bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Pulsed Coaxial Arcs
Authors: Fitzgerald J. E. , Benenson D. M.
Published: November 2010

Experiments were conducted upon a voltage pulsed coaxial argon plasma in a 1 cm dia, 13.6 cm long channel. Initial steady-state current and pressure were 81 A and 776 Torr, respectively. The final average current was about 1200 A. Rise times of current and center-line temperatures were about 200 μs. Using spectroscopic techniques, with data acquisition times of about 5 μs, radial distributions of temperature and pressure were obtained at various times into the transient. A final average temperature of about 18,000° K was obtained.
Temperature Fields in Structural Elements Subject to Fires
Authors: Sahota M. S. , Pagni P. J.
Published: November 2010

The transient, two-dimensional temperature field in a rectangular structural element subject to time dependent, nonlinear mixed boundary conditions has been obtained with a minimum of numerics. General results are given for two extreme fire histories, the American Society for Testing and Materials E-119 time-temperature curve and a short-duration high-intensity time-temperature curve. Comparisons are made with finite element and experimental temperature fields in a reinforced concrete column; good agreement is obtained. The stress field generated from the analytic temperature field also shows good agreement with finite element calculations. Applications to structural fires are discussed.
The Critical Time Step for Finite-Element Solutions to Two-Dimensional Heat-Conduction Transients
Authors: Myers G. E.
Published: November 2010

Computationally-useful methods of estimating the critical time step for linear triangular elements and for linear quadrilateral elements are given. Irregular nodal-point arrangements, position-dependent properties, and a variety of boundary conditions can be accommodated. The effects of boundary conditions and element shape on the critical time step are discussed. Numerical examples are presented to illustrate the effect of various boundary conditions and for comparison to the finite-difference method.
A Mixture Theory for Quasi-One-Dimensional Diffusion in Fiber-Reinforced Composites
Authors: Maewal A. , Gurtman G. A. , Hegemier G. A.
Published: November 2010

A binary mixture theory is developed for heat transfer in unidirectional fibrous composites with periodic, hexagonal microstructure. The case treated concerns a class of problems for which heat conduction occurs primarily in the fiber direction. Model construction is based upon an asymptotic technique wherein the ratio of transverse-to-longitudinal thermal diffusion times is assumed to be small. The resulting theory contains information on the distribution of temperature and heat flux in individual components. Mixture accuracy is estimated by comparing transient solutions of the mixture equations with finite difference solutions of the Diffusion Equation for an initial boundary value problem. Excellent correlation between “exact” and mixture solutions is observed. The construction procedures utilized herein are immediately applicable to other diffusion problems—in particular, moisture diffusion.
Heat Transfer in Laminar Flow Past a Rectangular Cavity With Fluid Injection
Authors: Johnson R. W. , Dhanak A. M.
Published: November 2010

The paper describes an analytical and experimental study of the effects of fluid injection on heat transfer in laminar air flow over a long square cavity. The Reynolds number (based on cavity width) ranged in value from 10 to 1000. The injection (of air) at the cavity wall was varied in velocity from 0 to 5 percent of the main stream. The results indicate the greatest reduction in heat transfer to be occurring at the reattachment point. An expression is suggested for predicting the approximate reduction in heat-transfer rate from the entire cavity surface.
Radiation Heat Transfer Through Molecular Gases at Large Optical Depth
Authors: Nelson D. A.
Published: November 2010

An asymptotically exact expression for radiation heat transfer through planar media is obtained at large optical depth for an exponential band model.
Transient Temperature Rise in Layered Media
Authors: Domingos H. , Voelker D.
Published: November 2010

An analytic expression for the temperature rise produced by a heat-generating layer in contact with a large body is obtained by the Laplace transform method. The solution is used to study the temperature distribution in thin film nichrome resistors under transient conditions.
Thermal Analysis of Some Subterrene Penetrators
Authors: Fisher H. N.
Published: November 2010

Various types of rock melting drills have been designed at Los Alamos. These have included density consolidating penetrators up to 90 mm in diameter of varying configurations. A number of these consolidators have been tested in loams, alluvium, and tuff. Extruders up to 87 mm in diameter designed for an improved advance rate have been used in alluvium and basalt. The results of thermal analyses of some of these existing penetrators under conditions of constant advance rate in tuff, alluvium, and basalt are presented. The basic finite element heat conduction code (AYER) used in the calculations is briefly reviewed along with the methods of including radiation, temperature dependent material properties, and power generation. The internal temperature distribution, power requirements, and possible advance rates are determined for various consolidating and extruding penetrators. The effects of rock properties, penetrator configuration, and thermal limitations on the advance rate are considered. Heater designs and the use of heat pipes in specific designs are discussed. A comparison with experimental test data is made where possible.
Turbulent Fluctuations and Heat Transfer for Separated Flow Associated With a Double Step at Entrance to an Enlarged Flat Duct
Authors: Seki N. , Fukusako S. , Hirata T.
Published: November 2010

An experimental study on heat-transfer in separated, reattached, and redevelopment regions behind a double step at entrance to a flat duct is presented. Measurements of turbulent fluctuation in a free shear layer are made by using a hot-wire anemometer. The experiments are carried out under a condition of uniform heat flux with the test fluid of air. Reynolds number ranges approximately from 4 × 103 to 2.5 × 105 and a step height ratio h/L is varied between 0.035 and 7.0. It is found that the heat-transfer rate in the separated region is closely connected with the behavior of transported heat to be represented by the product of velocity and temperature fluctuations in the free shear layer. An empirical equation is also proposed for the local Nusselt number in the separated and reattached regions.
Analysis of Early-Time Transient Heat Conduction by Method of Characteristics
Authors: Wiggert D. C.
Published: November 2010

The proposed equations describing early-time one-dimensional heat transfer are hyperbolic with temperature and flux being the dependent variables. The method of characteristics is applied resulting in a solution for the variables as functions of distance and time. A dimensionless parameter δ is introduced which is defined either as the inverse thermal propagation speed or relaxation time. The numerical solution yields explicitness, stability, and accuracy combined with ease of handling time-variable boundary conditions. Examples include predicted response to step inputs of flux or temperature at a surface or interface of materials and illustrate the transition from non-Fourier to Fourier-like diffusion.
Radiative Heating in Ice
Authors: Gilpin R. R. , Robertson R. B. , Singh B.
Published: November 2010

The energy fluxes that exist in an ice sheet exposed to a collimated beam of radiant energy were examined. A theoretical model was used which includes the effects of anisotropic scattering as well as the spectral dependence of the absorption coefficient of ice and of the incident radiation beam. Laboratory measurements were also made which generally confirm the predictions of the model. The results calculated from the model are primarily intended for use in analyzing two particular problems involving radiative transfer in ice. These are: (a) the assessment of the feasibility of using radiant energy sources as a means of removing ice from structures, and (b) the prediction of temperatures and internal melting in ice covers on lakes and rivers due to the absorption of solar radiation.
Sequential Estimation of Thermal Parameters
Authors: Beck J. V.
Published: November 2010

This paper presents a method for estimating the parameters appearing in heat transfer models. The method involves minimizing a function that is more general than that utilized in least squares. One of the unique features of the method is that it is sequential. Some of the advantages of this feature are that the basic equations are simple in that no matrix inverses are required, computer programs can be easily written to have an arbitrary number of parameters, and the sequential procedure provides information for development for better mathematical models for describing complex phenomena. Some examples are given.
Diffusion Transport in a Liquid Solution With a Moving, Semipermeable Boundary
Authors: Levin R. L. , Cravalho E. G. , Huggins C. E.
Published: November 2010

A one-dimensional model has been developed for diffusion transport in a binary liquid solution with a moving semipermeable boundary. The governing equations are basically Fick’s First and Second Laws in which the solute concentrations are replaced by the logarithms of the solute volume fractions. In the limit of negligible solute volume fraction, the analysis reduces to the classical one-dimensional diffusion equation. The complete form has been employed to describe the concentration polarization of solutes within human erythrocytes during freezing. The results show that the water transport process across the cell membrane is significantly affected by both the water permeation characteristics of the membrane and the diffusion of water within the intracellular medium. These results are consistent with experimental observations of red cell survival during freezing.
The Effect of Cooling Rate on the Formation of Dendritic Ice in a Pipe With No Main Flow
Authors: Gilpin R. R.
Published: November 2010

Dendritic ice forms in a pipe when there is no main flow through the pipe during the freezing process. This ice form occurs because the quiescent water supercools considerably below 0°C before ice nucleation occurs. It has been shown that growth of dendritic ice can cause blockage of a water pipe [1] much sooner than would have been predicted if the ice grew as a solid annulus. The extent of the dendritic growth is largely determined by the temperature distribution that exists in the pipe at the time of ice nucleation. In this paper the factors effecting the temperature distribution and thus the extent of dendritic ice growth are examined to determine the conditions under which blockage by dendritic ice is likely to occur. The factors that are important are the cooling rate the pipe is exposed to, the ice nucleation temperature, and the type of thermal boundary condition the pipe wall provides.
The Natural Convection of Air Over a Heated Plate With Forward-Facing Step
Authors: Hsieh C. K. , Coldewey R. W.
Published: November 2010

An experimental study of free convection flow of air over a vertically oriented, isothermal, heated plate with a forward-facing step was done. The step height was varied from 0.3175 to 0.9525 cm, and the distance of the step from the leading edge was varied from 7.62 to 15.24 cm. Temperature profiles were measured with a thermocouple probe, and velocity profiles were measured by photographing the trajectories of small dust particles carried along with the flow. For comparison purposes the same measurements were made for a flat plate. The results are nondimensionalized for comparison with the theoretical velocity and temperature profiles for a flat plate. A discussion of how the temperature and velocity profiles deform as the fluid passes over the step and the effect of step size and location on profile shape is included. The experimentally obtained temperature profiles are used to calculate the dimensionless heat-transfer coefficient. This coefficient is characterized in terms of the size and location of the step.
Heat Transfer From a Horizontal Plate Facing Upward to Superposed Liquid-Layers With Change of Phase
Authors: Shimada Y. , Mori Y. H. , Komotori K.
Published: November 2010

This paper presents an experimental examination of a novel technique to improve the convection heat transfer to a liquid whose boiling point is higher than the temperature of heated surface. A layer of an immiscible, denser, and more volatile “secondary liquid” is placed between the heated surface and the layer of the “primary liquid” which is to be heated. The secondary-liquid boils on the heated surface, and its vapor condenses in the upper primary-liquid layer. The rate of such a heat transfer exceeds by far that of natural convection heat transfer to the single primary-liquid layer with an increase of the surface temperature, and becomes approximately equal to that of boiling heat transfer to the single secondary-liquid layer.
Transient Heat Conduction in Cryogenic Current Cables Following a Loss-of-Coolant Accident
Authors: Bejan A.
Published: November 2010

The current supply cables of large superconducting magnet systems are cooled with an axial stream of cold helium vapor. If the flow of coolant is suddenly interrupted the current cables may overheat and burn up causing extensive damage to the entire system. The transient temperature distribution in the cable after the loss-of-coolant accident is derived analytically. The paper presents the maximum cable temperature versus time for a cryogenic current cable which stretches from room temperature (300 K) to a liquid helium-cooled superconducting system (4.2 K).
Heat Transfer in Turbulent Pipe Flow for Liquids Having a Temperature-Dependent Viscosity
Authors: Hanna O. T. , Sandall O. C.
Published: November 2010

Analytical approximations are developed to predict the effect of a temperature-dependent viscosity on convective heat transfer through liquids in fully developed turbulent pipe flow. The analysis expresses the heat transfer coefficient ratio for variable to constant viscosity in terms of the friction factor ratio for variable to constant viscosity, Tw, Tb, and a fluid viscosity-temperature parameter β. The results are independent of any particular eddy diffusivity distribution. The formulas developed here represent an analytical approximation to the model developed by Goldmann. These approximations are in good agreement with numerical solutions of the model nonlinear differential equation. To compare the results of these calculations with experimental data, a knowledge of the effect of variable viscosity on the friction factor is required. When available correlations for the friction factor are used, the results given here are seen to agree well with experimental heat transfer coefficients over a considerable range of μw/μb.
Theoretical Determination of Band Absorption for Nonrigid Rotation with Applications to CO, NO, N2O, and CO2
Authors: Chu K. H. , Greif R.
Published: November 2010

Results are determined for infrared absorption in a fundamental manner directly from the basic spectroscopic variables. Comparison with experimental data shows good agreement for small and moderate optical depths, but substantial differences result for very large optical depths. The basis for the discrepancy is discussed and further work is recommended.
Infrared Mean Absorption Coefficients of Luminous Flames and Smoke
Authors: Hubbard G. L. , Tien C. L.
Published: November 2010

A simple procedure has been developed for the calculation of the Planck mean emission and absorption coefficients and the Rosseland mean absorption coefficient for infrared radiation of the soot-gas mixtures commonly occurring in luminous flames and smoke. Specific results are presented for mixtures involving carbon dioxide, water vapor and carbon soot, the dominant species in most combustion systems. The close agreement between the various averages clearly demonstrates the usefulness of the mean absorption coefficient concept for applications.
An Investigation of the Minimum Film Boiling Temperature on Horizontal Surfaces
Authors: Yao Shi-chune , Henry R. E.
Published: November 2010

The frequency and magnitude of liquid-solid contacts in the film boiling of saturated ethanol and water on horizontal flat stainless steel and copper surfaces are examined with electrical conductance probes. It is observed that, at atmospheric pressure, contacts occur over a wide temperature range and are generally induced by hydrodynamic instabilities. In the ethanol system, these contacts can account for the entire heat transfer rate at the minimum film boiling temperature. The area and duration of contacts are strongly influenced by the dominant nucleation process, and thus, depend on the interface temperature and wettability of the solid. At elevated pressures, direct liquid-solid contacts in film boiling are essentially nonexistent for stainless steel and the first major contact corresponds to quenching of the surface. Under these conditions, spontaneous nucleation upon contact seems to be the controlling mechanism for the minimum film boiling temperature. The minimum point appears to be determined either by a Taylor instability vapor removal limitation or by spontaneous nucleation. The governing mechanism is the one which is stable at the lowest wall temperature.
The Effect of Internal Solidification on Turbulent Flow Heat Transfer and Pressure Drop in a Horizontal Tube
Authors: Thomason S. B. , Mulligan J. C. , Everhart J.
Published: November 2010

A simple analysis of the steady-state heat transfer and pressure drop in turbulent flow in a tube is presented for the case involving a “thin”, steady-state frozen deposit on the inside tube wall. Sparrow-Hallman-Siegel type internal flow convective heat transfer expressions and Blasius type pressure drop expressions are employed while neglecting second order interface curvature effects. Experimental heat transfer and pressure drop data are presented for comparison. It is shown that simple analyses of the type developed can be used to predict heat transfer and pressure drop in tube flow under freezing conditions and that, for the experimental conditions tested, basic agreement between theory and experiment was obtained. It is also shown experimentally that small nonuniformities in wall temperature can produce wide variations in pressure drop when a frozen layer exists within a tube.
Turbulent Flow of Water in a Tube with Circumferentially Nonuniform Heating, with or without Buoyancy
Authors: Schmidt R. R. , Sparrow E. M.
Published: November 2010

Experiments have been performed to study the effect of circumferentially nonuniform heating on the fully developed turbulent heat transfer characteristics for water flow in a horizontal circular tube. The use of a specially fabricated tube enabled heat to be supplied to the fluid over half its circumference, while the other half was unheated. Separate sets of experiments were conducted with the heated portion at the top and at the bottom. By varying the temperature level, the Prandtl number was varied from 3.5 to 11.5. The Reynolds number ranged from 3,000 to 70,000. The measurements enabled circumferential distributions of the Nusselt number, wall temperature, and heat flux to be determined, and circumferential average Nusselt numbers were also evaluated. Both the circumferential average and circumferential local results demonstrate that significant buoyancy effects are present for bottom heating at low Reynolds numbers and high Rayleigh numbers, and a criterion is deduced for the onset of these effects. The top heating experiments were not affected by buoyancy. The buoyancy-unaffected circumferential average Nusselt numbers increase smoothly over the entire range of Reynolds numbers, and the Prandtl number dependence is correlated as Pr0.47. These Nusselt numbers are within about ten percent of literature correlations (applicable for Re ≥ 10,000) for circumferentially uniform thermal conditions. The circumferential distributions of the Nusselt number and temperature on the heated wall tend toward uniformity when the turbulence is well developed (i.e., higher Reynolds numbers) or when buoyancy is present. The temperatures on the unheated wall are generally lower than the bulk temperature in the absence of buoyancy, but, when buoyancy is active, they are above the bulk temperature.
Determination of Unknown Coefficients in Parabolic Operators from Overspecified Initial-Boundary Data
Authors: Cannon J. R. , DuChateau P. C.
Published: November 2010

Application of some asymptotic boundary behavior results for solutions of nonlinear parabolic initial boundary value problems is made to the determination of unknown coefficients and parameters in parabolic operators from overspecified boundary data. Some numerical results on the determination of parameters is presented and discussed.
On the Scaling Laws for Air Clearing in Water-Type Pressure Suppression Systems
Authors: Sonin A. A. , Huber P. W.
Published: November 2010

A set of scaling laws is derived for the small-scale simulation of the air clearing phase of a loss-of-coolant accident in a nuclear powerplant with a water-type pressure suppression system. The laws are a refinement of those suggested by F. J. Moody. This paper discusses the assumptions underlying their derivation and deals with the problem of scaling the vent flow.
Pool Boiling Heat Transfer to Emulsions
Authors: Mori Y. H. , Inui E. , Komotori K.
Published: November 2010

The characteristics of steady pool boiling heat transfer from a horizontal wire to various emulsions were obtained experimentally. Sample emulsions were prepared by an ultrasonic method with water, oils whose boiling points are higher than that of water, and emulsifying agents. The kind of emulsifying agent affected remarkably the characteristics of heat transfer to oil-in-water emulsions. The kind of oil affected little the heat transfer to oil-in-water emulsions but strongly that to water-in-oil emulsions.
Experimental Study on the Effect of Orientation of Heating Circular Plate on Film Boiling Heat Transfer for Fluorocarbon Refrigerant R-11
Authors: Seki N. , Fukusako S. , Torikoshi K.
Published: November 2010

The characteristics of film boiling heat transfer from a heated horizontal circular brass plate to a pool of fluorocarbon R-11 are examined for the case in which only the top side of the plate is in contact with the liquid (facing upward) and for the case in which the bottom side of the plate is in contact with the liquid (facing downward). It is found that the film coefficient for the facing downwards orientation of the plate was found to be closely correlated by the following: Nu=0.35(L/CpΔT)Gr0.25·Pr0.25
Heat Transfer in Composite Solids with Heat Generation
Authors: Feijoo L. , Davis H. T. , Ramkrishna D.
Published: November 2010

Steady-state heat transfer problems have been considered in a composite solid comprising two materials, one, a slab, which forms the bulk of the interior and the other, a plate, which forms a thin layer around the boundary. Through the use of appropriate Green’s functions, it is shown that the boundary value problem can be converted into a Fredholm integral equation of the second kind. The integral operator in the integral equation is shown to be self-adjoint under an appropriate inner product. Solutions have been obtained for the integral equation by expansion in terms of eigenfunctions of the self-adjoint integral operator, from which the solution to the boundary value problem is constructed. Two problems have been considered, for the first of which the eigenvalues and eigenvectors of the self-adjoint operator were analytically obtained; for the second, the spectral decomposition was obtained numerically by expansion in a convenient basis set. Detailed numerical computations have been made for the second problem using various types of heat source functions. The calculations are relatively easy and inexpensive for the examples considered. These examples, we believe, are sufficiently diverse to constitute a rather stringent test of the numerical merits of the eigenvalue technique used.
An Evaporating Ethanol Meniscus—Part I: Experimental Studies
Authors: Renk F. J. , Wayner P. C.
Published: November 2010

The profile of an evaporating ethanol meniscus was measured as a function of the evaporative heat flux using interferometry. A measure of the evaporative heat flux was obtained using vapor deposited resistance thermometers. The meniscus profile was found to be stable and a function of the heat flux for the heat flux range of 0 – 1.36w/m of interline. These results were used in an analysis of capillary flow heat transfer in Part II.
Nucleation Processes in Large Scale Vapor Explosions
Authors: Henry R. E. , Fauske H. K.
Published: November 2010

A spontaneous nucleation model is proposed for the mechanisms which lead to explosive boiling in the free contacting mode. The model considers that spontaneous nucleation cannot occur until the thermal boundary layer is sufficiently thick to support a critical size vapor cavity, and that significant bubble growth requires an established pressure gradient in the cold liquid. This results in a prediction that, for an interface temperature above the spontaneous nucleation limit, large cold liquid droplets will remain in film boiling due to coalescence of vapor nuclei, whereas smaller droplets will be captured by the hot liquid surface and rapidly vaporize, which agrees with the experimental observations. The model also predicts that explosions are eliminated by an elevated system pressure or a supercritical contact interface temperature, and this is also in agreement with experimental data.
Heat Transfer from Aluminum to He II—Application to Superconductive Magnetic Energy Storage
Authors: Van Sciver S. W. , Boom R. W.
Published: November 2010

Heat transfer problems associated with large scale Superconductive Magnetic Energy Storage (SMES) are unique due to the proposed size of a unit. The Wisconsin design consists of a cryogenically stable magnet cooled with He II at 1.8 K. The special properties of He II (T <2.17 K) provide an excellent heat transfer medium for magnet stability. Design values are determined from an experimental study of heat transfer from aluminum to He II. Under near saturated conditions we observe a maximum surface heat flux of 1.7 W/cm2 at 1.91 K and a recovery at 0.7 W/cm2. The advantages of operating the magnet under subcooled conditions are exemplified by improved heat transfer. The maximum at 1.89 K and 1.3 atm pressure is 2.3 W/cm2 with recovery enhanced to 1.9 W/cm2. A conservative maximum heat flux of 0.5 W/cm2 with an associated temperature difference of 0.5 K has been chosen for design. Elements of the experimental study as well as the design will be discussed.
Characteristics of Fluidization of a Solid Particle Bed
Authors: Seki N. , Fukusako S. , Torikoshi K.
Published: November 2010

A criterion to predict the characteristic of fluidization of particles bed was discussed by adopting a modified Froude number, Frλc. The criterion derived from the hydrodynamic instability was compared with experimental data. In addition, the drag coefficient for particulate fluidized bed were found to be different from those measured for aggregative fluidized bed in a fully development fluidization.
Latent Heat-of-Fusion Energy Storage: Experiments on Heat Transfer from Cylinders During Melting
Authors: Bathelt A. G. , Viskanta R. , Leidenfrost W.
Published: November 2010

Melting from an array of three staggered, electrically heated cylinders imbedded in a paraffin (n-octadecane) has been studied. The shape of the melting front has been determined photographically, and the local heat transfer coefficients were measured using a shadowgraph technique. The experiments provide conclusive evidence of the important role played by natural convection on the timewise variation of the melt shape, the surface temperature and the instantaneous local as well as circumferentially averaged heat transfer coefficients around the imbedded heat sources. After a common solid-liquid interface is formed around the cylinders, natural convection circulation around each cylinder interacts strongly with the other two cylinders. The arrangement of heat sources affects significantly the melt shape but the circumferentially averaged instantaneous heat transfer coefficients differ only by about 10 percent for the two arrangements studied. The experimental findings indicate that natural convection effects are important and should be considered in analysis and design of systems involving phase change.
Depth of Permanent Indentations in Flat Plates Due to Loaded Cylindrical Rollers
Authors: Wickstrand N. M.
Published: November 2010

This paper reports the measurement of 296 combinations of load, roller diameter, and plate hardness. The diameters of the steel rollers ranged from 1/16 to 4 in. inclusive. The hardness of the steel plates ranged from 42 Rc to 61 Rc. Two series of tests are also included for titanium plates having a hardness of 40 Rc and 43 Rc, respectively. Equations are derived from this experimental data which can be used to estimate the depths of permanent indentation for a large range of roller diameters, plate hardness, and loads.
An Augmented, Small-Parameter Equation for the Squeeze-Film Journal Bearing
Authors: Strodtman C. L.
Published: November 2010

The asymptotic gas film equation for the squeeze-film journal bearing is solved for the quadratic and cubic terms in the series expansion in terms of the radial displacement. The load support calculated from this augmented, small parameter equation is compared to calculations from an all numerical procedure. Good agreement is shown to exist for large values of the radial displacement. A method of treating nonuniform excursion of the driving member by a root-mean-square amplitude and a shape factor is also given.
On Fluid Inertia Effects in Infinitely Wide Foil Bearings
Authors: Eshel A.
Published: November 2010

Equations for a foil over a lubricating film in which the effects of fluid inertia are taken into account are derived. Approximate solutions showing the effect of inertia and fluid compressibility are obtained. The effect of inertia is to increase considerably the fluid-film thickness.
A Shear-Stress Normal-Strain Cycle Relation to Fatigue in Bending, Torsion, and Rolling Contact
Authors: Lyman John
Published: November 2010

Previous work [4] has suggested a shear stress normal strain “potential” as a means of relating stress condition to fatigue of high-strength low-allow steels. Experimental data here permits the rationalization of the theory required in the prior analysis to be supported directly. An attempt is made to relate highly directed plastic deformations that have been observed in SKF 6309 ball bearing inner rings to directed shear-stress normal-strain configurations of the complex triaxial rolling contact stress cycle in the principal plane of rolling.
Thermal Distortion of Spiral-Grooved Gas-Lubricated Thrust Bearings
Authors: Wachmann C. , Malanoski S. B. , Vohr J. H.
Published: November 2010

Self-heating during operation causes a bearing to undergo thermal distortion. A method is presented to determine the consequent effects on the load capacity of a spiral-grooved air-lubricated thrust bearing designed for maximum load capacity. The effect of mode of heat removal is discussed. Appropriate performance curves and a worked example are given.
Effect of a High Traction Fluid on Skidding in a High Speed Roller Bearing
Authors: Kacmarsky W. M. , Hewko L. O.
Published: November 2010

Laboratory tests run under skid-prone conditions have shown that cage skid in a lightly loaded roller bearing, operating at speeds up to 3 million DN, can be reduced by using a high traction fluid as the bearing lubricant. With a Mil-L-23699 oil, maximum cage slip approached 65 percent. When the military specification oil was replaced by a fluid blended to develop a high coefficient of traction, the maximum cage slip, in the same bearing, was reduced to approximately 3 percent. The high traction oil did not comply with the Mil Specification; however, the dramatic reduction in skidding demonstrated the desirability of increasing the traction coefficients for fluids used to lubricate aircraft jet engine mainshaft bearings.
Visual Observations and Torque Measurements in the Taylor Vortex Regime Between Eccentric Rotating Cylinders
Authors: Castle P. , Mobbs F. R. , Markho P. H.
Published: November 2010

The instability of Taylor vortices in the flow between a stationary outer cylinder and an eccentric rotating inner cylinder has been investigated by visual observations and by torque measurements. It is shown that both a “weak” and “strong” wavy mode of instability can be detected by torque measurements, giving critical Taylor numbers in good agreement with visual observations.
Theoretical Investigation of Externally Pressurized Air-Suspension Conveyer With Multiple Supply Holes
Authors: Mori H. , Yabe H.
Published: November 2010

The externally pressurized air suspension conveyer is investigated theoretically. The supporting area of the conveyer is comparatively large, and has multiple air supply holes, whose positions may vary due to the relative motion of the article and the supporting surface. The analysis is made under the assumption of semi infinite area of supported surface with the discrete supply holes of the conveyer, and thereafter, with equivalent air feeding distributed over the conveyer surface. The case of the circular pad is analyzed as well in order to take into account the effect of the finite supported surface area. The distributed air feeding solution agrees well with the discrete supply hole solution as well as with experimental results.
Considerations on the Stiffness of Externally Pressurized Journal Bearings
Authors: Michelini R. C. , Ghigliazza R. S.
Published: November 2010

A direct method of computation that fully allows for hydrodynamic effects has been devised for the correct design of externally pressurized journal bearings fed with in compressible lubricant. With this method, the performance of bearings with independent and with crossrelated recesses were analyzed thoroughly, and the influence of hydrodynamic effects and the feeding system on bearing stiffness was determined.
High Cycle Rolling Contact Load Effects on the Microstructure of 50 Rockwell C AISI 52100 Steel
Authors: Lyman J. , Hall A. E.
Published: November 2010

An experimental program to determine the effect of cyclic radial rolling contact load on the microstructure of AISI 52100 steel quenched and tempered to 50 Rockwell C hardness is reported. The magnitude of the load was restricted to result in stress conditions that did not exceed the strain energy of distortion theory limit of elastic behavior. Cycling up to 109 cycles produced familiar “white etching” microstructural alterations around stress concentrators such as inclusions, but no microstructural effect related to the mathematical stress field was detected. Research to improve the elastic limit in high hardness-wear resistant steel appears to be needed.
The Series Hybrid Bearing—A New High Speed Bearing Concept
Authors: Anderson W. J. , Fleming D. P. , Parker R. J.
Published: November 2010

The series-hybrid bearing couples a fluid-film bearing with a rolling-element bearing such that the rolling-element bearing inner race runs at a fraction of shaft speed. A series-hybrid bearing was analyzed and experiments were run at thrust loads from 100 to 300 lb and speeds from 4000 to 30,000 rpm. Agreement between theoretical and experimental speed sharing was good. The lowest speed ratio (ratio of ball bearing inner-race speed to shaft speed) obtained was 0.67. This corresponds to an approximate reduction in DN value of 1/3. For a ball bearing in a 3 million DN application, fatigue life would theoretically be improved by a factor as great as 8.
The Crowned Circular Slider Bearing: Analysis and Test
Authors: Hays D. F. , Maki E. R.
Published: November 2010

A centrally pivoted crowned circular slider bearing has been analyzed and tested under conditions of incompressible lubrication. In the analysis a variational formulation was used in conjunction with finite difference techniques to obtain the operational characteristics of this slider bearing. Design curves were obtained for bearing load, friction, lubricant flow, and coefficient of friction, as a function of the crown height and the film ratio. A number of these bearings were tested under conditions of differing loads, speeds, and crown heights.
Elastohydrodynamic Lubrication in Rolling and Sliding Contacts
Authors: Rodkiewicz C. M. , Srinivasan V.
Published: November 2010

A solution to the elastohydrodynamic lubrication problem for the case of two rolling cylinders, at different speeds, is presented. The lubricant is assumed compressible throughout the region. The fourth-order Runge-Kutta method for the lubricant and an improved quadrature formula for the elastic calculations are used. Pressure and film-thickness profiles are presented for different rolling velocities. There is a good agreement with the experimental film thickness data, available in literature.
The Friction of Lead Films in Spherical Contact
Authors: Finkin E. F.
Published: November 2010

Recent advances in applied mechanics are utilized to show that Rabinowicz’s experimental results for the friction of lead films as a function of film thickness can be related to the dependence of real area of contact on film thickness.
Influence of Turbulence on Performance Characteristics of the Tilting Pad Thrust Bearing
Authors: Capitao J. W.
Published: November 2010

The influence of fluid film turbulence on the performance of centrally-pivoted tilting pad thrust bearings was analyzed. Major features of the analysis are: (1) today’s two predominant “engineering” turbulent flow theories are delineated and their quantitative predictions compared; (2) a spherical pad profile was assumed, and (3) an equal area technique was used in the finite difference equations. The results confirmed earlier predictions of increases in power loss and load capacity when compared to a laminar solution. Also, no significant differences were found between the results predicted by the two predominant turbulent flow theories. Power loss, load capacity, and hydrodynamic oil flow are given for 13, 15, and 17 in. sizes. Comparisons of laminar and turbulent numerical results are presented.
Lubricant Fluid Films With Directional Variable Viscosity
Authors: Tipei N. , Rohde S. M.
Published: November 2010

A new rheological model for lubricants containing additives having long molecules is presented. The viscosity of the fluid is assumed to depend on the angle between the viscous forces and the velocity vector at each point in the lubricating film. The characteristics and consequences of this model are discussed qualitatively and quantitatively. Results far a finite slider bearing lubricated with such a lubricant are presented.
The Gas-to-Liquid Interface of Spiral Groove Journal Bearings and its Effect on Stability
Authors: Bootsma J.
Published: November 2010

A spiral groove journal bearing has two significant advantages, compared with a plain journal bearing. These are the self-sealing capabilities and the favorable stability properties of the bearing under no-load or light-load conditions. Under eccentric operating conditions the axial width of the liquid film in such a bearing varies in the circumferential direction. The shape of the gas-to-liquid interface and its effect on load capacity and stability are investigated both theoretically and experimentally. It appears that there is a considerable difference in the shape of the gas-to-liquid interface, depending on whether it is the housing or the shaft that has spiral grooves, or more generally, on whether the load vector is rotating with respect to the grooves or not. It has further been found that the free boundary has an unfavorable effect on the stability of unloaded spiral groove journal bearing. A deep groove in the circumferential direction, close to the gas-to-liquid interface, can practically cancel this unfavorable effect.
Convective Inertia Effects in the Viscoseal
Authors: Meric R. A. , Macken N. A.
Published: November 2010

The performance characteristics of viscoseals are analyzed including the effects of convective inertia and the groove side wall. For the geometries studied, the present theory correlates the experimental data for the sealing and friction coefficient better than previous theories. The sealing coefficient is found to be dependent on the Reynolds number and groove width-to-depth aspect ratio. Leakage and critical Reynolds numbers are also discussed.
A Life Study of AISI M-50 and Super Nitralloy Spur Gears With and Without Tip Relief
Authors: Townsend D. P. , Zaretsky E. V.
Published: November 2010

Tests were conducted at 350 K (170 deg F) with groups of 8.9 cm (3.5-in.)-pitch-diameter spur gear with and without tip relief made of consumable-electrode vacuum melted (CVM) Super Nitralloy (5Ni-2Al) and CVM AISI M-50 steel. The AISI M-50 gears without tip relief had lives approximately 50 percent longer than the Super Nitralloy gears without tip relief. However, the Super Nitralloy gears with tip relief had lives equal to the AISI M-50 gears without tip relief. The difference in lives were not statistically significant. All gears failed by classical pitting fatigue at the pitch circle. However, the AISI M-50 gears with tip relief failed by tooth fracture. AISI M-50 gear sets without tip relief having a spalled gear tooth which were deliberately overrun after spalling had occurred, failed by tooth fracture.
Stability and Relative Stability of Porous Journal Bearing System With Axes Skewed
Authors: Singh D. V. , Sinhasan R.
Published: November 2010

This paper presents an analysis of the stability and relative stability of porous journal bearing system with journal and bearing axes skewed. For linearized system the paper includes the stability studies by Routh’s criteria and relative stability from the characteristic equations. For nonlinear systems, Liapunov functions have been constructed.
An Elastohydrodynamic Analysis of Transient Pumping Ring Operation
Authors: Zull L. M. , Kettleborough C. F.
Published: November 2010

The coupled elastic and hydrodynamic equations describing the transient behavior of a low capacity lubricant pumping and sealing device known as an oil pumping ring assembly have been solved numerically for both isothermal and adiabatic conditions in the lubricant film. Results show the transient behavior of the pressure, viscosity and temperature fields in the lubricant film, stresses developed in the pumping ring, and the amount of fluid pumped. A performance analysis over a limited range of component dimensions is also presented.
Durability of Graphite Films in Plastic Deformation
Authors: Schey J. A. , Lonn A. H.
Published: November 2010

The ability of solid lubricant (graphite) films to withstand repeated contact with a deforming cold or hot aluminum workpiece was investigated by three techniques. Ring compression very readily indicated the gradual wear of the film, but sliding at the interface was limited and tendencies to tool pick-up did not show up. Plane strain compression was much more useful in this respect; changes in the edge-profile of the compressed zone proved to be a sensitive indicator of friction, obviating the need for force measurements. Twist compression imposed the most severe conditions. In all instances, a sandblasted tool surface provided better lubricant retention than a polished one.
Friction and Wear Behavior of Cobalt
Authors: Ward R.
Published: November 2010

An investigation has been made of the friction and wear behavior of polycrystalline cobalt, over a wide range of rubbing conditions, to establish the general pattern of wear. Evidence has been obtained for the occurrence of three transitions, namely, mild to severe wear at low loads and speeds, severe wear back to mild at higher loads and speeds and a change to a particularly severe form of wear that has been related to the transformation of cobalt from α to β form in the vicinity of contacting asperities.
A Phase-Plane Simulation for Investigating the Effect of Unbalance Magnitude on the Whirl of Rotors Supported on Hydrodynamic Bearings
Authors: Seireg A. , Dandage S.
Published: November 2010

This paper describes a digital simulation of the dynamics of an unbalanced rigid rotor supported on hydrodynamic bearings. Whirl orbits can be developed from the start of rotation until the operating constant speed is attained. Response spectra are obtained to illustrate the trend of the influence of the magnitude of unbalance speed, average film viscosity, load, clearance and rotor start-up acceleration on the whirl amplitudes. The simulation procedure which is based on the phase-plane-δ method provides a general and effective tool of analysis for this class of problems. Although a rigid rotor on a simplified isoviscous film is considered for illustration, the procedure can be readily extended for the simulation of multirotor flexible shafts with more accurate film characteristics without making simplifying assumptions regarding the shape of the orbit or the film behavior.
Lubrication by a Melting Solid
Authors: Wilson W. R. D.
Published: November 2010

Theoretical models for a slider bearing which is lubricated by one of its surfaces melting are developed. Melting is assumed to be caused by frictional heating. Two cases are considered. In the first the slider melts. In the second the track on which the slider rubs melts. The analyses allow prediction of the film thicknesses and friction under conditions in which this mode of lubrication occurs. The results support the idea that the low friction found in contacts with ice near its melting point is due to lubrication by melting.
Dynamic Capacity and Surface Fatigue Life for Spur and Helical Gears
Authors: Coy J. J. , Townsend D. P. , Zaretsky E. V.
Published: November 2010

A mathematical model for surface fatigue life of gear, pinion, or entire meshing gear train is given. The theory is based on the statistical approach used by Lundberg and Palmgren for rolling-element bearings. Also equations are presented which give the dynamic capacity of the gear set. The dynamic capacity is the transmitted tangential load which gives a 90 percent probability of survival of the gear set for one million pinion revolutions. The analytical results were compared with test data for a set of AISI 9310 spur gears operating at a maximum Hertz stress of 1.71 × 109 N/m2 (248,000 psi) and 10,000 rpm. The theoretical life predictions were very good when material constants obtained from rolling-element bearing tests were used in the gear life model.
Flexible Wall Planar Flow Model for Tape Behavior in Vacuum Columns
Authors: Eshel A.
Published: November 2010

The flow through a narrow channel with a flexible wall is analyzed. In this problem the inlet width of the channel is prescribed by a guide but the distribution of channel width is not a priori known. The paper presents the results of the two flow models and compares them to experimental values.
Prediction of Traction in Sliding EHD Contacts
Authors: Kunz R. , Winer W. O.
Published: November 2010

An existing shear stress theory and lubricant rheological model were studied and evaluated by applying them to traction prediction in a sliding elastohydrodynamic point contact. Numerical calculations, using measured film thickness and surface temperature data, were compared with measured tractions under several conditions of normal load and sliding speed. In addition, the theory was used to study the effect on the traction of variations in the lubricant material properties.