bluuebunny/crossref_metadata_2025 huggingface dataset:
Stirling Engines With a Chemically Reactive Working Fluid—Some Thermodynamic Effects
Authors: Metwally M. M. , Walker G.
Published: November 2010

Stirling engines operate on closed regenerative thermodynamic cycles with compression and expansion of the working fluids at different temperature levels. They may be used as prime movers, refrigerating machines, heat pumps, or pressure generators. Conventional machines use a gaseous working fluid, but substantial improvement in specific output may be gained with a partially reactive, condensing working fluid. The working fluid then consists of an inert gaseous carrier with a chemically reactive, condensing working fluid such as nitrogen tetroxide (N2O4). This may be liquid in the cold compression space and then evaporates and dissociates in the regenerative process to be in the elemental gaseous phase in the hot expansion space. The change of state of one component reduces the required compression work and has the effect of increasing the engine volume compression ratio with consequent benefit to the specific output. The results obtained using idealized theory show that an improvement may be gained in net cycle work of twice the output with a simple gaseous working fluid with no penalties in size, weight, or cost of the engine. The degree of improvement depends on the design and operating conditions of the engine. The effects of variation of some of these parameters are explored.
Interaction of the Rotor Blade Shock Waves in Supersonic Compressors With Upstream Stator Vanes
Authors: Favrat D. , Suter P.
Published: November 2010

The shock waves formed at the leading edge of the rotor blades of a supersonic axial compressor with subsonic axial velocity move with these blades and simultaneously propagate upstream in the zone of the inlet guide vanes. These waves are diffracted and reflected on the vanes, inducing instationary pressure distributions which cause two main effects: a mean force on every vane corresponding to a supplementary flow deflection in the stator, and unsteady efforts on the vanes which may constitute a possible excitation of vibrations in bending and torsional modes. A good estimation of these effects is made from a complete analysis of the elementary case of the interaction between an ideal wave and an isolated stator vane. Optical Schlieren measurements confirm the theoretical analysis. The flow around the vanes and the oblique shock are generated, in a shock tube, by the same relatively strong shock, which is partly reflected on an oblique porous wall.
Experiments on the Transient Response of Oil-Film Dampers
Authors: Botman M. , Sharma R. K.
Published: November 2010

Oil-film dampers are used in turbomachinery to suppress undesirable shaft dynamic responses. They are located at the nonrotating outer race of selected main bearings. Experiments on the synchronous behavior of oil-film dampers under steady unbalance loads were reported previously [1]. In this paper results are presented of experiments on the transient response of dampers which are subject to simulated blade-loss loads at high speed. The tests were performed on the rig used for the synchronous tests. A method of data reduction was developed. Results are shown for a number of different masses released at various speeds and dampers with several clearances.
Aluminous Keatite—An Improved Rotary Ceramic Regenerator Core Material
Authors: Grossman D. G. , Lanning J. G.
Published: November 2010

Rotary lithium aluminum silicate (LAS) ceramic regenerator cores for gas turbines have had limited durability in applications using sulphur bearing hydrocarbon fuels such as diesel oil. The presence of sulphuric acid from the combustion process caused a lithium/hydrogen ion exchange and resulted in core failure. This paper describes a unique low thermal expansion aluminous keatite material (Corning Code 9460) which was developed to overcome the foregoing problem. Cores made from this new material have now operated over 6000 hr in Ford 707 gas turbines.
A High-Speed Rolling-Element Bearing Loss Investigation
Authors: Trippett R. J.
Published: November 2010

Little experimental data for losses of high-speed Conrad type ball bearings is presently found in the open literature. Hence the accuracy of published high-speed bearing-loss predictions is not known. Accurate predictions of high-speed ball bearing loss are important, however, in evaluating high-speed rotor support systems as well as determining cooling oil requirements for this type of bearing. The losses of a Conrad type ball bearing used to support the high-speed rotors in a vehicular gas turbine were measured. The effects of bearing axial load, rotor speed, lubricant viscosity, and lubricant flow rate on the bearing power consumption were determined. Power loss calculations, made from previously published equations for this type of bearing, did not correlate well with the measured high-speed bearing losses. New power loss equations are presented to predict the losses associated with high-speed deep-groove Conrad type ball bearings under well lubricated conditions.
Vibratory Forcing Functions Produced by Nonuniform Cascades
Authors: Barber T. J. , Weingold H. D.
Published: November 2010

A method is developed to predict the steady, two-dimensional incompressible flowfield through tandem cascades or multibody cascade geometries. The technique is adapted from the classical Douglas-Neumann method, in which a superposition of singularities is used to simulate the cascade geometries. The method is used to analyze the self-induced potential field interaction of a stator cascade with a finite thickness strut cascade behind it or integral within it, such as occurs in fan ducts and intermediate cases of large gas-turbine engines. The calculation predicts the magnitude and location of the nonuniform pressure distortion, which would be imposed on an upstream engine component, for a variety of cascade designs. Such a distortion is known to produce resonant stresses in an upstream rotor. Experimental corroboration of the analysis is presented for a cascade operating at M∞ = 0.49. Sensitivity of the distortion pattern to small strut restaggering is calculated and compared to test data.
Torquewhirl—A Theory to Explain Nonsynchronous Whirling Failures of Rotors With High-Load Torque
Authors: Vance J. M.
Published: November 2010

Numerous unexplained failures of rotating machinery by nonsynchronous shaft whirling point to a possible driving mechanism or source of energy not identified by previously existing theory. A majority of these failures have been in machines characterized by overhung disks (or disks located close to one end of a bearing span) and/or high power and load torque. This paper gives exact solutions to the nonlinear differential equations of motion for a rotor having both of these characteristics and shows that high ratios of driving torque to damping can produce nonsynchronous whirling with destructively large amplitudes. Solutions are given for two cases: (1) viscous load torque and damping, and (2) load torque and damping proportional to the second power of velocity (aerodynamic case). Criteria are given for avoiding the torquewhirl condition.
Fuel Spray Trajectory in Diesel Engines
Authors: Elkotb M. M. , Rafat N. M.
Published: November 2010

A detailed investigation of the effect of the shape of an open combustion chamber for diesel engine on the air velocity pattern, and consequently, on the trajectory of the fuel spray is given in this paper. A theoretical model for the calculation of the spray penetration, taking into consideration the heat transfer to the droplet, the variation of the drag force with Reynolds number, and air velocity pattern, is suggested. The effect of some working conditions on the spray shape, trajectory, and penetration is experimentally studied to verify the theoretical model and to correlate the results of using different medium pressures, initial spray velocity, and injection angle on the magnitude of fuel spray diameter and spray volume.
Investigations on Impulse Blade Cascades with Medium Deflection
Authors: Bammert K. , Ahmadi B.
Published: November 2010

The transformation of energy in the stages of high-reaction axial compressors can be considerably increased if the rotor blading consists of tandem cascades. This also involves aerodynamically higher loading of the stator cascades deflecting the flow. The behavior of the base, mean, and tip sections impulse cascades of the stator of a multi-stage axial compressor designed on this basis was examined in a two-dimensional cascade wind tunnel. The results of these investigations are reported and discussed.
Film Cooling of a Gas Turbine Blade
Authors: Ito S. , Goldstein R. J. , Eckert E. R. G.
Published: November 2010

The local film-cooling produced by a row of jets on a gas turbine blade is measured by a mass transfer technique. The density of the secondary fluid is from 0.75 to two times that of the mainflow and the range of the mass flux ratio is from 0.2 to three. The effect of blade-wall curvature on the film-cooling effectiveness is very significant. On the convex wall, a near tangential jet is pushed towards the wall by the static pressure force around the jet. For a small momentum flux ratio, this results in a higher effectiveness compared with that on a flat wall. At a large momentum flux ratio, however, the jet tends to move away from the curved wall because of the effect of inertia of the jet resulting in a smaller effectiveness on the convex wall. On the concave wall, the effects of curvature are the reverse of those described for the convex wall.
Evaluation of Portable Optical Property Measurement Equipment for Solar Selective Surfaces
Authors: Pettit R. B.
Published: November 2010

The operation and accuracy of portable optical measurement equipment for determining the solar absorptance, αs, and emittance, ε, of solar selective surfaces are presented. The optical equipment includes a Gier Dunkle Solar Reflectometer (Model MS-251) and a Willey Alpha Meter (Model 2150) for αs measurements and a Gier Dunkle Infrared Reflectometer (Model DB-100) and a Willey Ambient Emissometer (Model 2158) for ε measurements. The accuracy of the MS-251 for measurements of αs for electrodeposited black chrome coatings was determined to be better than ±0.03 absorptance units. For the same coatings, the Willey Alpha Meter accuracy was limited by deviations up to 0.11 absorptance units. The accuracy of the Gier Dunkle Infrared Reflectometer for ε(100°C) measurements is better than ±0.02 emittance units. Values for ε(100°C) determined with the Willey Emissometer using black chrome coatings are higher than the actual 100°C emittance. However, since the relationship is linear, the correct emittance can be calculated by multiplication by a constant factor.
Effect of Carbon Monoxide on the Reaction of Hydrogen Sulfide and Calcium Oxide
Authors: Schreiber C. H. , Petrie T. W.
Published: November 2010

Experiments were conducted with simulated low Btu coal gas to focus on the effect of carbon monoxide on the rate of reaction of calcium oxide and hydrogen sulfide. No significant effect of carbon monoxide concentrations up to 35 percent by volume was noted. Other parameters of interest for high temperature desulfurization process development were varied. Within the predicted precision error of ±40 percent and the observed scatter due to sample variation, hydrogen concentrations from 10 to 40 percent by volume had no effect. The observed reaction rate was not affected by progressive conversion of part of the solid samples from calcium oxide to calcium sulfide. Data at 700°C were compared with data in the literature and agree well. The data at 700°C plus others at 600 and 800°C show a temperature variation consistent with a constant activation energy. At 700°C, the reaction rate for 0.389 mm geometric mean particle diameters over a broad range of simulated coal gas compositions is K (s−1) = 1.66 × 10−4 [H2S]0.85 for calcined dolomite and K (s−1) = 1.50 × 10−4 [H2S]1.00 for calcined calcium carbonate. [H2S] is in percent by volume and ranges from 0.1 to 5.0 percent.
Factors Affecting the Design of Turbine-Condenser Connections
Authors: Fowler J. E.
Published: November 2010

Those features of the design of the interconnection between a large steam turbine and the condenser which may affect the plant heat rate or turbine reliability are reviewed. The performance losses resulting from geometric mismatching of turbine hood and condenser and those due to obstructions and extraneous flow injections are assessed. The effects on turbine reliability of differing arrangements for injecting extraneous steam or water flows are pointed out with examples. Suggestions are given for the practices to be followed in this area of plant design.
Stability of Squeeze-Film-Damper Supported Flexible Rotors
Authors: Rabinowitz M. D. , Hahn E. J.
Published: November 2010

Assuming the short bearing approximation and symmetric motions, the stability of the steady-state synchronous operation of centrally preloaded single-mass flexible rotors supported in squeeze-film bearing dampers is theoretically investigated. The stability regions are depicted over a wide range of system parameters and allow for easy determination of the stability of existing steady-state design data. The influence of rotor flexibility, rotor speed, bearing dimensions, lubricant viscosity, rotor mass distribution, and rotor unbalance on rotor-bearing system stability may be readily seen. In the absence of pressurization, instability regions were possible even with relatively high support damping, though no instability was indicated for speeds below the support natural frequency, or for bearing eccentricity ratio <0.4 at any speed. Pressurization of the lubricant supply was found to stabilize the system over the whole range of parameters investigated, regardless of unbalance, which would then be limited only by the bearing clearance. Data are presented which enable the minimum supply pressure to ensure full film lubrication to be conveniently determined.
Probabilistic Aspects of Designing with Ceramics
Authors: Paluszny A. , Wu W.
Published: November 2010

The paper reviews the design methodology for brittle materials which is being developed under the Ford/ARPA contract. Theoretical aspects of designing with high-temperature ceramics are discussed and demonstrated on a turbine rotor system. Statistical treatment of brittle behavior, based on Weibull’s model, is reviewed and relations for predicting probability of failure and material strength requirements for complex ceramic structures are presented. Reliability considerations, uncertainty of predictions, and need for proof testing are discussed. Similarly, a probabilistic treatment of time to failure of a typical turbine structure in the presence of slow crack growth is presented using fracture mechanics and Weibull relations.
Revised International Representations for the Viscosity of Water and Steam and New Representations for the Surface Tension of Water
Authors: Hendricks R. C. , McClintock R. B. , Silvestri G. J.
Published: November 2010

The Eighth International Conference on the Properties of Steam has adopted a new skeleton table and formulation for viscosity. The formulation is valid from the triple point to 1100 K (∼2000 R) and pressures to 100 MPa (∼15,000 psia). Comparisons are made between the calculated and the skeletal table values, and also between the new values and those in the 1967 ASME Steam Tables. A set of figures and tables in both English and SI units are presented to replace those in the Steam Tables. Sources for computer programs are given.
Fretting Wear of Heat Exchanger Tubes—Part I: Experiments
Authors: Blevins R. D.
Published: November 2010

The results of a series of measurements made on the fretting wear of heat exchanger tubes and support plates at room temperature in a nitrogen/air atmosphere are presented. The fretting wear is shown to be a function of the amplitude and frequency of tube vibration as well as the gap between the tube and the support plate and the mean load supported by the tube. An empirical model is developed in Part II for predicting the fretting wear.
Engineering Statistics—With Particular Reference to Performance Test Code Work
Authors: Benedict R. P. , Wyler J. S.
Published: November 2010

Various statistical relations, as applied in instrumentation in general, and as required in Performance Test Code (PTC) work in particular, are summarized in this paper. These concepts are applied in four PTC type problems to illustrate their use.
Decompression of Gas Pipelines During Longitudinal Ductile Fractures
Authors: King G. G.
Published: November 2010

An understanding is given of how gas pipelines decompress when they burst and fail longitudinally in a ductile mode. Transient gas flow equations expressing conservation of mass, momentum and energy are used to develop simple and realistic equations for gas pressure decay with time at a moving longitudinal ductile fracture. Gas thermo-dynamic properties and two-phase behavior are discussed. Friction and heat flux affect gas decompression and influence design to control longitudinal ductile fractures in gas pipelines.
Estimation of the Mechanical Properties of Fluid-Saturated Rocks Using the Measured Wave Motions
Authors: Yew C. H. , Jogi P. N. , Gray K. E.
Published: November 2010

A method for determining the material properties of a fluid-saturated rock via the measured wave motions is presented in this paper. The essence of the method is to compare the dispersive characteristics of the measured wave motions with that predicted by the Biot’s theory. The material properties of water-saturated Berea sandstone determined by this method agree, in general, with that determined from the standard laboratory test.
National Strategic Crude Oil Storage in the Weeks Island Dome Salt Mine—Part II: Rock Mechanics Evaluation
Authors: Van Sambeek L. L. , Hansen F. D. , Gnirk P. F. , Mahtab M. Ashraf
Published: November 2010

This paper, the second in a series of two, presents the results of a rock mechanics evaluation of the Weeks Island dome salt mine. The purpose of the evaluation was to assess the structural stability of the old mine workings in conjunction with a proposed new deeper mine level during the use of the facility for the long-term storage of crude oil under the Federal Energy Administration’s Strategic Petroleum Reserve Program. The scope of the work involved laboratory testing of the strength and deformational characteristics of the rock salt; determination of a minimum web (or sill) thickness between the old workings (within which crude oil would be stored) and a proposed new mine level development below; and assessment of the effects of crude oil emplacement and withdrawal on the mine stability, as related to both the old workings and the proposed new mine level development. The finite element results, wherein use was made of the strength and deformation properties of the salt from the laboratory tests, indicated that a minimum sill thickness of 90 m (300 ft) should be maintained between the old mine workings and the new level development. Furthermore, the emplacement and withdrawl of crude oil from the old workings will have little influence on pillar and sill stabilities for the entire mine, including the proposed lower level development. The only noticeable effect could, perhaps, be obtained in the creep rate due to changing stress conditions.
Failure of Inclined Boreholes
Authors: Bradley W. B.
Published: November 2010

A theoretical model of borehole failure has been developed which predicts the conditions for pressure-induced lost circulation (hydraulic fracturing) and borehole collapse. The model can be used to calculate the conditions of borehole failure in vertical and directional wells under normal and tectonic in-situ stress conditions. The results show that deviation and hole direction can significantly influence both lost circulation and borehole collapse. The paper concludes with an illustration on how this theoretical model can be used to select proper mud weights to prevent borehole failure.
Time-Domain Structural Response Simulation in a Short-Crested Sea
Authors: Shinozuka M. , Fang S.-L. S. , Nishitani A.
Published: November 2010

The responses of an offshore tower due to short-crested and long-crested ocean waves are investigated. A time-domain analysis is performed utilizing the recently developed method of generating sample functions of random processes. Numerical results include time histories of the water particle velocity and acceleration for ocean waves generated by mean wind velocity of 33 ft/sec (10 m/s) and 66 ft/sec (20 m/s) and also time histories of the tower response due to long-crested and short-crested seas. A direct comparison has been made between the responses obtained for long-crested and short-crested sea waves.
Supercavitating Cascade Analysis Based on Momentum Theorem
Authors: Oba R. , Ikohagi T.
Published: November 2010

An “accurate” analysis based on momentum theorem is proposed for finite cavity cascade foils of arbitrary shape. Some numerical results are given which show that (i) In the existing cascade flow models, the momentum theorem is not always satisfied. Therefore, the cavity drag contains an error. (ii) Low drag cascade foils are considerably cambered in the rear half and should be used within a certain required incidence limit.
Flow in the Entrance Region at Low Reynolds Numbers
Authors: Chen R.-Y.
Published: November 2010

This work extends the application of the momentum integral method to entrance flow problems with axial transport of vorticity. Laminar flow development of an incompressible Newtonian fluid in the entrance region of a circular tube and a parallel-plate channel at various Reynolds numbers is analyzed. Center-line velocity development and excess pressure drop in the entrance region are presented. Approximate solutions in closed form are also obtained. Results are compared with existing theoretical and experimental investigations and gives satisfactory accuracy. The effect of density variation on the flow is also investigated with the assumption of isothermal flow.
Asymmetric Cavitation Bubble Collapse
Authors: Mitchell T. M. , Hammitt F. G.
Published: November 2010

Numerical results describing the asymmetric collapse of vapor bubbles in an incompressible liquid for various cases of axial symmetry involving boundary conditions which prevent the maintenance of spherical symmetry are presented using a modified Marker-and-Cell (MAC) technique. The effects of fluid viscosity within the body of the liquid are considered, and upon the wall in the wall-proximity problem, but its effects at the bubble wall boundary are neglected. The cases studied include originally stationary spherical bubbles in a pressure gradient, an originally spherical bubble moving through an otherwise stationary liquid at uniform pressure, and an initially spherical bubble in a liquid at uniform pressure close to a rigid wall. This latter case applies approximately also to two identical bubbles collapsing in an infinite fluid in proximity to each other as shown by photographs here included. In all those cases which involve originally spherical bubbles, the bubble collapses in such a way as to form a jet.
Effect of Pressure on the Length of Cavity and Cavitation Damage Behind Circular Cylinders in a Venturi
Authors: Chandrasekhara D. V. , Syamala Rao B. C.
Published: November 2010

The effect of pressure on the length of cavity and cavitation damage is investigated with a venturi for cavities in water behind circular cylinders. The pressure range covered is 2.45 kgm/cm2 to 5.50 kgm/cm2 gage. Damage data are obtained for two sizes of cavitation sources of diameters 1.90 cm and 2.22 cm. Damage increased to a peak and decreased further with decrease in pressure. The studies on the length of cavity were extended to eight source diameters ranging from 0.95 cm to 3.18 cm. The increase in the length of cavity was slow up to about the length equal to 3 to 4 diameters and was rapid thereafter with decrease in pressure. The influence of test section boundaries on the phenomenon was investigated by observing the incipient, desinent, and choke cavitation conditions for fourteen blockage ratios ranging from 0.09 to 0.50. The boundary effects were less significant for blockage ratios less than 0.30. Attempts for unified correlations of the observed data by using weight loss at the beginning of steady-state zone corresponding to a maximum weight-loss rate in correlating the normalized volume of erosion with the normalized cavitation parameter, indicated peak damage at the same value of the normalized cavitation parameter.
Further Data on the Pressure Recovery Performance of Straight-Channel, Plane-Divergence Diffusers at High Subsonic Mach Numbers
Authors: Runstadler P. W. , Dolan F. X.
Published: November 2010

Measurements are reported of the pressure recovery of straight-channel, symmetric, single-plane-divergence diffusers with inlet Mach numbers between 0.2 and choking for an aspect ratio of 5.0. The data reported cover a range of length-to-throat width ratios L/W1 and divergence angles 2θ for diffuser geometries near peak recovery. These data complement data previously reported for AS = 0.25 and 1.0. Diffuser performance maps are given that show pressure recovery Cp as a function of diffuser geometry for fixed values of throat Mach number Mt, throat blockage B, and aspect ratio AS for the range of variables tested. Of significant importance to the designer is the alteration in the shape of the pressure recovery contours on the performance maps with variations in Mt, B, and AS. Also reported are data on the effect of changes in diffuser inlet Reynolds number, asymmetric distribution of inlet blockage around the throat periphery, and the influence of rounded throat corners on the pressure recovery behavior of the straight-channel diffuser. These data have underscored the necessity of understanding the cumulative effects of a number of secondary parameters on pressure recovery. The importance to the designer of a knowledge of how diffuser performance depends upon the diffuser geometric and inlet parameters is discussed.
Turbulent Mixing in the Developing Region of Coaxial Jets
Authors: Dura˜o D. , Whitelaw J. H.
Published: November 2010

Measurements of mean velocity, the three normal stresses and Reynolds shear stress are reported in the developing region of coaxial jet flows. The measurements were obtained with three velocity ratios, i.e., values of the ratio of maximum initial pipe velocity to maximum initial annulus velocity of 0, 0.23, and 0.62 and at downstream distances up to 17 outer diameters. The results show that coaxial jets tend to reach a self-preserving state much more rapidly than axisymmetric single jets; that the mean velocity, normal stresses, and Reynolds shear stress attain this state at a similar downstream location; and that, for the particular geometry investigated, a velocity ratio of around 0.15 corresponds to the slowest rate of development. Relationships between mean velocity gradient, Reynolds shear stress, and turbulent kinetic energy are examined to assess their ability to characterize the present flow: the results indicate the need to take account of the normal stresses in any proposed mathematical model.
A Simple Yet Theoretically Based Time Domain Model for Fluid Transmission Line Systems
Authors: Karam J. T. , Leonard R. G.
Published: November 2010

A simple, theoretically based time domain model for the propagation of small, arbitrary signals in a finite, circular, fluid transmission line is developed. A recent simple theoretical solution for the step response at a downstream point in a semi-infinite fluid line is combined with a two-port representation of a finite line. The major feature of this finite line model is two “filters” which represent a convolution of their arbitrary inputs with the unit impulse response at the equivalent location in a semi-infinite line. Experimental tests are reported which further verify the simple semi-infinite line solution and verify the response of several example systems containing finite lines. The models developed herein show good agreement with experiment. The major anomaly noted was an amplitude dependence in the experimental response for signals larger than one percent of the bulk modulus of the fluid. Since the theory represents a linearized, small perturbation model, such disagreement might have been anticipated and is viewed as a limitation, rather than invalidation, of the model. Finally, quantitative comparisons are made between the proposed model and those in current use.
Discharge Coefficient Correlations for Circular-Arc Venturi Flowmeters at Critical (Sonic) Flow
Authors: Arnberg B. T. , Britton C. L. , Seidl W. F.
Published: November 2010

Data are presented which tend to verify the theoretically predicted discharge coefficients for circular-arc venturi flow meters operating in the critical flow regime (sonic) at throat Reynolds numbers above 1.5 105. Extensive analysis of the data is presented using methods that are presently in process of international standardization. The data tend to verify the theoretically predicted decrease of 0.25 percent in the discharge coefficient during transition from laminar to a turbulent boundary layer. The transition occurred at a throat Reynolds number of 2.2 106, but the transition point probably changes as a function of several influences. The mean line of the measured data fell between the theoretical values for laminar and turbulent boundary layers. The scatter in 55 data points was ±0.212 percent (95 percent confidence level) from the mean line equation for Reynolds numbers from 4.1 104 to 3.4 106, which included the effects of several variables. Data were obtained from 17 venturis with throat sizes from 0.15 to 1.37 in. with Beta ratios ranging from 0.014 to 0.25. Four different test gases and three primary flow measurement facilities were used. Additional data are presented extending down to throat Reynolds numbers of 1.3 104 and throat diameters of 0.05 in. which indicate special problems in these regions. The state of the art for measuring venturi throat diameters presented a major limitation to the correlation effort. Calibration is necessary in many cases depending on various parameters and requirements. Additional study is needed to determine the optimum geometrical parameters at low Reynolds numbers, the optimum approach configuration for Beta ratios above 0.1, the effect of surface roughness on the discharge coefficient, and the effect of various operational variables such as flow pulsation and approach velocity profile. Also, a continuous effort should be made to improve the critical flow functions for real gases as better gas property data become available, and to extend these calculations to broader ranges of pressures and temperatures, and to other gases.
Metering Performance Investigation and Substantiation of the “Universal Venturi Tube” (U.V.T.): Part 1—Hydraulic Shape and Discharge Coefficient
Authors: Halmi D.
Published: November 2010

The UVT provides Classical Venturi tube type metering performance with less than half the laying length, no annular chambers, and about half the permanent head loss. Data presented reveal the flow mechanism inside the tube and substantiate its performance over a wide range of Reynolds numbers, line sizes, beta ratios, tube materials, upstream and downstream piping configurations for incompressible and compressible flow. The experience of the past five years indicates ± 0.5 percent two times standard deviation uncalibrated accuracy for C.I. UVT’s. Due to its depth and method, the substantiation work was unique; consequently, it is recommended as a standard procedure for the performance substantiation of any kind of flow meter presently in use or to be introduced in the future.
A Comparison Between Orifice and Flow Nozzle Laboratory Data and Published Coefficients
Authors: Miller R. W. , Kneisel O.
Published: November 2010

Prediction of orifice and flow nozzle coefficients from their dimensions is a matter of major concern. In the mid 1930’s, laboratory flow coefficient data were obtained for flange top orifices and for the ASME flow nozzle. The working equations and tolerances developed from these data provide the basis for AGA Report Nos. (2,3), Fluid Meters, and ISO R541. Recent statistical evaluation of these data indicated that the tolerance should be at least twice the published values. This paper presents a considerable body of previously unpublished precision flow calibration data on orifices and flow nozzles. The significant difference between these data and the original 1980 data is that they were obtained on devices not constructed for a controlled laboratory test program. The majority of these devices were not manufactured by Foxboro but were purchased by the user from different manufacturers and were flow calibrated at Foxboro for high accuracy measurement applications. Data plate dimensions were used in all calculations, and conformity to ASME code requirements was the responsibility of the manufacturer. These data are compared point-by-point to the ASME and other proposed equations. These results indicate that a tolerance of ±0.7 percent for nozzles and ±0.5 percent or less for orifice plates is possible using a regression analysis equation. This compares to the ±2.0 percent and ±1 percent tolerance on previously published data. These data also point up the need for further work to bring the coefficient equations into line for pipe sizes less than 4 in. and for pipe sizes 24 in. and larger, as well as for beta ratios greater than 0.7.
Gas Compression With the Liquid Jet Pump
Authors: Cunningham R. G.
Published: November 2010

The isothermal compression of a gas by a liquid jet in a mixing throat followed by secondary compression in a diffuser is described by a one dimensional model including frictional losses. Good theory-experiment agreement is shown; pump efficiencies can exceed 40 percent. Mixing throat and diffuser energy analyses are presented. The isothermal compression mechanism in the throat is related to momentum transfer while the diffuser process consists of a pistonlike compression of entrained gas bubbles by the continuous liquid medium. The efficiency of a liquid-jet gas pump depends primarily on the mixing loss. The mixing loss function, the throat compression ratio and the Mach number are developed as functions of the throat inlet velocity ratio v and the jet pump number n. A zero mixing loss criterion defines the theoretically possible region of pump operation. Design applications are discussed.
Turbulent Couette Flow
Authors: Wang A. K. , Gelhar L. W.
Published: November 2010

Turbulent flow between concentric rotating cylinders is analyzed using an energy balance hypothesis proposed by Zagustin. Predictions of the mean velocity profiles are obtained without any additional assumptions regarding the distribution of mixing length. The theoretical results compare favorably with previous observations with only the inner or outer cylinder rotating, and with new data for counter-rotating cylinders. The theoretical results are also consistent with observed features of plane Couette flow.
Compressible Flow Ejectors: Part I—Development of a Finite-Difference Flow Model
Authors: Hedges K. R. , Hill P. G.
Published: November 2010

A general method of calculating two-dimensional (plane and axisymmetric) mixing of a compressible jet in variable-area ducts has been developed. The method incorporates finite-difference approximations to the conservation equations, and is applicable to a wide range of Mach number, mass flow ratio, and initial conditions. The model was based on mixing length approximations deduced from boundary-layer and free-jet mixing for the upstream portion of the flow, and on a new mixing length distribution for the downstream zone which is entirely occupied by shear flow. The method has been tested and found satisfactory with existing data on boundary layer, constant-diameter duct entrance flow, constant-pressure jet mixing, and jet mixing in variable-area ducts. Part II of the paper describes tests of the method with new data from an experimental ejector study.
On the Flow Fields of Inertial Impactors
Authors: Marple V. A. , Liu B. Y. H. , Whitby K. T.
Published: November 2010

The flow field in an inertial impactor was studied experimentally with a water model by means of a flow visualization technique. The influence of such parameters as Reynolds number and jet-to-plate distance on the flow field was determined. The Navier-Stokes equations describing the laminar flow field in the impactor were solved numerically by means of a finite difference relaxation method. The theoretical results were found to be in good agreement with the empirical observations made with the water model.
Study of Flow and Thrust in Nozzle-Flapper Valves
Authors: Hayashi S. , Matsui T. , Ito T.
Published: November 2010

The Navier-Stokes equations and the equation of continuity describing the flow in the flat-faced nozzle-flapper valve are numerically solved by the iterative relaxation method and the effect of the flow contraction (vena contracta) occurring in the radial gap in the valve is investigated. Furthermore, an approximate formula for the flow force acting on the flapper is derived on the basis of the numerical solutions. The formula for the flow force is in good agreement with experimental results.
A Turbulent Energy Model for Flows With Drag Reduction
Authors: Hassid S. , Poreh M.
Published: November 2010

A simple turbulent energy model, based on an improved version of Wolfshtein’s model for Newtonian flows, with a variable damping parameter, is used to describe the effect of linear polymers on the velocity profile and the turbulent energy distribution in channel and pipe flows. Measured mean velocity profiles seem to be in good agreement with the model, which predicts as well the observed increase in turbulent energy near the wall in flows with drag reduction.
The Paradox of the Vena Contracta
Authors: Wilson M. P. , Teyssandier R. G.
Published: November 2010

The preponderance of evidence, both theoretical and experimental, appears to show that the vena contracta does not occur at the same location as the minimum pressure point in the Reynolds number range greater than 10,000. Fortunately, however, this result has little effect on the measurement engineer in the field. All of the coefficients for vena contracta taps remain valid except that they should probably be referred to as “minimum pressure point taps” unless someone can provide a simpler description.
Thermodynamic Effects on Developed Cavitation
Authors: Holl J. W. , Billet M. L. , Weir D. S.
Published: November 2010

The results of an investigation of thermodynamic effects are presented. Distributions of temperature and pressure in a developed cavity were measured for zero- and quarter-caliber ogives. A semiempirical entrainment theory was developed to correlate the measured temperature depression, ΔT, in the cavity. This theory correlates ΔTmax expressed in dimensionless form as the Jakob number in terms of the dimensionless numbers of Nusselt, Reynolds, Froude, and Pe´cle´t, and dimensionless cavity length, L/D. The results show that in general ΔT increases with L/D and temperature and the cavitation number based on measured cavity pressure is a function of L/D for a given model contour, independent of the thermodynamic effect.
Fluid Forces Induced by Vortex Shedding
Authors: Blevins R. D. , Burton T. E.
Published: November 2010

A semi-empirical, dynamic model for investigating the fluid forces induced on a bluff cylinder by vortex shedding is developed using random vibration theory. The model includes both spanwise correlation effects and the amplitude dependence of the correlated vortex forces. Model parameters are determined by experimental data. The results are then applied to determine the forces exerted on elastic cylinders at resonance with vortex shedding. The predictions are in good agreement with experimental data.
Liquid Jet Pumped by Rising Gas Bubbles
Authors: Hussain N. A. , Siegel R.
Published: November 2010

From observations of a stream of gas bubbles rising through a liquid, a two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. The bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they rise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature.
Three-Dimensional Boundary-Layer Computation on the Stationary End-Walls of Centrifugal Turbomachinery
Authors: Davis W. R.
Published: November 2010

An integral entrainment computation technique is presented for the three-dimensional boundary-layer growth on the stationary end-walls of centrifugal turbomachinery. The analytical model assumes axisymmetric inviscid core flow and viscous flow in the wall region, and the interaction between the two layers is considered. A novel form of the three-dimensional boundary-layer equations is presented. The form is physically appealing for this axisymmetric application and provides distinct advantages in the prediction of boundary-layer growth. It is demonstrated that it is essential to use the meridional boundary-layer profile to compute the Head entrainment function for this type of flow, as opposed to the streamwise velocity profile, as is more commonly done. Comparison with experimental measurements shows good agreement in the integral parameters. In addition, good agreement with experimental velocity profiles was achieved for a separating and reattaching flow.
Symmetrical Laminar Channel Flow With Wall Suction
Authors: Gupta B. K. , Levy E. K.
Published: November 2010

Entrance region solutions of the two-dimensional boundary layer equations are presented in terms of a convergent power series for steady, laminar, incompressible channel flow with uniform mass suction at the walls. The entrance solutions obtained using both uniform and parabolic velocity profiles at the inlet to the channel are compared to the solutions obtained from the similarity equations for a wide range of non-dimensional suction velocities (0 ≤ Rew ≤ 30). With a parabolic inlet velocity profile, the flow does not become fully developed for Rew > 7, except right at the downstream end of the channel (x = L). The similarity solutions are in good agreement with the entrance solutions over a reasonable length of the channel only for very small values of Rew. With a uniform inlet velocity profile, the flow does not become fully developed in the range 7 < Rew < 13, except right at x = L. In this case, the similarity equations should not be used to predict overall axial pressure variations except for very large values of Rew.
Development of a Retracting Vane/Centrifugal Main Fuel Pump for Gas Turbine Engines
Authors: Pech K. H. , Downing N. L.
Published: November 2010

Fuel pumps and metering systems are becoming more complex and expensive to meet the high performance requirements of advanced gas turbine engines. A simple, inlet throttled, centrifugal pump integrated with a retracting vane starting element provides the potential for a reliable, high performance design capable of reducing the cost, weight, and temperature rise of the fuel system. This paper presents the results of recent efforts to develop the retracting vane element and to integrate it with a vapor core centrifugal pump in order to meet the fuel performance and functional requirements of an advanced gas turbine main fuel pump.
Oscillating Turbulent Flow in a Conical Diffuser
Authors: Schachenmann A. A. , Rockwell D. O.
Published: November 2010

Turbulent boundary layers experiencing a time mean adverse pressure gradient and a controllable periodic oscillation are examined experimentally over a tenfold range of dimensionless frequencies, and amplitudes less than ten percent of the lime mean diffuser inlet velocity, for well defined diffuser inlet conditions. Organized velocity fluctuations of the diffuser core and boundary layer flow fields, along with organized wall pressure fluctuations, are characterized using a phase averaging process. Amplitudes of the core velocity fluctuations and wall pressure fluctuations decay in the streamwise direction. Depending on the dimensionless excitation frequency, the amplitude of the organized velocity fluctuations in the boundary layer can exceed the local core flow amplitude by as much as an order of magnitude. At relatively low dimensionless excitation frequency, the organized velocity fluctuation amplitude distribution within the boundary layer grows in an orderly fashion with streamwise distance, and the phase of these fluctuations consistently leads the local core flow fluctuation. At relatively high dimensionless excitation frequency, phase lags of the velocity fluctuations within the boundary layer, relative to the local core flow fluctuation, can extend across the entire boundary layer. Over the range of frequencies examined, the mean flow field of the diffuser remained essentially unaltered.
Direct Measurement of the Mean Flow Velocity Vector
Authors: Kirchhoff R. H. , Struziak R. M.
Published: November 2010

The response of a single inclined rotating hot wire anemometer was analyzed. The mean flow anemometer response equation was expanded in a Fourier Series about the fundamental frequency of rotation. Utilizing the d-c level and the first two harmonics of the response it is possible to construct the mean flow velocity vector within a solid angle determined by the mounting angle of the wire. The rotating anemometer response was measured using the technique of two phase lock-in detection to determine the first two harmonics and their phases relative to the fundamental frequency of rotation. Determination of the mean flow velocity vector using this technique was found to be feasible.
Computation of Annular, Turbulent Flow With Rotating Core Tube
Authors: Sharma B. I. , Launder B. E. , Scott C. J.
Published: November 2010

Numerical predictions are presented of fully-developed turbulent flow through a concentric annulus in which the core tube rotates about its axis. Comparisons are drawn with the extensive experimental data of Kuzay and Scott [1] which span Reynolds numbers from 1.7 to 104 to 6.5 × 104 and with rotational speeds of the core tube varying from zero to nearly 2.8 times the bulk axial velocity. Predictions have been obtained by means of an adapted version of the Patankar-Spalding [5], numerical procedure employing, as turbulent transport model, the version of the mixing length hypothesis applied by Koosinlin, Sharma and Launder [2] to flows on spinning cones and cylinders. Agreement with experiment is generally close at the higher relative swirl rates but the predictions of the swirling velocity profile deteriorate as the bulk flow rate is increased. The discrepancy seems to be due to the experimental data requiring a greater development length as the magnitude of the rotational velocity is reduced relative to that of the mean flow. Demonstrative developing-flow predictions are provided which exhibit closer agreement with the experimental data.