bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study of Some Three-Dimensional Laminar Free Convective Flows
Authors: Oosthuizen P. H.
Published: November 2010

Three-dimensional buoyancy-induced flows over plates and cylinders have been considered. The three-dimensional flow results either from the fact that the body is inclined to the horizontal or from the fact that there is a longitudinal acceleration component. Both the cases where this acceleration component is constant and the case where it varies linearly with the distance along the body have been considered. The study is based on the use of the constant-property boundary-layer equations. These equations have been rewritten in terms of dimensionless variables, and thus the resulting equations do not explicitly depend on the nature of mechanism causing the three-dimensional flow. These equations have been solved numerically using finite-difference methods, with heat-transfer distributions for various representative situations being deduced.
An Experimental Investigation of the Thermally Induced Flow Oscillations in Two-Phase Systems
Authors: Saha P. , Ishii M. , Zuber N.
Published: November 2010

An experimental study on the onset of thermally induced two-phase flow oscillations has been carried out in a uniformly heated boiling channel using Freon-113 as the operating fluid. The effects of inlet subcooling, system pressure, inlet and exit restrictions, and inlet velocity have been studied. The experimental data have been compared with the equilibrium as well as the nonequilibrium theory including the effect of subcooled boiling. It has been found that the effect of thermal nonequilibrium should be included in a theoretical model for accurate prediction of the onset and the frequency of thermally induced flow oscillations. A simplified stability criterion has also been presented and compared with the experimental data.
Prediction of Turbulent Forced Plumes Issuing Vertically Into Stratified or Uniform Ambients
Authors: Madni I. K. , Pletcher R. H.
Published: November 2010

A finite difference calculation method is used to solve the conservation equations of mass, momentum, and energy in differential form for a buoyant turbulent forced plume discharging vertically into both a uniform and a stratified quiescent ambient. This flow configuration is of interest relative to the discharge of thermal or sewage effluents into the ocean and the discharge of effluents from chimneys and cooling towers into a still atmosphere. The effects buoyancy on the turbulent transport model are discussed. The predictions, including the predicted maximum height of rise for the stratified ambient case, are compared with available experimental data and the results of other prediction methods.
Effect of Superheat and Cavity Size on Frequency of Bubble Departure in Boiling
Authors: Singh A. , Mikic B. B. , Rohsenow W. M.
Published: November 2010

A theoretical model has been developed to predict the effect of cavity size (both radius and depth), and superheat on frequency of bubble departure by considering the effect on waiting time (time between the last bubble departure and appearance of the next one on the surface) and bubble growth time. An increase in cavity size or decrease in surface superheat results in longer waiting time and bubble growth time, thus causing a lower frequency. The model explains qualitatively the observed effect of superheat and cavity size on bubble departure frequency during pool boiling experiments with water on artificial cavities drilled by laser.
The Effect of Noncondensable Gas on Film Condensation Along a Vertical Plate in an Enclosed Chamber
Authors: Mori Y. , Hijikata K. , Utsunomiya K.
Published: November 2010

Experiments on film condensation including noncondensable gas in an enclosed chamber have been carried out to clarify the effects of molecular weights of vapor and noncondensable gas and the convective motion induced by the vapor flow. From the experimental results of R113-air and CH3OH-mixed gas of He and Ar, it is shown that the separation of vapor and gas in the main flow is realized when the direction of gas flow in free convective boundary layer driven by concentration distribution of gas is the same as that of supplied vapor, whereas the homogeneous main flow occurs in the case of counter direction. It is also shown that in case of the separation of vapor and gas in the main flow the heat transfer coefficient is higher than that for an homogeneous main flow.
Transient Heat and Mass Transfer to a Drop in an Electric Field
Authors: Morrison F. A.
Published: November 2010

A circulating fluid motion is generated by an electric field imposed on a dielectric drop in another dielectric liquid. The motion of the drop surface may be from the poles to the equator or from the equator to the poles. Transient heat or mass transfer results in response to a sudden change in the temperature difference or concentration difference between the drop and the surrounding fluid. The low Reynolds number, high Peclet number response is analyzed. The boundary layer equations are solved exactly using a similarity transformation. Results are obtained for both directions of circulation. While local fluxes differ greatly when the flow reverses, and despite a lack of symmetry, the overall transfer rate is independent of the direction of flow. This result applies to the transient as well as the steady state.
Analysis of Heat Transfer by Natural Convection Across Vertical Fluid Layers
Authors: Raithby G. D. , Hollands K. G. T. , Unny T. E.
Published: November 2010

An analysis is presented which predicts the heat transfer across fluid layers bounded laterally by vertical isothermal surface and adiabatic surfaces on the top and bottom. The vertical temperature distribution in the core of the cavity is also predicted. Extensive comparisons of average Nusselt number and temperature distribution are made with experimental data for aspect ratios greater than 5. Good agreement between analysis and experiment is found. The heat-transfer equations for vertical layers are generalized to include layers which are tilted up to 20° from the vertical, making the results useful for the design of solar collectors.
Experimental and Predicted Recovery Temperature Distributions in a Rocket Nozzle With Gaseous Film Cooling
Authors: Williams J. J. , Giedt W. H.
Published: November 2010

The adiabatic wall temperature distribution in nozzles with gas injection through a peripheral slot at the entrance was investigated. Experimental wall temperature distributions were measured in a series of hot gas (hydrogen-air combustion as the primary source) tests with three geometrically different channels—a constant area duct, a gradually converging nozzle, and a rapidly converging nozzle. Cooling effectiveness was found to be significantly higher for the rapidly converging geometry. Prediction of recovery temperature distributions under the test conditions with available boundary layer computer programs was then investigated. Predicted results were consistently higher than measured. Significantly improved agreement between predicted and measured results was achieved by introducing effective initial temperature profiles in the injectant to account for gross mixing between the injectant gas (nitrogen) and free stream gas at the injection station.
Natural Convection Mass Transfer at Salt-Brine Interfaces
Authors: Chang C. , Vliet G. C. , Saberian A.
Published: November 2010

Experimental measurements of the rate of dissolution (mass transfer) at salt-brine interfaces have been made for variation of brine concentration from fresh water to near saturated brine, and variation of surface orientation from horizontal (facing downward) through the vertical to “near” horizontal (facing upward). Salt samples used were cut from an underground mine and the dissolution results are for “rough” surfaces—that is, after the surface has developed. Samples of approximately 1 m long were used, and the results obtained and presented are for turbulent flow. The correlated results are presented in the form of a coefficient CT as a function of θ (angle from vertical) where CT(θ) = Sh/(GrSc)1/3. The coefficient is found to be a very strong function of angle, being larger for the unstable orientations and smaller for the stable orientations than for the vertical. The data are compared to other turbulent natural convection mass and heat transfer data for vertical and inclined surfaces, and are found to exhibit considerably greater convection transport coefficients than for smooth surfaces.
Buoyant Jets Discharging Nonvertically Into a Uniform, Quiescent Ambient—A Finite-Difference Analysis and Turbulence Modeling
Authors: Madni I. K. , Pletcher R. H.
Published: November 2010

A differential approach for analysis of turbulent, axisymmetric, buoyant jets and plumes issuing nonvertically into a quiescent, uniform ambient is presented, in which the governing differential equations for conservation of mass, momentum, and energy, derived in a curvilinear, orthogonal coordinate system, are solved by a finite-difference method of the Dufort-Frankel type. This jet configuration is of interest with regard to the design of submerged, offshore outfalls from power plants. The analysis includes consideration of the transverse momentum equation as the jet follows a curved trajectory under the influence of buoyancy forces. The turbulent shear stress and heat flux terms in the governing equations are evaluated through a relatively simple turbulence model which accounts for the effect of buoyancy on the apparent turbulent viscosity through the gradient Richardson number. Predictions for buoyant jets discharging horizontally and at 45 deg to the horizontal are compared with recent experimental data and the results of other prediction methods.
Development of Wall and Free Plumes Above a Heated Vertical Plate
Authors: Sparrow E. M. , Patankar S. V. , Abdel-Wahed R. M.
Published: November 2010

An analysis has been made to determine the successive stages of development as the natural convection boundary layer on a steadily heated vertical plate evolves into a plume. Both the wall plume and the free plume are investigated. The wall plume develops along an adiabatic wall which is the vertical extension of the heated plate. The free plume is created as the boundary layer streams away from the upper edge of the plate. Since the plate is heated on only one of its faces, the free plume is initially unsymmetric. The development of these plumes does not admit similarity-type boundary layer solutions, and numerical techniques were, therefore, employed, with results being obtained for Prandtl numbers of 0.7, 2, 5, and 10. It was found that at sufficient downstream distances both plumes attain their respective fully developed behaviors (i.e., similar profiles at successive streamwise stations). For the wall plume, the development for all Prandtl numbers is completed at a position that is about five plate lengths above the leading edge of the heated plate. The development length for the free plume for Pr = 0.7 is about the same as that for the wall plume, but about 30 plate lengths are required for the development of the free plume when Pr = 10. The fully developed free plume is symmetric.
Variable Physical Properties in Laminar Heating of Pseudoplastic Fluids with Constant Wall Heat Flux
Authors: Gori Fabio
Published: November 2010

A theoretical investigation of the combined influence of natural convection and consistency variations in laminar heating of non-Newtonian fluids has been carried out. The heating of a power law fluid with an initially fully developed velocity profile flowing upward through a vertical tube with a constant wall heat flux was considered. The system of governing equations, complete with the convective terms, was solved numerically. Detailed comparisons with previous theoretical and experimental results were performed to check the integrity of the solutions obtained with the present approach. Local heat transfer coefficients, as a function of Graetz number, were presented. Local heat transfer results showed that for pseudoplastic fluids with smaller Prandtl number the parameter Pr was very important in the inlet and in the intermediate part of the tube.
Radiation From a Methanol Furnace
Authors: Grosshandler W. L. , Sawyer R. F.
Published: November 2010

Monochromatic intensity measurements are taken in a water-cooled furnace, 20 cm in diameter, burning methanol and a methanol/coal slurry. The primary interest is to determine the contribution of particulate radiation to the total intensity. Temperature, carbon dioxide, carbon monoxide, water, methanol, and particulate concentration levels are quantitatively measured throughout the furnace chamber. A computer code is discussed which integrates the equation of transfer over a nonhomogeneous path containing combustion gases and particulates. This allows comparison of the measured intensity with a theoretical prediction based upon known concentration and temperature profiles. The intensity and emittance measurements from the methanol furnace are compared with measurements in other experimental furnaces burning oil and gas.
Multi-Dimensional Radiative Transfer in Nongray Gases—General Formulation and the Bulk Radiative Exchange Approximation
Authors: Tsai S. S. , Chan S. H.
Published: November 2010

The present paper presents a general formulation of the radiative heat flux and its divergence for multi-dimensional radiative problems involving nongray absorbing-emitting gases. The expressions obtained are in terms of total band absorptance rather than the spectral absorption coefficient. Thus the frequency integration is eliminated, and the expressions are more compact. They avoid the necessity of detailed spectral absorption coefficient data for radiative transfer computations. Also presented is the bulk radiative exchange approximation together with its refinement. It is proposed to circumvent the mathematical complexity inherently imbedded in nongray multidimensional problems. The approximation, which is valid in the optically thin and thick limits, is found to be general and useful, not only because of its simplicity, but also because of its accuracy in all optical conditions.
Linearized Stability Analysis of Film Condensation
Authors: U¨nsal M. , Thomas W. C.
Published: November 2010

A modified Yih analysis is used to investigate the stability of laminar film condensation on a vertical wall. The analysis presented leads to closed-form expressions for the wave amplification rate, the wave velocity, the neutral stability curve, and the critical Reynolds number. It is found that the condensation mass transfer rate has a dual role in the instability-inducing mechanism. Results indicate that surface tension, viscosity, and the overall effect of condensation mass transfer tend to stabilize while gravity tends to destabilize the flow. The critical distance predictions are an order of magnitude larger than the predictions from previous theories.
Effect of Free-Stream Turbulence on Heat Transfer through a Turbulent Boundary Layer
Authors: Simonich J. C. , Bradshaw P.
Published: November 2010

Measurements in a boundary layer in zero pressure gradient show that the effect of grid-generated free-stream turbulence is to increase heat transfer by about five percent for each one percent rms increase of the longitudinal intensity. In fact, even a Reynolds analogy factor, 2 × (Stanton number)/(skin-friction coefficient), increases significantly. It is suggested that the irreconcilable differences between previous measurements are attributable mainly to the low Reynolds numbers of most of those measurements. The present measurements attained a momentum-thickness Reynolds number of 6500 (chord Reynolds number approximately 6.3 × 106) and are thought to be typical of high-Reynolds-number flows.
Calculation of a Turbulent Boundary Layer Downstream of a Step Change in Surface Temperature
Authors: Browne L. W. B. , Antonia R. A.
Published: November 2010

Mean temperature and heat flux distributions in a thermal layer that develops within a momentum boundary layer subjected to a step change in surface temperature are calculated using two different methods. The method of Bradshaw and Unsworth, which uses the method of Bradshaw, Ferriss and Atwell to determine the mean velocity and Reynolds shear stress distributions and then assumes a constant turbulent Prandtl number for the heat flux calculation, yields heat flux distributions that are significantly different than the available experimental results at small distances from the step. Good agreement between calculations and experimental values is achieved when the distance x from the step is about 20 δ0, where δ0 is the boundary layer thickness at the step. To obtain good agreement with measurements of heat flux and mean temperature near the step, estimated distributions of turbulent viscosity and effective Prandtl number have been derived using an iterative updating procedure and the calculation method of Patankar and Spalding. These distributions are compared with those available in the literature. Calculated heat flux distributions show that the internal thermal layer is only likely to reach self-preserving conditions when x exceeds 40 δ0.
Laminar Boundary Layer Swirling Flow with Heat and Mass Transfer in Conical Nozzles and Diffusers
Authors: Meena B. K. , Nath G.
Published: November 2010

The flow and heat transfer for a steady axisymmetric laminar incompressible boundary layer swirling flow with mass transfer in a conical nozzle and a diffuser have been studied. The partial differential equations governing nonsimilar flow have been solved numerically using an implicit finite-difference scheme after transforming them into new coordinates having finite ranges. The results indicate that, both for the nozzle and diffuser, swirl exerts a strong influence on the longitudinal skin friction, but its effect on the tangential skin friction and heat transfer is comparatively small. In the case of the nozzle, even for a small value of the dissipation parameter at the inlet, the heat transfer rapidly increases near the end of the nozzle; whereas in the case of the diffuser, no such trend is observed. Suction increases the skin friction and heat transfer, but injection does the reverse. The results are found to be in good agreement with those of the local nonsimilarity and momentum integral methods except near the end of the nozzle or diffuser, but they differ appreciably from those of the local similarity method except near the inlet.
An Evaporating Ethanol Meniscus—Part II: Analytical Studies
Authors: Renk F. J. , Wayner P. C.
Published: November 2010

A model of capillary flow heat transfer is used to analyze the data obtained in Part I. The results indicate that fluid flow resulting from a change in the meniscus profile replenishes the liquid evaporated in a stationary evaporating meniscus. Local evaporative heat fluxes can be very high near the interline region of a finite contact angle meniscus. Therefore, a small stationary evaporating meniscus can be used as a very effective local heat sink.
Influence of Thermal Radiation on the Temperature Distribution in a Semi-Transparent Solid
Authors: Amlin D. W. , Korpela S. A.
Published: November 2010

The importance of radiation on the temperature distribution in a semi-transparent solid is reported. The first-order differential approximation of radiation is combined with conduction analysis to investigate the temperature profiles in a plane slab and a rectangular region. The coupled nonlinear partial differential equations are solved numerically by either a standard implicit or an implicit alternating direction method. Results obtained for opaque boundaries are in good agreement with exact formulations found in the literature. An extension to partially transparent boundaries is made and results presented.
Band Radiation within Diffuse-Walled Enclosures—Part II: An Approximate Method Applied to Simple Enclosures
Authors: Nelson D. A.
Published: November 2010

An asymptotically exact approximate method of analysis for band radiation has been applied to some simple enclosures. The principal feature of the method is direct utilization of band absorption formulations for absorbing-emitting media. The procedure is shown to be capable of arbitrarily high accuracy and to have very acceptable errors for low order approximations.
Natural Convection of Mercury in a Magnetic Field parallel to the Gravity
Authors: Seki M. , Kawamura H. , Sanokawa K.
Published: November 2010

Experimental and numerical studies were carried out on the natural convection of mercury in a rectangular container heated from a vertical wall. A magnetic field was applied parallel to the gravity vector and to the heated wall. Experimental results showed that the magnetic field decreased the Nusselt number considerably in the low region of the Grashof number. The effect of the parallel field was found to be less than that for a field normal to the gravity vector, but it is still not negligible. Numerical results on the Nusselt number were found to predict approximately the experimental ones. Calculated velocity profiles displayed noticeable changes due to the application of the magnetic field. A broad stagnation region was formed in the core of the container.
Natural Evaporation of Sodium with Mist Formation: Part I—Measurement of Evaporation Rates and Comparison of Values against Theoretical Predictions
Authors: Kumada T. , Ishiguro R. , Sato T. , Abe T.
Published: November 2010

Measurements were made of the rate of natural evaporation into a stagnant argon or helium atmosphere from a rectangular-shaped surface of liquid sodium placed on the bottom floor of an evaporation test box. The tests were carried out at various levels of sodium temperature and inert gas pressure under conditions where mist formation could be expected. The values obtained as the Sherwood number were compared with those predicted by various theoretical models. The overall results revealed that the enhancement of evaporation brought about by mist formation significantly increased as the sodium temperature did. It was concluded that the previous theoretical models were not adequate for obtaining correct values for the evaporation rate.
Mixed Convection on Inclined Surfaces
Authors: Mucoglu A. , Chen T. S.
Published: November 2010

An analysis is performed to study the effects of buoyancy force on the heat transfer characteristics of laminar forced convection flow over an inclined flat surface which is either maintained at a uniform temperature or subjected to a uniform heat flux. Numerical results are presented for Prandtl numbers of 0.7 and 7 over a wide range of values of the buoyancy force parameters, with the angle of inclination ranging from 0 to 90 deg from the vertical. In general, it is found that for both surface heating conditions, the local friction factor and the local Nusselt number increase with increasing buoyancy force for assisting flow and decrease with increasing buoyancy force for opposing flow. In addition, the effects of the buoyancy force on these two quantities are found to diminish as the angle of inclination increases. A comparison is also made of the results between the case of uniform wall temperature and the case of uniform surface heat flux.
Homogeneous Vapor Nucleation and Superheat Limits of Liquid Mixtures
Authors: Pinnes E. L. , Mueller W. K.
Published: November 2010

Two features distinguish vapor nucleation in multicomponent liquids from the single component case. Both result from the unequal volatilities of the species. One is that the vapor phase may contain several components; the other is that nucleus formation alters the composition of the nearby liquid. These two features are incorporated into the classical theory of homogeneous nucleation to yield a general theory applicable to multicomponent liquids. The theory is applied to binary hydrocarbon mixtures by using an equation of state extrapolated into the metastable region. Superheat limits thus calculated are compared with published experimental results.
Effect of Three Advanced Lubricants on High-Temperature Bearing Life
Authors: Bamberger E. N. , Zaretsky E. V. , Anderson W. J.
Published: November 2010

Rolling-element fatigue tests were conducted with 120-mm bore angular-contact ball bearings made of AISI M-50 steel with a synthetic paraffinic oil, a fluorocarbon, and a 5P4E polyphenyl, ether. At 600 deg F under a low-oxygen environment, the synthetic paraffinic oil and the fluorocarbon gave bearing lives approximately 14 and 3 times AFBMA-predicted (catalog) life, respectively. With the polyphenyl ether, bearing life was less than AFBMA-predicted (catalog) life in an air environment at 600 deg F. At temperatures of 400 and 500 deg F with the synthetic paraffinic oil there was no statistical difference in life from those bearings tested with the same fluid at 600 deg F. For the synthetic paraffinic oil and the fluorocarbon, bearing fatigue was subsurface initiated. For the polyphenyl ether, bearing failure was mainly from surface distress, wear, and superficial pitting.
The Maximum Principle Approach to the Optimum One-Dimensional Journal Bearing
Authors: Maday C. J.
Published: November 2010

Pontryagin’s Maximum Principle is used to determine the journal bearing which supports the maximum load for a given minimum film thickness and a specified load direction. The one-dimensional configuration which uses a constant-viscosity, incompressible lubricant is considered. Comparison shows that the optimum bearing carries a load about 13.5 percent greater than the maximum carried by the usual full-Sommerfeld bearing and about 121 percent greater than that carried by the half-Sommerfeld unit. The problem is formulated subject to the constraints of a fixed load direction and a specified minimum film thickness while the only boundary condition imposed is that the pressure must vanish at the inlet and at the outlet. The actual extent of the bearing is determined in the optimization process and it is shown that this extent is 360 deg. Further, the bearing is stepped with only two regions of different but constant film thickness.
Electrodeposited and Hardened Iron for Rolling Contact Fatigue Applications
Authors: Kepple R. K. , Mantel E. R. , Klingenmaier O. J. , Mattson R. L.
Published: November 2010

A new approach to the material cleanliness problem in rolling contact fatigue involving the use of hardened electrolytically deposited iron (or iron-nickel alloy) is discussed. It was demonstrated that the fatigue strength of surfaces prepared by case hardening electrodeposited iron or iron–4 percent nickel can be equivalent to the best of commercial rolling element bearing materials. Three base materials to which the plated material was applied were investigated. These covered a broad range of quality. The associated deposit thickness problem was investigated. Excellent fatigue properties were obtained if the deposit thickness was great enough to avoid fatigue development in the base material. With deposit thicknesses less than this amount, some improvement in fatigue life was obtained over that of the unplated base material.
A Numerical Method and Higher Approximations for a Self-Acting, Gas-Lubricated Bearing of Finite Length
Authors: Kao Hsiao C.
Published: November 2010

A method for treating a self-acting, gas-lubricated journal bearing of finite length is presented, which is a compromise between the analytic solution and numerical results. Analytic solutions have been obtained here which are essentially the higher approximations of the ph linearization. The obtained solutions compare closely with the numerical results and satisfy the condition given by Elrod and Burgdorfer.
Design Charts for Optimum Bearing Configurations: 1—The Full Journal Bearing
Authors: Moes H. , Bosma R.
Published: November 2010

This paper presents a new design chart for the full journal bearing using dimensionless groups containing all relevant parameters the designer is mainly interested in. Some illustrative examples of how to use this chart have been added. The main object, however, is the introduction of a new way of presenting bearing data of all kinds of hydrodynamic bearings in such a way that they are directly suitable for design purposes. Particular attention has been paid to the possibility of optimization procedures which follow logically and directly from this chart. Other types of film bearings shall be treated in later papers.
Fluid Rheological Effects in Sliding Elastohydrodynamic Point Contacts With Transient Loading: 2—Traction
Authors: Sanborn D. M. , Winer W. O.
Published: November 2010

This paper describes the results of the traction measurements obtained in the experiment discussed in the companion paper entitled “Fluid Rheological Effects in Sliding Elastohydrodynamic Point Contacts With Transient Loading: I.—Film Thickness.” Under the conditions investigated, the traction values appear to be primarily a function of the sliding velocity. Large variations in fluid composition and inlet viscosity had little influence on the tractive force. It was also found that rapid application of the normal load had a negligible effect on the traction.
Analysis of a Porous Gas Foil Bearing
Authors: Baumann G. W.
Published: November 2010

The objectives of this study were to analyze the porous cylindrical gas film foil bearing at low pressures and to provide an engineering design method based on the variable parameters of the bearing and the fixed parameters of the application. The theoretical analysis was divided into three parts: an analysis of flow in the porous medium, a study of the flow in the channel between the bearing cylinder and foil, and an analysis of the elastic strain in the foil. An experimental analysis followed, in which a foil was supported on an air bearing at different supply pressures. The edge separation was measured by microscopy techniques and compared to the prediction obtained from the computer analysis. They agreed almost perfectly.
The Friction and Wear of Thin, Sintered, Fluoride Films
Authors: Lavik M. T. , McConnell B. D. , Moore G. David
Published: November 2010

Results are presented for the bonding of thin, sintered, fluoride films of BaF2 and CaF2 with mono-aluminum phosphate. Friction and wear behavior of these films has been defined in terms of film compositional changes, film curing procedures, and substrate variations when subjected to varying levels of temperature and load. Mono-aluminum phosphate was found to greatly enhance the adhesion of the sintered fluoride film. There was a strong dependence of wear life at 1000 deg F on the mono-aluminum phosphate content of the film. Films containing 6 vol. percent phosphate appear to be near optimum and exhibited wear lives of 1,000,000 load cycles under sliding conditions in a dual rub-shoe device with friction coefficient levels in the order of 0.10 to 0.20. Near-optimum values were determined for cure temperature (950 deg C), and surface finish (23 μ in. rms) on rhodium-plated substrates. Graphite and gold were added to the aluminum phosphate bonded BaF2: CaF2 films. Both additives were found to lower the friction coefficient at room temperature.
The Gas Liquid Interface and the Load Capacity of Helical Grooved Journal Bearings
Authors: Bootsma J.
Published: November 2010

Self-acting helical-grooved journal bearings, lubricated by an incompressible Newtonian liquid and operating under laminar conditions, have under favorable conditions a negligible leakage due to the inward pumping action of the grooves. During concentric running, the axial position of the gas liquid interface created in the grooved section of the bearing does not vary in circumferential direction (local effects due to a finite number of grooves are not taken into account). During eccentric running, however, the width of the liquid region, i.e., the interface varies in circumferential direction due to pressure differences in the lubricant film. For a complete herringbone journal bearing the interaction between the shape of the interface and the pressure distribution has been studied both theoretically and experimentally.
The Effects of Wall Conductance on Torque of the MHD Viscous Coupler and Hydrostatic Thrust Bearing
Authors: Kamiyama S. , Sato A.
Published: November 2010

An approximate analysis of the magnetohydrodynamic flow between rotating disks shows that the torque of rotating disks is strongly affected by the wall conductance. Also, considering the application to a viscous coupler or a hydrostatic thrust bearing operating under the extreme temperature, the operating characteristics of such MHD devices are analyzed.
Theoretical and Experimental Pressure Distribution in Supersonic Domain for an Inherently Compensated Circular Thrust Bearing
Authors: Poupard M. , Drouin G.
Published: November 2010

The authors present an equation describing the pressure distribution in the supersonic domain, for a lightly loaded bearing, including a friction factor as an explicit term. This paper contains also a few experimental curves showing the effect of rounding the edge of an inherently compensated orifice.
Evaluating of the Lubricating Properties of Chemically Upgraded MoS2
Authors: Ritsko J. E. , Laferty J. M. , Hubbell R. D.
Published: November 2010

Properties of MoS2 refined by chemically processing molybdenite from a copper-bearing ore are compared to those of MoS2 from the primary commercial material in the United States. The properties include crystal structure, chemical composition, oxidation resistance, and lubricating ability in bonded solid lubricant films. Both materials have the same crystal structure and similar chemical compositions. However, the chemically processed MoS2 does not have the carbon impurities present in the other MoS2. This new material performed just as well as the commercially available MoS2 in three types of bonded solid lubricant films in wear-life tests.
Inertia and Energy Effects in the Developing Gas Film Between Two Parallel Flat Plates
Authors: Elrod H. G. , Chu T. Y.
Published: November 2010

Inertia and temperature effects in entrance flow between parallel flat plates are investigated with the use of boundary-layer theory. In addition, an approximate theory is developed which is implemented by a “gas table” similar to that employed for conventional Fanno-line computations.
Power Losses Due to Secondary Flow Between Rotating Eccentric Cylinders
Authors: Younes M. A. M. A. , Mobbs F. R. , Coney J. E. R.
Published: November 2010

The presence of secondary vortex motions in the flow between eccentric rotating cylinders is shown to increase the power input requirements to the inner rotating cylinder at any eccentricity ratio. The effect of superimposing axial flow is to delay the onset of instability and hence decrease this power input to the system. An evaluation of the rotational power losses due to instability as compared with the pumping power required to introduce the necessary axial flow rates is carried out for three gap-radius ratios.
Examination of Abrasion Resistance Criteria for Some Ductile Metals
Authors: Finkin E. F.
Published: November 2010

Various abrasive wear resistance criteria are reviewed. These include hardness, modulus of elasticity, elastic strain limit, elastic-to-plastic contact transition factor, and elastic strain energy capacity. Experimental data from Khrushchov and Babichev, for the abrasion of a series of copper-nickel and lead-tin binary alloys, are used to evaluate the postulated abrasive wear resistance criteria. Modulus of elasticity shows a good correlation. Hardness is found not to correlate with wear resistance. The other abrasion resistance criteria are found to give ambiguous results. Wear resistance does not accurately follow the E1.3 power law found by Khrushchov for large differences in Young’s modulus when the changes in Young’s modulus are small, say within a factor of three. When comparing ductile materials of the types examined here for abrasion resistance, over a range of Young’s modulus within a factor of three, one can assume to a good approximation that abrasion resistance varies directly with Young’s modulus.
An Analysis of Grease and Oil Lubricated Spiral Grooved Bearings
Authors: Dewar D. M.
Published: November 2010

Mathematical models for grease and oils are put forward and used to solve a two-dimensional Reynolds’ equation with a quasi three-dimensional energy equation for any geometry of spiral groove bearing. Using numerical methods, results are presented for the temperature distributions in through-flow and block-centered thrust bearings; conical bearings and herringbone grooved journal bearings can also be dealt with. The overall bearing parameters, namely, load-carrying capacity, stiffness, and running torque at various eccentricity ratios are shown along with their dependence upon the prevailing thermal conditions.
Analytical Solutions for Incompressible Spiral Groove Viscous Pumps
Authors: Hsing F. C.
Published: November 2010

Exact solutions for a class of incompressible spiral-grooved viscous pumps were obtained by solving the dynamic perturbation equations based on the governing equations of the well-known narrow groove theory. The resulting closed-form analytical expressions contain two integration constants which can be determined by appropriate boundary conditions pertinent to a specific application and design. A flat thrust bearing was chosen to illustrate the application of these results. The load-carrying capacity calculated from present theory was compared with those obtained by other investigator [2]. The agreement is extremely good. No attempt was made to generate design charts for various designs since the resulting expressions obtained in this work can be used quite easily in a straightforward fashion.
Transient Analysis of a Planar Hybrid Foil-Bearing Model
Authors: Eshel A.
Published: November 2010

Analysis of the dynamic behavior of planar foil bearings is presented for the case when both self acting and external pressurization effects are present. From it, responses to arbitrary disturbances or initial conditions may be deduced. Graphical examples for the film response to step reduction in tension and to a moving pressurization source are shown.
Surface Defects in Drawn Aluminum Magnet Wire
Authors: Wright R. N. , Male A. T.
Published: November 2010

The fine surface defect structure of commercial EC grade aluminum magnet wire has been characterized and four basic component types have been identified. A grading system has been established for each of the component defects. Intermediate process surface characterization studies and laboratory drawing experiments have been performed to clarify the origin of the defects. The potential role of drawing lubrication in repairing or compounding the defect structure has been demonstrated and the mechanics of a drawing related repair process have been clarified through study of the effects of rod drawing on hardness indentations.
Some Friction and Lubrication Problems in the Metalworking of the Superalloys
Authors: Berry J. T.
Published: November 2010

The present paper discusses some of the friction related problems associated with the upsetting and sheet forming of nickel chromium base superalloys at temperatures between ambient and 1200 F. It continues by reviewing some of the works of the author and his colleagues in examining the effects of certain of the components of potential industrial metalworking lubricants. In the course of the research an interesting synergistic effect pertaining to lubricant components has been uncovered, a difficulty concerning the brinelling of die materials evidenced and an attempt made to utilize some of the interesting potential tool materials, for example carbides and nitrides, that have recently become available. In connection with the latter, preliminary results indicate some promising values of the friction coefficient in 1200 F tests at a 20 percent average deformation upon Inconel 625 and 718 workpieces. However, it is pointed out that in using these tooling materials special precautions must be taken regarding the provision of adequate support by sub-tooling.
Analysis of Infrared Spectra of Fluid Films in Simulated EHD Contacts
Authors: Lauer J. L. , Peterkin M. E.
Published: November 2010

Interferometry has provided the sensitivity needed for the gathering, through suitable windows, of infrared absorption and emission spectra of excellent resolution (<1 cm−1) from sample volumes even as small as EHD contact regions. Thus the power of molecular vibrational spectroscopy can be used to determine phase changes and structural changes in fluids subjected to conditions prevailing in EHD contacts. In this paper, some of the infrared methods are illustrated by the description of preliminary work in which the cavity of a high-pressure diamond anvil cell was used for contact simulation. Reference is made to a fluorescence-spectroscopic method of pressure determination in the diamond cell, which is also helpful in locating liquid/glass transition points.
Geometrical Effects on the Wear of Polymers and Carbons
Authors: Lancaster J. K.
Published: November 2010

Accelerated wear tests involving small areas of contact are frequently used both as an aid to materials selection for dry bearings and for basic studies of wear. It is shown that whilst a general correlation may exist between the wear rates of polymer composites in accelerated tests and during operation as dry journal bearings, discrepancies can occur. The latter are primarily attributable to the differences in the apparent areas of contact. The various ways in which the apparent contact area may influence the wear of dry bearing materials—polymers and carbons—are examined and discussed. Particular attention is given to the role of transfer to, and polishing of the counterface metal during the early stages of sliding. The wear process of polymers and carbons during sliding, against relatively smooth metals is often assumed to be one of fatigue on a localised asperity scale. The implications of this process on the variations of wear rate with load and counterface surface roughness are examined. The use of very small contact areas, to increase the sensitivity of wear measurement, can give rise to misleading variations of wear rate with load, resulting from the trapping of debris within the contact area.
Friction and Wear of Self-Lubricating Metallic Materials
Authors: Rabinowicz E.
Published: November 2010

An experimental and analytical study has been carried out to discover the factors which determine the friction and wear coefficients of composites consisting of a hard metal matrix and a softer filler. To be effective the filler should have a lower metallurgical compatibility than the matrix against the other sliding surface. The concentration of the filler should be at least a few percent so that it can be smeared out over the matrix surface, and there is an upper limit to filler concentration associated with loss of bulk strength of the composite. A simple calculation suggests that large particles of filler material are better than fine particles with 20 micrometer particles being the smallest that are fully effective.
Spherical and Conical Spiral Groove Bearings—Part I: Theory
Authors: Bootsma J.
Published: November 2010

The performance of spherical and conical spiral groove bearings lubricated with a Newtonian, incompressible liquid is investigated. This work covers both complete and incomplete filling of the bearing gap with a liquid. In an incompletely filled bearing gap a gas-to-liquid interface occurs. Under radially eccentric operating conditions the location of the interface is related to the pressure distribution in the lubricating film. Part I treats a theory based on the smooth pressure concept. A perturbation method serves to determine the pressure distribution and, in the case of an incompletely filled bearing gap, also the location of the gas-to-liquid interface. From the pressure distributions, different for the two cases, formulas have been derived for the radial and axial load capacity. Comparison of the results obtained with this perturbation method with the results obtained with a numerical method lead to the conclusion that the former results can be used in practice as long as practically no cavitation occurs in the bearing. Previously reported experiments with spiral groove journal bearings confirm this. In spiral groove bearings the groove dimensions which lead to a satisfactory operation of the bearing are generally such that even with fairly marked eccentricities there is practically no occurrence of cavitation. Part II will treat the results obtained with the theory of Part I.
Prediction of Ball Motion in High-Speed Thrust-Loaded Ball Bearings
Authors: Gentle C. R. , Boness R. J.
Published: November 2010

This paper describes the development of a computer program used to analyze completely the motion of a ball in a high-speed, thrust-loaded ball bearing. Particular emphasis is paid to the role of the lubricant in governing the forces and moments acting on each ball. Expressions for these forces due to the rolling and sliding of the ball are derived in the light of the latest fluid models, and estimates are also made of the cage forces applicable in this specific situation. It is found that only when lubricant viscoelastic behavior is considered do the theoretical predictions agree with existing experimental evidence.
Dynamic Life Estimation for Track Surfaces Under Periodic Loadings and Nonuniform Backup Supports
Authors: Hartnett M. J. , Palazotto A. N.
Published: November 2010

Presented herein is a design model which may be employed to estimate the life of a nonuniformly supported surface acted upon by a translating cylinder when the latter is subjected to periodic loadings. The Lundberg-Palmgren theory of contact fatigue is employed in conjunction with a modified finite element method thereby allowing the prediction of fatigue life for a roller track system. First, a method is advanced using the finite element analysis technique by which pressure resulting from the contact of a roller and a track with nonuniform back-up supports may be determined, next, the basic dynamic capacity rating of the track system, equivalent fatigue load ratings, and reliability fundamentals are reviewed or presented from the Palmgren theory. Finally, the entire procedure is applied to a practical application.
An Estimation of the Effect of Fluid Inertia on the Performance of the Plane Inclined Slider Thrust Bearing With Particular Regard to Turbulent Lubrication
Authors: King K. F. , Taylor C. M.
Published: November 2010

It is common in the analysis of fluid film bearings to neglect the effect of convective fluid inertia. There has been some interest in recent years as to the validity of this assumption in high Reynolds number turbulent flows. Analytical techniques appropriate to the solution of finite width bearing problems considering fluid inertia have been proposed by others. The authors have applied one such method to the plane inclined slider thrust bearing and found that for some situations inertial effects may be important.
Transmissibility Study of a Flexibly Mounted Rolling Element Bearing in a Porous Bearing Squeeze-Film Damper
Authors: Cusano C. , Funk P. E.
Published: November 2010

The purpose of this investigation is to study the transmissibility characteristics of a centrally preloaded porous bearing squeeze-film damper supporting a rolling element bearing. Using the short-bearing approximation and isothermal, incompressible lubrication, transient and steady-state data are presented which show that, for the range of parameters considered, porous bearing dampers exhibit superior transmissibility characteristics over equivalent dampers using solid bearings. The data presented are for squeeze-film porous bearings having a wall thickness-to-length ratio of 0.1 and three degrees of permeability, including the case of zero permeability which corresponds to a solid bearing.
Erosive-Corrosive Wear of Copper
Authors: Rabinowicz E. , Chakravarthy K.
Published: November 2010

Copper specimens whose temperature was varied from room temperature to 500°C were eroded by sand particles. The amount of metal removed increased monotonically over this temperature range except for temperatures between 350 and 425°C. Within this temperature band the erosive action prevented spalling, and thus had a beneficial effect in reducing the overall material removal rate.