bluuebunny/crossref_metadata_2025 huggingface dataset:
The Radiation of Sound From an Airfoil Immersed in a Laminar Flow
Authors: Clark L. T.
Published: November 2010

The results of an experimental and analytical investigation of sound generation by single airfoils are presented. Airfoil sections studied were representative of those used in modern axial compressors; included were modified 65 series and double circular arc profiles. The radiation of sound from the airfoil immersed in the potential core of a free jet discharging through an acoustic chamber was measured. Acoustic data were obtained for the velocity range 200 through 800 ft/sec. Measurements of wake correlation volumes and turbulence velocity components were used in an analytical model to predict the spectrum of the sound radiated by the airfoil. Sound generation was found to be dependent upon the square of the component of turbulent velocity normal to the airfoil chord. In the velocity range 300 to 800 ft/sec, the overall sound pressure level was found to be dependent upon free stream velocity to the sixth power. A correlation of the normal component of turbulent velocity was found to exist with the momentum thickness of the wake.
Combustion and Fouling Characteristics of Two Canadian Lignites
Authors: Friedrich F. D. , Lee G. K. , Mitchell E. R.
Published: November 2010

The report describes combustion tests with Bienfait lignite from Saskatchewan and Onakawana lignite from James Bay. They were burned in a pilot-scale, pulverized-fired boiler primarily to study combustion performance and fireside fouling tendencies under slag-tap conditions. Flame stability and complete combustion were readily obtained, although satisfactory slag tapping was not achieved with either fuel. Fireside ash deposit samples, representing each fuel, were collected from various parts of the boiler and subjected to exhaustive analyses. The results indicate that, when burning Bienfait lignite, selective deposition of ash constituents takes place, resulting in a eutectic composition downstream of the furnace exit. In the case of Onakawana lignite, selective ash deposition did not occur. Deposit analyses, fusion temperatures, and enrichment ratios are given for both fuels.
The Generation of Pollution-Free Electrical Power From Solar Energy
Authors: Cherry W. R.
Published: November 2010

Projections of the U. S. electrical power demands over the next 30 years indicate that the U. S. could be in grave danger from power shortages, undesirable effluence, and thermal pollution. A pollution free method of converting solar energy directly into electrical power using photovoltaics on the ground shows that sunlight falling on about 1 percent of the land area of the 48 states could provide the total electrical power requirements of the U. S. in the year 1990. By utilizing and further developing some NASA technology, a new source of electrical power will become available. Such a development is attractive from conservation, social, ecological, economic, and political standpoints. While the cost of producing solar arrays by today’s methods prohibits their use for large scale terrestrial plants, the paper suggests how the cost may become acceptable, especially as conventional fuels become scarcer and more expensive. Some of the desirable reasons for developing methods to convert solar energy to electrical power are: to conserve our fossil fuels for more sophisticated uses than just burning, to reduce atmospheric pollution by 20 percent, to convert low productive land areas into high productive land areas, to make the U. S. less dependent upon foreign sources of energy, and to learn to utilize our most abundant inexhaustable natural resource.
Analysis of Feedwater Pump Suction Pressure Decay Under Instant Turbine Load Rejection
Authors: Liao G. S. , Leung P.
Published: November 2010

As steam-electric generating plant unit sizes increase, and as the capacities of the feedwater pumps increase, the design provision of an adequate suction for the safe operation of the feedwater pumps becomes increasingly important, especially when the pumps take suction from a deaerator within the regenerative cycle. The design provision of sufficient suction head for feedwater pumps operating under a maximum and stable turbine load is rather simple. However, the design of an adequate suction head to meet an instant turbine load rejection from maximum load is rather complex. It deals with the rate of pressure decay within the deaerator, mass of condensate stored, size of suction pipes, rate of change of condensate temperatures entering the deaerator, and numerous other transient parameters. Previously published literature [1–5] offers approximate solutions which assumed a constant temperature of condensate entering the deaerator during transient opertion under load rejection. Such an assumption generally results in an unnecessarily conservative design. Particularly, it may not be economically justifiable for very large units to be designed on that basis. This paper presents a complete analysis of this transient operating condition for the purpose of designing an economic optimum feedwater pump suction system for safe and reliable operation. Varying temperatures of the condensate entering the deaerator during transient operation are considered. Mathematic derivations augmented by numerical examples are included, to facilitate system design.
Corrosion of Metals by Liquid Vanadium Pentoxide and the Sodium Vanadates
Authors: Kerby R. C. , Wilson J. R.
Published: November 2010

The rates of liquid vanadate corrosion of iron, nickel and several alloys containing iron, nickel, and chromium have been examined by the use of both static and dynamic accelerated corrosion tests. The dynamic corrosion test involved the rotation of metal disks in the vanadate melts. Corrosion products on the surface of the corroded specimens and in the vanadate melts were examined and identified. The rates of corrosion were found to depend on temperature, oxygen partial pressure, the composition, amount and turbulence of the liquid vanadates, the composition of the metals or alloys in contact with the liquid vanadates, and the duration of the corrosion tests. A mechanism for metal corrosion in the presence of liquid vanadates is proposed.
A Potassium-Steam Binary Vapor Cycle for Better Fuel Economy and Reduced Thermal Pollution
Authors: Fraas A. P.
Published: November 2010

Both fuel supply and thermal pollution considerations that are becoming progressively more important strongly favor the development of a higher temperature, and more efficient, thermodynamic cycle for electric power plants. About 200,000 hr of operation of boiling potassium systems, including over 15,000 hr of potassium vapor turbine operation under the space power program, suggest that a potassium vapor topping cycle with a turbine inlet temperature of ∼1500 deg F merits consideration. A design study has been carried out to indicate the size, cost, and development problems of the new types of equipment required. The results indicate that a potassium vapor cycle superimposed on a conventional 1050 deg F steam cycle would give an overall thermal efficiency of about 54 percent as compared to only 40 percent from a conventional steam cycle. Thus the proposed system would have a fuel consumption only 75 percent and a heat rejection rate only 50 percent that of a conventional plant. Further, it appears possible that the capital charges for the proposed plant might be lower than those for a conventional plant. A high grade fuel oil or gas will be required, but this is likely to be necessary anyway to meet increasingly stringent limitations on SO2, NOx, and ash emissions.
Effectiveness and Heat Transfer With Full-Coverage Film Cooling
Authors: Metzger D. E. , Takeuchi D. I. , Kuenstler P. A.
Published: November 2010

The paper presents experimental results for performance of full-coverage film cooled surfaces. Effectiveness and heat transfer are measured on plane surfaces with discrete injection through the surface at an array of points into a turbulent mainstream boundary layer. The injection is normal to the surface, through circular holes arranged in both in-line and staggered patterns with 4.8 hole diameters used for both the row-to-row spacing and the hole-to-hole spacing within a single row. Both the film and mainstream fluids are air, and property differences are kept small throughout the study. Uniform injection over the entire array at film-to-mainstream velocity ratios of 0.1 and 0.2 with a uniform wall temperature boundary condition are covered. Results are compared with predictions using superposition of available single hole local effectiveness values.
Experimental Evaluation of the Effects of a Blunt Leading Edge on the Performance of a Transonic Rotor
Authors: Reid L. , Urasek D. C.
Published: November 2010

A rotor designed for a tip relative Mach number of 1.4 and a pressure ratio of 1.8 was tested with two different leading edge configurations, to evaluate experimentally the effects of leading edge thickness on the performance of a transonic rotor. The rotor was first tested with a leading edge thickness that resulted in a normal blade gap blockage of approximately 3 percent at the rotor tip and increased to about 4 percent at the rotor hub. The rotor leading edge was then cut back to produce a leading edge thickness which resulted in a normal blade gap blockage of about 6 percent at the tip and the hub remained at about 4 percent. The increased leading edge thickness resulted in a decrease in the rotor overall peak efficiency of 3.5 points at design speed. The major portion of this loss in efficiency occurred in the outer 30 percent of the blade span. At 90 and 70 percent of design speed, the increased leading edge thickness had a relatively small effect on rotor efficiency.
A Wake and an Eddy in a Rotating, Radial-Flow Passage—Part 1: Experimental Observations
Authors: Moore J.
Published: November 2010

The effects of rotation and secondary flows on flow in rotating, radial-flow passages are investigated. Pressure and hot-wire measurements are made on the developing flow in a single, rotating radial-outflow channel of simple geometry. The channel has straight radial walls, and is of constant height. It is double shrouded, has a total angle of 15 deg, and an area ratio of 3.1:1. The results indicate the formation of a large wake region on the suction (trailing) side of the passage, at high flow rates. At low flow rates, a pressure-side eddy was observed.
End-Wall Boundary Layers in Axial Compressors
Authors: Hirsch Ch.
Published: November 2010

Various aspects of an end-wall boundary-layer theory in axial compressors, as formulated originally by Mellor and Wood, are analyzed. This analysis contains three parts. In the first part the original formulation is used with a mainstream flow calculation in order to predict overall performances on a single stage compressor. Comparison with experimental data shows the limitation of the assumption of constant shape factor and skin-friction coefficient. In the second part, through an analysis of existing detailed experimental profiles of flow properties behind blades, empirical values for the coefficients of the theory are deduced. It appears that the skin-friction coefficient takes up unusual high values near the tip of the rotor blades and that the hub boundary layer at the outlet is not collateral. In the last part, the basic equations are reformulated in streamline coordinates. This should allow eventual incorporation of the shape factor variation and the Reynolds number effects as well as the introduction of the wall skewing angle. A modification of the original closure equation is proposed allowing for the noncollateral character of the boundary layer at the blade outlet. The original formulation appears as a limit for low skewing angles.
Heat Transfer From a Shrouded Disk System With a Radial Outflow of Coolant
Authors: Haynes C. M. , Owen J. M.
Published: November 2010

This paper describes a combined theoretical and experimental study of the heat transfer from an air-cooled gas turbine disk using the model of a plane disk rotating close to a shrouded stator. Numerical solutions of the boundary layer equations are obtained by assuming a modified system geometry, and it is shown that this technique yields adequate estimates of moment coefficients and mean Nusselt numbers for the air-cooled disk. Experimental results show the effect of rotational speeds up to 4000 rev/min, coolant flow rates up to 2 lb/s, stator clearances and shroud clearances up to 2.7 in., on the mean Nusselt numbers for a 30-in-dia disk and its stator.
Rotor Design to Attenuate Flow Distortion—Part II: An Unsteady Thin Airfoil Cascade Analysis
Authors: Savell C. T. , Wells W. R.
Published: November 2010

The transfer of stationary circumferential inlet distortion through a rotor is analyzed using unsteady thin airfoil cascade theory which can account for the distortion wave length, rotor chord and cascade solidity. The model consists of representing each blade by a moving doublet filament of finite length immersed in a compressible stream containing a velocity distortion. The study is limited to an unloaded, flat plate rotor. This model provides a new physical interpretation for the flow adjustments observed ahead of the rotor and for the generation of sound when an inlet distortion is imposed. The analytical results show the influence of solidity and other rotor design parameters on the distortion transfer. They are found to approach the semi-actuator disk results as the solidity tends to infinity.
The Decay of Highly Skewed Flows in Ducts
Authors: Quinn B.
Published: November 2010

The development of a very nonuniform or skewed velocity profile in passing through a diffuser has been examined from the point of view of velocity components induced by line vortices. Account is taken of the effect of dissipation and straining on the strengths of the vortices and the intensities of the induced velocities. Changes with the integrated momentum of the perturbation velocities contribute to the local pressure in the duct, or diffuser, along with friction forces and area changes. An expression is derived for the pressure coefficient of a highly skewed profile flowing through a duct of arbitrary section. The results of experiments with an ejector apparatus are presented and found to support the analytical conclusions. In contrast with slightly skewed flows, diffusion will not inhibit the decay of highly skewed profiles.
The Calculation of the Quasi-Three-Dimensional Flow in an Axial Gas Turbine
Authors: Biniaris S.
Published: November 2010

The flow is calculated within the entire region from far upstream to far downstream of the blade rows and this not only between the blade rows but especially within the blade passages. It is assumed that the flow is steady, adiabatic, and inviscid. However, compressibility, blade forces in all directions, blade thickness, and total enthalpy gradients are taken into account. The shape of the meridional cross section can be arbitrary. The blades can be either cylindrical or twisted. The numerical solution is based on the finite-difference method. The discretization error, the stability error, and the iteration error of the numerical solution are determined.
On the Calculation of Two-Dimensional Subsonic and Shock-Free Transonic Flow
Authors: Ribaut M. , Vainio R.
Published: November 2010

Application of the potential theory to the full equations of two-dimensional compressible flow has yielded a method of calculation valid for isolated airfoils as well as for cascades situated on an arbitrary surface of revolution. Various computed subcritical and supercritical flows are presented and compared with exact solutions. Close relation between convergence interval and the existence of discontinuities in the solution was established, which makes it possible to recognize and develop transonic flow patterns having no or only weak shocks.
Basic Flow Analyses Used in the Study of Broad-Band Noise in Compressors
Authors: Buckens F.
Published: November 2010

The propagation of sound in a moving compressible fluid displays interesting features which are important in the problem of noise generation in compressors. Without considering the discrete frequency noise generated by interacting rotating blades and stationary parts, a perturbation method applied to the equations of flow motion in an idealized continuous medium leads to an equation of density waves propagation in a nonhomogeneous moving fluid. The right-hand side is considered as describing distributed noise sources which involve velocity fluctuations. On the left-hand side there appears a negative diffusive effect due to a negative divergence of the velocity field, which downstream entails a streamwise amplification of the intensity of the sound generated upstream. Further, there is a dispersive effect entailing, for a given wave number, a group velocity which in a simple example is shown to be larger than the phase velocity and to become imaginary for a velocity divergence sufficiently high in absolute value. This, together with the amplification effect, may explain the relative importance of the high frequency band in the actual noise spectra of compressors. An attempt at determining the coefficients of the acoustical equation for compressors is made in the schematic Beltrami-Gromeka case of a helicoidal axisymmetrical flow. With simplified assumptions on the behavior of density, depending either solely on the axial coordinate or only on the radial one, both types of axial and radial compressors are considered simultaneously and the method of analytical solution applied. It is emphasized that this treatment is restricted to the mechanical aspect of the broad-band noise generation.
Performance of Radial Flow Turbines Under Pulsating Flow Conditions
Authors: Kosuge H. , Yamanaka N. , Ariga I. , Watanabe I.
Published: November 2010

Investigations of the pulsating flow performances of an inward radial flow turbine were performed. The quasi-steady flow performances predicted from the measured transient pressure ratio and from steady flow performance data were compared with the measured mean performances under pulsating flow conditions over the pulse frequency range of 30 Hz–70 Hz. The validity of this quasi-steady flow assumption was treated more generally than by the hitherto employed method by adopting a new empirical parameter which indicates both the pressure pulse shape and the amplitude of pressure fluctuation, in addition to the pulse frequency.
Effects of Shear Deformation, Rotary Inertia, and Elasticity of the Support on the Resonance Frequencies of Short Cantilever Beams
Authors: Beglinger V. , Bolleter U. , Locher W. E.
Published: November 2010

The purpose of this paper is to contribute to the assessment of the influence of shear deformation, rotary inertia, and elasticity of the support on the resonance frequencies of short turbomachinery blades. To obtain defined test conditions and to model the stiffest possible root design, the study is made on beams and supports machined from one piece. Experimental results show good agreement with results obtained from the finite element program NASTRAN. An estimate of the combined effects obtained by taking the individual effects multiplicatively, with the effect of the elasticity of the support being computed on the basis of known static influence coefficients of the elastic half space, results in a frequency reduction larger than measured.
Multiple Jet Correlations for Gas Turbine Engine Combustor Design
Authors: Cox G. B.
Published: November 2010

A correlation method has been developed for predicting the temperature field produced by a single row of closely-spaced jets penetrating into a hot confined crossflow. The correlation procedure predicts the temperature field as a function of the distance downstream of the jet injection plane and pertinent geometric and flow variables. Predicted results are compared with measured data. The tests are selected to represent combinations of geometries or flow variables which give strong verification of the correlations and which are pertinent to gas turbine engine combustor design.
The Effect of Water/Residual Oil Emulsions on Air Pollutant Emissions and Efficiency of Commercial Boilers
Authors: Hall R. E.
Published: November 2010

Two commercially available water-in-oil emulsifiers were tested to determine the effect of water/residual oil emulsions on air pollutant emissions and thermal efficiency of a packaged boiler. Of the two emulsifiers, one (Cottell reactor) utilized low pressure mechanical and ultrasonic energy and the other (total emulsifier) utilized high pressure mechanical energy. Each emulsifier was tested at a constant oil flow rate with varying amounts of water over a range of stoichiometric ratios. Water/residual oil emulsions from both emulsifiers significantly reduced particulate mass. With the Cottell reactor smoke emissions were significantly reduced, whereas with the Total emulsifier smoke emissions increased and peaked with a 20 percent water emulsion, then decreased as water was increased to 30 percent. Neither emulsifier had any significant effect on emissions of NO, SO2, or HC when firing water/residual oil emulsions. Both emulsifiers were capable of improving efficiency by approximately 2 percent under certain conditions.
High-Temperature Corrosion in Gas Turbine and Steam Boilers by Fuel Impurities—Part VI: A Statistical Study of the Effects of Sodium, Temperature and Additive on Corrosion Rate and Slag Friability
Authors: May W. R. , Zetlmeisl M. J. , Annand R. R.
Published: November 2010

Corrosion rate and slag friability data on several systems containing Na2SO4, V2O5, PbO, MgSO4, and SiO2 have been examined with a stepwise regression correlation procedure. Correlations were developed relating Na/V, additive/V and temperature as independent variables to corrosion rate and slag friability as dependent variables. The superiority of magnesium over silicon as a corrosion inhibitor was demonstrated while the opposite was shown for slag friability. A critical Na/V ratio was found for certain additive levels and temperature. Below this level, the corrosion rate can be reduced to a minimum. Threshold temperatures were also established. Above these temperatures, the corrosion rate cannot be reduced to zero regardless of the Na/V ratio.
Gas Turbine Hot-Stage Parts in Aggressive Atmospheres
Authors: Lee S. Y. , Young W. E.
Published: November 2010

Westinghouse experience in burning heavy residual fuels in gas turbines dates back 25 years when such fuels were burned in a 2000 hp turbine powering a locomotive. In this paper we present case histories for several turbines burning fuels potentially corrosive, erosive, or deposit forming. These include in addition to the locomotive turbine, several turbines operating on heavy liquid fuels in Brazil, Panama, Italy, Japan, and Yugoslavia. Additional field experience is now being accumulated with high temperature machines, supplemented with laboratory testing. Over the years a number of groups representing technical societies have worked on corrosion problems. Their work and accomplishments are summarized.
Pressure Loss Coefficient of Impingement Cooled Leading Edge System of a Turbine Blade
Authors: Mukherjee D. K.
Published: November 2010

The pressure loss coefficient of an impingement cooled system similar to that often used to cool the leading edge of a turbine blade has been determined from model test. The influence of Reynolds number in the range tested is negligible. However, the influence of relative distance of the jet holes from the surface to be cooled is very significant.
Three-Dimensional Flow Within a Turbine Cascade Passage
Authors: Langston L. S. , Nice M. L. , Hooper R. M.
Published: November 2010

Detailed measurements of the subsonic flow in a large-scale, plane turbine cascade were made to evaluate the three-dimensional nature of the flow field. Tests were conducted at a passage aspect ratio of 1.0 with a collateral inlet boundary layer. Flow visualization was done on airfoil and endwall surfaces. Velocity and pressure measurements were taken before and behind the cascade and in six axial planes within a cascade passage, using a five-hole probe. Hot wire measurements were taken in the endwall boundary layer within the cascade passage. The characteristics of the endwall boundary layer are presented, showing that three-dimensional separation is an important feature of end-wall flow. A large part of the endwall boundary layer was found to be very thin when compared to the cascade inlet boundary layer. Data showing the growth of aerodynamic loss through the passage are discussed.
Analytical and Experimental Investigation of the Stability of Intershaft Squeeze Film Dampers—Part 1: Demonstration of Instability
Authors: Hibner D. H. , Kirk R. G. , Buono D. F.
Published: November 2010

Modern high-speed multishaft gas tubine engines incorporate viscous damped bearings to decrease overall system vibration and bearing loads. As viscous damper technology is applied to advanced engine design, more sophisticated analytical and experimental techniques are required to prove new concepts. This analysis will present the results of an investigation of the feasibility of damping engine vibration with a viscous damped intershaft bearing on a two-shaft gas turbine engine. Experimental results from a rotor dynamics simulation rig indicate an instability of the rotor system at speeds above a fundamental critical speed. An analytical model of the two-rotor system is presented and the results of both a classical stability analysis and a time transient response analysis verify the experimental data. The analytical model may be used to predict the stability of two-shaft engines which incorporate an intershaft damped bearing.
Finite Element Simulation of Rotor-Bearing Systems With Internal Damping
Authors: Zorzi E. S. , Nelson H. D.
Published: November 2010

The implementation of finite element simulations for the study of rotor dynamic systems has been the subject of recent publications. Since the finite element offers obvious modeling advantages, particularly in modeling large-scale systems, this study extends the linear finite element concept to provide a detailed evaluation of damped rotor stability. In this work the effects of both internal viscous and hysteretic damping have been incorporated into the finite element model. Both produce circulatory terms in the generalized equations of motion which encourages the destabilization of this nonconservative system. Results are presented for both hysteretic and viscous forms of damping. Both forms of internal damping destabilize the rotor system and induce nonsynchronous forward precession. The stabilizing effects of anisotropic bearing stiffness and external damping are also demonstrated.
Mathematical Model for Spray Cooling Systems
Authors: Frediani H. A. , Smith N.
Published: November 2010

A mathematical model of a large-scale spray cooling system is described. The continuity and energy equations are developed for a cellular model representing a single spray in a system of sprays. The equations are solved using a finite-difference solution along a drop trajectory for both water and air parameters. The results of the cellular analysis are incorporated into a system model in which the interaction between sprays for both the water and air is considered. The model was used to simulate existing systems employing multiple rows of sprays, and the results of the calculations compare well with the available data.
Design and Development of a High-Pressure Combustor for Aero-Gas-Turbines
Authors: Suzuki K. , Ishii A. , Horiuchi S. , Saito T. , Matsuki M. , Torisaki T.
Published: November 2010

Research on a high-pressure combustor for turbofan engines has been carried out at National Aerospace Laboratory (Tokyo). In the first step, a design point of research combustor was fixed from a initial program of FJR Turbofan development. Then the combustor-type was developed, and the major dimensions were decided mainly from the experiences of JR-series lift jet engines, and partly from published data. As the next step, various-segment-type and full-annular-type combustors were tested at the pressure up to 15 bar.
Fuel Controller Design in a Once-Through Subcritical Steam Generator System
Authors: Lin Yu-Hwan , Nielsen R. S. , Ray A.
Published: November 2010

Established techniques have been applied for modeling a once-through subcritical steam generator in an oil-fired 386 MW(e) power generation system. The model was used to design a fuel controller which was implemented in the actual plant. The resulting minimum stable operating level of the system has been reduced from 220 MW(e) to flash tank level of 130 MW(e), and the customary load rate-of-change during normal operation improved from approximately 2 MW/min to 9 MW/min.
Prediction of Compressor Performance in Rotating Stall
Authors: Day I. J. , Greitzer E. M. , Cumpsty N. A.
Published: November 2010

A correlation is presented for predicting the performance characteristics of single and multistage axial compressors in rotating stall. The correlation is derived from new measurements of stalled compressor performance which have been obtained using a series of different compressor builds. In these experiments the compressor design parameters were systematically varied so that the influence of each could be clearly seen. It is shown that the stall cell blockage is an important parameter for correlating the flow regimes in stall, and hence the overall compressor performance. The resulting correlation, which has been developed based on a heuristic model of the stalled flow, can be applied to predict whether a given compressor will exhibit full-span or part-span stall, as well as the extent of the stall-unstall hysteresis loop. In particular, it is shown that as the number of stages and/or the design value of axial velocity parameter increases, the trend is toward both full-span stall and large hysteresis loops.
The Space Shuttle Main Engine High-Pressure Fuel Turbopump Rotordynamic Instability Problem
Authors: Childs D. W.
Published: November 2010

The SSME (Space Shuttle Main Engine) HPFTP (High-Pressure Fuel Turbopump) has been subject to a rotordynamic instability problem, characterized by large and damaging subsynchronous whirling motion. The original design of the HPFTP (from a rotordynamic viewpoint) and the evolution of the HPFTP subsynchronous whirl problem are reviewed. The models and analysis which have been developed and utilized to explain the HPFTP instability and improve its stability performance are also reviewed. Elements of the rotordynamic model which are discussed in detail include the following: (a) hydrodynamic forces due to seals, (b) internal rotor damping, (c) bearing and casing support stiffness asymmetry, and (d) casing dynamics. The stability and synchronous response characteristics of the following two design alternatives are compared: (a) a “stiff” symmetric bearing support design and (b) a damped asymmetric stiffness design. With appropriate interstage seal designs, both designs are shown, in theory to provide substantially improved stability and synchronous response characteristics in comparison to the original design. The asymmetric design is shown to have better stability and synchronous response characteristics than the stiffly supported design.
Experimental Study of the Flow Field Within a Transonic Axial Compressor Rotor by Laser Velocimetry and Comparison With Through-Flow Calculations
Authors: Dunker R. J. , Strinning P. E. , Weyer H. B.
Published: November 2010

The flow field ahead, within, and behind the rotor of a transonic axial compressor designed for a total pressure ratio of 1.51 at a relative tip Mach number of 1.4 has been studied in detail using an advanced laser velocimeter. The tests were carried out at 70 and 100 percent design speed (20,260 rpm) and equivalent mass flows corresponding to the point of maximum isentropic efficiency. The tests yielded quite complete data on the span- and gap-wise velocity profiles, on the three-dimensional shock waves in and outside of the rotor blade channels, and on the blade wakes. Some of the experimental results will be submitted, discussed, and compared to corresponding analytical data of a through-flow calculation. The comparison reveals considerable discrepancies inside the blade row between the two-dimensional calculation and the experiments primarily due to the loss and deviation correlations used, as well as to the distribution of losses and flow angles inside the blade channels.
Analytical Modeling of Helical Screw Turbines for Performance Prediction
Authors: Margolis D. L.
Published: November 2010

An analysis is first performed to determine the exposed frontal area and effective volume as a function of rotor angle for circular lobed helical screw turbines. It is shown that once the female to male lobe ratio is set, the entire design is determined with respect to the male rotor pitch radius. These volume and area functions are then used in an overall dynamic model of the turbine. The model includes inlet and exhaust dynamics, leakage throughout the turbine, and the thermodynamics within the lobes. “Start up” of the system can be tested which is particularly important in determining critical speeds. The principal intended use of the model is for comparative parametric studies.
Moisture Measurements in a Low Pressure Steam Turbine Using a Laser Light Scattering Probe
Authors: Wyler J. S. , Desai K. J.
Published: November 2010

The paper describes the development of a moisture probe using the principle of laser light attenuation. The probe response was calculated for various droplet sizes and steam conditions. A calibration under known conditions in a special test facility agreed with the predictions for a fog droplet size of 0.2 μm. Using this calibration, measurements were made in a low pressure steam turbine of approximately 500 MW output. Typical distributions of moisture along the blade height are presented.
Plate Fin Regenerators for Industrial Gas Turbines
Authors: Cuffe K. W. , Beatenbough P. K. , Daskavitz M. J. , Flower R. J.
Published: November 2010

This paper reviews Harrison Radiator’s various designs and improvements in the Industrial Gas Turbine Regenerator that it has been supplying over the past 20 years, and describes a new design regenerator intended for high cyclic and/or high temperature operation. Design improvements and surface changes have occurred to keep pace with the changing consumer’s requirements and application. These changes have been effective in improving the cyclic ability of the regenerator and in reducing the field maintenance required on the earlier models due to the changing mode of operation. The new regenerator design has been created to meet the changing requirements of the applications.
Rotor Wake Generated Unsteady Aerodynamic Response of a Compressor Stator
Authors: Fleeter S. , Jay R. L. , Bennett W. A.
Published: November 2010

An experimental investigation was conducted to determine the fluctuating pressure distribution on a stationary vane row, with the primary source of excitation being the wakes from the upstream rotor blades. This was accomplished in a large scale, low speed, single stage research compressor. The forcing function, the velocity defect created by the rotor wakes, was measured with a crossed hot-wire probe. The aerodynamic response on the vanes was measured by means of flush mounted high response dynamic pressure transducers. The dynamic data were analyzed to determine the chordwise distribution of the dynamic pressure coefficient and aerodynamic phase lag as referenced to a transverse gust at the vane leading edge. Vane suction and pressure surface data as well as the pressure difference across the vane were obtained for reduced frequency values ranging from 3.65 to 16.80 and for an incidence angle range of 35.5 deg. The pressure difference data were correlated with a state-of-the-art aerodynamic cascade transverse gust analysis. The correlation was quite good for all reduced frequency values for small values of incidence. For the more negative incidence angle data points, it was shown that a convected wake phenomena not modeled in the analysis existed. Both the first and second harmonic unsteady pressure differential magnitude data decrease in the chordwise direction. The second harmonic magnitude data attains a value very nearly zero at the vane trailing edge transducer location, while the first harmonic data is still finite, albeit small, at this location. That the magnitude of the unsteady pressure differential data approaches zero near to the trailing edge, particularly the second harmonic data which has reduced frequency values to 16.8, is significant in that it reflects upon the validity of the Kutta condition for unsteady flows.
An Experimental Study of Three-Dimensional Turbulent Boundary Layer and Turbulence Characteristics Inside a Turbomachinery Rotor Passage
Authors: Anand A. K. , Lakshminarayana B.
Published: November 2010

Three-dimensional boundary layer and turbulence measurements of flow inside a rotating helical channel of a turbomachinery rotor are described. The rotor is a four-bladed axial flow inducer operated at large axial pressure gradient. The mean velocity profiles, turbulence intensities and shear stresses, and limiting stream-line angles are measured at various radial and chordwise locations, using rotating triaxial hot-wire and conventional probes. The radial flows in the rotor channel are found to be higher compared to those at zero or small axial pressure gradient. The radial component of turbulence intensity is found to be higher than the streamwise component due to the effect of rotation. Flow near the annulus wall is found to be highly complex due to the interaction of the blade boundary layers and the annulus wall resulting in an appreciable radial inward flow, and a large defect in the mainstream velocity. Increased level of turbulence intensity and shear stresses near the midpassage are also observed near this radial location.
Alternative Aircraft Fuels
Authors: Longwell J. P. , Grobman J.
Published: November 2010

The efficient utilization of fossil fuels by future jet aircraft may necessitate the broadening of current aviation turbine fuel specifications. The most significant changes in specifications would be an increased aromatics content and a higher final boiling point in order to minimize refinery energy consumption and costs. These changes would increase the freezing point and might lower the thermal stability of the fuel, and could cause increased pollutant emissions, increased combustor liner temperatures, and poorer ignition characteristics. This paper discusses the effects that broadened specification fuels may have on present-day jet aircraft and engine components and the technology required to use fuels with broadened specifications.
Powerplant Integration—The Application of Current Experience to Future Developments
Authors: Brown T. W. , Talbot J. E.
Published: November 2010

The Concorde powerplant represents a highly successful solution to the problem of integration of powerplant aerodynamics for the Mach 2 plus SST. It comprises a relatively simple mechanical design with high overall efficiency and a remarkable degree of tolerance to aircraft maneuverability, atmospheric transients, and engine handling. Aerodynamic integration requirements, particularly in the field of intake/engine compatibility lead to stringent requirements for overall control, both in steady-state and dynamic modes, resulting in complex difinition for the intake control system with a need to introduce cross-talk between inlet control and engine in addition to the normal engine, reheat, and nozzle interrelationships. The multiunit control system of mixed digital and analogue form has led to certain problems in the development stages due to the inflexibility of analogue content and has been through many functional changes in order to realize the full potential of the installed powerplant. A revision of the system design concept both in the field of definition and airworthiness requirements is necessary to achieve a satisfactory datum for a future supersonic transport aircraft. Such avenues are explored in the remainder of the paper in the context of low risk aerodynamic progress in conjunction with a sophisticated control system, a standard against which all future proposals for supersonic transports must be assessed.
Effect of Mainstream Variables on Jets Issuing from a Row of Inclined Round Holes
Authors: Kadotani K. , Goldstein R. J.
Published: November 2010

The effects of boundary layer thickness, Reynolds number and free stream turbulence intensity on jets issuing from a row of inclined holes are investigated from the viewpoint of film cooling. The local film cooling effectiveness and mean velocity and mean temperature distributions are measured. The turbulent eddy diffusivities are evaluated from calculations based on a heat source model. The boundary layer thickness and the free stream turbulence significantly influence the jet-mainstream interaction process and consequently the film cooling performance.
Effective Bending Properties for Stress Analysis of Rectangular Tubesheets
Authors: Soler A. I. , Hill W. S.
Published: November 2010

The analysis of perforated plates has immediate application to tubesheet design. However, successful tubesheet stress analysis requires knowledge of tubesheet elastic properties; considerable effort has therefore been directed toward their determination. The research effort to date has focused on triangular and square, fully packed tube arrays usually employed in circular tubesheets. In this paper, a simple analytical expression is proposed which is suitable for determination of the effective bending stiffness of a perforated plate having both fully packed and laned arrays. Using available data on triangular and square tube arrays, together with some additional test data on tube arrays in common use on large power plant condensers with rectangular tubesheets, it is shown that a simple analytical relationship for determination of required effective bending stiffness gives good agreement with available data.
Heat Transfer Coefficients Around Cylinders in Crossflow in Combustor Exhaust Gases
Authors: Dils R. R. , Follansbee P. S.
Published: November 2010

The local heat-transfer coefficient at the surface of a component placed in combustor exhaust gases can be determined from an analysis of surface temperature oscillations induced by fluctuations of the exhaust-gas temperature. Within a prescribed bandwidth, the relative amplitudes of the Fourier components of the gas and surface temperature waves are a simple function of the local heat-transfer coefficient and the thermal properties of the component. This method of measuring the local heat-transfer coefficient is described in this paper and heat transfer coefficients measured around small cylinders in crossflow (Re = 4000–20,000) are reported. Measurements of the transient response of cylinders abruptly placed in the exhaust-gas stream were conducted to determine the accuracy of the wide bandwidth method. Wide bandwidth gas temperatures and velocities and their cross correlations in the combustor exit were measured to characterize the large-scale exhaust-gas dynamics. It is shown that the stagnation line heat-transfer coefficients are uniformly higher than those obtained in low-turbulence cold gas streams; the magnitude of the stagnation line Nusselt number increases with the measured turbulent intensity. Away from the stagnation line in the unseparated region, the dependence of the local heat-transfer coefficients on the angle from the stagnation line is in agreement with earlier data measured in cold gas streams.
Design Methodology for Ceramic Structures
Authors: Trantina G. G. , deLorenzi H. G.
Published: November 2010

Unique design techniques are required to successfully take advantage of the superior high temperature structural strength of ceramic materials. The design methodology described here combines the results of a finite element stress analysis with a statistical analysis in order to predict the probability of failure of a ceramic structure. The strength degradation of a ceramic material as a result of subcritical crack growth under constant and cyclic loading conditions is incorporated into the methodology. Critical material properties such as strength, Weibull modulus, and the strength degradation exponent are discussed. A tapered disk and a wedge specimen are analyzed. When subjected to thermal shock, these specimens simulate the stresses in critical regions of structures such as the trailing edge of a gas turbine vane. Finally, applications of the design methodology to ceramic transition pieces are discussed where similar probabilities of failure are obtained for single-piece and four-piece designs.
The NOx Emission Levels of Unconventional Fuels for Gas Turbines
Authors: Hung W. S. Y.
Published: November 2010

An experimentally verified NOx emission model for gas turbines has been reported previously. The model has been modified to determine the NOx emission levels of various fuels as compared to No. 2 distillate oil. The NOx emission levels of various conventional and unconventional gas turbine fuels of interest are predicted. The predicted NOx emission levels for these fuels, including methanol, ethanol, propane, and hydrogen, are in good agreement with available laboratory and field data from stationary, aircraft, and automotive gas turbine combustors. The predicted results should be applicable to other fuel-lean, heterogeneous combustion systems.
Fan Inlet Disturbances and Their Effect on Static Acoustic Data
Authors: Bekofske K. L. , Sheer R. E. , Wang J. C. F.
Published: November 2010

There is evidence that measurements of fan-rotor inlet noise taken during static test situations are at variance with aircraft engine flight data. In particular, static tests generally yield a significantly higher tone at blade passing frequency than that measured during flight. An experimental program was carried out to investigate this discrepancy. Inlet ground vortices and large-scale inlet turbulence were generated intentionally in an anechoic test chamber. Far-field acoustic measurements and inlet flow field hot film mappings of a fan rotor were then carried out to study the influence of such inlet disturbances at a static test facility. Experimental results indicate that the acoustic effect of such disturbances appears to be less severe for supersonic than for subsonic tip speeds. Further, a reverse flow that occurs on the exterior cowl in static test facilities appears to be an additional prime candidate for creating inlet disturbances and causing variance between flight and static acoustic data.
Altitude Engine Test of a Turbofan Exhaust Gas Mixer to Conserve Fuel
Authors: Cullom R. R. , Johnsen R. L.
Published: November 2010

A comparison of the specific fuel consumption was made with and without an internal mixer installed in a low bypass ratio, confluent flow turbofan engine. Tests were conducted at several Mach numbers and altitudes for core to fan stream total temperature ratios of 2.0 and 2.5 and mixing lengths of L/D = 0.95 and 1.74. For these test conditions, the specific fuel consumption improvement varied from 2.5 to 4.0 percent.
Pressure Instrumentation for Gas Turbine Engines—A Review of Measurement Technology
Authors: Armentrout E. C. , Kicks J. C.
Published: November 2010

Many types and designs of pressure measuring instrumentation are used during the development and testing of gas turbine engines. This paper provides an overview of more commonly available pressure transducers and their characteristics. Probe designs for use in both steady-state and dynamic pressure measurement systems are reviewed. Techniques used to qualify instrument probes and the methods used to calibrate pressure transducers during engine testing are described.