bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudomonas fluorescenscontamination of a feline packed red blood cell unit and studies of canine units
Authors: Kessler Rebecca J. , Rankin Shelley , Young Sheri , O'Shea Kathleen , Calabrese Maria , Guldin Amy , Lipson Nicole , Oakley Donna A. , Giger Urs
Published: October 2009

Background:While screening programs have reduced the risk of infectious disease transmission by donors in human and veterinary blood banking, bacterial contamination of blood products has emerged as a major complication in human medicine.

Objectives:To describe aPseudomonas fluorescens(Pf)‐contaminated feline packed RBC (pRBC) unit and experimentally investigate Pf‐contaminated canine pRBCs.

Methods:Canine pRBCs were inoculated with Pf‐rich pRBCs from the sentinel feline unit and stored at 4°C or 20°C for 72 hours. Aliquots from the pRBCs were serially evaluated by microscopy, culture, and a eubacterial 16S rRNA real‐time PCR assay.

Results:One Pf‐contaminated feline unit turned black after 22 days of storage and was removed from the blood bank; a source was not found, and no other contaminated units were identified. Canine pRBCs spiked with 5 or 25 μL of the sentinel unit became culture‐ and/or 16S PCR‐positive at ≥8 hours at 20°C and 48 hours at 4°C and developed a color change at ≥24 hours. Sensitivity studies indicated that without incubation, inoculation of ≥100 μL Pf‐rich pRBCs was necessary for a positive 16S PCR test result.

Conclusions:P. fluorescensgrows in stored pRBCs slowly at 4°C and rapidly at 20°C. Screening of blood products for color change, estimating bacterial concentration with microscopy, and 16S PCR testing are simple and fast ways to detect bacteria in stored blood. Aseptic collection, temperature‐controlled storage, and regular visual monitoring of stored units is recommended. Discolored units should not be transfused, but examined for bacterial contamination or other blood product quality problems.
Correlation for Flow Boiling Critical Heat Flux in Thin Rectangular Channels
Authors: Tanaka Futoshi , Hibiki Takashi , Mishima Kaichiro
Published: October 2009

The effect of heated length on critical heat flux (CHF) in thin rectangular channels under atmospheric pressure has been studied. CHF in small channels has been widely studied in the last decades but most of the studies are based on flow in round tubes and number of studies focused on rectangular channels is relatively small. Although basic triggering mechanisms, which lead to CHF in thin rectangular channels, are similar to that of tubes, applicability of thermal hydraulic correlations developed for tubes to rectangular channels are questionable since heat transfer in rectangular channels are affected by the existence of nonheated walls and the noncircular geometry of channel circumference. Several studies of CHF in thin rectangular channels have been reported in relation to thermal hydraulic design of research reactors and neutron source targets and correlations have been proposed, but the studies mostly focus on geometrical conditions of the application of interest and therefore effect of channel parameters exceeding their interest is not fully understood. In his study, CHF data for thin rectangular channels have been collected from previous studies and the effect of heated length on CHF was examined. Existing correlations were verified with data with positive quality outlet flow but none of the correlations successfully reproduced the data for a wide range of heated lengths. A new CHF correlation for quality region applicable to a wide range of heated lengths has been developed based on the collected data.
Effect of Internal Wick Structure on Liquid-Vapor Oscillatory Flow and Heat Transfer in an Oscillating Heat Pipe
Authors: Xu Jiajun , Zhang Yuwen , Ma Hongbin
Published: October 2009

Liquid-vapor oscillating flow and heat transfer in a vertically placed oscillating heat pipe (OHP) with a sintered particle wick structure are analyzed in this paper. The oscillatory flow of the liquid slug is driven by the variations in pressures in the vapor plug due to evaporation and condensation. The evaporation and condensation heat transfer coefficients are obtained by solving the microfilm evaporation and condensation on the sintered particles. The sensible heat transfer between the liquid slug and the channel wall are obtained by analytical solution or empirical correlations depending on whether the liquid flow is laminar or turbulent. The effects of the sintered particles wick structure on the oscillatory flow, as well as sensible and latent heat transfer, are analyzed and compared with the results without wick structure. A parametric study on the oscillatory flow and heat transfer in the OHP with sintered particle wick structure is also performed.
Chemical and Physical Properties of Soot as a Function of Fuel Molecular Structure in a Swirl-Stabilized Combustor
Authors: Himes R. M. , Hack R. L. , Samuelsen G. S.
Published: October 2009

Soot samples were extracted from a swirl-stabilized, liquid-fuel fired laboratory combustor to (i) assess the validity of the ASTM smoke point test in predicting the sooting characteristics of fuels in complex combustion systems and (ii) assess the effect of fuel molecular structure and smoke suppressant additives on the physical and chemical properties of soot. Fuels utilized were shale JP-8, iso-octane, and blends of iso-octane with either decalin, toluene, tetralin, or 1-methylnaphthalene such that smoke points similar to JP-8 were achieved. Each fuel was separately blended with 0.05 percent (by weight) ferrocene smoke suppressant. The results indicate that the ASTM test can be misleading, increased fuel molecular complexity increases soot content of higher molecular weight polycyclic aromatics, and ferrocene additive reduces small particle number density but not necessarily the soot mass loading.
Vibrations of Blades With Variable Thickness and Curvature by Shell Theory
Authors: Lee J. K. , Leissa A. W. , Wang A. J.
Published: October 2009

A procedure for analyzing the vibrations of rotating turbomachinery blades has been previously developed. This procedure is based upon shallow shell theory, and utilizes the Ritz method to determine frequencies and mode shapes. However, it has been limited heretofore to blades of uniform thickness, uniform curvature, and/or twist and rectangular planform. The present work shows how the procedure may be generalized to eliminate the aforementioned restrictions. Nonrectangular planforms are dealt with by a suitable coordinate transformation. This, as well as variable thickness, curvature and twist, require using numerical integration. The procedure is demonstrated on four examples of cantilevered blades for which theoretical and experimental data have been previously published: (1) flat plate with spanwise taper, (2) flat plate with chordwise taper, (3) twisted plate with chordwise taper, and (4) cylindrical shell with chordwise taper.
A Mixing-Length Model for the Prediction of Convex Curvature Effects on Turbulent Boundary Layers
Authors: Adams E. W. , Johnston J. P.
Published: October 2009

A mixing-length model is developed for the prediction of turbulent boundary layers with convex streamwise curvature. For large layer thickness ratio, δ/R > 0.05, the model scales mixing length on the wall radius of curvature, R. For small δ/R, ordinary flat wall modeling is used for the mixing-length profile with curvature corrections, following the recommendations of Eide and Johnston [7]. Effects of streamwise change of curvature are considered; a strong lag from equilibrium is required when R increases downstream. Fifteen separate data sets were compared, including both hydrodynamic and heat transfer results. In this paper, six of these computations are presented and compared to experiment.
Measurements of Heat Transfer Distribution Over the Surfaces of Highly Loaded Turbine Nozzle Guide Vanes
Authors: Nealy D. A. , Mihelc M. S. , Hylton L. D. , Gladden H. J.
Published: October 2009

The results of an experimental study of aerodynamic (surface velocity) and heat transfer distributions over the surfaces of two different, highly loaded, low-solidity contemporary turbine vane designs are presented. The aerodynamic configurations of the two vanes were carefully selected to emphasize fundamental differences in the character of the suction surface pressure distributions and the consequent effect on surface heat transfer distributions. The experimental measurements were made in moderate-temperature, three-vane cascades under steady-state conditions. The principal independent parameters (Mach number, Reynolds number, turbulence intensity, and wall-to-gas temperature ratio) were varied over ranges consistent with actual engine operation, and the test matrix was structured to provide an assessment of the independent influence of each parameter. These measurements are intended to serve as verification data for a parallel analytical code development effort. The results of this parallel effort are briefly reviewed, and the principal conclusions to date are summarized.
An Experimental Investigation of Endwall Heat Transfer and Aerodynamics in a Linear Vane Cascade
Authors: York R. E. , Hylton L. D. , Mihelc M. S.
Published: October 2009

The purpose of this experimental investigation was to produce a data base of end-wall heat transfer data under conditions that simulate those in the passage of the first-stage stator in advanced turbine engines. The data base is intended to be sufficiently complete to provide verification data for refined computational models, and to provide a basis for advanced core engine endwall cooling designs. A linear, two-dimensional cascade was used to generate the data base. The test plan provided data to examine the effects of exit Mach number, exit Reynolds number, inlet boundary layer thickness, gas-to-wall temperature ratio, inlet pressure gradients, and inlet temperature gradients. The data generated consist of inlet, intrapassage, and exit aerodynamic data plus intrapassage endwall heat flux, adiabatic wall temperature measurements, and inlet turbulence data.
Comparison of Visualized Turbine Endwall Secondary Flows and Measured Heat Transfer Patterns
Authors: Gaugler R. E. , Russell L. M.
Published: October 2009

Various flow visualization techniques were used to define the secondary flows near the endwall in a large scale turbine vane cascade. The cascade was scaled up from one used to generate endwall heat transfer data under a joint NASA-USAF contract. A comparison of the visualized flow patterns and the measured Stanton number distributions was made for cases where the inlet Reynolds number and exit Mach number were matched. Flows were visualized by using neutrally buoyant helium-filled soap bubbles, by using smoke from oil soaked cigars, and by a new technique using permanent marker pen ink dots and synthetic wintergreen oil. For the first time, details of the horseshoe vortex and secondary flows can be directly compared with heat transfer distributions. Near the cascade entrance, there is an obvious correlation between the two sets of data, but well into the passage the effect of secondary flow is not as obvious.
Full-Coverage Discrete Hole Wall Cooling: Discharge Coefficients
Authors: Andrews G. E. , Mkpadi M. C.
Published: October 2009

Factors influencing the design of full coverage drilled plate wall cooling systems for gas turbine combustors are studied. It is shown that the large number of small diameter holes required result in a low Reynolds number operating regime. The physical features giving rise to the hole pressure loss are examined, and it is shown that under hot conditions heat transfer within the hole can appreciably alter the hole mass flow for a fixed pressure loss. It is shown that this effect may be used to estimate the hole outlet temperature and the results show that the heat transfer within the combustor wall may be very significant. The rise in coolant temperature within the wall appreciably alters the blowing rate and hence influences the hot gas side convective heat transfer to the plate. The influence of an impingement plate on hole discharge coefficients is also investigated and shown to be small.
Analysis of Film Cooling and Full-Coverage Film Cooling of Gas Turbine Blades
Authors: Eckert E. R. G.
Published: October 2009

Film cooling has become a standard method for the protection of the skin of gas turbine blades against the influence of the hot gas stream. The cooling air is usually injected into the boundary layer covering the skin through one or two rows of holes. A calculation method to predict heat transfer to the skin of a film cooled wall based on two parameters—the film effectiveness and a heat transfer coefficient defined with the adiabatic wall temperature—has been widely accepted. More recently, those sections of a turbine blade skin requiring intensive cooling are covered over its entire area with holes through which cooling air is ejected. A different method to predict the temperature of this section by this “full coverage film cooling” has been proposed which is based on two different parameters θ and K. The air used for the cooling of the perforated section of the skin also provides protection to a solid section located downstream in the normal film cooling process. The two methods are reviewed, and it is discussed under what conditions and in which way results obtained with one method can be transformed to the parameters used in the other one. Published data [8, 9] are used to calculate film cooling effectiveness values and Stanton numbers based on the adiabatic wall temperature for a perforated wall and a solid surface downstream of 11 rows of holes with coolant injection. The results demonstrate the advantage of this method which has been shown in previous experiments with ejection through one or two rows of holes, for film cooling of a solid surface. For full-coverage film cooling, there is still the advantage that a heat transfer coefficient defined with the adiabatic wall temperature is independent of temperature difference within the restrictions imposed by the superposition model.
Effect of an Oscillating Flow Direction on Leading Edge Heat Transfer
Authors: Marziale M. L. , Mayle R. E.
Published: October 2009

An experimental investigation was conducted to examine the effect of a periodic variation in the angle of attack on heat transfer at the leading edge of a gas turbine blade. A circular cylinder was used as a large-scale model of the leading edge region. The cylinder was placed in a wind tunnel and was oscillated rotationally about its axis. The incident flow Reynolds number and the Strouhal number of oscillation were chosen to model an actual turbine condition. Incident turbulence levels up to 4.9 percent were produced by grids placed upstream of the cylinder. The transfer rate was measured using a mass transfer technique and heat transfer rates inferred from the results. A direct comparison of the unsteady and steady results indicate that the effect is dependent on the Strouhal number, turbulence level, and the turbulence length scale, but that the largest observed effect was only a 10 percent augmentation at the nominal stagnation position.
Measurement and Analyses of Heat Flux Data in a Turbine Stage: Part I—Description of Experimental Apparatus and Data Analysis
Authors: Dunn M. G. , Rae W. J. , Holt J. L.
Published: October 2009

Parts I and II of this paper report the measurements and analysis of detailed heat flux distributions obtained on the nozzle guide vane (NGV), rotor, and shroud of the full-stage rotating turbine of the Garrett TFE 731-2 engine. Part I includes a description of the experimental apparatus, a discussion of the measurements performed and a discussion of the data analysis procedure. Part II is composed of a presentation of experimental conditions, a discussion of results, and comparison of these results with predictions obtained using a flat-plate technique and with predictions obtained using STAN5. The essential features of the measurement program are that a shock tube is used as a short-duration source of heated air and miniature thin-film heat-flux gages are used to obtain detailed measurements on the component parts. The gasdynamic and physical parameters of the experiment are representative of typical engine operating conditions.
Substructuring and Wave Propagation: An Efficient Technique for Impeller Dynamic Analysis
Authors: Henry R. , Ferraris G.
Published: October 2009

This paper is of particular interest of gas turbine designers because it proposes an efficient method for dynamic analysis of rotationally periodic structures encountered in turbomachines. It combines the advantages of a substructure technique and that of wave propagation in periodic systems. The mode shapes and frequencies are obtained from the analysis of a single repetitive sector of the whole structure. The finite element method is the numerical method used. A detailed application of the method to a centrifugal compressor impeller is reported along with experimental verification of the computed results.
Blade Vibration Measurements on Centrifugal Compressors by Means of Telemetry and Holographic Interferometry
Authors: Haupt U. , Rautenberg M.
Published: October 2009

Blade vibration measurements have been carried out on a high-pressure, high mass-flow centrifugal compressor to determine the excitation mechanism. For the experimental investigation, semiconductor strain gages with a multichannel telemetry system were used. The measuring points on the blades have been chosen using the results of a stress calculation for the vibrating blade by means of the FE-method. A research program was started with blade vibration measurements in different operating ranges of the compressor and with two types of diffusers. Results are presented for the blade excitations obtained by throttling the compressor at various rotational speeds and for the cases of passing resonances by increasing the rotational speed at constant throttle valve position. Results were obtained for blade excitations caused by: 1) the nonuniformity of the flow in the diffuser, 2) the stalled flow near the surge-line, 3) the blades of a vaned diffuser and 4) the surge. The investigations have been completed by optical measurements to find out the vibrational modes of the different blades in rotating operation. These tests were carried out by means of a holographic interferometric system using an optical derotator up to a rotational speed of n = 20,500 rpm.
Interaction of Upstream Flow Distortions With High-Mach-Number Cascades
Authors: Englert G. W.
Published: October 2009

This analytical study models features of the interaction of flow distortions, such as gusts and wakes, with blade rows of advance-type fans and compressors having high-tip Mach numbers. A typical distortion is assumed to have harmonic time dependence and is described, at a far upstream location, in three orthogonal spatial coordinates by a double Fourier series. It is convected at supersonic velocity relative to a linear cascade described as an unrolled annulus. Conditions are selected so that the component of this velocity parallel to the axis of the turbomachine is subsonic, permitting interaction between blades through the upstream as well as downstream flow media. A strong, nearly normal shock is considered in the blade passages which is allowed curvature and displacement. The flows before and after the shock are linearized relative to uniform mean velocities in their respective regions. Solution of the descriptive equations is by adaptation of the Wiener-Hopf technique. This enables a determination of distortion patterns through and downstream of the cascade, and of pressure distributions on the blade surfaces. Details of interaction of the distortion with the in-passage shock are discussed. Influences of amplitude, wavelength, and phase of the distortion on lifts and moments of cascade configurations are presented. Numerical results are clarified by reference to an especially orderly pattern of upstream vortical motion in relation to the cascade parameters.
A Theory of Rotating Stall of Multistage Axial Compressors: Part III—Limit Cycles
Authors: Moore F. K.
Published: October 2009

A theory of rotating stall, based on single parameters for blades-passage lag and external-flow lag and a given compressor characteristic yields limit cycles in velocity space. These limit cycles are governed by Lienard’s equation with the characteristic playing the role of nonlinear damping function. Cyclic integrals of the solution determine stall propagation speed and the effect of rotating stall on average performance. Solution with various line-segment characteristics and various throttle settings are found and discussed. There is generally a limiting flow coefficient beyond which no solution is possible; this probably represents stall recovery. This recovery point is independent of internal compressor lag, but does depend on external lags and on the height-to-width ratio of the diagram. Tall diagrams and small external lags (inlet and diffusor) favor recovery. Suggestions for future theoretical and experimental research are discussed.
Wall Boundary Layer Development Near the Tip Region of an IGV of an Axial Flow Compressor
Authors: Lakshminarayana B. , Sitaram N.
Published: October 2009

The annulus wall boundary layer inside the blade passage of the inlet guide vane (IGV) passage of a low-speed axial compressor stage was measured with a miniature five-hole probe. The three-dimensional velocity and pressure fields were measured at various axial and tangential locations. Limiting streamline angles and static pressures were also measured on the casing of the IGV passage. Strong secondary vorticity was developed. The data were analyzed and correlated with the existing velocity profile correlations. The end wall losses were also derived from these data.
Theory of Blade Design for Large Deflections: Part I—Two-Dimensional Cascade
Authors: Hawthorne W. R. , Wang C. , Tan C. S. , McCune J. E.
Published: October 2009

As a step in the development of an analytical method for designing highly loaded, three-dimensional blade profiles for axial compressors and turbines, a simple two-dimensional method was first investigated. The fluid is assumed to be incompressible and inviscid, the blades of negligible thickness, and the mean tangential velocity is prescribed. The blades are represented by a distributed bound vorticity whose strength is determined by the prescribed tangential velocity. The velocity induced by the bound vortices is obtained by a conventional Biot-Savart method assuming a first approximation to the blade profile. Using the blade surface boundary condition, the profile is then obtained by iteration. It is shown that this procedure is successful even for large pitch-chord ratios and large deflections. In order to develop a method for use in three dimensions, the velocity is divided into a pitchwise mean value and a value varying periodically in the pitchwise direction. By using generalized functions to represent the bound vorticity and a Clebsch formulation for the periodic velocity, series expressions are obtained which can be adapted to three-dimensional problems. Several numerical results were obtained using both approaches.
Theory of Blade Design for Large Deflections: Part II—Annular Cascades
Authors: Tan C. S. , Hawthorne W. R. , McCune J. E. , Wang C.
Published: October 2009

A method of designing highly loaded blades to give a specified distribution of swirl is presented. The method is based on a newly developed, three-dimensional analysis. In the present application, the flow is assumed to be incompressible and inviscid (the annulus has constant hub and tip radii), and the blades are of negligible thickness. A simple free vortex swirl schedule is assumed. The flow velocity is divided into circumferentially averaged and periodic terms. The Clebsch formulation for the periodic velocities is used, and the singularities are represented by periodic generalized functions so that solutions may be obtained in terms of eigenfunctions. The blade profile is determined iteratively from the blade boundary condition. Results from the computer program show how blade number, aspect, and hub-tip ratios affect the blade shape. The blade profiles for a given swirl schedule depend not only on the aspect ratio but also on the stacking position (i.e., the chordwise location at which this thin blade profile is radial), and so too do the mean axial and radial velocities. These effects occur whether the number of blades is large or small, and we conclude that even in incompressible flow the blade element or strip theory is not generally satisfactory for the design of high-deflection blades. The analysis derives the geometrical conditions for the blade profiles on the walls of the annulus which are needed to satisfy the wall boundary conditions in the idealized flow, but which in any practical example will be modified by the presence of wall boundary layers and blade thickness. In the limit when the number of blades approaches infinity, a bladed actuator duct solution is obtained. The conditions for the blade profile at the walls are absent, but the stacking position and aspect ratio still affect the axial and radial velocity distributions for the same swirl schedule.
Prediction of Cascade Flow Fields Using the Averaged Navier-Stokes Equations
Authors: Shamroth S. J. , McDonald H. , Briley W. R.
Published: October 2009

A numerical solution procedure for the ensemble-averaged, compressible, time-dependent Navier-Stokes equations is applied to predict the flow about a cascade of airfoils operating in the transonic flow regime. The equations are solved by the consistently split, linearized block implicit (LBI) method of Briley and McDonald. Boundary conditions are set so as to specify upstream total pressure and downstream static pressure. Turbulence is modeled by a mixing length model. Predictions are made for flow through a compressor cascade configuration. The method yields converged solutions within a relatively small number of time steps ( ≈ 150), which give good comparisons with experimental data.
Flow in a Turbine Cascade: Part 1—Losses and Leading-Edge Effects
Authors: Moore J. , Ransmayr A.
Published: October 2009

An experimental investigation was conducted to study the effect of the leading-edge shape on the overall losses in a large-scale linear cascade of turbine blades. The leading-edge shapes used were a cylinder and a wedge. The cascade was designed to be geometrically similar to the cascade used by Langston et al. at United Technologies Research Center, with the same span/chord and pitch/chord ratios. Measurements of wall static pressure on the blades and of total pressure and flow direction downstream of the cascade showed only minor changes due to the alteration of the leading-edge shape. The measurements of the flow and loss distributions downstream of the cascade complement the results of Langston et al., which showed the flow development only within the cascade. The downstream flow is important, however, as apppoximately 50 percent of the losses occur downstream of the trailing edge. Regions of high loss were found near midspan at an axial location 40 percent of the axial chord downstream of the trailing edge. The sources of fluid in these regions are determined in Part 2.
Flow in a Turbine Cascade: Part 2—Measurement of Flow Trajectories by Ethylene Detection
Authors: Moore J. , Smith B. L.
Published: October 2009

In Part 1 of this paper, measurements of total pressure loss were described at an axial location 40 percent of the axial chord downstream of the trailing edge of a turbine cascade. These results revealed regions of high loss near midspan away from the walls and in the bulk of the flow. In this second part, the origins of fluid in these regions are traced using an ethylene detection technique. Ethylene injection near the blade leading edges and gas sampling downstream and near the blade trailing edges gives information about flow trajectories and mixing through the cascade. Details of the flame ionization detection system used to measure the ethylene concentrations are discussed.
An Experimental and Computational Study of Transonic Three-Dimensional Flow in a Turbine Cascade
Authors: Camus J.-J. , Denton J. D. , Soulis J. V. , Scrivener C. T. J.
Published: October 2009

Detailed experimental measurements of the flow in a cascade of turbine rotor blades with a nonplanar end wall are reported. The cascade geometry was chosen to model as closely as possible that of a H.P. gas turbine rotor blade. The blade section is designed for supersonic flow with an exit Mach number of 1.15 and the experiments covered a range of exit Mach numbers from 0.7–1.2. Significant three-dimensional effects were observed and the origin of these is discussed. The measurements are compared with data for the same blade section in a two-dimensional cascade and also with the predictions of two different fully three-dimensional inviscid flow calculation methods. It is found that both these calculations predict the major three-dimensional effects on the flow correctly.
Three-Dimensional Flow Measurements in a Turbine Scroll
Authors: Tabakoff W. , Vittal B. V. R. , Wood B.
Published: October 2009

A study was conducted to determine experimentally the flow behavior in combined scroll nozzle assembly of a radial inflow turbine. Hot film anemometry technique was used to measure the three-dimensional flow velocity in the scroll. The through-flow and secondary flow velocity components are measured at various points in three scroll sections.
An Experimental Study of Rotating Stall in a Multistage Axial-Flow Compressor
Authors: Das D. K. , Jiang H. K.
Published: October 2009

The flow field and the distribution of the flow parameters in the rotating stall regime in a three stage axial flow compressor were obtained in detail using three-hole cylindrical probes containing fast response transducers in association with a digital data acquisition system and an ensemble averaging technique. An appreciable amount of experimental data are presented in this paper with a critical discussion on those.
Tip Clearance Flow in a Compressor Rotor Passage at Design and Off-Design Conditions
Authors: Lakshminarayana B. , Pandya A.
Published: October 2009

The flow field in the tip clearance region of a compressor rotor at an off-design condition is reported in this paper. The earlier data at the design condition have also been reinterpreted and correlated with the blade and the flow parameters. The measurements inside the rotor tip region are acquired using a miniature hot-wire sensor of “V” configuration. The instantaneous velocity data are analyzed by the ensemble-averaging technique to derive the blade-to-blade velocity field at various axial and radial locations between the rotor tip and the casing. The flow and the blade pressure data at the design condition are compared with the data at the off-design condition (lower blade loading). In addition to a reduction in the leakage velocities, its chordwise variation is also altered substantially at the lower blade loading.
Experimental Measurement of Alford’s Force in Axial Flow Turbomachinery
Authors: Vance J. M. , Laudadio F. J.
Published: October 2009

This paper presents the results of experimental measurements made on a small, high-speed, axial-flow test apparatus to verify the existence of Alford’s force and to investigate the validity of his mathematical prediction model. The measurements show that the cross-coupled aerodynamic force is linearly proportional to rotor eccentricity, and to stage torque, as predicted by Alford’s theory. However, it was found that the force is also speed-dependent, and that the inlet flow conditions to the stage have a pronounced effect. For some special combinations of rotor speed and stage torque, the direction of the force is reversed.
A Systematic Computational Design System for Turbine Cascades, Airfoil Geometry, and Blade-to-Blade Analysis
Authors: Ye Z.-Q.
Published: October 2009

This paper describes a systematic computational design system for two-dimensional turbine cascades. The system includes a sequence of calculations in which airfoil profiles are designed from velocity diagram requirements and specified geometric parameters, followed by an inviscid global streamline curvature analysis, a magnified reanalysis around the leading edge, and a transitional profile boundary layer and wake mixing analysis. A finite area technique and a body-fitted mesh are used for the reanalysis. The boundary layer analysis is performed using the dissipation-integral method of Walz which has been modified in the present application. Several turbine airfoil profile geometry designs are presented. Also two sample cascade design cases and their calculated performance for a range of Mach numbers and incidence angles are given and discussed.
On the Theory of the Wells Turbine
Authors: Gato L. M. C. , Falca˜o A. F. de O.
Published: October 2009

A theoretical investigation is presented concerning the aerodynamic performance of the Wells turbine, a self-rectifying, axial-flow turbine suitable for energy extraction from a reciprocating air flow. A two-dimensional analysis is developed, and expressions, based on potential flow, are derived for the blade shape maximizing the turbine efficiency. Three-dimensional effects and profile losses are then accounted for by means of an actuator disk theory, which shows that large radial distortions of axial velocity profile can occur, depending on blade shape, with important implications on the extent of the stall-free conditions.
Spray Characteristics of Plain-Jet Airblast Atomizers
Authors: Rizk N. K. , Lefebvre A. H.
Published: October 2009

The effects of air and liquid properties and atomizer dimensions on the spray characteristics of plain-jet airblast atomizers are examined. Mean drop size and drop-size distribution are measured using an improved form of light scattering technique. The test range includes wide variations in air velocity, air pressure, air/liquid ratio, and liquid viscosity. The experimental data generally confirm the results of previous studies on prefilming types of airblast atomizers. They show that increases in air velocity, air pressure, and air/liquid ratio all tend to produce a more uniform spray and a lower mean drop size. It is also observed that any change in air properties, liquid properties, and atomizer geometry that lowers the mean drop size also produces a more uniform distribution of drop sizes in the spray.
An Experimental Study of Local and Mean Heat Transfer in a Triangular-Sectioned Duct Rotating in the Orthogonal Mode
Authors: Clifford R. J. , Morris W. D. , Harasgama S. P.
Published: October 2009

This paper presents a selection of experimental results that examines the influence of orthogonal-mode rotation on local and mean heat transfer in a triangular-sectioned duct with potential application to cooled turbine rotor blades. It is shown that Coriolis acceleration can have a beneficial influence on mean heat transfer relative to the nonrotating case at the lower range of turbulent pipe flow Reynolds numbers studied. Also, rotational buoyancy has been shown to have a noticeable effect over this same Reynolds number range in that progressively increasing buoyancy brings about an attendant reduction in heat transfer. As the Reynolds numbers are increased, say, beyond 30,000, buoyancy effects were found to have little influence on mean heat transfer over the speed range covered. Local axial variations in heat transfer along the duct were also measured, and severe reductions in local heat transfer were detected under certain operating circumstances.
A Horseshoe Vortex in a Duct
Authors: Moore J. , Forlini T. J.
Published: October 2009

A Rankine half-body is used to model the three-dimensional flow caused by a blunt obstruction in a flow passage. The body is located in a duct bounded by two plane endwalls and two side walls shaped like potential-flow streamlines. A thick turbulent boundary layer on the endwall forms a horseshoe vortex flow as it encounters the leading edge of the body. Flow measurements are presented showing the inlet flow and the three-dimensional flow downstream of the leading edge. Sufficient data are presented for this to be a test case for the development of three-dimensional viscous flow codes.
Nonequilibrium Throughflow Analyses of Low-Pressure, Wet Steam Turbines
Authors: Yeoh C. C. , Young J. B.
Published: October 2009

The paper describes a throughflow computational method that combines wet steam theory with an axisymmetric streamline curvature technique in order to predict nonequilibrium effects in low-pressure steam turbines. The computer program developed is able to deal with both subsonic and fully choked supersonic flows, and steam properties are represented by a truncated virial equation of state. A number of theoretical test cases have been investigated, including the nonequilibrium flow in the primary nucleating stage of a low-pressure turbine and the complete analysis of a six-stage, 320-MW operational turbine. The calculations are the first of their kind in being able to provide information on the spanwise variation of the Wilson point, the average droplet size nucleated, the degree of supercooling throughout the flowfield, the thermodynamic wetness loss, and the nonequilibrium choking mass flow rate in addition to the aerodynamic parameters which are of interest to the designer.
Combined-Cycle System With Novel Bottoming Cycle
Authors: Kalina A. I.
Published: October 2009

A new thermodynamic energy cycle has been developed using a multicomponent working agent. This cycle is designed to replace the currently used Rankine Cycle as a bottoming cycle for a combined-cycle energy system as well as for generating electricity using low-temperature heat sources. Several combined power systems based on this cycle have been designed and cost-estimated. The efficiency of this cycle is from 1.6 to 1.9 times higher than that of the Rankine Cycle system, at the same border conditions. The investment cost per unit of power output for this cycle is lower than that for the Rankine Cycle system in approximately direct proportion to the energy advantage. The application of this cycle as a bottoming cycle in combined-cycle systems involves the use of an energy system which utilizes heat from the exhaust of a gas turbine, resulting in an increase in overall efficiency of up to 20 percent above the efficiency of the combined systems using the Rankine bottoming cycle. As a result, a thermal efficiency in the range of 50–52 percent can be achieved using a conventional gas turbine. The project to build the first experimental installation is now in progress. This installation is to become operational at the end of 1984.
Effect of New Blade Cooling System With Minimized Gas Temperature Dilution on Gas Turbine Performance
Authors: Kawaike K. , Kobayashi N. , Ikeguchi T.
Published: October 2009

Recent developments in high-performance and high-reliability gas turbine engines necessitate enforced cooling to maintain the blade temperature at reasonably low levels associated with increased turbine inlet temperature and compressor pressure ratio. However, the gas turbine performance is strongly penalized by the consumption of cooling flow, resulting in temperature dilution of hot mainstream, aerodynamic mixing loss, and pumping power loss. In this paper, a new practical blade cooling system using state-of-the-art engineering, which aims at minimizing the dilution effect, is presented. Trade-off studies between performance and reliability in terms of blade metal temperature are performed to evaluate cooling systems. Analytical comparison of different cooling systems demonstrates that the proposed cooling system provides significant improvements in performance gain and growth potential over conventional air cooling systems.
The Influence of Fuel Hydrogen Content Upon Soot Formation in a Model Gas Turbine Combustor
Authors: Bowden T. T. , Pearson J. H. , Wetton R. J.
Published: October 2009

The sooting tendencies of various fuel blends containing either single-ring or polycyclic aromatics have been studied in a model gas turbine combustor at a pressure of 1.0 MPa and varying values of air/fuel ratio. Sooting tendencies were determined by flame radiation, exhaust soot, and infra-red absorption measurements. The results of this study have indicated that, even for fuels containing high concentrations of naphthalenes or tetralins (> 10 percent v), fuel total hydrogen content correlates well with fuel sooting tendency. The present results are explained by a hypothesis that assumes that the majority of soot is formed in regions of high temperature, low oxygen content, and low fuel concentration, e.g., the recirculation zone.
The Marine Environment and Its Influence on Inlet System Design
Authors: Shelton L. V. , Carleton R. S.
Published: October 2009

Historically, two of the principal hindrances to the design of effective marine gas turbine inlet systems have been the inability to define the marine environment and to identify the influence of this environment on the inlet system configuration. This paper summarizes the work done by the U.S. Navy to qualitatively and quantitatively define the composition of the marine atmosphere and identify inlet system design practices that can be employed to assist in designing an effective combustion air inlet system.
Evolution of NOx Abatement Techniques Through Combustor Design for Heavy-Duty Gas Turbines
Authors: Hilt M. B. , Waslo J.
Published: October 2009

The role played by oxides of nitrogen in the formation of photochemical smog has been known for many years. However, because of the relatively small fraction of power generated by gas turbines, there were no significant attempts at limiting gas turbine NOx emissions in the United States until about 15 years ago. This paper outlines General Electric’s experience with NOx abatement techniques from then until the present.
Medium-Speed Diesel Engines: Part II—Lubricants, Their Characteristics and Evaluation
Authors: Thomas F. J. , Ahluwalia J. S. , Shamah E. , van der Horst G. W.
Published: October 2009

Fuel costs can exceed 50 percent of the total diesel plant’s operational expenditures. To reduce fuel costs, medium-speed engines are now available with improved fuel consumption and ability to burn residual fuels. Part II of this paper reviews characteristics of lubricants suitable for use with distillate, residual, and blended fiels in medium-speed engines. Examples are shown of how lubricants and their additives control engine wear, deposits, and oxidation, and how fuel consumption is affected by viscosity. Control of insolubles and the purification of used lubricants are discussed.
Axial Fan Performance With Blade-Base Clearance
Authors: Wright T.
Published: October 2009

A study to evaluate the influence of increasing the clearance between blade and hub on a controllable pitch axial fan (CPAF) is presented. Fan performance was measured over a range of increasing clearance for several settings of blade pitch angles. The resulting variations of pressure rise, flow rate, and efficiency have been correlated as functions of established clearance parameters with good results. The study shows that large base clearances may result in reductions in efficiency and flow rate of 5 percent or greater in a typical CPAF configuration.
Development of a Case Vibration Measurement System for the DC-990 Gas Turbine
Authors: Kidd H. A.
Published: October 2009

The continued use of gas turbines in industrial applications and increased customer desires for trend analysis has led gas turbine suppliers to develop sophisticated, reliable, cost-effective vibration monitoring systems. This paper discusses the application of case vibration monitoring systems and the design criteria for each component. Engine installation, transducer mounting brackets, types of transducers, interconnecting cables and connectors, charge amplifiers, and signal conditioning and monitoring are considered. Examples are given of the benefits experienced with the final system in several of Dresser Clark’s engine development programs, by manufacturing and production testing, and by Dresser’s field service staff.
Lateral Gear Shaft Dynamics Control Torsional Stresses in Turbine-Driven Compressor Train
Authors: Simmons H. R. , Smalley A. J.
Published: October 2009

An experimental evaluation of a gas turbine/compressor train yielded excellent correlation between measured and predicted torsional critical speeds. Torsional strain signals acquired at a coupling location provide basic data from which damping factors at resonance are found to vary from 1 to 6 percent, depending on mode shape. Resonant stress levels for the mode with low damping would be a factor of 2 higher than predictions based on industry accepted assumptions. Other modes are found to have considerably more damping than expected. Experimental data and a coupled torsional-lateral damped eigenvalue analysis show that this damping variation is related to pinion and gear lateral bearing motion. Conservative damping values are predicted by the coupled analysis.
Weak Limits of Premixed Gases
Authors: Odgers J. , Kretschmer D. , Halpin J.
Published: October 2009

Experimental values of weak and rich limits, for a wide range of fuel-oxygen-inerts mixtures (H2, CO, CH4, C3H8, O2, Ar, He, N2, CO2), are presented for a number of tube diameters. The significance of the results is discussed, and with the use of other published data, a weak limit correlation is proposed that demands knowledge only of the fuel composition, its calorific value, and the specific heat of the stoichiometric products at 298 K. The correlation is applicable to simple or complex mixtures, with or without inert addition, and applies over an initial temperature range from 298–1000 K. It is also capable of application to a much wider range of fuels than those investigated experimentally. The accuracy of the parameter is as good as, or better, than those currently in use.
Film Cooling on a Gas Turbine Blade Near the End Wall
Authors: Goldstein R. J. , Chen H. P.
Published: October 2009

The local film cooling effectiveness on a gas turbine blade with a row of discrete cooling jets has been measured using a mass transfer technique. Particular emphasis is placed on phenomena near the end wall of the blade. This region contains a horseshoe vortex system modified by a passage vortex. On the concave (pressure) surface the film cooling performance is not greatly altered by the presence of the end wall. On the convex surface of the blade the film cooling is essentially absent in a triangular region extending from near the region of peak curvature on the blade to its trailing edge. This unprotected region closely corresponds to the location of the passage vortex as indicated by flow visualization. The passage vortex sweeps away the injected coolant flow from the surface. Upstream of the unprotected area the injected flow is skewed toward the middle span of the blade. The influence of the end wall extends about one-half chord length up from the end wall in the present experiments.