bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Instability in Plane Poiseuille Flow
Authors: Nakayama W. , Hwang G. J. , Cheng K. C.
Published: November 2010

The conditions marking the onset of longitudinal columnar vortices due to buoyant forces are studied for fully developed laminar flow between two infinite horizontal parallel plates with nonlinear basic temperature profile. The wall temperatures at the bottom and top plates, T1 and T2, respectively, are assumed to vary linearly in the main flow direction. The nonlinear basic temperature distribution and connective motion due to longitudinal disturbance component give rise to the influence on stability criteria: This influence may be expressed by a characteristic parameter representing the effect of longitudinal temperature gradient. Numerical values for critical Rayleigh numbers based on temperature difference, T1 − T2, are found for various Prandtl numbers and the parameter μ characterizing the effect of longitudinal wall temperature gradient. An increase in value for μ reduces the critical Ra further to a value less than 1708 when T1 > T2, and this tendency becomes pronounced as Pr increases. Results for the cases T1 ≦ T2 also show that the vortex rolls can be caused by the effect of longitudinal temperature gradient. Tentative discussion in terms of Richardson number is made to define the region where columnar vortices have priority of appearance over two-dimensional Tollmien-Schlichting waves. The computed secondary flow streamlines and perturbation temperatures show that the mode of convection motion is also affected by the parameter μ.
Optimum Arrangement of Rectangular Fins on Horizontal Surfaces for Free-Convection Heat Transfer
Authors: Jones Charles D. , Smith Lester F.
Published: November 2010

Experimental average heat-transfer coefficients for free-convection cooling of arrays of isothermal fins on horizontal surfaces over a wider range of spacings than previously available are reported. A simplified correlation is presented and a previously available correlation is questioned. An optimum arrangement for maximum heat transfer and a preliminary design method are suggested, including weight considerations.
Heat Transfer to Horizontal Gas-Solid Suspension Flows
Authors: Depew C. A. , Cramer E. R.
Published: November 2010

Heat transfer and pressure-drop characteristics of a gas-solid suspension flow in a horizontal circular tube were investigated using glass spheres of two sizes, 30 and 200 micron. The airflow rate was held constant at three different values in a 0.71-in-ID tube such that Reynolds numbers of 10,000, 15,000, and 30,000 were produced. Solid loading ratios on a mass basis were as large as 7. The purpose of the investigation was to observe the effect of stratification on the heat transfer characteristics of the system. The pressure-drop results indicate that the solids were suspended in all cases, but the heat transfer data slum significant difference between the temperature of the tube wall at the top and bottom with the small particles. Nusselt numbers were as much as 2-1/2 times larger on the bottom side than on the top side. No such effect was produced with the large particles. The pressure-drop data indicate significant wall interaction for the large size, but not for the small size.
Effects of Gravity and Size Upon Film Boiling From Horizontal Cylinders
Authors: Lienhard J. H. , Sun Kauo-Hwa
Published: November 2010

The vapor removal mechanism during film boiling on horizontal cylinders has been observed over an 81-fold variation of gravity and a tenfold variation of radius. These measurements are the basis for an assessment of prior predictions of wavelength. A significant low-gravity transition point in the vapor removal mechanism is identified and explained. “Best” formulas are recommended for the prediction of the wavelength and the minimum heat flux. These depend upon a single parameter which represents both size and gravity.
Laminarization of a Turbulent Boundary Layer in Nozzle Flow—Boundary Layer and Heat Transfer Measurements With Wall Cooling
Authors: Back L. H. , Cuffel R. F. , Massier P. F.
Published: November 2010

Boundary layer and heat transfer measurements are presented for flow through a cooled, conical nozzle with a convergent and divergent half-angle of 10 deg for a wall-to-total-gas temperature ratio of about 0.5. A reduction in heat transfer below values typical of a turbulent boundary layer was found when values of the parameter K = (μe/ρeue2) (due/dx) exceeded about 2 to 3 × 10−6. The boundary layer measurements, when viewed in conjunction with the heat transfer measurements, reveal the complicated nature of the flow and thermal behavior and their interrelationship when laminarization occurs.
Film Condensation of Potassium Using Copper Condensing Block for Precise Wall-Temperature Measurement
Authors: Wilcox Stanley J. , Rohsenow Warren M.
Published: November 2010

Major differences exist in results published by investigators of film condensation of liquid metal vapors. In particular, the reported dependence of the condensation coefficient on pressure has raised questions about both the precision of the reported data and the validity of the basic interphase mass transfer analysis. An error analysis presented in this investigation indicates that the reported pressure dependence of the condensation coefficient at higher pressures is due to an inherent limitation in the precision of the condensing wall temperature measurement. The magnitude of this limitation in precision is different for the various test systems used. The analysis shows, however, that the primary variable affecting the precision of the wall temperature measurement is the thermal conductivity of the condensing block. To verify the analysis, potassium was condensed on a vertical surface of a copper condensing block. The copper block was protected from the potassium with nickel plating. Condensation coefficients near unity were obtained up to higher pressures than those previously reported for potassium condensed with stainless steel or nickel condensing blocks. These experimental results agree with the prediction of the error analysis. In addition, a discussion of the precautions used to eliminate the undesirable effects of both noncondensable gas and improper thermocouple technique is included. It is concluded from the experimental data and the error analysis that the condensation coefficient is equal to unity and that the pressure dependence reported by others is due to experimental error.
Stagnation-Point Heat-Transfer Rate in Nitrogen Plasma Flows: Theory and Experiment
Authors: Okuno Arthur F. , Park Chul
Published: November 2010

A theory for the heat transfer to the stagnation point of a hemisphere in a supersonic, high-enthalpy, low-density nitrogen plasma flow was developed. The theory assumed a flow that is frozen with respect to molecular dissociation and relaxing with respect to ionization. The calculations for this partially frozen flow yielded heat-transfer rates that were generally lower than predicted by other theories for both frozen and equilibrium flows. Experimental heat-transfer rates from measurements in a high-enthalpy constricted-arc tunnel agreed with the theoretical value within 10 percent in the mean.
Experimental Investigation of Radiative Transfer Between Metallic Surfaces at Cryogenic Temperatures
Authors: Domoto G. A. , Boehm R. F. , Tien C. L.
Published: November 2010

Experimental measurements of the radiative heat flux between two parallel copper disks in the liquid-helium temperature range are presented. The temperature levels investigated were primarily for the higher temperature disk (emitter) at 10.0 deg K and 15.1 deg K and the lower temperature disk (receiver) at approximately 4.5 deg K. For the 15.1 deg K emitter temperature, the spacing was varied from 0.201 cm to 0.001 cm. For the 10 deg K emitter case, the spacing was varied from 0.044 cm to 0.005 cm. Experimental data at small spacings show a definite spacing dependence of radiative transfer which agree qualitatively with the predicted result. Based on the measurements at large spacings, an estimate of the total hemispherical emissivity for the copper surfaces in the liquid-helium temperature range indicates a value of 0.015, which is approximately one order of magnitude higher than predicted. The possible causes for the discrepancies are discussed.
Vibration Effects on Convective Heat Transfer in Enclosures
Authors: Forbes R. E. , Carley C. T. , Bell C. J.
Published: November 2010

The effect of mechanical vibrations on natural convective heat transfer in an enclosure of rectangular cross-section was investigated experimentally. The enclosure was comprised of two vertical and opposed surfaces which were maintained at different temperatures, surrounded by four other adiabatic surfaces. Vibration stresses were applied to this heat transfer cell by mounting it vertically on the armature of an electrodynamic vibrator. Frequencies from 0 to 4000 Hertz and accelerations from 0 to 110 g’s were utilized in the investigation. The results show that vibration of a thermally active enclosure can have a significant effect on its heat transfer characteristics especially near the resonant natural frequency of the column of fluid contained within the enclosure. Increases in convective heat transfer coefficients of as much as 50 percent were obtained during this investigation. A correlation equation was developed by utilizing the dynamic response characteristics of the fluid column when considered as a seismic mass.
Heat Transfer From Plasma in Tube Flow
Authors: Schmidt P. S. , Leppert G.
Published: November 2010

Heat transfer data are reported for partially ionized argon flowing in a water-cooled circular tube, 1/2 in. in dia. Experiments were run with initial mixed-mean temperatures up to 21,000 deg R at Reynolds numbers from 140–527 based on equilibrium properties evaluated at the entrance mixed-mean temperature. Measured plasma flow Nusselt numbers computed on an enthalpy basis correlate well with low temperature, constant property results after the first 5–10 diameters of the tube entrance region; closer to the entrance, Nusselt numbers were about 30 percent higher than constant property entrance region predictions. The tendency of the data to approach the constant property solution rapidly was predicted by a laminar finite-difference analysis for plasma flow published earlier [1]. The analysis was modified for the present study to improve its accuracy. The finite-difference theory under predicts the heat transfer in the first few tube diameters; two possible reasons for this discrepancy are the poor resolution in the inlet enthalpy profiles near the tube wall and nonequilibrium between electrons and heavy particles in this region.
Radiative and Convective Conducting Fins on a Plane Wall, Including Mutual Irradiation
Authors: Donovan R. C. , Rohrer W. M.
Published: November 2010

The radiative and convective heat transfer from a fin array consisting of longitudinal rectangular fins on a plane surface has been theoretically investigated by mathematically describing the interaction among the heat conduction in the fin, the convective heat transfer to the fluid medium, and the radiant exchange of the fin with the neighboring elements. Solutions for the fin temperature distribution, the local radiative heat fluxes over the fin and base surfaces, the total radiative heat transfer, the total convective heat transfer, and the effectiveness of the fins were found. In the primary range of physical interest, the fins usually cause a considerable increase in the convective component of the heat transfer but either cause decreases or only slight increases in the radiative component. Thus convection is generally the more effective mode of heat transfer in fin arrays, and the effectiveness of the fins decreases as the radiative component increases.
Free Convection Through Vertical Plane Layers of Non-Newtonian Power Law Fluids
Authors: Emery A. F. , Chi H. W. , Dale J. D.
Published: November 2010

Experimental measurements of the heat transferred from a constant heat flux hot wall across vertical plane layers of several pseudoplastic non-Newtonian fluids with generalized Prandtl numbers of 10–500 are reported for a range of Grashof moduli and layer height to width ratios. The rheological properties of the fluids are discussed and it is shown that the similarity analysis of free convection for constant-temperature vertical flat plates presented by Acrivos for infinite Prandtl numbers can be used to correlate the data. Several temperature profiles are given and compared to those measured in water.
Critical Rayleigh Numbers for Natural Convection of Water Confined in Square Cells With L/D From 0.5 to 8
Authors: Heitz W. L. , Westwater J. W.
Published: November 2010

An experimental study of heat transfer modes in water heated from below was conducted using test cells of square cross section, 0.5 × 0.5 in., and heights of 1.25 to 4 in. Heat transfer was unidirectional and parallel to gravity. Tests both included and excluded the maximum density region of 4 deg C. Ice was present above the liquid during certain runs. The three modes of heat transfer, conduction and laminar and turbulent natural convection, were characterized by temperature profiles, fusion-front velocities and positions, and fluid flow patterns. Transitions between modes occur at well-defined critical Rayleigh numbers which are distinct functions of the L/D of the liquid. The critical values are not affected by the presence of ice, motion of the fusion front, or the temperatures of the warm and cold boundaries, if the Rayleigh number is calculated as described. The L/D was varied from 0.5 to 8 and the critical Rayleigh numbers varied from about 1700 to 108.
The Influence of Turbulence on Mass Transfer From Cylinders
Authors: Kestin J. , Wood R. T.
Published: November 2010

This paper describes new local mass-transfer measurements from two cylinders, coated with a layer of paradichlorobenzene (p-C6H4Cl2), to air. The cylinders were placed in cross flow, and measurements were performed at three nominal values of the Reynolds number (75, 100, 125 × 103) as well as at varying levels of turbulence intensity. In the range where the boundary layer is laminar, the effect of turbulence intensity is always to increase the transfer rate, approximately by a constant factor φ which depends on the turbulence intensity as well as the Reynolds number. Across the turbulent boundary layer and wake the influence is not systematic, as both increases and decreases are observed. The data for the stagnation line are compared with other measurements. They can all be correlated against the single parameter TuRe1/2, as suggested by a semiempirical theory due to Smith and Kuethe. However, the global correlation equation (a second-degree polynomial) differs from the originally proposed linear relationship, and the uncertainty is one of ±8 percent.
Local Non-Similarity Thermal Boundary-Layer Solutions
Authors: Sparrow E. M. , Yu H. S.
Published: November 2010

A solution method is described and applied for treating non-similar thermal boundary layers. The solutions are locally autonomous (that is, independent of information from other streamwise locations) and are found by solving quasi-ordinary differential equations of the similarity type. All non-similar terms appearing in the conservation equations are retained without approximation, and only in derived subsidiary equations are terms selectively neglected. The accuracy of the results can be appraised from comparisons internal to the method itself. Thermal boundary-layer non-similarity arising both from velocity-field, non-similarity and from streamwise variations of surface temperature are analyzed. Numerical results for the surface heat transfer and for the boundary-layer temperature distribution are presented for various physical situations.
Experiments on the Onset of Longitudinal Vortices in Laminar Forced Convection Between Horizontal Plates
Authors: Akiyama M. , Hwang G. J. , Cheng K. C.
Published: November 2010

An experimental investigation is carried out to determine the onset of longitudinal columnar vortices due to buoyant forces for fully developed laminar forced convection between two infinite horizontal plates, each wall subjected to identical uniform axial temperature gradient but maintained at temperatures T1 and T2 (T1 > T2, T1 < T2, and T1 = T2) at lower and upper surfaces, respectively. The limiting case with vanishing axial temperature gradient and heating from below (T1 > T2) is known to have a critical Rayleigh number of 1708 and is used to check the accuracy of the testing apparatus. The onset of secondary flow is determined by a direct flow-visualization technique using cigarette smoke, and confirmed by a transverse temperature-profile measurement using a single thermocouple traverse. Experimental results for the critical Rayleigh number are compared with theory and the agreement is found to be good.
Interaction of a Heated Jet With a Deflecting Stream
Authors: Ramsey J. W. , Goldstein R. J.
Published: November 2010

An experimental investigation of the interaction of a heated jet with a deflecting flow has been performed in a wind tunnel. The secondary (jet) flow is introduced at angles of 90 and 35 deg to the mainstream flow direction. Visualization studies using tufts of yarn and a carbon dioxide-water fog are reported. Temperature profiles in the interaction region are presented for blowing rates (ratio of mass flux of injected gas to mass flux of free stream) from 0.1 to 2.0 for normal injection and at blowing rates of 1.0 and 2.0 for 35 deg injection. Velocity and turbulence-intensity profiles are reported for normal injection at blowing rates of 1.0 and 2.0.
Heat Transfer to Evaporating Liquid Films
Authors: Chun K. R. , Seban R. A.
Published: November 2010

Results are presented for the heat-transfer coefficient for evaporation from the surface of water films flowing along the outside surface of a vertical tube for the cases of laminar and turbulent flow. Correspondence with results for condensation and liquid heating is shown and the transition from laminar to turbulent flow is indicated to depend on quantities other than Reynolds number.
Heat and Mass Transfer in an Incompressible Turbulent Boundary Layer
Authors: Brundrett E. , Nicoll W. B. , Strong A. B.
Published: November 2010

The van Driest damped mixing length has been extended to account for the effects of mass transfer through a porous plate into a turbulent, two-dimensional incompressible boundary layer. The present mixing length is continuous from the wall through to the inner-law region of the flow, and although empirical, has been shown to predict wall shear stress and heat transfer data for a wide range of blowing rates.
The Free Convection of Heat from a Vertical Plate to Several Non-Newtonian “Pseudoplastic” Fluids
Authors: Dale J. D. , Emery A. F.
Published: November 2010

The local heat transfer, temperature, and velocity profiles were measured and numerically predicted for the free convection of heat from a vertical constant flux plate to several concentrations of carboxymethylcellulose (CMC) and carboxypolymethylene (Carbopol) powders in water. The fluids were found to have the thermal properties of water and in the shear stress range of interest to follow the power law of Ostwald–de Waele with flow indices varying from 0.395 to 1.0 and with fluid consistencies of 30 to 2300 times that of water. The tests were conducted using either of two plates (12 and 24 in. high) immersed in such a large tank (3000 lb of fluid) that the viscometric properties of the fluid remained unchanged, even for the long test periods used. All fluids, including those with yield stresses and those which suffered free surface effects, were found to transfer heat which could be correlated by the generalized Newtonian correlation Nux=C(Grx*Prx*n)13n+2 which suggests that the precise velocity characteristics of the fluid are of minor importance in determining the heat transfer performance of the system. The numerical solutions, based upon the boundary layer assumptions and the power-law model, were in excellent agreement with the experimental measurements.
Measurement of Free Convection Velocity Field around the Periphery of a Horizontal Torus
Authors: Aihara T. , Saito E.
Published: November 2010

Free convection velocity fields around the peripheries of horizontal tori in air have been measured for diameter ratios of 0.5, 0.3, and 0 (a cylinder) by utilizing the trajectories of fine zinc stearate particles. The induced flow through the torus opening and the curvature of the great circle were found to influence the velocity profiles and the location of the upper and lower stagnation points. Experimental profiles for tori are compared with theoretical results for cylinders and spheres proposed by others.
Heat and Mass Transfer in the Vicinity of the Vapor-Gas Front in a Gas-Loaded Heat Pipe
Authors: Edwards D. K. , Marcus B. D.
Published: November 2010

An analysis is presented of axially conducting gas-controlled heat pipes leading to a predictive capability for the heat and mass transfer along the heat pipe. In addition, experimental results are presented which verify the analysis, and computational results are presented which show the relative influence of various parameters which affect the system behavior. In particular it was found that axial heat conduction is of much greater importance than axial mass diffusion in establishing the wall temperature profiles and condenser heat-transfer characteristics of gas-loaded heat pipes. However, mass diffusion and, consequently, the choice of working fluid and control gas are of considerable importance in establishing the “diffusion freezeout rate” if the potential exists for freezing of vapor which penetrates the gas-blocked portion of the condenser. It is believed that the analysis and associated computer program are useful tools for designing gas-loaded heat pipes.
Heat Transfer in a Channel with a Porous Wall for Turbine Cooling Application
Authors: Debruge L. L. , Han L. S.
Published: November 2010

A method of cooling turbine blades internally by continuous injection through an interior baffle is analyzed. The analytical model consists of a two-dimensional channel formed by a solid wall (blade surface) and a porous plate (injection source). Based on incompressible- and laminar-flow assumptions, the velocity and the temperature fields are determined. The Nusselt numbers for a power-law surface-temperature variation are obtained and expressed in terms of the Prandtl and the Reynolds numbers. A related problem of cooling the turbine disk is also solved.
Heat Transfer in Plasma Systems using Magnetically Rotated Arcs
Authors: Humphreys J. F. , Lawton J.
Published: November 2010

A study has been made of heat transfer from an argon-arc plasma to a constraining tubular enclosure down which the plasma was discharged. An applied axial magnetic field caused the arc to rotate rapidly. Large increases in the heat-transfer rates to the tube were observed with rotation and it was shown that these increases were due to the swirling flow and turbulence caused by the arc’s motion.
Thermal-Radiation Properties of Thin Metallic Films on Dielectrics
Authors: Forsberg C. H. , Domoto G. A.
Published: November 2010

The spectral radiation properties of thin metallic films are obtained through the numerical solution of the governing integrodifferential equation for the anomalous skin effect with size effects included. The theory predicts that at low temperatures there will be a film thickness for which the emittance is a minimum. This minimum, which is lower than the emittance for a bulk specimen, is apparently due to interference effects arising from the finite film thickness. It is also found that for certain cases transmission through a film is not negligible compared with the emission from the film. The analysis is extended to include metal-coated dielectric films, and the theoretical results are compared with existing experimental data.
Convection Heat Transfer in a Contained Fluid Subjected to Vibration
Authors: Pak H. Y. , Winter E. R. F. , Schoenhals R. J.
Published: November 2010

An experimental investigation of the effect of vibration on convection heat transfer from a horizontal cylinder has been performed for the case in which the entire system, both the heated surface and the fluid, are simultaneously subjected to vibration. A 0.032-in-dia horizontal wire served as the heated surface. The ranges of the experimental variables were: temperature difference, 10 to 100 deg F; vibration frequency, 30 to 240 Hz; acceleration amplitude, 1 to 5 g’s. Improvements in heat transfer due to vibration were observed, with the maximum increase being 200 percent. According to dimensional analysis, the Nusselt number depends on five independent parameters. A dimensionless correlation describing the measured heat-transfer data is given.
Application of a Heat-Transfer Model to Determine Regional Blood Flow Rate
Authors: Eberhart R. C. , Jackson M. , Trezek G. J.
Published: November 2010

The temporal patterns of central and skin temperature may provide important predictive and diagnostic information during the recovery period from major surgery. Experimentally it is found that large changes in toe temperature occur at a predictable time, early in the postoperative period. These changes reflect cardiovascular dynamics and are related to modern concepts of thermoregulation. In order to explore the contribution of time-varying blood flow to heat transfer, a heat-transfer model was applied to the great toe. This model allowed prediction of toe blood flow rate from measurements of the central and skin temperatures. Experimental verification of the analytically determined blood flow rates was made using a modified technique of venous occlusion plethysmography.
Correlations for Laminar Forced Convection with Uniform Heating in Flow over a Plate and in Developing and Fully Developed Flow in a Tube
Authors: Churchill S. W. , Ozoe H.
Published: November 2010

Asymptotic solutions for Pr → 0 and Pr → ∞ and numerical solutions for intermediate Pr were obtained for a uniformly heated flat plate. The method of Churchill and Usagi was utilized to construct a simple correlation for these values. The same method was used to develop simple correlations for plug flow and fully developed flow in a uniformly heated tube. These correlations were in turn combined to develop correlations for the available experimental data and computed values for developing flow in a uniformly heated tube. Derivations and test calculations in which convection normal to the wall was neglected reveal that this error is significant but insufficient to explain all of the discrepancies in the computed values.
Heat Transfer through Semitransparent Solids
Authors: Anderson E. E. , Viskanta R. , Stevenson W. H.
Published: November 2010

The heat transfer through a plane layer of a semitransparent solid is investigated experimentally for conditions under which the radiative transport must be considered. Temperature profiles measured with a Mach–Zehnder interferometer and the total heat flux are compared to rigorous analysis employing a rectangular multiband model of the spectral-absorption coefficient and simplified approximate techniques. Results for opaque and semitransparent boundary conditions are presented for three sample thicknesses. Fused quartz is employed for the specimen, as its thermophysical properties are similar to those of several materials which are commonly exposed to severe thermal conditions, it has excellent high-temperature and interferometric properties, and its strong infrared absorption peak serves as a critical test of a band model. For the experimental conditions which are considered, it is shown that the coupling of conduction and radiation cannot be neglected for the prediction of the heat transfer, although no appreciable influence on the temperature profile was observed. Approximate analytical techniques are shown to be accurate in this situation.
Free-Convective Heat Transfer to a Supercritical Fluid
Authors: Nishikawa Kaneyasu , Ito Takehiro , Yamashita Hiroyuki
Published: November 2010

The influence of heater material on free-convective heat transfer from wires to carbon dioxide in the supercritical region was investigated. Three types of flow configuration were observed for nichrome and alumel wires: (a) conventional laminar-flow free convection, (b) an oscillating flow in which (a) and a bubble-like flow alternated, (c) a bubble-like flow in which masses of fluid similar to bubbles appeared successively near the heating surface. Neither (b) nor (c) was observed with a platinum wire. The heat-transfer rate increased suddenly when the flow configuration changed from (a) to (b). The transition in flow structure occurred when the temperature difference between the heater and fluid exceeded about 200 deg C.
Recalculation of Hilpert’s Constants
Authors: Fand R. M. , Keswani K. K.
Published: November 2010

In this paper, two new sets of constants are presented for use in conjunction with two empirical correlation equations that represent Hilpert’s data for heat transfer from cylinders to air in crossflow.
Non-Fourier Effects at High Heat Flux
Authors: Maurer M. J. , Thompson H. A.
Published: November 2010

This brief investigates analytically non-Fourier effects in high flux conditions using the relaxation model for heat conduction. Unlike the Fourier model, the relaxation model predicts an instantaneous jump in the surface temperature of solids subjected to a step change in the surface heat flux. Under sufficiently high flux, 107 w/cm2, this jump in temperature may be several hundred degrees in magnitude, resulting in severe thermal stresses at the surface.
Stability of Buoyant Boundary Layers and Plumes, Taking Account of Nonparallelism of the Basic Flows
Authors: Haaland S. E. , Sparrow E. M.
Published: November 2010

Consideration is given to the linear stability of buoyant boundary layers and plumes which belong to the class of flows for which (a) the streamwise velocity vanishes in the free stream and (b) the transverse velocity is inward-directed and has a finite value in the free stream. Disturbance equations for such flows are derived taking account of the fact that the basic flows depend upon the streamwise coordinate. The formulation is specialized to the case of the natural convection plume generated by a horizontal line source of heat. The existence of the so-called bottling effect is demonstrated, wherein the disturbance vorticity and temperature are contained within the boundary layer of the flow. The neutral stability curve exhibits both a minimum Grashof number and a lower branch, in contrast to the neutral curve for the conventional stability analysis, which does not exhibit these features. Consideration is given to the amplification of disturbances and to the frequencies which are the most amplified. Results are also presented for the limiting case of inviscid instability.
Transient Heat Transfer Analysis of Alloy Solidification
Authors: Muehlbauer J. C. , Hatcher J. D. , Lyons D. W. , Sunderland J. E.
Published: November 2010

Approximate solutions are obtained for the temperature distribution and rate of phase change for the transient one-dimensional solidification of a finite slab of a binary alloy. The alloy is selected to avoid the eutectic composition so that solidification takes place over a range of temperatures. The slab is initially superheated and has a uniform temperature distribution. Solidification occurs after one surface is cooled by convection while the other surface is insulated. Temperature distributions are determined analytically and experimentally and are in reasonably good agreement.
Experimental Measurement of Heat Transfer to a Cylinder Immersed in a Large Aviation-Fuel Fire
Authors: Russell L. H. , Canfield J. A.
Published: November 2010

Presented are the results of an experimental effort to quantify some of the heat transfer parameters pertaining to the luminous flame that results from the uncontrolled combustion of an 8-ft × 16-ft pool of JP-5 aviation fuel. The temperature and effective total radiant heat flux, both as temporal mean quantities, were measured as functions of position within the quasi-steady burning flame as it existed in a quiescent atmosphere. A grid of infrared radiometers and radiation-shielded thermocouples served as the primary sensing equipment. A determination was made of the perimeter-mean convection coefficient applicable to a horizontally oriented, smooth, 8.530-in-dia circular cylinder immersed at a particular location within the JP-5 flame. The value of this coefficient was the result of a solution to a nonlinear, inverse conduction problem in which the convective heat flux at the cylinder surface was estimated by utilizing a measured temperature history inside the cylinder. An expression relating this coefficient to more general flame/cylinder systems was developed.
An Experimental Study of Turbulent Heat Transfer in Converging Rectangular Ducts
Authors: Yang J. W. , Liao Nansen
Published: November 2010

The turbulent heat transfer rate, wall temperature, and pressure distributions in the hydrodynamically and thermally developing region of rectangular converging ducts of taper angle 0, 2-1/2, 5, and 7-1/2 deg have been determined experimentally. The heating condition is such that the top and bottom walls are uniformly heated while the two side walls are unheated. The fluid is air and the experiments cover the Reynolds number range from 2.4 × 104 to 4.8 × 104. The results show that the heat transfer coefficient is increased by the increasing of either the taper angle or the inlet Reynolds number. An empirical correlation between the local Nusselt number and the local Reynolds number was determined.
Theoretical Determination of Absorption With an Emphasis on High Temperatures and a Specific Application to Carbon Monoxide
Authors: Lin J. C. , Greif R.
Published: November 2010

The absorption of a vibrational-rotational band has been studied and the contribution from the first hot band has been included. A specific application has been made to carbon monoxide and good agreement with experimental results has been obtained.
An Exact Solution for the Flow of Temperature-Dependent Viscous Fluids in Heated Rectangular Ducts
Authors: Butler H. W. , McKee D. E.
Published: November 2010

An exact solution has been developed for the fully-developed flow of fluids having temperature-dependent viscosity and thermal conductivity in rectangular ducts with transverse heat conduction. The problem is uniquely defined in terms of four parameters: the height-to-width ratio, E, the product of the friction factor and the Reynold’s number, f·Re, the temperature ratio across the duct, T2/T1, and the exponent of the viscosity dependence on temperature. The results indicate that significant departures from the isothermal case may obtain for heated flows.
Cooling of a Very Hot Vertical Surface by a Falling Liquid Film
Authors: Sun K. H. , Dix G. E. , Tien C. L.
Published: November 2010

The present study analyzes the cooling of a very hot vertical surface by a falling liquid film. An analytical model is developed to characterize this phenomenon in three distinctive regions: a dry region ahead of the wet front, a sputtering region immediately behind the wet front, and a continuous film region further upstream. The analysis leads to predictions of the wet front velocity, the sputtering length, and the temperature profiles with respect to the wet front. The heat transfer mechanisms are shown to be dependent upon two temperature parameters characterizing the initial wall temperature and the temperature range for sputtering, and two Biot numbers comparing the convective heat transfer in the liquid film region and the sputtering region with longitudinal heat conduction. The predictions are in good agreement with existing experimental results.
Plume Rise From Large Thermal Sources Such as Dry Cooling Towers
Authors: Sneck H. J. , Brown D. H.
Published: November 2010

An experimental study of the dry buoyant plume rise from a finite size source into a stably stratified atmosphere has been performed. The test results are correlated with a recently published theory, which is shown to be applicable to a wide range of discharge conditions. Methods for predicting the height of the stratified plume accumulation, as well as the maximum rise height of the plume are presented.
Heat and Mass Transfer of Spray Canals
Authors: Porter R. W. , Chen K. H.
Published: November 2010

A numerical analysis is presented for the heat-exchanger performance of open, direct-contact evaporative spray cooling of large electric power plants. Floating spray modules are placed essentially in series in this large-scale application. The module “unit performance” is formulated in terms of Number of Transfer Units (NTU) as suggested by elementary drop dynamical theory. The overall canal performance is analyzed by a numerical procedure of marching along from pass to pass of spray modules. Hydrodynamic mixing within the canal and air-vapor circulation interference above the canal are incorporated as suggested by theoretical considerations and field experiments. The analysis was applied to a number of field tests of several spray canals and the apparent values of NTU were correlated with wind speed.
Two-Dimensional Transient Temperature Distribution in Cylindrical Bodies With Pulsating Time and Space-Dependent Boundary Conditions
Authors: Copley J. A. , Thomas W. C.
Published: November 2010

The two-dimensional conduction equation is solved for a hollow cylinder subjected to a series of heat flux pulses on the inner boundary. The periodic heat flux is represented by an exponentially decreasing pulse with a spatial distribution of peak magnitude. The analytical techniques and representation of the boundary conditions apply to different situations involving pulsating boundary conditions. An application to the gun barrel heating problem is given. Calculated bore surface and internal temperature histories are in good agreement with experimental data. During the actual firing time in rapidly-firing guns, results show that external cooling is generally ineffective for controlling barrel bore surface temperature.
A Numerical Method for Heat Conduction Problems
Authors: Reiser M. J. , Appl F. J.
Published: November 2010

A singular integral method of numerical analysis for two-dimensional steady-state heat conduction problems with any combination of temperature, gradient, or convection boundary conditions is presented. Excellent agreement with the exact solution is illustrated for an example problem. The method is used to determine the solution for a fin bank with convection.
Steady Conduction of Heat in Linear and Nonlinear Fully Anisotropic Media by Finite Elements
Authors: Padovan J.
Published: November 2010

Using a constrained variational procedure, a finite element approximation is developed which can treat steady heat conduction in anisotropic media whose thermal material properties may be spatially, as well as, temperature dependent. Based on the element approximation, the numerical results of several linear and nonlinear steady conduction problems are presented. These reveal the important effects of thermal material anisotropy.
Laminar Forced Convection Over Rotating Bodies
Authors: Chao B. T. , Greif R.
Published: November 2010

A simple computational procedure is described for ascertaining the heat or mass transfer in laminar forced convection over a rotating body of revolution. The analysis is applicable to nonuniform surface condition and for fluids having a large or a moderate value of the Prandtl (Schmidt) number. Examples are given to illustrate the usefulness of the analysis as well as to expose its limitation.
Heat Conduction in Solids With Random Initial Conditions
Authors: Ahmadi G.
Published: November 2010

The problem of heat conduction in solids with random initial condition is studied. A general theory is first discussed and several examples are considered. It is observed that the homogeneity of the random initial condition is sufficient for the homogeneity of the temperature field in an unbounded domain. But in bounded domains the random temperature field becomes nonhomogeneous even though the initial condition is homogeneous.
Low Knudsen Number Heat Transfer From Two Spheres in Contact
Authors: Morrison F. A. , Reed L. D.
Published: November 2010

Heat transfer from an acrosol aggregate composed of two touching spheres is investigated analytically. In the range of interest, the Knudsen number is small and the Peclet number negligible. The Nusselt number of a sphere is found to be reduced by the presence of a neighbor and by temperature jump. Expressions for the Nusselt number are obtained.
A Generalized Prediction of Heat Transfer Surfaces
Authors: LaHaye P. G. , Neugebauer F. J. , Sakhuja R. K.
Published: November 2010

A new way of presenting the heat transfer data is shown. This leads to a dimensionless performance plot between a “heat transfer performance factor” and a “pumping power factor” with a nondimensional “flow length between major boundary layer disturbances” as a varying parameter. This approach leads to the possibility of approximately presenting all surface geometries on a single “idealized” performance plot, the nondimensional “flow length” being a geometrical characteristic of each surface. The method can be used to predict approximately the heat transfer performance characteristics of a new, untested surface. The plot permits the rapid assessment and comparison of various heat transfer geometries for a given application. The performance plot is valid only in the turbulent flow regime. The method will prove invaluable in optimizing a design accounting for space limitations, economic restraints, and system considerations such as pumping power and effectiveness tradeoffs.
Modified Single-Blow Technique for Performance Evaluation on Heat Transfer Surfaces
Authors: Liang C. Y. , Yang Wen-Jei
Published: November 2010

The existing single-blow, maximum-slope transient technique has been commonly applied for determining heat transfer performance of heat exchanger units or surfaces. However, results lack in accuracy and technical difficulties arise when it is applied to heat exchanger surfaces or units with NTU value smaller than 3.5. In the present paper, a modified single-blow technique is developed which can be applied to systems of any NTU values. Both theoretical analysis and experiments are performed. The validity of the present technique is borne out by the good agreement between experimental data and the existing theoretical solutions.
An Analytical Investigation of Forced Convection Heat Transfer to Fluids Near the Thermodynamic Critical Point
Authors: Sastry V. S. , Schnurr N. M.
Published: November 2010

A numerical solution is carried out for heat transfer to fluids near the thermodynamic critical point for turbulent flow through a circular tube with constant wall heat flux. An adaptation of the Patankar-Spalding implicit finite difference marching procedure is used. Agreement of the results with experimental data for water and carbon dioxide show the solution to be quite accurate very near the critical point provided the wall temperature at inlet is less than the pseudocritical temperature of the fluid.
Graetz Problem in Curved Square Channels
Authors: Cheng K. C. , Lin R. C. , Ou J. W.
Published: November 2010

Thermal entrance region heat transfer problem in curved square channels is solved by a numerical method for the two basic thermal boundary conditions of constant wall temperature and uniform wall heat flux by including the curvature ratio effect in the formulation as an independent parameter. Solutions are obtained for Pr = 0.1, 0.7, 5, 10.05 and 500 and Dean numbers ranging from 0–488. Local Nusselt number results are qualitatively similar to those reported in the literature for the case of curved circular pipes. The numerical results for the asymptotic Nusselt number agree well with the only experimental data available for the case of uniform wall heat flux. A correlation equation for the asymptotic Nusselt number is proposed.
Effect of Uniform Rotation on Streamlines in Benard Convection Cells Induced by Surface Tension and Buoyancy
Authors: Gopalakrishnan Nair C. V.
Published: November 2010

The work of Nield [1] is extended to include the effect of uniform rotation about a vertical axis. As the rate of rotation increases the velocity perturbation vector becomes more and more symmetrical with the midlayer for buoyancy driven convection, and asymmetrical for surface tension driven convection. The result which shows that the rotation weakens the coupling of the buoyancy and surface tension forces is confirmed.
Extrapolation Errors in Thermal Contact Resistance Measurements
Authors: Thomas T. R.
Published: November 2010

In the classic split-bar determination of thermal contact resistance the temperature drop across the interface is estimated by extrapolating a temperature gradient measured remotely. It is shown that this can give rise to substantial errors which cannot greatly be reduced by increasing the number of measurements. It is suggested that due to extrapolation errors few interface temperature drops have ever been determined to better than 1/2 °K, and that this may account for some of the discrepancies between published contact resistances, particularly those measured at high loads.
The Modeling of a Thermosyphon Type Permafrost Protection Device
Authors: Reid R. L. , Tennant J. S. , Childs K. W.
Published: November 2010

One promising device for protection of permafrost is the concentric tube thermosyphon. In the winter, the difference in temperature between the annulus and the tube provides a buoyant driving force to move the air down the tube and up the annulus. The resultant heat transfer freezes and subcools the permafrost. The paper describes in detail the flow and heat transfer by solving the boundary layer equations for velocity and temperature considering conduction and radiation at the boundaries. The predicted thermosyphon performance is compared with experimental data. The results for heat removal rate are generally within 10–20 percent.
A Note on Howard’s Model for Turbulent Natural Convection
Authors: Davenport I. F. , Judson King C.
Published: November 2010

A model for turbulent natural convection based on the cyclic destruction and rebuilding of the boundary layer has been proposed by Howard [6]. A close look at more recent experimental data shows that the boundary layer is probably not destroyed as Howard postulated, but is stable with thermals growing upon it and producing the periodicity of the phenomenon. A modified model is proposed.
The Thermodynamics of Water Transport From Biological Cells During Freezing
Authors: Silvares O. M. , Cravalho E. G. , Toscano W. M. , Huggins C. E.
Published: November 2010

A thermodynamic model for the freezing of biological cells has been developed and has been applied to human erythrocytes. Analytical expressions describing the dynamics of water loss during the several stages of the freezing process have been derived from a cell modeled as an open system surrounded by a membrane permeable to water only. The permeability of the membrane to water is the most significant cell parameter in this process and in the present model, and is assumed to be a function of the temperature and osmolality of the extracellular solution. The resulting set of differential equations describing the cell freezing process is solved numerically for various cooling rates. For cooling rates less than 3000 K/min, erythrocytes lose 95 percent of their intracellular water before the eutectic temperature is reached. For cooling rates greater than 3000 K/min, the fraction of intracellular water remaining at the eutectic temperature is a strong function of cooling rate. The effect of supercooling of the extracellular solution on the kinetics of the cell water loss is also analyzed. As a consequence of the supercooling, the volume of water present intracellularly at a given temperature is substantially greater than when no supercooling occurs. This condition favors intracellular ice formation and is consistent with experimental observations in this laboratory.