bluuebunny/crossref_metadata_2025 huggingface dataset:
Boundary-Layer Cooling by Spattered Particles
Authors: Steverding B.
Published: February 2012

The phenomenon of spattering of ablating liquid films is studied under the condition that gas bubbles penetrate the liquid film. The characteristic material parameter for spattering is the surface tension. Contrary to general belief, it will be shown that spattering will not always decrease ablation effectiveness and that, under certain “ideal” conditions, effective boundary-layer cooling by spattered particles may be achieved. Ideal spattering can only occur when the surface tension has a distinct value for a given flow condition. The phenomenon of preferential ablation may be explained by this phenomenon.
Film Boiling of Saturated Nitrogen Flowing in a Vertical Tube
Authors: Laverty W. F. , Rohsenow W. M.
Published: February 2012

A study is made of film boiling of a saturated nitrogen flowing upward through a uniformly heated tube. Visual experimental observations demonstrate that the annular flow regime which exists at very low qualities is broken up at higher qualities to form a dispersed flow of liquid droplets in a vapor matrix. Analysis of experimentally determined tube wall temperature distributions shows that a significant amount of vapor superheat is present throughout the film-boiling process. A method is presented by which both an upper bound and an estimated value of the heat-transfer coefficient for the dispersed flow regime may be calculated.
Heat Transfer in Separated, Reattached, and Redevelopment Regions Behind a Double Step at Entrance to a Flat Duct
Authors: Filetti E. G. , Kays W. M.
Published: February 2012

Experimental data are presented for local heat transfer rates near the entrance to a flat duct in which there is an abrupt symmetrical enlargement in flow cross section. Two enlargement area ratios are considered, and Reynolds numbers, based on duct hydraulic diameter, varied from 70,000 to 205,000. It is found that such a flow is characterized by a long stall on one side and a short stall on the other. Maximum heat transfer occurs in both cases at the point of reattachment, followed by a decay toward the values for fully developed duct flow. Empirical equations are given for the Nusselt number at the reattachment point, correlated as functions of duct Reynolds number and enlargement ratio.
Experiments on Turbulent Heat Transfer in a Tube With Circumferentially Varying Thermal Boundary Conditions
Authors: Black A. W. , Sparrow E. M.
Published: February 2012

An experimental investigation, supported by analysis, was performed to determine the heat transfer characteristics for turbulent flow in a circular tube with circumferentially varying wall temperature and wall heat flux. Air was the working fluid. The desired boundary conditions were achieved by electric heating within the wall of a tube whose thickness varied circumferentially. In this way, ratios of maximum-to-minimum wall heat flux as large as two were attained. Local heat transfer coefficients, deduced from the experimental data, display a circumferential variation that is substantially smaller than the heat flux variation. In general, lower heat transfer coefficients correspond to circumferential locations of greater heating, while higher coefficients correspond to locations of lesser heating. The predictions of prior analyses appear to overestimate the circumferential variation of the heat transfer coefficient. A specially designed probe was employed to measure the radial and circumferential temperature distributions within the flowing airstream. On the basis of these measurements, as well as from the heat transfer results, it is concluded that, in the neighborhood of the wall, the tangential turbulent diffusivity is greater than the radial turbulent diffusivity. The axial thermal development was found to be more rapid on the lesser-heated side of the tube than on the greater-heated side. Experimentally determined circumferential-average heat transfer coefficients agreed well with the predictions of analysis.
Compressible Boundary Layer-Inviscid Flow Interactions in Entrance Region of Internal Flows
Authors: Blankenship V. D. , Chung P. M.
Published: February 2012

The coupling between the inviscid flow and the compressible boundary layer in the developing entrance region for internal flows is analyzed by solving the particular inviscid flow-boundary layer interaction problem. The interaction problem is solved by postulating certain series forms of solutions for the inviscid region and the boundary layer. The boundary-layer equations and inviscid-flow equations are perturbed to third order and each generated equation is solved numerically. In order to preserve the universality of each of the perturbed boundary-layer equations, the perturbation parameter is described by an integral equation which is also solved in series form. The final results describing the interaction problem are then constructed for any given conditions by forming the three series to a consistent order of magnitude. This technique of coordinate perturbation is generalized to show how it may be applied to the entrance regions of pipe flows, including mass injection or suction, and also to the laminar boundary layers in shock tube flows. It demonstrates analytically the manner in which the boundary layer and inviscid flow interact and create a streamwise pressure gradient. In particular, the interaction problem which occurs in shock tube flows is solved in detail by the use of this generalized method, as an example.
Effect of Side Walls on Natural Convection Between Horizontal Plates Heated From Below
Authors: Catton I. , Edwards D. K.
Published: February 2012

Experimental results are presented giving the Rayleigh number at which convection initiates in a closed cell and the Nusselt number versus Rayleigh number relationship which prevails after convection is initiated. Over 700 data points were obtained for two types of cells heated from below, one a phenolic-fiberglass hexcell of low thermal conductivity and the other aluminum hexcell of high thermal conductivity. Relations based upon the Malkus-Veronis power integral technique and a concept of an equivalent wave number are shown to give good correlation of the experimental data for both the low and high conductivity side walls.
Appropriate Mean Absorption Coefficients for Infrared Radiation of Gases
Authors: Abu-Romia M. M. , Tien C. L.
Published: February 2012

In this paper, a study is made on the calculation of appropriate mean absorption coefficients for the infrared radiation of gases. The Planck and Rosseland mean absorption coefficients for the optically thin and optically thick gases are expressed as functions of the spectroscopic and thermodynamic properties of the gas. Values of the Planck and Rosseland mean absorption coefficients are presented for carbon monoxide, carbon dioxide, and water vapor in the temperature range from 1000 to 5000 deg Rankine. To illustrate the application of these results, the radiative heat flux is calculated for the simple case of a planar medium.
Effect of Small Spacings on Radiative Transfer Between Two Dielectrics
Authors: Cravalho E. G. , Tien C. L. , Caren R. P.
Published: February 2012

Two phenomena which influence the energy transfer by thermal radiation between two solid dielectrics separated by a vacuum gap are described. For typical dielectric systems, it is shown that these coupled phenomena, which are termed wave interference and radiation tunneling, influence the radiative transfer to the extent that the classical Stefan-Boltzmann radiation law is inadequate to describe the net energy transfer. Since both phenomena are significant only when the distance of separation between the surfaces of the solids is of the same order of magnitude as the wavelength of the radiation, their effect is greatest when the spacing is small. However, the actual magnitude of the difference between the present treatment and the classical approach is a complicated function of the surface spacing, the refractive indexes of the solids, and the temperatures of the solids, and can be as large as an order of magnitude.
Effect of Thermocouple Cavity on Heat Sink Temperature
Authors: Beck James V. , Hurwicz H.
Published: February 2012

An analysis is made of problems associated with prediction of and correction for temperature disturbance created by thermocouples placed beneath a surface of a heat sink (or calorimeter) exposed to heat flux during re-entry. Two of the important factors affecting temperature measurement are discussed: (a) The disturbance created by the thermocouple itself, “hot spot.” (b) The fact that the thermocouple has to be placed at some distance from the heat flux surface and thus not measuring the surface temperature. The magnitude of the surface hot spot caused by the presence of the thermocouple is determined, and optimum location of the thermocouple is found where the undisturbed surface temperature may be read with least over-all error.
Freezing of a Growing Liquid Column
Authors: Horvay G.
Published: February 2012

The one-dimensional problem is treated in which a liquid metal column, of the original temperature ϑ0, is supplied with additional metal at the top, of temperature ϑb, at the rate v ft/min. At the bottom of the column a heat sink of temperature ϑa is maintained. The case in which ϑa exceeds the fusion temperature is solved for v = const, both rigorously and approximately; the case in which ϑa is below the fusion temperature so that a freezing front sweeps upward in the column is next treated by an approximate method. The foregoing analysis may represent, for instance, the filling stage of a casting process. The present analysis will be adapted to the more important continuous casting process in a succeeding paper.
Heat Transfer to Fully Developed Laminar Flow in a Circular Tube With Arbitrary Circumferential Heat Flux
Authors: Reynolds W. C.
Published: February 2012

A solution is presented for fully developed laminar heat transfer in a circular tube with arbitrary circumferential heat flux. Examples included indicate that the influence of circumferential heat-flux variation on wall temperatures can be quite significant and provide some insight into the nature of the effects. The analysis allows calculation of wall temperatures for any arbitrary peripheral heat-flux variation for fully developed laminar flow under the restriction of constant axial heat input.
Magnetohydrodynamic Effects Upon Heat Transfer for Laminar Flow Across a Flat Plate
Authors: Cess R. D.
Published: February 2012

Forced-convection heat transfer for laminar flow of electrically conducting fluids across a flat plate is considered for a magnetic field of constant inductance acting normal to the free stream velocity and fixed relative to the plate. The boundary condition on the surface of the plate is taken to be either a constant temperature or constant heat flux, and solutions are presented for the following cases: (a) Fluids having a Prandtl number of unity for which both Joule heating and frictional heating are accounted for; (b) fluids having moderate and large Prandtl numbers for negligible Joule and frictional heating; and (c) fluids having low Prandtl numbers for negligible frictional heating.
Experiments on Heat Transfer From Spheres Including Combined Natural and Forced Convection
Authors: Yuge T.
Published: February 2012

Experiments on heat transfer between spheres and air flow were carried out in the range of Reynolds numbers from 3.5 to 1.44 × 105 and Grashof numbers from 1 to 105. Empirical formulas for forced, natural, and combined convection are presented and comparison made with other investigations. A graphical procedure, based on experimental results, is used to predict the heat-transfer performance for combined natural and forced convection.
Transient Temperatures and Thermal Stresses in Hollow Cylinders Due to Heat Generation
Authors: Schmidt John E. , Sonnemann George
Published: February 2012

A general solution for the transient temperatures and thermal stress is obtained for a right circular cylinder with internal heat generation varying exponentially with the radius by use of Hankel transforms. Curves for the maximum thermal stresses are presented for diameter ratios up to 1.2 and for a variety of internal heat-generation rates for internal heat-generation transients with both cylinder walls maintained at zero reference temperature at all times.
Thermal-Contact Resistance in Finned Tubing
Authors: Gardner Karl A. , Carnavos T. C.
Published: February 2012

Interference-fit finned tubes depend for their heat-transfer capability upon a contact pressure between fin and tube. The bond resistance under such conditions is relatively small compared to the other resistances in the heat-flow path. At elevated temperatures, however, differential thermal expansion between fins and tubes completely relaxes the contact pressure and introduces an additional gap resistance; this may become a significant part of the total resistance to heat transfer. A theoretical method for predicting the gap resistance is derived in terms of the fin and tube dimensions, their physical properties, the fluid temperatures and heat-transfer coefficients, and the initial contact pressure. Test data on five finned-tube units representing embedded, tension-wound, and muff-type fins are given in graphical and tabular form. Very good agreement is found between theory and test in two of the interference-fit units. The other two show only fair agreement.
Heat Transfer to Liquid Metals With Variable Properties
Authors: Viskanta R. , Touloukian Y. S.
Published: February 2012

The problem of heat transfer to liquid metals with variable physical properties for the case of fully developed turbulent flow in cylindrical tubes of constant diameter is studied, the fluid under consideration being heated or cooled by a constant and uniform heat flux at the wall. The similarity theory between momentum and heat transfer is used. Using the von Karman universal velocity profile the differential equations for turbulent flow with heat transfer are solved for the Prandtl number and the kinematic viscosity, each having five different sets of temperature-dependent exponents of a1 and a2. Calculated temperature distributions, mixing-cup temperatures, as well as relations between Nusselt versus Peclet numbers are presented for the cases of heat addition, heat extraction, and the nonvariable-property case.
A Summary of Experiments on Turbulent Heat Transfer From a Nonisothermal Flat Plate
Authors: Reynolds W. C. , Kays W. M. , Kline S. J.
Published: February 2012

The results of an extensive experimental investigation of heat transfer to a turbulent incompressible boundary layer from a nonisothermal flat plate are summarized. Data presented extend the range of low-Mach-number confirmation of the von Karman analogy to Reynolds numbers of 4 × 106 for an isothermal plate. Data for a step wall-temperature distribution confirm experimentally the preferable expression for this important superposition kernel case. Data from a variety of other examples confirm the use of the superposition theories to predict heat transfer from nonisothermal surfaces.
Application of Variational Methods to Radiation Heat-Transfer Calculations
Authors: Sparrow E. M.
Published: February 2012

A variational method is presented for solving a class of integral equations which arise in radiation heat-transfer problems. First, to demonstrate the formulation of radiation problems in terms of integral equations, consideration is given to a system consisting of two nonblack, finite, parallel plates. After a general description of the variational method, its use is illustrated by application to the parallel-plate system. Comparisons are made which show very good agreement with exact solutions.
Smoothed Pressure-Volume-Temperature Data for Water in the Critical Region Derived From Experimental Measurements
Authors: Nowak E. S. , Grosh R. J. , Liley P. E.
Published: February 2012

A graphical technique was used to derive pressure-volume-temperature data from previous American, Czechoslovakian, and Russian experimental measurements. The data were derived at close intervals throughout the region encompassed by pressures from 3000 to 4000 psia, specific volumes from 0.030 to 0.120 cu ft per lb, and temperatures from 690 to 752 F. The average deviation of experimental values of pressure from the derived values was less than one part in 10,000 in the region for specific volumes greater than the critical volume (0.0525 cu ft per lb) and was less than ten parts per 10,000 in the region for specific volumes less than the critical volume. These deviations are thought to be insignificant since they are entirely within the uncertainty of recent experimental measurements [8]. In a previous paper [13], deviations of some 100 to 200 parts in 10,000 in pressure were shown to exist between the data of various steam tables. Since the data in the steam tables were derived from the same primary data used in this paper, one may conclude that these deviations greatly exceed the experimental uncertainty and must therefore be charged to previous interpolation methods and the previous paucity of data. One of the important results of this study was the establishment of the fact that there was excellent agreement between recent measurements by Kirillin, et al. [7–10], and older measurements by Keyes and Smith [5] and by Havlicek and Miskovsky [2].
Some Temperature and Pressure Measurements in Confined Vortex Fields
Authors: Savino Joseph M. , Ragsdale Robert G.
Published: February 2012

Studies were conducted on vortex flow generated within two right circular cylinders by injecting air through longitudinal vanes forming the chamber. The length to diameter ratios were 0.107 and 0.50. Experimental end wall static pressure distributions, some total pressures, and total temperature data are presented. The most significant finding was the large radial variations in the total temperature; this is related to the Ranque-Hilsch effect. Also discussed is the relationship between the static wall pressures and the effective velocities in the vortex.
An Analytical Study of Laminar Film Condensation: Part 2—Single and Multiple Horizontal Tubes
Authors: Chen Michael Ming
Published: February 2012

The boundary-layer equations for laminar film condensation are solved for (a) a single horizontal tube, and (b) a vertical bank of horizontal tubes. For the single-tube case, the inertia effects are included and the vapor is assumed to be stationary outside the vapor boundary layer. Velocity and temperature profiles are obtained for the case μvρv/μρ ≪ 1 and similarity is found to exist exactly near the top stagnation point, and approximately for the most part of the tube. Heat-transfer results computed with these similar profiles are presented and discussed. For the multiple-tube case, the analysis includes the effect of condensation between tubes, which is shown to be partly responsible for the high observed heat-transfer rate for vertical tube banks. The inertia effects are neglected due to the insufficiency of boundary-layer theory in this case. Heat-transfer coefficients are presented and compared with experiments. The theoretical results for both cases are also presented in approximate formulas for ease of application.
Determination of Boiling Film Coefficient for a Heated Horizontal Tube in Water-Saturated Wick Material
Authors: Allingham William D. , McEntire Jack A.
Published: February 2012

Using an absorbent wick material saturated with a coolant has become attractive from a design standpoint for some missile-cooling applications. However, published data for predicting film coefficients are very limited. In this study, boiling film coefficients for a 1.0-in. OD horizontal copper tube embedded in water-saturated ceramic fiber-wick material were correlated over a heat-flux range from 1000 to 10,000 Btu per hr sq ft by the dimensionless equation hCG′CμK0.6ρLσP20.21=0.072DeG′μ−0.77 where G′=QAελ The presence of wick material next to a heat-transfer surface decreases turbulence in the region near the surface, increases the effective surface area, and provides active sites for bubble formation. This produces a higher film coefficient at low heat flux than occurs with pool boiling. At higher heat flux, the wick-boiling film coefficient was lower than for pool boiling.
Measured Variations in Local Surface Temperatures in Pool Boiling of Water
Authors: Hsu S. T. , Schmidt F. W.
Published: February 2012

An investigation of the surface-temperature variation during nucleate pool boiling at atmospheric pressure was conducted. The effect of surface temperature, heat flux, and heating-surface material was investigated. The temperature variation of the surface was found by a specially fabricated thermocouple placed in contact with it. The average maximum temperature variation may be found from the following equation: ΔTavgmax=c[q(f/α)1/2]−αqΔTsur−satk The exponent a is a function of surface roughness. The rate of heat flow was denoted by q in Btu/sq ft-hr, α the thermal diffusivity in sq ft/hr, f the frequency of variations in cphr, k the thermal conductivity in Btu/ft-hr-deg F, and ΔTsur−sat the temperature difference between the heating surface and the saturation temperature of water. The coefficient c and exponent a were determined experimentally for various heating-surface materials and surface finishes.
Velocity Distributions, Temperature Distributions, Effectiveness and Heat Transfer for Air Injected Through a Tangential Slot Into a Turbulent Boundary Layer
Authors: Hartnett J. P. , Birkebak R. C. , Eckert E. R. G.
Published: February 2012

A detailed study of the heat transfer for tangential air injection through a single slot into a turbulent boundary layer on a flat plate is presented; the results apply to a specific slot size, one injection rate, and a fixed free-stream velocity. Boundary-layer velocity and temperature profiles for a number of positions downstream from the point of injection are presented as well as plate-temperature distribution and heat-transfer data for adiabatic and constant heat input-wall boundary conditions.
Truncation Error Estimates for Numerical and Analog Solutions of the Heat-Conduction Equation
Authors: Freed N. H. , Rallis C. J.
Published: February 2012

A practical method is presented for obtaining a meaningful estimate of the truncation error associated with fully finite-difference forms of the heat-conduction equation. The analysis is applied in this instance to the Liebmann analog equations. It may also be used with other manual and analog methods of computation, where the error due to mesh size is relatively large. An example is given deriving error estimates for a case of one-dimensional heat flow.
Axial Temperature Distribution for a Nuclear Reactor With Sinusoidal Space and Exponential Time-Varying Power Generation
Authors: Doggett W. O. , Arnold E. L.
Published: February 2012

Analytic temperature distributions are obtained for the fuel and coolant regions of a heterogeneous, convection-cooled reactor with axial power variation ewt sin (πz/H). The fundamental assumption in the governing differential equations is that the temperature distribution in the fuel region does not vary in the direction transverse to the coolant flow. The solutions involve two and three-parameter integrals encountered and numerically evaluated previously which are integrated herein and arranged in a form suitable for desk calculations. Closed-form expressions are developed for the final steady-state axial distributions which are applicable at times long in comparison with the characteristic temperature-response times.
Experimental Ablation Rates in a Turbulent Boundary Layer
Authors: Bartlett E. P. , Denison M. R.
Published: February 2012

An exploratory experimental program on the ablation of graphite, a combustible sublimator, is reported which verifies an analysis of turbulent ablation rates previously developed. A blowdown system was employed using a mixture of oxygen and nitrogen as the working gas. The use of a high percentage of oxygen enabled the simulation of re-entry ablation conditions. Ablation rates were predicted within 30 per cent with no adjustment of empirical constants derived from incompressible turbulent skin-friction experiments. The predictions were consistently high. Temperature of the reacting surface, determined by means of a radiamatic pyrometer, was predicted within 10 per cent. The analysis can be applied to a wide variety of ablation materials including those which go through a liquid phase, provided proper account is taken of the chemistry, and provided the simplifying assumptions are valid.
Transient Temperature Measurement Errors in Heated Slabs for Thermocouples Located at the Insulated Surface
Authors: Burnett D. R.
Published: February 2012

A method is developed for estimating the error in “cold side” transient temperature measurements of slabs heated at one surface which is due to conduction of heat away from the junction through a thermocouple wire. Results are presented for a range of slab thickness/wire diameter ratios.
The Development of Free Convection Between Heated Vertical Plates
Authors: Bodoia J. R. , Osterle J. F.
Published: February 2012

The development of free convection in a viscous fluid between heated vertical plates is investigated. The basic governing continuity, momentum, and energy equations are expressed in finite difference form and solved numerically on a digital computer. Results are obtained for the variations of velocity, temperature, and pressure throughout the flow field assuming the fluid to enter the channel with ambient temperature and a flat velocity profile. The flow and heat-transfer characteristics of the channel are studied and a development height established. A comparison is made between the results of this theoretical investigation and the experimental work of Elenbaas.
Analysis of Film Boiling on Vertical Surfaces
Authors: Koh J. C. Y.
Published: February 2012

The two phase flow problem in laminar film boiling on a vertical flat plate is analyzed. The shear stress and vapor velocity at the vapor-liquid interface are taken into account. The problem is treated by solving simultaneously the boundary-layer equations for the vapor and liquid phases. In contrast to the film-condensation problem where the heat transfer is independent of the ρμ ratio, and where the interfacial shear can be neglected for a Prandtl number of unity or larger, it is shown that the ρμ ratio is an important parameter in the film-boiling heat transfer, and that the interfacial shear is quite different from zero.
Heat Transfer by Simultaneous Conduction and Radiation in an Absorbing Medium
Authors: Viskanta R. , Grosh R. J.
Published: February 2012

Heat transfer by simultaneous conduction and radiation in a thermal radiation absorbing and emitting medium is considered. Consideration is given to a one-dimensional system consisting of two, diffuse, nonblack, infinite, isothermal, parallel plates separated by a finite distance. The space between the plates is filled with a thermal radiation absorbing and emitting medium. The problem is formulated in terms of a nonlinear integro-differential equation and the solution is obtained by reducing it to a nonlinear integral equation. The numerical results are obtained by an iterative method. The temperature distributions and heat transfer are calculated. Two approximate methods for formulating radiant heat-transfer problems are presented and comparisons of the results are made with the most exact solution.
Steady-State Conduction With Variable Thermal Conductivity
Authors: McMordie Robert K.
Published: February 2012

A method is developed for solving two-dimensional, steady-state heat-transfer problems with thermal conductivity dependent on temperature. The quantity ∫ KdT is employed in the analysis and although this quantity has been known for some time,2, 3 it seems that the real usefulness of this quantity in analysis has not been, in general, recognized.
The Influence of a Radial Temperature Gradient on the Instability of Fluid Flow in an Annulus With an Inner Rotating Cylinder
Authors: Becker K. M. , Kaye Joseph
Published: February 2012

The problem of instability of diabatic flow between rotating, concentric cylinders has been studied analytically. The basic equations were reduced to a form identical to that of a similar instability fluid flow problem, namely, the instability of a horizontal layer of fluid heated from below. The latter problem has been solved by Pellew and Southwell, and their solution was used to calculate and predict the instability of diabatic flow in the annulus. The results of the analysis show that heating of the inner rotating cylinder stabilizes the flow, while heating of the outer stationary cylinder destabilizes the flow.
Infrared Techniques for Temperature Measurement in Plasmajets
Authors: Tourin Richard H.
Published: February 2012

The application of monochromatic radiation pyrometry to measurement of plasma temperatures was investigated. Infrared emission and absorption spectra of nitrogen, argon, and helium plasmajets, with various admixtures, were measured. Strong infrared emission was observed in various lines and bands in the plasma spectra, extending from the visible region to 7.0 μ. The observed infrared absorption was generally low. Temperatures measured ranged from below 2000 deg K for a N2 plasmajet heavily seeded with CO2, to 13,000 deg K for pure Ar. Temperature gradients in a plasmajet were inferred from observations made through various regions of the jet.
The Effects of Hall and Ion Slip on the Electrical Conductivity of Partially Ionized Gases for Magnetohydrodynamic Re-Entry Vehicle Application
Authors: Brunner M. J.
Published: February 2012

The presence of a partially ionized gas around a hypersonic vehicle permits the application of magnetohydrodynamic (MHD) devices during re-entry. The operation of such MHD devices on a re-entry vehicle will largely depend on the magnitude of the electrical conductivity of the gas between the electrodes. In some cases it may be necessary to seed the air in order to insure high conductivity. The operation of the re-entry vehicle at relatively low gas densities and high magnetic fields will produce Hall and ion slip effects which may materially reduce the effective conductivity between the electrodes. The electrical conductivity including Hall and ion slip effects for air is presented for a wide range of pressures and temperatures and for a typical re-entry vehicle, with and without seeding. The electrical conductivity is evaluated for equilibrium conditions considering the number density and collision cross sections for electrons, neutrals, and ions. The Hall and ion slip effects are evaluated from the degree of ionization, the cyclotron frequency, and the time between collisions for electrons, neutrals, and ions.
Temperature Distributions in Long Cylindrical Shells
Authors: Frank Irving , Gray Edward I.
Published: February 2012

Temperature distributions are found for long cylindrical shells subject to heat inputs which vary with angular co-ordinate. Two cases are considered: 1 Steady state—considering internal radiation heat transfer only. 2 Steady state—considering internal radiation and circumferential conduction.
On the Size Range of Active Nucleation Cavities on a Heating Surface
Authors: Hsu Y. Y.
Published: February 2012

The importance of surfare condition on nucleate boiling has long been recognized. It has also been known that only cavities of a narrow size range can be active nucleation sites. In order to define the size range of active cavities as a function of wall temperature or heat flux, a model is proposed. The model pictures a bubble nucleus at a site enveloped by a warm liquid. The nucleus will begin to grow into a bubble only when the surrounding liquid is sufficiently superheated. The time required for the liquid to attain this superheat is called the waiting period. The transfer of heat from the superheated liquid into the bubble is considered to be a transient conduction process. A cavity is considered effective only if the waiting period is finite. This criterion gives the limiting sizes of effective cavities. The equations show that maximum and minimum sizes of effective cavities are functions of subcooling, pressure of the system, physical properties, and the thickness of the superheated liquid layer. Comparison of theoretical prediction with experimental data from several sources was made. The fluids considered were ether, pentane, and water, with water under various degrees of subcooling. The theory did predict the incipience of boiling and size range of cavities successfully.
Laminar Free Convection Boundary-Layer Perturbations Due to Transverse Wall Vibration
Authors: Schoenhals R. J. , Clark J. A.
Published: February 2012

A perturbation technique is used to obtain analytically the velocity and temperature oscillations in a laminar free convection boundary layer on a plane wall vibrating transversely. The problem is divided into high and low values of ω4x where ω and x are, respectively, the dimensionless frequency and distance from the leading edge. Solutions are compared by plotting the oscillating components of the wall shear stress and temperature gradient. Results in the intermediate region of ω4x are estimated by extrapolation of the solutions obtained for each limiting region.
Heat Transfer From an Oscillating Horizontal Wire to Water
Authors: Deaver F. K. , Penney W. R. , Jefferson T. B.
Published: February 2012

An investigation has been made to determine the effect of low frequency oscillations of relatively large amplitude on the rate of heat transfer from a small horizontal wire to water. Frequencies from 0 to 4.25 cps and amplitudes to 2.76 in. were employed. Temperature differences up to 140 deg F provided heat flux from 2000 to 300,000 Btu/hr ft2. A Reynolds number was defined based on the mean velocity of the wire, and it was shown that heat-transfer rates may be predicted by either forced, free, or mixed convection correlations depending on the relative magnitudes of Reynolds and Grashof numbers.
Thermal Radiation Energy Exchange Shape Factors for Non-Lambertonian Surfaces
Authors: Blanton Roy W. , Picha K. G.
Published: February 2012

Real surfaces involved in thermal radiation exchange processes do not emit or reflect radiation with equal intensity in all directions, i.e., the surfaces are not diffuse. Shape factors for two geometrical cases for surfaces which are electrical conductors are presented as well as an estimate of the error resulting from assumed Lambertonian radiation emission for one case.
Thermal Efficiency of Coated Fins
Authors: Plamondon J. A.
Published: February 2012

The surfaces of a fin from which heat is rejected solely by radiation may have to be coated to obtain high values of thermal emissivity. In order to determine the influence of the conductive resistance of a coating on the thermal performance of a fin, an analysis was undertaken. Two equations are derived to describe the heat-transfer characteristics of a coated fin: One, a differential equation for the temperature profile on the radiating surfaces of the coating; and two, an equation for the relative thermal performance of the fin in terms of fin efficiency. The equations are solved numerically, and the fin efficiencies are plotted as a function of two dimensionless parameters which appear in the differential equation. These efficiencies are compared with those for fins in which the conductive resistance of the coating is ignored.
On the Solution of the Diffusion Equation With a Heat Source
Authors: Hovanessian S. A.
Published: February 2012

Analytical and finite difference solutions are developed for the temperature distribution in a medium of rectangular cross section having uniform properties and either constant temperature or insulated boundaries and with a line heat source of constant strength perpendicular to the section. The analytical solutions are infinite series which converge rapidly except at the source location where they diverge to infinity. The finite difference solutions are given in closed form. The temperature values obtained from the latter are compared to those of the former and the effect of time step and space increments on the finite difference solutions studied.
Effect of Arbitrary Nonsteady Wall Temperature on Incompressible Heat Transfer
Authors: Goodman T. R.
Published: February 2012

The title problem is solved using an integral method and ignoring viscous dissipation. A partial differential equation is derived which yields as special cases Lighthill’s non-uniform heat-transfer formula and the nonsteady heat conduction in a slab. The differential equation is then specialized to the nonsteady but uniform heat transfer on a flat plate. Comparisons with other solutions are made when available, and it is shown that the integral method produces accuracy of a few per cent in these limiting cases.
Transient Natural Convection From Vertical Elements—Appreciable Thermal Capacity
Authors: Gebhart B.
Published: February 2012

Natural convection transients are considered for laminar boundary-layer flow on vertical surfaces by the method previously presented by the present author. Cases are solved for elements having finite thermal capacity as, e.g., electric heaters or reactor elements. A wide range of thermal capacity is considered for fluid Prandtl numbers in the range 0.01 to 1000; for a step in internal energy generation rate. The Prandtl number effect is shown to be very small, in the generalized variables employed, and the range of thermal capacity which results in true convection transients is clearly delineated.
A Nernst Effect Power Generator
Authors: Angrist S. W.
Published: February 2012

The direct conversion of heat to electricity by means of the Nernst effect is analyzed. The Nernst effect is the creation of an electrical potential perpendicular to both an applied temperature difference and an applied magnetic field. The effect is pronounced in semiconductors which have large mobility, large mobility ratio, and relatively small energy gap. Indium antimonide exhibits theoretically the best performance to date. A Nernst effect generator using indium antimonide experiencing an applied temperature difference of 300 deg K and a magnetic flux density of 10 kilogauss would have a thermal efficiency of about 1.6 percent and a power density of 10 watts per cubic centimeter.
A Class of Similarity Solutions to the Boundary-Layer Energy Equation
Authors: Edgerton R. H.
Published: February 2012

This note presents a class of simple similarity solutions to the incompressible boundary-layer energy equation which appear to have been overlooked in papers on the subject. It is shown that one simple solution is particulary applicable to the axisymmetric stagnation point heat-transfer problem.
An Experimental Study of Sodium Pool Boiling Heat Transfer
Authors: Noyes R. C.
Published: February 2012

An experiment is described in which a saturated sodium pool was boiled from the surface of a horizontal 3/8-in-dia cylindrical test section. Measurements of surface temperature and heat flux during nucleate boiling were made at pool temperatures between 1200 and 1500 deg F and at heat fluxes up to 800,000 Btu/hr-ft2. Burnout heat flux measurements were made at pool pressures between 0.5 and 1.5 psia. Empirical correlation of the nucleate boiling data showed heat-transfer coefficients somewhat higher than previous prediction. A new nondimensional burnout correlation is derived which brings the sodium measurements into agreement with published burnout values for water and various organic liquids.
A Method for Predicting the Mean Thermal Conductivity of Insulating Materials at Other Than Experimental Conditions
Authors: Jones C. E.
Published: February 2012

A procedure whereby experimental thermal conductivity data can be readily extrapolated to operating conditions quite different from test conditions is presented. Use of this technique can also lessen the amount of experimental data that must be collected and ease experimental problems.
On the Hydrodynamic Transitions in Nucleate Boiling
Authors: Moissis Raphael , Berenson Paul J.
Published: February 2012

The two hydrodynamic transitions which take place in nucleate boiling off a horizontal surface are described. The first, which is governed by continuity considerations, results in a change in the vapor removal process from an intermittent to a continuous one. The second, which is a result of a Taylor-Helmholtz instability, determines the maximum (“burnout”) heat flux. Equations are presented which predict with good accuracy the two transition heat fluxes.
Comparison of Geometric Absorption Factors With Geometric Mean Beam Lengths
Authors: Wiebelt J. A.
Published: February 2012

The use of geometric mean beam lengths as compared to the use of geometric absorption factors for evaluation of energy transfer by radiation heat transfer with a participating gas is examined for perpendicular rectangles.
The Viscosity of Superheated Steam up to 275 Deg C: A Refined Determination
Authors: Kestin J. , Richardson P. D.
Published: February 2012

This paper describes a series of measurements made with an oscillating disk viscometer of the viscosity of superheated steam. These measurements were made on eight isotherms, ranging from 148 deg C to 275 deg C, and thus go to a temperature higher than previously achieved with steam in this type of instrument. The measurements again show that in the range of temperature investigated the viscosity of superheated steam decreases with increasing density. The precision of the present measurements has permitted a simple correlation to be made of the effect of temperature and density upon the viscosity. From this it now appears that the temperature at which the density effect ceases to be negative is about 315 deg C. The correlation of the present results is μμpoise=88.020+0.32827tdegC+0.00021350t2(degC)2−−ρg/cm31858−5.90tdegC The standard deviation of the measurements from this is 0.26 μpoise.
Interaction of Heat Transfer by Conduction, Convection, and Radiation in a Radiating Fluid
Authors: Viskanta R.
Published: February 2012

Consideration is given to the interaction of conduction, convection, and radiation in a fully developed laminar flow. The flat duct consists of two diffuse, nonblack, isothermal parallel surfaces a finite distance apart; the fluid between them emits and absorbs thermal radiation. The problem is formulated in terms of a nonlinear integro-differential equation, and the solution is obtained by a method employed by Barbier. Numerical examples show the influence of the system parameters such as the optical thicknesses, the ratio which determines the relative role of energy transport by conduction to that by radiation, the emissivity of the duct walls as well as the differences between heating and cooling on the temperature variations across the duct and on the heat-transfer characteristics. Two methods for obtaining approximate temperature distributions for optically transparent and opaque radiating media are outlined and the results discussed.
The Thermal Instability of Completely Confined Fluids Inside Some Particular Configurations
Authors: Ostrach S. , Pnueli D.
Published: February 2012

This paper deals with the thermal stability of completely confined fluids subject to a body force and a temperature gradient which are parallel and oriented in the same direction. It describes a method to obtain upper bounds to the instability criterion (the critical Rayleigh number) for piecewise cylindrical configurations, and demonstrates the use of this method treating some particular practical configurations. These upper bounds are shown to coincide with the critical Rayleigh number under some conditions. An account of experimental investigation of three of the particular configurations is presented and the experimental results compare favorably with the computed upper bounds.
An Application of Least Squares Method to the Solution of the Inverse Problem of Heat Conduction
Authors: Frank Irving
Published: February 2012

When the temperature of a body at some point is known, it is generally possible to determine the rate of heat input to the surface of the body. However, when the temperatures are determined experimentally, it will be found that there is some uncertainty in the solution for the rate of heat input. It is suggested that a least square method be used to determine the rate of heat input which best fits the experimental data.
Radiation Heat Transfer in Semigray Enclosures With Specularly and Diffusely Reflecting Surfaces
Authors: Bobco R. P.
Published: February 2012

The calculation of radiation heat fluxes in an enclosure of plane, gray surfaces with an arbitrary number of specularly reflecting and diffusely reflecting areas is cast into a form convenient for engineering design purposes. The image analysis of Sparrow, Eckert, and Jonsson is utilized to define a set of shape functions analogous to the familiar shape, or angle, factors used in enclosures which consist of diffuse surfaces only. The shape functions are used to derive a coefficient equivalent to Hottel’s gray body factor, F. The present analysis is extended to include interreflection phenomena with semigray surfaces which are postulated to emit energy in one spectral region and absorb energy in a different spectral region. Examples are given to indicate the utility of the present formulation for performing parametric design studies of complex enclosures and space vehicles.
Heat Transfer and Forces for Free-Molecule Flow on a Concave Cylindrical Surface
Authors: Sparrow E. M. , Jonsson V. K. , Lundgren T. S. , Chen T. S.
Published: February 2012

An analysis has been carried out to determine the local and overall heat-transfer rates, the adiabatic wall temperature, and the forces exerted when a high-speed, free-molecule flow is incident on a concave cylindrical surface. The flow may impinge on the surface at an arbitrary angle of attack. Additionally, the thermal accommodation coefficient may be arbitrary, and the degree of concavity of the surface may be varied at will from a semicircular cross section to a relatively flat circular arc. The concavity causes molecules to interreflect back and forth between surface elements. Even with the interreflections, the heat-transfer rate continues to depend linearly on the difference between the wall temperature and the adiabatic wall temperature. The interreflections are found to have a greater effect on both the heat transfer and the force results as the accommodation co-efficient decreases and as the degree of concavity and the angle of attack increase.
Analysis of the Critical Heat-Flux Condition in High-Pressure Boiling Water Flows
Authors: Tippets F. E.
Published: February 2012

Based on the two-phase flow patterns shown in high-speed motion pictures of the process, a general working equation is derived which relates the critical heat flux for high-pressure bulk boiling water in forced convection to the significant local flow parameters and fluid properties. The equation is applied to a representative selection of several hundred data points from the major available sources for the purpose of investigating trends in the data and to test the validity of the equation.