bluuebunny/crossref_metadata_2025 huggingface dataset:
Unsteady Laminar Flow in a Duct With Unsteady Heat Addition
Authors: Perlmutter Morris , Siegel Robert
Published: February 2012

An analysis is made of transient heat transfer with transient laminar flow between heated (or cooled) parallel plates. The transient processes are caused by simultaneously changing the fluid pumping pressure and either the wall temperature or the wall heat flux. The solution is obtained for both the thermal entrance and fully developed heat-transfer regions. The slug-flow simplification is made; that is, the velocity at any instant of time is taken as uniform throughout the channel. The fluid temperature distribution, however, depends on both the axial co-ordinate and the position within the channel cross section. A few numerical examples are carried out which give some insight into various transient processes such as those occurring during a nuclear-reactor shutdown.
The Effect of a Longitudinal Magnetic Field on Pipe Flow of Mercury
Authors: Globe Samuel
Published: February 2012

An experimental investigation has been made of the effect of an axial magnetic field on transition from laminar to turbulent flow and on the turbulent friction factor for pipe flow of mercury. Magnetic-flux densities up to 5700 gauss were obtained with a water-cooled solenoid. Pipes of glass and aluminum were used of approximately 0.1 to 0.2 in. diam. The maximum Hartmann number, with the hydraulic radius (half the actual radius) taken as the characteristic length, was about 20. Measurements were made of the pressure gradient and velocity of flow. The transition Reynolds number was determined from the curve of friction factor against Reynolds number. The results show an increasing value of minimum transition Reynolds number with Hartmann number. The magnetic field also brought about a decrease in the turbulent friction factor and corresponding shear force at the wall.
Unsteady Laminar Free Convection
Authors: Chung P. M. , Anderson A. D.
Published: February 2012

The unsteady, laminar, free-convection boundary layer is analyzed with the Grashof number considered to be time-dependent through either the uniform wall temperature or the acceleration field. Two geometries are considered; the vertical plate and the horizontal circular cylinder. A set of parameters is derived through which it is possible to describe the unsteady behavior of the boundary layer. These parameters allow solutions of the pertinent differential equations to be expressed in series form and an infinite number of sets of perturbation equations result. Numerical integrations of the first few sets are shown graphically. These results enable one to visualize and to calculate, quite readily, the time-dependent deviations from the quasi-steady velocity and temperature profiles as well as the deviation in heat transfer.
Radiant Interchange Between Circular Disks Having Arbitrarily Different Temperatures
Authors: Sparrow E. M. , Gregg J. L.
Published: February 2012

The problem of radiant heat transfer between parallel disks has been analyzed by generalizing the standard gray-body enclosure theory. In particular, the assumption that the radiant flux leaving a surface and the local heat flux are uniformly distributed over the surface has been lifted by an integral equation formulation. It has been shown that the general problem of disks at arbitrarily different temperatures can be conveniently broken down into two subproblems, each of which can be solved independently of the temperature level. Numerical solutions of the governing integral equations have been carried out for spacing ratios h/R (h = spacing, R = disk radius) ranging from 5.0 to 0.05 and for emissivities ranging from 0.1 to 0.9. Local heat-transfer results have been presented which, depending on spacing and emissivity, display marked variations over the disk surface. Over-all heat-transfer results have been calculated and compared with the predictions of the standard simplified enclosure theory. These predictions of the simplified theory were found to be unexpectedly good, especially in view of the large surface variations of the local heat transfer.
Heat Conduction Through Walls During Fire
Authors: Tjoan Lie Tiam
Published: February 2012

An expression is given for the temperature rise of a wall exposed on one side to a standard fire. It appears that calculated and experimental results agree with each other when a theoretical thermal conductivity is assumed which is a power of the thermal conductivity at room temperature.
A Comparison of Analytical and Experimental Local Heat Fluxes in Liquid-Propellant Rocket Thrust Chambers
Authors: Welsh William E. , Witte Arvel B.
Published: February 2012

Experimental data are presented showing heat-flux distributions measured calorimetrically with several liquid-propellant rocket thrust-chamber configurations. Thrust levels of the experimental chambers were from 300 to 5000 lb. Enzian-type and axial-stream showerhead propellant injectors were utilized with hydrazine (N2H4) and nitrogen tetroxide (N2O4) propellants. Nozzle-contraction-area ratios of 8 to 1, 4 to 1, and 1.64 to 1 were tested, each having a 5-in. inlet diameter. Characteristic chamber lengths ranged from 16.95 to 62.8 in. The comparison between the experimental heat flux and the analytical heat flux using the method of Bartz [1] was found to be closest in the nozzle-expansion region. The experimental heat-flux measurements ranged between 80 per cent above and 45 per cent below the analytical estimates at the nozzle throat, however. These differences were dependent upon thrust-chamber configuration, injector type, and chamber pressure, and apparently resulted from nonideal combustion and flow characteristics. It is concluded that a priori determination of heat-flux distribution along the thrust-chamber length was possible only to a first approximation for the conditions of these tests.
Radiation Interchange in a Nongray Enclosure Containing an Isothermal Carbon-Dioxide-Nitrogen Gas Mixture
Authors: Edwards D. K.
Published: February 2012

Data and computational methods used in calculating radiant interchange through isothermal carbon-dioxide-nitrogen mixtures are reviewed. The utility of band-absorption correlations is illustrated by the development of criteria for selection of band limits and geometric absorption factors for the simple infinite parallel plane enclosure.
Velocity and Temperature Profiles in Turbulent Boundary Layers With Tangential Injection
Authors: Seban R. A. , Back L. H.
Published: February 2012

Velocity and temperature profiles are presented for the turbulent boundary layer downstream of a tangential injection slot for the further clarification of the film-cooling problem. The profiles refer primarily to an injection mass velocity of 0.36 times that of the free stream; these and other auxiliary results demonstrate a complex hydrodynamic and relatively simple thermal behavior in which the temperature profiles appear to be similar in all cases. By using this correspondence together with the approximation of a fully developed hydrodynamic layer in most of the downstream region, it is possible to rationalize the adiabatic wall temperatures that have been presented previously.
Forced Convection Heat Transfer From a Uniformly Heated Sphere
Authors: Brown W. S. , Pitts C. C. , Leppert G.
Published: February 2012

An approximate analytical solution is presented for the variation of the local heat-transfer coefficient over the forward half of a uniformly heated sphere. Experimental measurements with water over a Reynolds number range of 5000 to 480,000 and a Prandtl number range of 2.2 to 6.8 give local coefficients which are in good agreement with analytical results. Average heat-transfer coefficients for the uniformly heated sphere are slightly higher than similar results reported earlier [1] for an isothermal sphere. The effect of variations of heat flux on the average heat-transfer coefficient is correlated in a manner similar to that which was used for the isothermal data. Three different duct sizes were used in the experiment to determine the effect of this variable, and the correlations which are presented are based on duct-to-sphere diameter ratios of 2, 2.67, and 4.
Measurements of Diabatic Flow in an Annulus With an Inner Rotating Cylinder
Authors: Becker K. M. , Kaye Joseph
Published: February 2012

The present paper is part of the second phase of an investigation of the phenomena and variables which control the rate of heat transfer in the air gap of a rotating electrical machine. Experimental data for diabatic flow in an annulus are summarized and compared with the results of previous studies. The data are examined in terms of the types of flow processes occurring in an annulus, and it is found that the results for diabatic flow clearly confirm those obtained for adiabatic flow in showing the existence of three, and possibly four, modes of flow in this annulus. These modes are: (1) Laminar flow; (2) laminar-plus-Taylor-vortexes flow; (3) turbulent flow; (4) turbulent-plus-vortexes flow. The heat-transfer data were subdivided into the following two limiting cases and one general case: Case A. Axial flow with zero rotation. Case B. Rotation of inner cylinder with zero axial flow. Case C. General case of combined axial flow and rotation. The heat-transfer data from this study and of previous investigations were correlated in terms of Reynolds number and Taylor number over a wide range of these variables in terms of fairly simple equations. Radial temperature profiles in the annular gap were measured for the diabatic flow and aided in the understanding of the different flow phenomena in the annulus with an inner rotating cylinder.
Forced Convection Heat Transfer From a Uniformly Heated Cylinder
Authors: Perkins H. C. , Leppert G.
Published: February 2012

Forced convection heat transfer from a cylindrical heating element with crossflow occurs in many situations of practical interest, but heat-transfer coefficients for liquids have been reported in the literature only for Reynolds numbers below 200. This paper correlates new data taken with water and ethylene glycol at Reynolds numbers from 40 to 100,000 and Prandtl numbers from 1 to 300. The effects of temperature differences large enough to produce significant changes in viscosity across the boundary layer have also been investigated and are correlated in terms of a viscosity ratio.
Rapid Calculation of Radiant Energy Transfer Between Nongray Walls and Isothermal H2O or CO2 Gas
Authors: Edwards D. K. , Nelson K. E.
Published: February 2012

Calculation of band absorption and, consequently, radiant transfer to nongray walls can be made by use of the fractional band absorption obtained from recent band absorption measurements. The fractional band absorption and other quantities needed for calculation of radiation heat transfer to isothermal H2O or CO2 gas are presented graphically for convenient use.
Radiant Absorption Characteristics of Concave Cylindrical Surfaces
Authors: Sparrow E. M.
Published: February 2012

Consideration is given to the absorption of radiant energy on nonblack, concave cylindrical surfaces on which radiation from some external source is incident. The multiple reflections which may occur between various parts of the concave surface are fully accounted for. The analysis is carried out both for diffusely, and for specularly, reflecting surfaces. Also included are both situations where the surface is fully illuminated (though not necessarily uniformly) or where a portion of the surface lies in a shadow. For a wide range of surface configurations, numerical results are presented for the surface distribution of the absorbed energy and for the total energy absorbed.
An Enclosure Theory for Radiative Exchange Between Specularly and Diffusely Reflecting Surfaces
Authors: Sparrow E. M. , Eckert E. R. G. , Jonsson V. K.
Published: February 2012

A systematic and convenient method has been devised for the calculation of the radiant interchange within an enclosure containing both specularly reflecting and diffusely reflecting surfaces. The new formulation makes use of simple properties of the images formed by plane mirrors, and this does away with the need to keep account of individual rays as they are reflected on the specular surfaces. With this image technique, heat-transfer calculations for a specular-diffuse enclosure are no more difficult than those for a fully diffuse enclosure. The method is illustrated by application to specific enclosure geometries.
Unsteady Natural Convection in the Vicinity of a Doubly Infinite Vertical Plate
Authors: Schetz J. A. , Eichhorn R.
Published: February 2012

The viscous flow equations for the unsteady free convection of a fluid near a doubly infinite vertical plate whose temperature or heat flux is an arbitrary function of time are treated by means of Laplace transforms. Exact solutions are obtained for several typical examples with arbitrary Prandtl number. The results are then generalized to give integral expressions for the velocity and temperature fields due to any prescribed time variation in wall temperature or surface heat flux.
Laminar Heat Transfer in Tubes Under Slip-Flow Conditions
Authors: Sparrow E. M. , Lin S. H.
Published: February 2012

The effects of low-density phenomena on the fully developed heat-transfer characteristics for laminar flow in tubes has been studied analytically. Consideration is given to the slip-flow regime wherein the major rarefaction effects are manifested as velocity and temperature jumps at the tube wall. The analysis is carried out for both uniform wall temperature and uniform wall heat flux. In both cases, the slip-flow Nusselt numbers are lower than those for continuum flow and decrease with increasing mean free path. Extension of the results is made to include the effects of shear work at the wall, temperature jump modifications for a moving fluid, and thermal creep.
Axially Symmetric Laminar Free Mixing With Large Swirl
Authors: Steiger Martin H. , Bloom Martin H.
Published: February 2012

Viscous laminar axially symmetric free mixing with large swirl is investigated by a boundary-layer type of analysis with integral methods. Large swirl generates axial pressure gradients as well as large radial pressure gradients, and therefore alters the streamwise flow. Examples calculated for both incompressible and compressible flow show that the wake may be significantly lengthened by large swirl. However, this effect is shown to be diminished in the compressible case where higher free-stream Mach numbers lead to decreased densities, and to decreased centrifugal effects, decreased radial pressure gradients, and decreased axial pressure gradients. In the limiting special case of small or moderate swirl the results agree with those previously obtained by Steiger and Bloom [1] in analysis wherein the induced pressure gradients were neglected a priori.
Application of a Momentum Integral Model to the Study of Parallel Channel Boiling Flow Oscillations
Authors: Meyer J. E. , Rose R. P.
Published: February 2012

A method is discussed for treating oscillations in flow through a heated boiling channel which connects two plenum regions of constant pressure difference. The approach is based on a numerical solution of pointwise difference equations representing conservation laws in fluid and metal. It is appropriate for spatially varying heat flux, flow with or without slip, and large perturbations. Details of the method, comparison with experiment, and features which distinguish it from other analytical models are discussed.
Measurements of Transient Natural Convection on Flat Vertical Surfaces
Authors: Gebhart B. , Adams D. E.
Published: February 2012

Experimental measurements of natural convection transients in air and in water are compared with the results of the integral analysis presented by the first author. An application of infrared techniques to the measurement of transient surface temperatures is described. The measurements, over a wide range of thermal capacity, are reduced to the variables which arose in the analysis and the measured responses are in essentially complete agreement with the results of that analysis for the case of a step in input flux. None of the measurements of natural convection transients on vertical plates has indicated temperature overshoot for the step condition.
Heat Transfer From Flames Impinging on Flat and Cylindrical Surfaces
Authors: Anderson J. E. , Stresino E. F.
Published: February 2012

An experimental investigation was made to determine the heat-transfer distribution obtained when a flame impinges on flat and cylindrical surfaces. The combustion systems studied were oxygen-hydrogen, oxygen-propane, oxygen-acetylene, and air-methane with combustion stream velocities varying from 1 ft/sec to 4600 ft/sec. Data taken with cylindrical heat-transfer surfaces are consistent with available heat-transfer correlation for low temperature gases provided the effect of chemical reaction on the thermal conductivity for flame temperatures above 3500 deg R is taken into consideration. Data taken with flat heat-transfer surfaces can be correlated quite well in a generalized curve partially based on theoretical reasoning.
Surface Recombination and Heat Transfer in a Dissociated Diatomic Gas—Part 2
Authors: Cottingham W. B. , Grosh R. J.
Published: February 2012

Results are presented for the recombination coefficient of hydrogen atoms on a stainless-steel surface as a function of pressure, temperature, and concentration. These results are compared with theoretical predictions. Results are also presented for a heat-transfer ratio. The results cover a range of Knudsen numbers from 0.08 to 4.2, a range of Reynolds numbers from approximately 0.004 to 0.2, and an upstream Mach number of approximately 0.1.
Mass and Heat Transfer From an Enclosed Rotating Disk With and Without Source Flow
Authors: Kreith Frank , Doughman E. , Kozlowski H.
Published: February 2012

The heat-transfer characteristics of a partially enclosed rotating disk have been investigated experimentally by means of a mass-transfer analog. Mass-transfer rates to air from naphthalene coated disks of 4 and 8 in. diameter were measured at speeds between zero and 10,000 rpm and the influence of the spacing between the rotating disk and its housing was investigated with and without source flow. From the experimental results a dimensionless correlation equation suitable for predicting average heat and mass-transfer coefficients for rotating disks with source flow in turbulent flow at rotational Reynolds numbers up to 4 × 105 was deduced. The flow pattern was investigated by means of a hot wire, a smoke visualization technique, and the china clay method.
A Design-Oriented Optimization of Simple Tapered Radiating Fins
Authors: Reynolds W. C.
Published: February 2012

Results of extensive numerical studies of simple linearly tapered radiating fins are presented in a novel design-oriented manner. A noniterative optimization procedure is made possible by this presentation scheme. The optimization of fin geometry allows for consideration of associated structure whose weight depends on the fin length. The importance of considering this structure in selecting fin geometry is demonstrated.
On the Approximate Solutions of Heat-Conduction Problems
Authors: Erdogan Fazil
Published: February 2012

Integral transforms are used in the application of the weighted residual methods to the solution of problems in heat conduction. The procedure followed consists in reducing the given partial differential equation to an ordinary differential equation by successive applications of appropriate integral transforms, and finding its solution by using the weighted-residual methods. The undetermined coefficients contained in this solution are functions of transform variables. By inverting these functions the coefficients are obtained as functions of the actual variables.
Pool Boiling of Benzene, Diphenyl, and Benzene-Diphenyl Mixtures Under Pressure
Authors: Huber D. A. , Hoehne J. C.
Published: February 2012

Experimental measurements are presented for the nucleate boiling of benzene, diphenyl, and benzene-diphenyl mixtures on a 3/8-in. od horizontal tube. The data were obtained in a pool boiling apparatus at pressures ranging from 13.5 to 488.5 psia. For the pure fluids, the nucleate boiling heat-transfer data were best correlated by the Rohsenow [12], Gilmour [8], and Levy [10] equations. Critical heat flux data reported for these fluids are correlated with those in the literature. The critical heat flux values for the pure fluids were best correlated by the Bernath relationship [1]; however, none of the literature expressions adequately predicted the large increases in critical heat flux that were obtained when small percentages of benzene were added to diphenyl. Similar increases in critical heat flux, when small amounts of volatile components are added, have been noted before, but no generalized correlations have been advanced. Some of the discrepancy may be due to inadequate knowledge of physical property data for the mixtures and failure to account for the mass transfer which occurs in bubble growth of multicomponent mixtures.
Heat-Transfer Coefficient of Inviscid Fluid Freezing Onto a Moving Heat Sink
Authors: Bueckner H. , Horvay G.
Published: February 2012

When a cold slab travels at speed U through a liquid metal bath, it freezes out metal at the rate of V. It is shown that the problem of determining the heat-transfer coefficient h at the interface of the liquid and solid phases is equivalent—under certain simplifying assumptions—to solving the (time-independent) wave equation in a sector. For the case of α ≡ arctan V/U < π/4, treated in the present paper, the problem is reduced, through suitable changes of variables and a Fourier sine transform, to the solution of Dirichlet’s problem for the Laplace equation. The temperature field T(X, Y) is expressed as an inverse sine transform, involving a single integration (in the transform variable). One finds that at the entrance cross section to the bath, X = 0, the heat-transfer coefficient is zero, then it rapidly approaches the asymptotic (“fully developed”) value h = γcV cos α. The heat-transfer coefficient is determined in closed form for α = π/6, π/4, and asymptotic expressions of it are derived for very small and very large distances from the origin when α is arbitrary (0 < α < π/4). Numerical evaluation of the heat-transfer coefficient at the solid-liquid interface is carried out for α = π/36, π/12, π/4. Plots of the temperature field T for these angles are also shown, along rays ϑ = π/6, π/3, π/2 to the horizontal.
The Effect of Pressure, Geometry, and the Equation of State Upon the Peak and Minimum Boiling Heat Flux
Authors: Lienhard J. H. , Schrock V. E.
Published: February 2012

The peak and minimum boiling heat fluxes for a variety of fluids are correlated with pressure, with geometry as a parameter. These correlations are achieved with the use of nondimensionalizing functions of invariant fluid properties that are based upon Zuber’s proposed mechanism for the extreme heat fluxes and upon the Law of Corresponding States. The method of correlation is applied with success to data from the literature as well as to new measurements provided by the authors. A clear contribution of geometry is identified.
Laminar Flow Heat Transfer to a Gas With Large Temperature Differences
Authors: Kays W. M. , Nicoll W. B.
Published: February 2012

This paper contains the results of three experiments on laminar gas flow heat transfer with moderately large temperature differences. The cases considered are laminar flow inside a circular tube with heating, with cooling, and flow normal to a circular tube with heating. All experiments were performed with air. Temperature ratios up to 1.9 were used in the experiments with flow inside a circular tube, and up to 3.0 in the flow normal to a circular tube experiment. In the laminar internal flow experiments it was found that the constant property thermal entry length solutions of Sellars, Tribus, and Klein [7], and Siegel, Sparrow, and Hallman [8] are accurately applicable to a gas with temperature ratios up to 1.9 if all fluid properties are evaluated at local mixed mean temperature. For flow normal to a circular tube with heating, the constant properly experimental correlations appear to be applicable to gas flow for temperature ratios up to 3.0 if fluid properties are evaluated at free stream temperature.
Heat Transfer Between a Gas and a Spherical Surface With the Combined Action of Free and Forced Convection
Authors: Klyachko L. S.
Published: February 2012

The critical analysis of Yuge’s work on heat transfer between a gas and a spherical surface is carried out and refined calculation formulas are given in a criterion form.
Laminar Heat Transfer in a Channel With Unsteady Flow and Wall Heating Varying With Position and Time
Authors: Siegel R. , Perlmutter M.
Published: February 2012

An analysis is made of incompressible laminar forced convection heat transfer between two parallel plates that have a specified heat production to be dissipated at their surfaces. The heat production can vary in an arbitrary manner with time and position along the channel, starting from an initially isothermal condition. The fluid velocity is assumed constant over the channel cross section, but can vary with time. The variation of fluid temperature over the channel cross section is accounted for. General relations are presented in closed form and their application is illustrated by carrying out some typical examples. The results are compared with previous analyses that have assumed constant temperatures over the channel cross section and a constant heat-transfer coefficient.
Effect of Wall Electrical Conductance on Magnetohydrodynamic Heat Transfer in a Channel
Authors: Yen J. T.
Published: February 2012

Effect of wall electrical conductance on laminar fully developed magnetohydrodynamic heat transfer in a channel with constant wall heat flux and exact magnetohydrodynamic boundary conditions are investigated. For channels with insulated walls, viscous dissipation is more important than joule heating for all Ec and M. For sufficiently large wall conductance, viscous dissipation is dominated by joule heating for all Ec, if M is large enough; both are in turn dominated by wall heat flux if Ec is large enough for all M. These and other conclusions are discussed in this paper.
First-Order Perturbations of Laminar Free-Convection Boundary Layers on a Vertical Plate
Authors: Yang Kwang-Tzu , Jerger Edward W.
Published: February 2012

A perturbation analysis for laminar free convection along a vertical plate, utilizing the classical boundary-layer solution as the zeroth-order approximation, is presented. First-order perturbations for the velocity and temperature fields have been calculated in detail for Prandtl numbers of 0.72 and 10.0. The propagation of leading-edge singularity into the first-order perturbations is examined and discussed. Good agreement is found between the present solution and experimental data.
Critical Heat Fluxes and Flow Patterns in High-Pressure Boiling Water Flows
Authors: Tippets F. E.
Published: February 2012

High-speed motion pictures (4300 pictures/sec) of boiling water flow patterns in conditions of forced flow at 1000 psia pressure in a vertical heated rectangular channel were taken over the range of mass velocities from 50 to 400 lb/sec-ft2, fluid states from bulk subcooled liquid flow to bulk boiling flow at 0.66 steam quality, and heat fluxes up to and including the critical heat flux level. Eighty critical heat flux determinations were made in the course of the experiment at 1000 psia in conditions of bulk boiling. The motion pictures provide photographic evidence of the general arrangement of the flow in conditions of bulk boiling at high pressure with heat fluxes near and including the critical heat flux level.
Bubble Boundary Layer and Temperature Profiles for Forced Convection Boiling in Channel Flow
Authors: Jiji L. M. , Clark J. A.
Published: February 2012

The inception of bubbles for forced convection flow over a heated plate in a pressurized channel and their consequent mutual interaction in the formation of a “bubble boundary layer” was investigated. A high pressure closed loop was designed to permit photographic study of boiling over the heated plate and to provide for the measurements of temperature profiles in the boiling fluid. The plate, which is 0.50 in., by 0.48 in., was vertically oriented in a rectangular channel 0.50 in., by 0.46 in., in cross section. Photographs and temperature profile measurements were obtained for forced convection boiling of distilled and degassed water at pressures of 200 to 1000 psia, velocities of 1 to 6 ft/sec, subcooling of 50–300 deg F. Experimental data on the bubble boundary-layer thickness were correlated to within ±20 percent by a single equation covering the range of variables investigated.
Geometric Mean Beam Lengths for Radiant Heat-Transfer Calculations
Authors: Dunkle R. V.
Published: February 2012

This is the second in a series of three papers concerned with radiant heat transfer between people and their surroundings. While the first paper in the series was confined to human configuration factors, the second and third papers have much wider applicability. This particular paper is concerned primarily with the geometrical relationships determining radiant interchange within a rectangular enclosure containing an absorbing and radiating medium. Equations, tables, and examples are given for geometric mean beam lengths and configuration factors between parallel or perpendicular rectangles. Curves are also presented for the mean beam length between a small sphere and a rectangle which can be used to approximate the mean beam length between a person and a rectangular panel.
Film Boiling of Steam-Water Mixtures in Annular Flow at 800, 1100, and 1400 Psi
Authors: Polomik E. E. , Levy S. , Sawochka S. G.
Published: February 2012

Film boiling heat-transfer coefficients, beyond “burnout,” of 800–2000 Btu/hr ft2 deg F, were measured with steam-water mixtures in annular flow at pressures of 800, 1100, and 1400 psi with healer temperatures not exceeding 1000 deg F. Variation of co-efficients with pressure, mass velocity, and steam quality are presented together with a correlation in the range of parameters studied.
Individual Row Heat Transfer in a Crossflow In-Line Tube Bank
Authors: Welch C. P. , Fairchild H. N.
Published: February 2012

Individual row heat-transfer coefficients are presented for air flowing across 10-row in-line tube banks at close back spacings with heat flow from air to tube. The Reynolds number range covered is approximately 1000 to 20,000 with heat fluxes of 640 Btu/hr-sq ft to 12,500 Btu/hr-sq ft. The effect of both tube row number and Reynolds number is shown. These effects are different for tangent (tubes touching in direction of airflow) and nontangent tubes.
Experimental Effects of Transverse Oscillations on Free Convection of a Vertical, Finite Plate
Authors: Blankenship V. D. , Clark J. A.
Published: February 2012

The effects of transverse oscillation on free convection from a vertical, finite plate is investigated experimentally. This paper supplements an earlier paper wherein analytical results were reported. In that paper it was reported that oscillation slightly decreases the heat-transfer rate for laminar flow. The experimental results are in accord. However, more important is the fact that the oscillation forces the flow to become turbulent whereby large increases in heat-transfer rate are obtained. Experimental results are given for heat-transfer rate, both laminar and turbulent, and transition.
Film Boiling on a Horizontal Tube in Increased Gravity Fields
Authors: Pomerantz M. L.
Published: February 2012

The influence of acceleration on saturated pool film boiling from the outside of a horizontal 0.188 in. OD, stainless-steel tube is reported. Freon-113 at approximately atmospheric pressure was used as the test liquid. Heat-transfer coefficients were determined for the experimental ranges: (a) temperature differences of 200 to 500 deg F; (b) heat fluxes of 5000 to 25000 Btu/hr-ft2; and (c) accelerations of 1 to 10 times normal acceleration. Data were correlated by adding a dimensionless parameter to the theoretical equation derived by Bromley for film boiling. High-speed motion pictures were taken from which interbubble distances, bubble periods, and bubble breakoff diameters were measured.
Confirmation of Gambill-Greene Straight-Flow Burnout Heat Flux Equation at Higher Flow Velocity
Authors: Mayersak J. , Raezer S. D. , Bunt E. A.
Published: February 2012

A test of the validity in a higher flow range of the Gunther equation (as modified by Gambill and Greene) for predicting burnout heat flux in linear flow was required during the development of copper electrodes for plasma arc heaters. An experiment employing ohmic heating of a stainless steel tube yielded a burnout value in good agreement with that predicted in the range of heat fluxes close to the maximum previously recorded.
Friction and Heat-Transfer Measurements to Turbulent Pipe Flow of Water (Pr=7 and 8) at Uniform Wall Heat Flux
Authors: Allen R. W. , Eckert E. R. G.
Published: February 2012

Measurements are reported of overall test section friction and of local heat transfer for the case in which hydrodynamically developed turbulent flow of water enters a uniformly heated circular tube. Systematic data are given for various heating rates and are shown to extrapolate to the zero heating rate or constant fluid property condition. In the thermal entrance region, variable property results are shown to agree with the measurements of Hartnett and constant property results are shown to agree with the analytical results of Sparrow, Hallman, and Siegel. Variable property test section friction results are shown to follow the wall temperature rule of Eagle and Ferguson. Constant property heat-transfer results at Pr = 8 are shown to yield a Reynolds number exponent which increases systematically from 0.84 at Re = 15,000 to 0.87 at Re = 100,000. Nusselt numbers at Pr = 8 are in excellent agreement with the analytical results of Sparrow, Hallman, and Siegel.
Heat, Mass, and Momentum Transfer Inside Frosted Tubes—Experiment and Theory
Authors: Chen M. M. , Rohsenow W.
Published: February 2012

The paper presents a combined experimental and theoretical study on the heat, mass, and momentum transfer in a frosted heat exchanger tube. Experimental evidence suggests that the behavior of the frosted tube is largely determined by the surface roughness of the frost layer. Based on simple stability considerations and the well-known rough pipe results of Nikuradse and von Karman, a theory is presented which predicts the frost surface roughness as functions of RePrkkf and the frost thickness. The theoretical results are shown to be in qualitative agreement with observed results. Heat-transfer and pressure drop calculations based on the predicted roughness are also found to be in fair agreement with observed results.
Studies of the Developing Flow Between Concentric Cylinders With the Inner Cylinder Rotating
Authors: Astill K. N.
Published: February 2012

The present paper is part of the third phase of an investigation of the phenomena and variables which control the rate of heat transfer in the air gap of a rotating electrical machine. Experimental studies were made in the developing adiabatic flow of air in an annulus having a rotating inner cylinder and stationary outer cylinder. Experiments were made to determine when Taylor vortices, and/or turbulence occurred as a function of Reynolds number of the flow; rotational speed of the inner cylinder; and distance from the inlet. Lines of demarcation of the several modes of flow were established for positions along the axis of the annulus. Two length effects were present: the distance to the point where vortices occurred and the distance required for the vortices to develop. A criterion is presented for determining the point in a developing flow where Taylor vortices originate. The value is given in terms of the dimensionless parameter, ωr1δb*νδθ*r1>24. A discussion of the occurrence of vortices in well-developed flows is presented.
Variational Analysis of Ablation for Variable Properties
Authors: Biot M. A. , Agrawal H. C.
Published: February 2012

The application of variational and Lagrangian thermodynamics is extended to problems of heat conduction with melting boundaries. The physical properties of the conducting material are considered to be temperature dependent. In particular, the material Alumina (Al2/O3) representing a class of ceramic materials for which the effective conductivity keff = kphonon + kphoton is subjected to above treatment and the temperature distribution and the melting rate are found. The results are compared with the constant-conductivity case.
On the Application of the Source Theory to the Solution of Problems Involving Phase Change: Part 2—Transient Interface Heat and Mass Transfer in Multicomponent Liquid-Vapor System
Authors: Yang Wen-Jei , Clark J. A.
Published: February 2012

The source theory is applied to obtain approximate solutions for determining the time-dependent interfacial location and the rate of phase change at the interface of a suddenly pressurized, multicomponent liquid-vapor system. Numerical calculations for the phase change of one and two-component cryogenic systems of nitrogen-nitrogen, helium-nitrogen, and oxygen-nitrogen show that the approximate solutions which are of a considerably simpler form compare favorably with the existing exact solutions. A conclusion is reached that the approximation by the source theory is dependable for low rates of phase change. The applicability of the source theory is discussed in regard to the geometrical configuration of the system and the nature of the phase change.
Heat Transfer in Film Boiling With Pulsating Pressures
Authors: Di Cicco D. A. , Schoenhals R. J.
Published: February 2012

The purpose of this exploratory experimental investigation was to determine the effect on the heat-transfer rate when a pulsating pressure is applied to a stable film boiling system. The test section used consisted of a 0.030-in-dia horizontal platinum wire. The boiling medium was monofluorotrichloromethane, C Cl3F, commercially available in high purity as Refrigerant 11. A boiling curve was obtained at atmospheric pressure. In addition, pulsating tests were conducted for various pulsing rates and for three different test wire temperatures. Periodic pressure pulses of approximately 100 psi were applied to the system. The initial results thus far obtained in this investigation show a substantial increase in the heat-transfer rate for pulsing frequencies ranging from 11.3 cps to 25.8 cps. The improvement is noted to be from 59.5 percent to 103 percent above the heat-transfer rate for film boiling at atmospheric pressure at the same temperature difference between the test wire and the fluid. It was also found that the heat-transfer rate achieved was higher than the average of the heat-transfer rate for atmospheric pressure film boiling and that for subcooled film boiling at the peak pressure achieved in pulsing. For the higher pulsing frequencies, the heat-transfer rate was found to be even greater than that for subcooled film boiling at the peak pressure.
Temperature Distribution in Cocurrent Two-Phase (Liquid-Liquid) Laminar Flow on Inclined Surfaces
Authors: Bentwich M. , Sideman S.
Published: February 2012

The steady-state temperature distribution in stratified two-phase, laminar viscous flow down an inclined solid plane is analyzed. With the plane and atmosphere kept at constant uniform temperatures, the temperature distribution is evaluated for various heat-transfer coefficients at the exposed surface. Graetz’s general approach is adopted here so that this solution holds for arbitrary given temperatures at a transverse section upstream. This method is modified here so as to account for the discontinuities of the physical properties at the interface. This analysis thus yields a detailed account of the heat-transfer mechanism which takes place at the interface.
Laminar Film Condensation on a Porous Vertical Wall With Uniform Suction Velocity
Authors: Jain K. C. , Bankoff S. G.
Published: February 2012

A perturbation method developed by Chen for laminar film condensation on a vertical, constant-temperature wall, taking into account condensate subcooling and vapor drag, is refined and extended to the case where some of the condensate is sucked off at constant velocity through a porous wall. The refinement consists of a single, rather than a double, power-series expansion in the heat capacity and the acceleration parameters. The extension consists of an exact solution of the Nusselt problem with constant suction velocity, followed by a perturbation procedure to take into account the heat capacity and acceleration effects. The results show that substantial increases in heat transfer can be effected in this manner, especially at high Prandtl numbers.
Combined Forced and Free-Convection Laminar Flow
Authors: Szewczyk A. A.
Published: February 2012

Effects of buoyancy forces on a forced-convection laminar flow as well as the forced-convection effects on a purely free-convection laminar flow about a vertical flat plate are analyzed. Solutions are obtained by expanding the stream function and the temperature function into series in terms of the parameter Grx/Rex2 when approaching from the forced-convection side, whereas for the free-convection approach in terms of the parameter (Grx/Rex2)−1/2. Velocity and temperature profiles, shear stress, and heat transfer are given for various values of the governing parameters.
Transpiration-Induced Buoyancy and Thermal Diffusion-Diffusion Thermo in a Helium-Air Free Convection Boundary Layer
Authors: Sparrow E. M. , Minkowycz W. J. , Eckert E. R. G.
Published: February 2012

A detailed analytical study has been carried out to examine the effects of buoyancy in a boundary layer where there is mass injection through a porous surface. Specific consideration is given to helium injection into air in the stagnation-point region of a horizontal cylinder. Mass and energy transport by thermal diffusion and diffusion thermo are also included in the analysis. It is found that both the transpiration-induced buoyancy and the diffusional transports play a decisive role in determining the heat transfer when the wall-to-stream temperature ratio (Tw/T∞) is only moderately different from unity. In particular, when Tw/T∞ > 1, the tendency of the transpiration-induced buoyancy to increase the heat transfer is opposed by the action of diffusion thermo. For the condition of the adiabatic wall, the wall temperature may exceed the stream temperature by an appreciable amount; this is due to diffusion thermo. The predictions of the analysis are compared with available experimental data.
Errors in a Finite-Difference Solution of the Heat Flow Equation
Authors: Kardas Alan
Published: February 2012

This note gives magnitudes of discretization errors incurred in a finite difference solution of the heat flow equation in a symmetric slab with the boundary conditions of the third kind.
A Study of Forced Convection Heat Transfer to Supercritical Hydrogen
Authors: Hess H. L. , Kunz H. R.
Published: February 2012

Hydrogen heat-transfer data in the supercritical region has been compared with an analysis based on fully developed turbulent pipe flow with variable fluid properties. The comparison indicated an additional variable property effect not included in the analysis. However, this approach led to the correlation of the data over the full range of experimental conditions. These results indicate that the mechanism of supercritical heat transfer with hydrogen can be explained on the basis of variable fluid property effects without postulating a new mechanism for heat transfer, as done in previous investigations. It was also found that the pipe flow equation with fluid properties based on the film temperature can be made to correlate the data by correcting the calculated values with a simple function of wall to bulk kinematic viscosity ratio. This method provides a rapid means for determining supercritical hydrogen heat transfer with accuracy sufficient for most purposes.
Prediction of Two-Phase Critical Flow Rate
Authors: Levy S.
Published: February 2012

An analytical model to predict two-phase critical flow rate is proposed. The model is based upon thermal equilibrium, a “lumped” treatment of the two-phase velocity (each phase is represented by a single mean velocity), and upon the neglect of frictional and hydrostatic pressure losses. A comparison of the proposed predictions with available test results and previous analyses shows that: (a) The present model agrees very well with the published test data; (b) In contrast to all other analyses, the model requires no assumption about the gas void fraction.
Effects of Roughness of Metal Surfaces on Angular Distribution of Monochromatic Reflected Radiation
Authors: Birkebak R. C. , Eckert E. R. G.
Published: February 2012

A detailed experimental study has been carried out to examine the influence of surface roughness conditions on the reflection characteristics of metal surfaces for monochromatic thermal radiation. Surfaces used were prepared by standard optical grinding techniques using a range of sizes of grit of the grinding compounds. Various definitions of reflectances are presented to facilitate in the discussion of the results. Biangular, specular, and hemispherical-angular reflectance measurements are discussed in terms of the optical root-mean-square surface roughness, wavelength of reflected radiation, and surface material. The experimental results are compared with the available predictions from theoretical analysis.
Laminar Film Condensation on a Porous Horizontal Tube With Uniform Suction Velocity
Authors: Frankel N. A. , Bankoff S. G.
Published: February 2012

The analysis of Bankoff and Jain [10] of film condensation on a vertical porous plate with uniform suction velocity is extended to the case of a horizontal porous tube. Integral momentum and energy balances are written for the system, including the effects of interface drag and condensate heat capacity, and the dimensionless equations are solved using a perturbation technique. All dependent variables are expressed in a double power series in the two perturbation parameters, ξ = kΔt/μλ (acceleration parameter) and α (dimensionless suction velocity), and the resulting equations are solved up to the second order perturbation. An asymptotic solution valid for high values of α is derived, and this solution together with the perturbation solution describes the system for a wide range of α. The case of heat transfer in a zero gravity field is treated, and the Nusselt number is found to be directly proportional to the suction velocity. Based on the results it is concluded that significant increases in heat transfer are possible with the use of suction.
Radiative Heat Transfer in Absorbing, Emitting, and Scattering Media
Authors: Love T. J. , Grosh R. J.
Published: February 2012

An analysis of the effect of anisotropic scattering on radiant heat transfer is presented. The equation of transfer for a scattering, absorbing, and emitting media is simplified by restricting the analysis to axially symmetric plane parallel geometry. The scattering medium is assumed to be composed of spherical particles of uniform diameter and complex refractive index. The scattering functions are taken from the literature and are the result of the application of Mie Theory of Electromagnetic Scattering.
The Emissivity of Transition Metals in the Infrared
Authors: Seban R. A.
Published: February 2012

Absorptivities of iron, nickel, and platinum are presented for room temperature and emissivities for temperatures of the order of 2000 deg R for wavelengths from 1 to 15 microns. These are compared to the predictions made from Roberts’ theory for absorption by two sets of charge carriers, using the parameters that he deduced, and favorable correspondence is achieved with the absorptivity of iron and of nickel at room temperature. Following his postulate that all of the change in electrical conductivity that is consequent to the temperature rise occurs in the more important set of carriers, adequate predictions of the emissivity at high temperature are obtained as well.