plate boundary layers undergoing natural transition. Local heat transfer coefficients, skin friction coefficients, and profiles of velocity, temperature, and Reynolds normal and shear stresses are presented. A case with no transition and transitional cases with 0.68 percent and 2.0 percent free-stream disturbance intensities were investigated. The locations of transition are consistent with earlier data. A late-laminar state with significant levels of turbulence is documented. In late-transitional and early-turbulent flows, turbulent Prandtl number and conduction layer thickness values exceed, and the Reynolds analogy factor is less than, values previously measured in fully turbulent flows.
Fiber Optics for Propulsion Control Systems
Authors: Baumbick R. J.
Published: October 2009

The term “fiber optics” means the use of dielectric waveguides to transfer information. In aircraft systems with digital controls, fiber optics has advantages over wire systems because of its inherent immunity to electromagnetic noise (EMI) and electromagnetic pulses (EMP). It also offers a weight benefit when metallic conductors are replaced by optical fibers. To take full advantage of the benefits of optical waveguides, passive optical sensors are also being developed to eliminate the need for electrical power to the sensor. Fiber optics may also be used for controlling actuators on engine and airframe. In this application, the optical fibers, connectors, etc., will be subjected to high temperatures and vibrations. This paper discusses the use of fiber optics in aircraft propulsion systems, together with the optical sensors and optically controlled actuators being developed to take full advantage of the benefits which fiber optics offers. The requirements for sensors and actuators in advanced propulsion systems are identified. The benefits of using fiber optics in place of conventional wire systems are discussed as well as the environmental conditions under which the optical components must operate. Work being done under contract to NASA Lewis on optical and optically activated actuators sensors for propulsion control systems is presented.
Local Heat-Transfer Measurements on a Large Scale-Model Turbine Blade Airfoil Using a Composite of a Heater Element and Liquid Crystals
Authors: Hippensteele S. A. , Russell L. M. , Torres F. J.
Published: October 2009

Local heat-transfer coefficients were experimentally mapped along the midchord of a five-times-size turbine blade airfoil in a static cascade operated at room temperature over a range of Reynolds numbers. The test surface consisted of a composite of commercially available materials: a mylar sheet with a layer of cholesteric liquid crystals, which change color with temperature, and a heater sheet made of a carbon-impregnated paper, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat-transfer coefficients were mapped over the airfoil surface. The local heat-transfer coefficients are presented for Reynolds numbers from 2.8×105 to 7.6×105. Comparisons are made with analytical values of heat-transfer coefficients obtained from the STAN5 boundary layer code. Also, a leading-edge separation bubble was revealed by thermal and flow visualization.
Heat-Transfer Distribution Around a Cylinder in Pulsating Crossflow
Authors: Andraka C. E. , Diller T. E.
Published: October 2009

The effects of sinusoidal flow pulsations on the heat transfer from a cylinder to a crossflow at Re = 50,000 were investigated. A range of different pulsation amplitudes of up to 25% and frequencies both above and below the natural shedding frequency were used. The pulsating flow was clean and well organized. It had greater than 95% of the power at the fundamental frequency with a low turbulence level (less than 0.5%). The time-averaged local heat transfer was experimentally measured for a constant-temperature surface-boundary condition using a small heat flux gage in the cylinder wall. Distributions were obtained by rotating the cylinder through 180 deg. The experiments showed no significant increase of heat transfer due to the flow pulsation in either the wake or attached boundary layer region. Small local increases were found near the separation point.
Application of a Navier–Stokes Analysis to Flows Through Plane Cascades
Authors: Scha¨fer O. , Fru¨hauf H.-H. , Bauer B. , Guggolz M.
Published: October 2009

A newly developed method is used to compute a variety of laminar/turbulent, attached/separated flows through plane turbine or compressor cascades. The thin-layer or full Navier–Stokes equations are solved in a 2-D or quasi-2-D/quasi-3-D form taking into account variable axial velocity density ratio/cascade aspect ratio. The turbulence is modeled by the Baldwin–Lomax algebraic two-layer eddy viscosity approach. Improved mesh generation and discretization techniques are introduced. A fully implicit formulation of the flow problem is developed which ensures high stability and convergence. Numerous quantitative comparisons of viscous solutions with experiments and other existing solutions are performed to validate the method. First results on the applicability of the thin-layer assumption are included.
Pressure Loss Due to the Tip Clearance of Impeller Blades in Centrifugal and Axial Blowers
Authors: Senoo Y. , Ishida M.
Published: October 2009

The pressure loss based on the tip clearance of impeller blades consists of the pressure loss induced by the leakage flow through the clearance and the pressure loss for supporting fluid against the pressure gradient in the channels and in the thin annular clearance space between the shroud and the impeller. Equations to evaluate these losses are derived and the predicted efficiency drop is compared with experimental data for two types of centrifugal impellers. Furthermore, the equations are simplified for axial impellers as a special case, and the predicted efficiency drop is compared with the experimental data for seven cases in the literature. Fair agreement demonstrates plausibility of the present model.
Calculations of Two and Three-Dimensional Transonic Cascade Flow Fields Using the Navier-Stokes Equations
Authors: Weinberg B. C. , Yang R.-J. , McDonald H. , Shamroth S. J.
Published: October 2009

The multidimensional, ensemble-averaged, compressible, time-dependent Navier-Stokes equations have been used to study the turbulent flow field in two and three-dimensional turbine cascades. The viscous regions of the flow were resolved and no-slip boundary conditions were utilized on solid surfaces. The calculations were performed in a constructive ‘O’-type grid which allows representation of the blade rounded trailing edge. Converged solutions were obtained in relatively few time steps (∼ 80–150) and comparisons for both surface pressure and heat transfer showed good agreement with data. The three-dimensional turbine cascade calculation showed many of the expected flow-field features.
The Importance of Circumferential Non-uniformities in a Passage-Averaged Quasi-Three-Dimensional Turbomachinery Design System
Authors: Jennions I. K. , Stow P.
Published: October 2009

The purpose of this paper is to show, for both rotating and non-rotating blade rows, the importance of including circumferential non-uniform flow effects in a quasi-three-dimensional blade design system. The paper follows from previous publications on the system in which the mathematical analysis and computerized system are detailed. Results are presented for a different stack of the nozzle guide vane presented previously and for a turbine rotor. In the former case it is again found that the blade force represents a major contribution to the radial pressure gradient, while for the rotor the radial pressure gradient is dominated by centrifugal effects. In both examples the effects of circumferential non-uniformities are detailed and discussed.
Investigations of the Effect of Annulus Taper on Transonic Turbine Cascade Flow
Authors: Bra¨unling W. , Lehthaus F.
Published: October 2009

In a test facility for rotating annular cascades with three conical test sections of different taper angles (0, 30, 45 deg), experiments are conducted for two geometrically different turbine cascade configurations, a hub section cascade with high deflection and a tip section cascade with low deflection. The evaluation of time-averaged data derived from conventional probe measurements upstream and downstream of the test wheel in the machine-fixed absolute system is based on the assumption of axisymmetric stream surfaces. The cascade characteristics, i.e., mass flow, deflection, and losses, for a wide range of inlet flow angles and outlet Mach numbers are provided in the blade-fixed relative system with respect to the influence of annulus taper. Some of the results are compared with simple theoretical calculations. To obtain some information about the spatial structure of the flow within the cascade passages, surface pressure distributions on the profiles of the rotating test wheels are measured at three different radial blade sections. For some examples those distributions are compared with numerical results on plane cascades of the same sweep and dihedral angles and the same aspect ratios. The computer code used is based on a three-dimensional time-marching finite-volume method solving the Euler equations. Both experimental and numerical results show a fairly good qualitative agreement in the three-dimensional blade surface pressure distributions. This work will be continued with detailed investigations on the spatial flow structure.
Vibration Characteristics of Mistuned Shrouded Blade Assemblies
Authors: Valero N. A. , Bendiksen O. O.
Published: October 2009

An investigation of the mode localization phenomenon associated with mistuning is presented for shrouded blade assemblies. The calculations are based on a generic finite element model, which permits modeling of arbitrary mistuning and both slipping and nonslipping shroud interfaces. The results presented indicate that interactions occur between mistuning and slip effects, with maximum mode localization occurring when the shrouds slip freely. Certain modes are found to be very sensitive to shroud slip, and in some cases completely change character when slip occurs. Mode localization is most pronounced in the predominantly bending modes, and varies considerably from mode to mode. As the ratio of interblade coupling strength to mistuning strength is increased, the effect of mistuning is observed to decrease significantly. This result has important implications for the flutter problem, since it suggests that the stabilization effect available from mistuning is significantly less for a shrouded rotor as compared to an unshrouded rotor.
On the Importance of Shear Deformation, Rotatory Inertia, and Coriolis Forces in Turbine Blade Vibrations
Authors: Ansari K. A.
Published: October 2009

This paper is concerned with the significance of the effects of shear deformation, rotatory inertia, and Coriolis forces in the analysis of turbine blade vibrations. Since these are quite pronounced at the high frequency ranges encountered in turbine blade vibration problems, they should not be overlooked although their inclusion paves the way for a complicated nonlinear analysis. An approximate analysis technique is presented which involves an application of the stationary functional method using the normal modes of a discretized model. Numerical results for a typical blade are obtained and discussed. An advantage of this analysis as applied to a lumped parameter model is that nonlinear modes higher than the fundamental can also be easily computed and assessed.
Study on Two-Phase Fuel Distributions in High-Speed Hot Transverse Air Stream
Authors: Yang Mao-lin , Gu Shan-jian , Li Xiang-yi
Published: October 2009

It was found that fuel distribution in a hot high-speed transverse air stream differed greatly from that in a cold stream. In a hot air stream there exist two-phase fuel distributions, and hence, two mass center lines extending downstream. Experimental results of fuel distributions are presented. By using the model of trajectory with diffusion and also considering the fuel evaporation, a semi-empirical method to predict two-phase fuel distributions has been developed.
Mass Balancing of Hollow Fan Blades
Authors: Kielb R. E.
Published: October 2009

This paper uses a typical section model to investigate analytically the effect of mass balancing as applied to hollow, supersonic fan blades. A procedure to determine the best configuration of an internal balancing mass to provide flutter alleviation is developed. This procedure is applied to a typical supersonic shroudless fan blade which is unstable both in the solid configuration and when it is hollow with no balancing mass. The addition of an optimized balancing mass is shown to stabilize the blade at the design condition.
An Efficient Method for Predicting the Vibratory Response of Linear Structures With Friction Interfaces
Authors: Bazan E. , Bielak J. , Griffin J. H.
Published: October 2009

A simple methodology to study the steady-state response of systems consisting of linear elastic substructures connected by friction interfaces is presented. Assuming that only the first Fourier components of the friction forces contribute significantly to the system response, the differential equations of motion are transformed into a system of algebraic complex equations. Then, an efficient linearized procedure to solve these equations for different normal loads in the friction interfaces is developed. As part of the solution procedure, a criterion to determine the slip-to-stuck transitions in the joint is proposed. Within the assumption that the response is harmonic, any desired accuracy can be obtained with this methodology. Selected numerical examples are presented to illustrate practical applications and the relevant features of the methodology. Due to its simplicity, this methodology is particularly appropriate for performing parametric studies that require solutions for many values of normal loads.
The Production of Jet Fuel From Alternative Sources
Authors: Lander H. R. , Reif H. E.
Published: October 2009

The most significant potential source of aviation gas turbine fuels in the continental United States is the western oil shale located in the Rocky Mountain States of Colorado, Utah, and Wyoming. Nearly 600 billion barrels of recoverable oil is located in this area. This paper discusses the availability of oil shale and reviews the recovery, upgrading and refining schemes necessary to produce fuel which can be used in present-day aircraft. Other synthetic fuels are discussed with regard to the processing necessary to produce suitable fuels for today’s high-performance aircraft. Heavy oil and tar sand bitumen are likely to be refined in the next decade. Methods for producing suitable fuels are discussed. The chemical structure of these sources, which is basically cyclic, leads to the potential for heavier fuels with more energy per given volume and therefore longer range for certain aircraft. This exciting possibility is reviewed.
CFD for Engine-Airframe Integration
Authors: Paynter G. C. , Forester C. K. , Tjonneland E.
Published: October 2009

This article provides an assessment of current CFD technology with application to propulsion integration, a definition of research and development needed to extend the technology, and a discussion of numerical error assessment and control. The CFD technology is divided into the elemental areas of the computer system, algorithms, geometry and mesh generation, turbulence modeling, and experimental validation; the current status and major issues in each of these areas are defined. Sources of numerical error are identified and some strategies for determining and controlling these are presented. CFD will have an impact on propulsion integration equivalent to that of the wind tunnel as CFD technology matures. This maturation will lead to a system which integrates the elemental areas of CFD for applications.
New Cement-Based Materials for Engine Construction
Authors: Love M.
Published: October 2009

A study of new and unconventional materials for use in engine construction highlighted several interesting developments. One which stood out as providing useful physical properties at low cost was the cement-based material known as NIMS. A design study for a cylinder block molded from this material was undertaken and a novel construction method devised. In order to gain practical experience with the material, a valve cover for a four-cylinder gasoline engine has been designed and manufactured. The cover is being developed on an engine in a test vehicle and shows potential for noise reduction with little or no increase in cost or weight.
Reciprocating Compressor Frame Distortion During a Cold Start
Authors: Smalley A. J.
Published: October 2009

This paper presents measurements of vertical and horizontal distortions of a compressor frame during the days following a cold start. The distortions are measured using a laser beam directed along the back of the compressor at the level of the bearings. Laser targets attached to the frame generate voltages proportional to the vertical and horizontal displacement of the targets relative to the laser beam. Data are acquired by a microcomputer and high-speed A-to-D converter. Coherent averaging techniques reduce the influence of vibration on these readings to a tolerable level. Frame distortion readings are supplemented by temperatures measured at a number of points on the compressor frame and foundation block. Averaged signals from laser targets and thermocouples are logged by the computer every 2 min. Two sets of results are presented: one for a compressor mounted on a concrete block with a sand–cement full bed grout, the other for a compressor mounted on epoxy chocks. Data for the full bed grout unit cover a 53-h period. Data for the chock-mounted unit cover a 96-h period. Both units show some unexpected distortion transients during the first 24 h, and the magnitude of these is significantly greater for the full bed grout unit. Both units exhibit pronounced swings in frame distortion as ambient temperature changes from day to night. This daily cycling with ambient temperature, in particular, shows the need for careful interpretation of isolated readings of frame or crankshaft bearing alignment. The frame distortion and temperature data are supplemented by predictions of nominal crankshaft bending stress resulting from the observed misalignment.
Centrispun High Alloy Steel Castings for Gas Turbine Applications
Authors: Nixon P. G.
Published: October 2009

Extensive use has been made by the gas turbine industry of centrispun castings of certain highly alloyed heat resisting steels. The paper outlines the main features of the centrispinning process and discusses the advantages that one could expect, not only in mechanical properties, but also in cost and the casting to shape in refractory molds. Results of mechanical tests on sections cut from representative castings are given and show the high order of the tensile strength to be expected.
Experiments on Spray Interactions in the Wake of a Bluff Body
Authors: Rudoff R. C. , Houser M. J. , Bachalo W. D.
Published: October 2009

The dynamics of spray drop interaction within the turbulent wake of a bluff body were investigated using the Aerometrics Phase Doppler Particle Analyzer, which determines both drop size and velocity. Detailed measurements obtained included spray drop size, axial and radial velocity, angle of trajectory, and size-velocity correlations. The gas-phase flow field was also ascertained via the behavior of the smallest drops. Results showed dramatic differences in drop behavior when interacting with turbulence for the various size classes. Small drops were recirculated in a pair of toroidal vortices located behind the bluff body, whereas the larger drops followed the general direction of the spray cone angle. This was documented via backlit photography. Local changes in number density were produced as a result of lateral convection and streamwise accelerations and decelerations of various drop size classes. The spray field interaction illustrated by these data effectively reveals the complexity associated with the development of the spray and casts some doubts toward attempting to describe sprays via simple integral quantities such as the Sauter mean diameter.
An Innovative Approach to Nuclear Reactor Design Certification
Authors: Brown N. W. , Gyorey G. L. , Genetti B. K. , Smith M. A.
Published: October 2009

General Electric has proposed that the US Nuclear Regulatory Commission (NRC) consider adding an Appendix to 10CFR50 that would specifically address NRC Safety Review and Design Certification of advanced reactors through use of an experience building test program. The proposal was made in conjunction with the Department of Energy (DOE)-sponsored review of the General Electric advanced Liquid Metal Reactor (LMR) concept, Power Reactor Inherently Safe Module (PRISM). This paper provides a description of the proposed new 10CFR50 Appendix. It also provides the basis for the proposed new approach to Design Certification and outlines the plans that are in place for further review and consideration by the NRC.
Neutron and Positron Techniques for Fluid Transfer System Analysis and Remote Temperature and Stress Measurement
Authors: Stewart P. A. E.
Published: October 2009

Nonintrusive radiation techniques have been routinely used, since 1970, for the determination of metal component movements and clearances within engines using high-energy x-rays. Oil system operation was first analyzed using “cold” neutrons in 1975 and, since 1980, positron-emitting isotope tomography has been developed using multiwire proportional counters to determine the X, Y, and Z coordinates of labeled oil volumes within engines. The tomographic system will allow a plane-by-plane inspection across an engine or rig to be carried out using radioisotope images overlaid by an engine general arrangement drawing. It is presently proposed that epithermal neutrons may be used for remote, noninvasive metal temperature measurement within engines or rigs. Finally, neutron diffraction may also be used for internal stress determination within compressor or turbine disks. Consideration is being given to carrying out remote stress measurements in a spinning pit or, perhaps, within an engine using this technique.
STAEBL/General Composites With Hygrothermal Effects (STAEBL/GENCOM)
Authors: Rubinstein R.
Published: October 2009

A computer code has been developed to perform structural optimization of turbine blades made from angle ply fiber composite laminates. Design variables available for optimization include geometric parameters such as blade thickness distribution and root chord, and composite material parameters such as ply angles and numbers of plies of each constituent material. Design constraints include resonance margins, forced response margins, maximum stress, and maximum ply combined stress. A general description of this code is given. Design optimization studies for typical blades are presented.
Studies on Combustion, Vibration, and Noise in High-Speed Diesel Engines Through Newly Developed Measuring Instruments
Authors: Izumi S. , Takemi M. , Ishida M. , Suetsugu H. , Maeda T. , Yoshimura Y.
Published: October 2009

The authors have been conducting studies on the reduction of exhaust emissions using a high-speed diesel engine. By applying composite countermeasures consisting of five items: (1) timing retard, (2) optimization of fuel injection system, (3) water-in-oil type emulsified fuel, (4) application of ignition improver, and (5) an increase in airflow quantity, an exhaust NOx level less than half of the original was attained while retaining the original low levels of fuel consumption, smoke density, and engine noise. The authors developed new measuring instruments in order to grasp the true nature of combustion, especially to clarify the delicate change in combustion. By using these instruments, the combustion phenomena were analyzed accurately, speedily, and synthetically on various aspects such as combustion mode, vibration, noise, thermal loading, heat balance, etc. The complicated combustion behavior in the cylinder has been clarified in part by simultaneous measurement of cylinder pressure at several points.
Minimum Weight Design of a Rotor Bearing System With Multiple Frequency Constraints
Authors: Shiau Ting Nung , Hwang Jon Li
Published: October 2009

The objective of the present study is to develop an efficient design algorithm for minimum weight design of a rotor bearing system under the requirements of operational speed range, i.e., multiple frequency constraints, to increase the performance of an existent rotor system. The system is modeled as an assemblage of rigid disks, shaft elements with distributed mass and stiffness, and discrete bearings. The system design variables are the inner radius of shaft elements and the stiffnesses of bearings. The optimization techniques employed to compare the results are method of exterior penalty function, method of feasible directions, and method of modified feasible directions. The parameter sensitivity analysis of the system is also presented. Three examples are used to demonstrate the merits of the design algorithm. The results indicate that the weight of the rotor bearing system can be significantly reduced at the optimum stage.
Impact Excitation Tests to Determine the Influence Coefficients for Balancing Lightly Damped Rotors
Authors: Tonnesen J. , Lund J. W.
Published: October 2009

Experiments have been conducted to evaluate a supplementary method for balancing lightly damped rotors. The rotor, while running, is excited by an impact generator, and the response is measured at the bearings by transducers for displacement, force, and acceleration. An FFT analyzer is employed to obtain the frequency-dependent transfer functions from which the corresponding influence coefficients can be calculated. The results are compared with the values obtained from the conventional trial weight method, and they are also used in a successful balancing of the rotor.
Temperature Transformation for High-Temperature Heat Pumps
Authors: Radermacher R. , Howe L. A.
Published: October 2009

A heat pump cycle is introduced that allows heat pumping between two very high temperature levels, while the suction temperature of the working fluid vapor passing through the compressor is considerably lower. This effect of “Temperature Transformation” is achieved by using a working fluid mixture instead of a single pure component and by employing an unconventional cycle design. The proposed cycle allows the extension of heat pump applications to high temperature levels without encountering operating problems for conventional compressors. This cycle and its features are explained. Its performance has been calculated and the results are presented and discussed.
Advanced Research and Technology Development Fossil Energy Materials Program
Authors: Judkins R. R. , Bradley R. A.
Published: October 2009

The Advanced Research and Technology Development (AR&TD) Fossil Energy Materials Program is a multifaceted materials research and development program sponsored by the Office of Fossil Energy of the U.S. Department of Energy. The program is administered by the Office of Technical Coordination. In 1979, the Office of Fossil Energy assigned responsibilities for this program to the DOE Oak Ridge Operations Office (ORO) as the lead field office and Oak Ridge National Laboratory (ORNL) as the lead national laboratory. Technical activities on the program are divided into three research thrust areas: structural ceramic composites, alloy development and mechanical properties, and corrosion and erosion of alloys. In addition, assessments and technology transfer are included in a fourth thrust area. This paper provides information on the structure of the program and summarizes some of the major research activities.
Experimental Method for Combustion Efficiency Calculation in a Reheat Duct
Authors: Cadiou A.
Published: October 2009

An efficient method for the experimental measurement of the combustion efficiency in a reheat duct has been developed at ONERA. Such a method is useful because numerous reheat tests are necessary to study the effect of geometry and flow characteristics on reheat performances. Static pressure measurements along the duct and gas sampling in its outlet cross section are the basis of this downstream-to-upstream method. Experimental results with a tri-annular V-gutter flame holder are presented. These results are also used for comparison with theoretical two-dimensional calculations applied to reheat ducts that ultimately may reduce the number of experiments necessary for the development of reheat combustion chambers.
Suppressing the Infrared Signatures of Marine Gas Turbines
Authors: Birk A. M. , Davis W. R.
Published: October 2009

The exhaust plumes and visible areas of the engine exhaust ducting associated with marine gas turbines are major sources of infrared (IR) radiation on ships. These high-radiance sources make excellent targets for IR-guided threats. In recent years significant efforts have been made to reduce or eliminate these high-radiance sources to increase the survivability of naval and commercial ships when sailing in high-risk areas of the world. Typical IR signature suppression (IRSS) systems incorporate film cooling of visible metal sources, optical blockage to eliminate direct line-of-sight visibility of hot exhaust system parts, and cooling air injection and mixing for plume cooling. Because the metal surfaces radiate as near black bodies, every attempt is made to reduce the temperatures of the visible surfaces to near ambient conditions. The exhaust gases radiate selectively and therefore do not have to be cooled to the same degree as the metal surfaces. The present paper briefly describes the motivation for incorporating IRSS into the exhaust systems of marine power plants. IRSS hardware developed in Canada by the Canadian Department of National Defence and Davis Engineering Limited is presented along with details of their operating principles. A typical installation is presented and discussed. Design impacts on the ship are described with reference to engine back pressure, noise, and weight and center of gravity effects.
Fiber Metal Acoustic Material for Gas Turbine Exhaust Environments
Authors: Beaton M. S.
Published: October 2009

FELTMETAL® fiber metal acoustic materials function as broad band acoustic absorbers. Their acoustic energy absorbance occurs through viscous flow losses as sound waves pass through the tortuous pore structure of the material. A new FELTMETAL® fiber metal acoustic material has been designed for use in gas turbine auxiliary power unit exhaust environments without supplemental cooling. The physical and acoustic properties of FM 827 are discussed. Exposure tests were conducted under conditions that simulated auxiliary power unit operation. Weight gain and tensile strength data as a function of time of exposure at 650°C (1202°F) are reported. Fabrication of components with fiber metal acoustic materials is easily accomplished using standard roll forming and gas tungsten arc welding practices.
Application of Advanced Diagnostics to Airblast Injector Flows
Authors: McVey J. B. , Kennedy J. B. , Russell S.
Published: October 2009

Experimental data on the characteristics of the spray produced by a gas turbine engine airblast fuel injector are reported. The data acquired include the mass-flux distribution, measured by use of a high-resolution spray patternator; the gas-phase velocity field, measured by use of a two-component laser-Doppler velocimeter; and the liquid droplet size and velocity distributions, measured by use of a single-component phase-Doppler anemometer. The data are intended for use in assessments of two-phase flow computational methods as applied to combustor design procedures.
Structural Analysis Applications
Authors: McKnight R. L.
Published: October 2009

The programs in the structural analysis area of the HOST program emphasized the generation of computer codes for performing three-dimensional inelastic analysis with more accuracy and less manpower. This paper presents the application of that technology to Aircraft Gas Turbine Engine (AGTE) components: combustors, turbine blades, and vanes. Previous limitations will be reviewed and the breakthrough technology highlighted. The synergism and spillover of the program will be demonstrated by reviewing applications to thermal barrier coatings analysis and the SSME HPFTP turbine blade. These applications show that this technology has increased the ability of the AGTE designer to be more innovative, productive, and accurate.
The Theory and Operation of Evaporative Coolers for Industrial Gas Turbine Installations
Authors: Johnson R. S.
Published: October 2009

This paper discusses the theory of evaporative cooling and describes the application of wetted rigid media evaporative coolers to gas turbines. Calculations of parameters used to predict evaporative cooler performance are included. Also included are discussions of evaporative cooler design, installation, operation, feedwater quality, and the causes and prevention of water carry-over.
Reduction of Nitrogen Oxides in Engine Exhaust Gases by the Addition of Cyanuric Acid
Authors: Caton J. A. , Siebers D. L.
Published: October 2009

Nitric oxide concentrations in a portion of the exhaust of a diesel engine operated with equivalence ratios between 0.25 and 0.75 were reduced by up to 98 percent by the addition of cyanuric acid. The cyanuric acid was combined with the exhaust gas in an electrically heated quartz flow reactor. The effects of the key process parameters (temperature, exhaust gas composition and residence time, and the overall engine equivalence ratio) on NO reduction by cyanuric acid were investigated. Nitric oxide reduction was evident at flow reactor temperatures above 700 K. The maximum nitric oxide reduction varied from 80 percent for a reactor temperature of 1180 K and an engine equivalence ratio of 0.25 to 98 percent for a temperature of 1120 K and an equivalence ratio of 0.75. The temperature range over which 60 percent or greater nitric oxide reduction was obtained was 1100 to 1340 K. Increasing the exhaust gas carbon monoxide concentration lowered the required reactor temperature and increased the temperature range for significant nitric oxide reduction. Increasing the exhaust gas nitric oxide concentration lowered the ratio of cyanuric acid to nitric oxide required for maximum nitric oxide reduction.
On Heat Transfer Measurements in Diesel Engines Using Fast-Response Coaxial Thermocouples
Authors: Assanis D. N. , Badillo E.
Published: October 2009

Finite element models of fast-response CO-AX thermocouples typically used for heat transfer measurements in diesel engines have been developed. Due to the small differences in thermal properties between the thermoelements and the iron engine components, CO-AX thermocouples are capable of measuring transient temperatures of iron components within an accuracy of 98 percent. However, these relatively small errors in temperature measurement result in as high as 25 percent errors in peak surface heat flux calculations. This implies that heat flux results depend not only on the temperature of the surface thermocouple junction, but are also sensitive to its time rate of change. Increasing the thin film thickness can significantly alter the heat flux profile deduced from surface junction temperatures.
Environmental Aspects of Coal-Fueled Diesel Engines
Authors: Williams M. C. , Holcombe N. T. , McMillian M.
Published: October 2009

Conventional diesel engines are considered by some to be contributors to environmental problems since they emit NOx, a suspected acid rain precursor. Initial testing has shown that CWS-fueled diesels emit substantially reduced NOx emissions. While emissions of particulates and SOx may be potentially higher with coal fuels, assessment of the control technology indicates excellent potential for meeting existing and future standards for these emissions. As a result of activities managed by the Morgantown Energy Technology Center, the economic and technical feasibility of CWS-fueled diesel engines has been determined. Recently, both General Electric and A. D. Little/Cooper Bessemer were selected for 5-year contracts aimed at developing by 1993 the components and subsystems necessary for subsequent private sector demonstration and commercialization of coal-fueled diesel power systems. The development of these CWS-fueled systems will necessitate the application of hot gas cleanup contaminant control technology to ensure that the systems burn coal in an environmentally sound manner. The objective of this paper is to discuss the environmental concerns, emission goals, and the control methodologies, devices, and strategies that will be used to ensure CWS-fueled diesel engines will meet current and potential environmental standards.
Component Wear in Coal-Fueled Diesel Engines
Authors: Flynn P. L. , Leonard G. L. , Mehan R. L.
Published: October 2009

Practical use of coal-fueled diesel engines depends on the improvement of component durability. The wear characteristics of standard materials in the coal-fueled engine were studied first. Candidate wear-resistant materials were sorted by bench-scale tests. The best material combinations were applied to small-scale engine tests for operation on seeded diesel fuel. Components with hard materials and coatings were scaled up for coal-water mixture testing on the locomotive engine. Results indicate practical solutions for ring and liner wear and positive progress toward defining the material requirements for the fuel injection nozzle.
Piston Motion and Thermal Loading Analyses of Two-Stroke and Four-Stroke Cycle Engines for Locomotives
Authors: Haddad S. D.
Published: October 2009

Two-stroke cycle and four-stroke cycle diesel engines are in use in rail traction, with the four-stroke cycle design dominating the field. Cycle simulations using computer programs have shown that the conventional two-stroke cycle is somewhat inferior to its four-stroke cycle counterpart in combustion efficiency and thermal loading. Research at Sulzer concluded that the conventional two-stroke cycle engine is not very suitable for locomotive application. A survey by Ricardos, based on an investigation of engines in current production for traction application, suggested that there are potentials in two-stroke cycle design. This paper presents a summary of the results of a research project concerned with comparison of two well-proven typical locomotive diesel engines, one with a two-stroke cycle and the other with a four-stroke cycle. Performance, mechanical loading, thermal loading, and vibration were chosen as parameters to be investigated to provide information on the status of the two cycles in relation to power range, fuel consumption, reliability, and durability, with a view to assisting the users of locomotive engines to make the correct choice.
Turbocharging Systems With Control Intervention for Medium Speed Four-Stroke Diesel Engines
Authors: Meier E. , Czerwinski J.
Published: October 2009

The turbocharging systems of highly boosted four-stroke diesel engines (BMEP 25 bar/363 psi) have to cope with two basic problems: lack of air and compressor surge at reduced engine speed. In the case of medium speed engines for ship propulsion and stationary applications, the following three control interventions have proved to be successful solutions: (1) waste gating air or exhaust gas at full load and speed, (2) using a compounded or independent exhaust gas driven power turbine that can be shut off at part load and speed, and (3) blowing air from the compressor outlet to the turbine inlet through a controlled bypass. The effect of these control interventions on engine performance is shown by examples and analyzed by means of characteristic quantities for the efficiency of the turbocharging system and the engine. The definitions and meanings of these quantities are explained in the first part of the paper.
Electrostatic Dispersion of Diesel Fuel Jets at High Back Pressure
Authors: Kwack E. Y. , Back L. H. , Bankston C. P.
Published: October 2009

An experimental study of electrostatically atomized and dispersed fuel jets has been conducted in room temperature N2 gas for various back pressures to 41.8 atm. No. 2 diesel fuel was injected through an electrostatic spray triode designed for high-pressure operation. Charge density measurements were conducted at various combinations of injection velocities, electric potentials, and back pressures. The charge density of fuel drops increased up to 1.5 C/m3 with increasing electric potential until breakdown occurred. After breakdown the charge density was reduced by 40 to 60 percent and again increased but more slowly as electric potential increased. At higher flow rates, breakdown occurred at higher voltages. At higher back pressure, lower charge density was obtained and breakdown occurred at higher voltages. Visual observations showed that significant electrostatic dispersion was accomplished at high back pressures, and that the average drop size was about the same as the spray triode orifice diameter.
A Parametric Analysis Microcomputer Model for Evaluating the Thermodynamic Performance of a Reciprocating Brayton Cycle Engine
Authors: Tsongas G. A. , White T. J.
Published: October 2009

A novel Brayton open-cycle engine is under development. It operates similarly to a gas turbine engine, but uses reciprocating piston compressor and expander components. The design appears to have a number of advantages, including multifuel capability, the potential for lower cost, and the ability to be scaled to small sizes without significant loss in efficiency. An interactive microcomputer model has been developed that analyzes the thermodynamic performance of the engine. The model incorporates all the important irreversibilities found in piston devices, including heat transfer, mechanical friction, pressure losses, and mass loss and recirculation. There are 38 input parameters to the model. Key independent operating parameters are maximum temperature, compressor rpm, and pressure ratio. While the development of the model and its assumptions are outlined in this paper, the emphasis is on model applications. The model has demonstrated itself to be a powerful tool for evaluating engine thermal efficiency, net specific work, and power. It can be used to analyze the performance of individual engine designs, to generate performance “maps” that graphically represent engine operating characteristics, and to perform sensitivity analysis to compare the relative effects of various input parameters. Examples of each of these model applications are discussed. Recommendations for model improvements and for further engine development work are made. The need for better experimental data to verify some critical model assumptions is stressed.
Inhomogeneity of Fluid Flow in Stirling Engine Regenerators
Authors: Jones J. D.
Published: October 2009

The literature relating to inhomogeneity of flow in regenerators is briefly reviewed. It is noted that, in contrast to other applications of regenerators, relatively little attention has been paid to the consequences of flow inhomogeneity for thermal regeneration in Stirling cycle machines. The construction of regenerator capsules for a large stationary Stirling engine is described. A test rig is developed to measure the gas velocity profile across the face of the packed regenerator capsules under steady flow conditions. Measured flow profiles for a number of different matrix materials and construction techniques are presented, and it is noted that stacked-mesh regenerator matrices tend to display marked inhomogeneities of flow. The consequences of flow inhomogeneity for flow friction and regenerator effectiveness are analyzed theoretically, and approximate formulae deduced. One method for reducing flow inhomogeneity in stacked-screen matrices is described.
The Design of Rotor Blades Taking Into Account the Combined Effects of Vibratory and Thermal Loads
Authors: Bahree R. , Sharan A. M. , Rao J. S.
Published: October 2009

The present work involves the design of rotor blades based on the thermal as well as centrifugal and nozzle excitation forces in the transient state. The finite element analysis has been used to calculate these stresses. The nozzle excitation forces have been modeled as a series of impulses occurring at instants of time known from the solution of kinematic equations.