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RESEARCH PAPERS

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):273-278. doi:10.1115/1.3679931.

A general solution for the transient temperatures and thermal stress is obtained for a right circular cylinder with internal heat generation varying exponentially with the radius by use of Hankel transforms. Curves for the maximum thermal stresses are presented for diameter ratios up to 1.2 and for a variety of internal heat-generation rates for internal heat-generation transients with both cylinder walls maintained at zero reference temperature at all times.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):279-290. doi:10.1115/1.3679932.

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

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):294-302. doi:10.1115/1.3679937.

The effects of mass injection or removal at the surface of a rotating disk on heat transfer and on the flow field about the disk are studied. Consideration is given to gaseous systems which are composed of either one or two component gases. Solutions of the equations which govern the hydrodynamics, energy transfer, and mass diffusion have been obtained over the entire range from large suction velocities to large blowing velocities. Results are given for the velocity, temperature, and mass-fraction distributions, as well as for the heat-transfer, mass-transfer, and torque requirements. The effects of the mass transfer are discussed in detail. It is shown that fluid injection sharply decreases the heat transfer at the surface.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):303-312. doi:10.1115/1.3679938.

Experimental results are presented for the effectiveness and for the heat-transfer coefficient for a film cooling system in which air was used both for the film and for the free-stream fluids. Injection occurred at a single tangential slot near the leading edge of the plate and the slot size was varied. All flows were turbulent and the injection velocities covered a range from much less to much greater than the free-stream velocity. Correlations are realized for both the effectiveness and for the heat-transfer coefficient and, as in the past experience with such systems, separate specifications are needed for injection velocities greater and less than the free-stream velocity.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):313-324. doi:10.1115/1.3679941.

Data are reported on rates of sublimation mass transfer from an adiabatic, sharp-edged flat plate exposed to air streams at Mach numbers of 0.43, 2.0, and 3.5. Thickness decrease of the subliming naphthalene coating, plate surface temperature, and flow conditions were measured. An analysis of friction and heat transfer in turbulent compressible flow has been extended to mass transfer at low rates. Agreement between theory and data is good over the entire range of Reynolds numbers from 3 × 104 to 9 × 106 . The effect of compressibility on mass transfer is found to be slightly greater than on friction. The measurement of the sublimation rate of thin coatings of solids provides a powerful technique of obtaining local friction coefficients, being simpler and of a wider applicability than the method involving force measurements on small floating surface elements.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):333-339. doi:10.1115/1.3679946.

The problem of heat transfer to liquid metals with variable physical properties for the case of fully developed turbulent flow in cylindrical tubes of constant diameter is studied, the fluid under consideration being heated or cooled by a constant and uniform heat flux at the wall. The similarity theory between momentum and heat transfer is used. Using the von Karman universal velocity profile the differential equations for turbulent flow with heat transfer are solved for the Prandtl number and the kinematic viscosity, each having five different sets of temperature-dependent exponents of a1 and a2 . Calculated temperature distributions, mixing-cup temperatures, as well as relations between Nusselt versus Peclet numbers are presented for the cases of heat addition, heat extraction, and the nonvariable-property case.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):341-348. doi:10.1115/1.3679951.

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

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):349-359. doi:10.1115/1.3679952.

Measurements of both the hydrodynamic and thermal characteristics of flow over an axial cylinder at subsonic speeds are reported. It was found that the boundary layer along an axial cylinder tends to become asymmetrical as it approaches the transition point. This asymmetry vanishes again in turbulent flow. For both laminar and turbulent flow, the average boundary-layer growth could be predicted by the standard flat-plate relationships, and simple methods were deduced for determining the effective hydrodynamic length of the boundary layers. Local and total heat-transfer measurements were made with both laminar and turbulent flow for various unheated starting lengths followed by linearly increasing wall temperatures. For laminar flow, agreement with theory was obtained, this agreement being improved by the Seban and Bond cylindrical curvature correction. The turbulent-flow results indicated preference for the theory of Seban. Isothermal equations represent turbulent heat transfer within approximately 20 per cent when the wall-temperature variations are not too abrupt.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):360-368. doi:10.1115/1.3679953.

Heat flux conveyed by diffuse radiation from surface A1 and A2 through an absorbing medium is expressed by the relation

Q1−2 = J1 ∫A1×A2 f(l12)
  (cos θ1 cos θ2/πl122)dA1dA2
where J1 is the radiosity of A1 (sum of the emitted, reflected, and transmitted flux per unit area), l12 is the radiation beam (the distance between surface elements dA1 and dA2 ), θ1 and θ2 are the angles between the radiation beam and the normals to the surface elements, and f(l12 ) is the function describing the absorption law. The foregoing four-dimensional integral is transformed into a sum of one-dimensional integrals for the cases of opposite-parallel and adjoining-perpendicular rectangles. The results are suitable for numerical integration with any total absorption law obtained from the actual distribution of monochromatic absorptivities over the whole spectrum.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):369-374. doi:10.1115/1.3679956.

Thermal radiation is considered from the inside surface of a heated cylindrical enclosure. A specified heat input is imposed at the enclosure wall and the surface temperature distribution is determined. The analysis considers both black and diffuse gray-body radiation and obtains a simple relation between the two. The energy equation, which is a linear integral equation, is solved by three methods: (a) Use of a separable kernel; (b) numerical integration; and (c) variational methods.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):375-380. doi:10.1115/1.3679957.

A variational method is presented for solving a class of integral equations which arise in radiation heat-transfer problems. First, to demonstrate the formulation of radiation problems in terms of integral equations, consideration is given to a system consisting of two nonblack, finite, parallel plates. After a general description of the variational method, its use is illustrated by application to the parallel-plate system. Comparisons are made which show very good agreement with exact solutions.

Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):381-386. doi:10.1115/1.3679961.
Abstract
Commentary by Dr. Valentin Fuster

DISCUSSIONS

TECHNICAL BRIEFS

J. Heat Transfer. 1960;82(4):387-388. doi:10.1115/1.3679964.
Abstract
Commentary by Dr. Valentin Fuster
Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):392-393. doi:10.1115/1.3679966.
Abstract
Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):393-396. doi:10.1115/1.3679967.
Abstract
Commentary by Dr. Valentin Fuster
J. Heat Transfer. 1960;82(4):396-398. doi:10.1115/1.3679968.
Abstract
Commentary by Dr. Valentin Fuster

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