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Results for “CONDUCTIVE HEAT TRANSFER”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Effect of location in an array on heat transfer to a cylinder in crossflow

An experiment was conducted to measure the heat transfer from a heated cylinder in crossflow in an array of circular cylinders. All cylinders had a length-to-diameter ratio of 3.0. Both in-line and staggered array patterns were studied. The cylinders were spaced 2.67 diameters apart center-to-center in both the axial and transverse directions to the flow. The row containing the heated cylinder remained in a fixed position in the channel and the relative location of this row within the array was changed by adding up to five upstream rows. The working fluid was nitrogen gas at pressures from 100 to 600 kPa. The Reynolds number ranged based on cylinder diameter and average unobstructed channel velocity was from 5,000 to 125,000. Turbulence intensity: profiles were measured for each case at a point one half space upstream of the row containing the heated cylinder. The basis of comparison for all the heat transfer data was the single row with the heated cylinder. For the in-line cases the addition of a single row of cylinders upstream of the row containing the heated cylinder increased the heat transfer by an average of 50 percent above the base case. Adding up to five more rows caused no increase or decrease in heat transfer. Adding rows in the staggered array cases resulted in average increases in heat transfer of 21, 64, 58, 46, and 46 percent for one to five upstream rows, respectively.

Simoneau, R. J.↗
NASA NTRS2004

Brush/Fin Thermal Interfaces

Brush/fin thermal interfaces are being developed to increase heat-transfer efficiency and thereby enhance the thermal management of orbital replaceable units (ORUs) of electronic and other equipment aboard the International Space Station. Brush/fin thermal interfaces could also be used to increase heat-transfer efficiency in terrestrial electronic and power systems. In a typical application according to conventional practice, a replaceable heat-generating unit includes a mounting surface with black-anodized metal fins that mesh with the matching fins of a heat sink or radiator on which the unit is mounted. The fins do not contact each other, but transfer heat via radiation exchange. A brush/fin interface also includes intermeshing fins, the difference being that the gaps between the fins are filled with brushes made of carbon or other fibers. The fibers span the gap between intermeshed fins, allowing heat transfer by conduction through the fibers. The fibers are attached to the metal surfaces as velvet-like coats in the manner of the carbon fiber brush heat exchangers described in the preceding article. The fiber brushes provide both mechanical compliance and thermal contact, thereby ensuring low contact thermal resistance. A certain amount of force is required to intermesh the fins due to sliding friction of the brush s fiber tips against the fins. This force increases linearly with penetration distance, reaching ~1 psi (~6.9 kPa) for full 2-in. (5.1 cm) penetration for the conventional radiant fin interface. Removal forces can be greater due to fiber buckling upon reversing the sliding direction. This buckling force can be greatly reduced by biasing the fibers at an angle perpendicularly to the sliding direction. Means of containing potentially harmful carbon fiber debris, which is electrically conductive, have been developed. Small prototype brush/fin thermal interfaces have been tested and found to exhibit temperature drops about onesixth of that of conventional meshing-fin thermal interface, when fabricated as a retrofit. In this case, conduction through the long, thin metal fins themselves becomes a thermal bottleneck. Further improvement could be made by prescribing aluminum fins to be shorter and thicker than those of the conventional meshing-fin thermal interfaces; the choice of height and thickness would be optimized to obtain greater overall thermal conductance, lower weight, and lower cost.

Knowles, Timothy R.↗
NASA NTRS1972

Thermal history of the moon.

The thermal history of the lunar interior has been investigated for many sets of parameters and initial conditions by the construction of mathematical models. These models have been extended to include the effects of melting and redistribution of radioactive heat sources with time. The models considered include the possibility of heat transfer by lattice conduction, radiative transfer, removal of radioactive heat sources and, in a molten zone, fluid convection. The energy sources are divided into initial temperature sources that operate during the formation of the moon or shortly thereafter, and long-lived radioactive heat sources.

Reynolds, R. T.↗
NASA NTRS1993

High thermal conductivity of diamond

The objectives of this educational exercise were to demonstrate the high rate of heat flow from a synthetic diamond coupon and to compare it to a commonly used thermal conductor, such as copper. The principles of heat transfer by conduction and convection may also be demonstrated. A list of equipment and supplies and the procedure for the experiment are presented.

Stephan, Patrick M.↗
NASA NTRS1984

Heat transfer and oil flow studies on a single-stage-to-orbit control-configured winged entry vehicle

Results are presented for oil flow and phase change paint heat transfer tests conducted on a 0.006 scale model of a proposed single stage to orbit control configured vehicle. The data were taken at angles of attack up to 40 deg at a free stream Mach number of 10 for Reynolds numbers based on model length of 0.5 x 10 to the 6th power, 1.0 x 10 to the 6th power and 2.0 x 10 to the 6th power. The magnitude and distribution of heating are characterized in terms of angle of attack and Reynolds number aided by an analysis of the flow data which are used to suggest the presence of various three dimensional flow structures that produce the observed heating patterns. Of particular interest are streak heating patterns that result in high localized heat transfer rates on the wing windward surface at low to moderate angles of attack. These streaks are caused by the bow-shock/wing-shock interaction and formation of the wing-shock. Embedded vorticity was found to be associated with these interactions.

Helms, V. T., III↗
NASA NTRS1982

Applications of perturbation techniques

Two perturbation techniques were applied to two singular perturbation problems in heat transfer to obtain uniformly valid solutions which can serve as benchmarks for finite difference and finite element techniques. In the first problem, the method of strained parameters coupled with the application of a solvability condition is used to obtain a uniform solution for the problem of unsteady heat conduction in a long nearly circular cylinder. In the second problem, the method of matched asymptotic expansion coupled with Van Dyke's matching principle is used to obtain a uniform solution for the problem of one dimensional conduction-convection heat transfer of a uniform fluid flow.

Kandil, O. A.↗
NASA NTRS2017

Heat Loads Due to Small Penetrations in Multilayer Insulation Blankets

The main penetrations (supports and piping) through multilayer insulation systems for cryogenic tanks have been previously addressed by heat flow measurements. Smaller penetrations due to fasteners and attachments are now experimentally investigated. The use of small pins or plastic garment tag fasteners to each the handling and construction of multilayer insulation (MLI) blankets goes back many years. While it has long been understood that penetrations and other discontinuities degrade the performance of the MLI blanket, quantification of this degradation has generally been lumped into gross performance multipliers (often called degradation factors or scale factors). Small penetrations contribute both solid conduction and radiation heat transfer paths through the blanket. The conduction is down the stem of the structural element itself while the radiation is through the hole formed during installation of the pin or fastener. Analytical models were developed in conjunction with MLI perforation theory and Fouriers Law. Results of the analytical models are compared to experimental testing performed on a 10 layer MLI blanket with approximately 50 small plastic pins penetrating the test specimen. The pins were installed at 76-mm spacing inches in both directions to minimize the compounding of thermal effects due to localized compression or lateral heat transfer. The testing was performed using a liquid nitrogen boil-off calorimeter (Cryostat-100) with the standard boundary temperatures of 293 K and 78 K. Results show that the added radiation through the holes is much more significant than the conduction down the fastener. The results are shown to be in agreement with radiation theory for perforated films.

Structural attachments↗
NASA NTRS1971

Technique for measuring high-temperature thermal conductivity of solids by the use of a heat pipe.

A suggested technique for accurately measuring thermal conductivity of solids in the temperature range 800-1500 C is presented. The procedure employs the sample to be tested in series combination with a high-temperature heat pipe and a heat-transfer device, which has a variable thermal conductance. By changing the thermal conductance of the heat-transfer unit and measuring the change in heat-pipe power input to maintain a constant heat-pipe temperature, one can accurately measure the heat flux through the sample in conjunction with the temperature drop across it. This steady-state technique has some inherent advantages over methods currently employed to measure thermal conductivity at elevated temperatures.

Forman, R.↗
NASA NTRS2026

Hybrid Modeling Study on Grain Evolution in the Metal Welding Process and Its Potential Lunar Application

Metal is most commonly used structural material in a wide range of spacecraft, and welding is the principal method for joining metal components into functional systems. However, conducting welding experiments under extreme environments—such as microgravity or vacuum conditions in space—is prohibitively expensive and experimentally challenging. To overcome these limitations, multi-physics computational welding models provide a cost-effective and versatile alternative. In this work, the authors have developed a coupled thermal (fluid) microstructure simulation framework to model metal welding under varying gravity conditions. The framework integrates a mixed-mode heat transfer formulation (conduction, convection, and radiation) with molten pool fluid dynamics, enabling accurate prediction of temperature fields and weld-pool geometry. A grain growth model is further incorporated to capture the spatial and temporal evolution of microstructure, including grain size distribution and morphological transitions during solidification. This approach provides detailed insight into molten pool evolution and grain-level microstructure development throughout the welding process. By explicitly parameterizing environmental conditions, the model supports extrapolation to off-Earth manufacturing scenarios such as welding on the lunar surface. Tantalum—chosen in this study due to its high melting point, oxidation resistance, and mechanical stability at elevated temperatures—serves as the material system for model demonstration. Beyond Tantalum, the integrated multi-physics framework offers broad applicability for predictive welding simulations of various structural and refractory metals or alloys used in extreme terrestrial or extraterrestrial environments.

kinetic Monte Carlo (SPPARKS)↗
NASA NTRS1984

Effect of location in an array on heat transfer to a short cylinder in crossflow

An experiment was conducted to measure the heat transfer from a heated cylinder in crossflow in an array of circular cylinders. All cylinders had a length-to-diameter ratio of 3.0. Both in-line and staggered array patterns were studied. The cylinders were spaced 2.67 diameters apart center-to-center in both the axial and transverse directions to the flow. The row containing the heated cylinder remained in a fixed position in the channel and the relative location of this row within the array was changed by adding up to five upstream rows. The working fluid was nitrogen gas at pressures from 100 to 600 kPa. The Reynolds number range based on cylinder diameter and average unobstructed channel velocity was from 5,000 to 125,000. Turbulence intensity profiles were measured for each case at a point one half space upstream of the row containing the heated cylinder. The basis of comparison for all the heat transfer data was the single row with the heated cylinder. For the in-line cases the addition of a single row of cylinders upstream of the row containing the heated cylinder increased the heat transfer by an average of 50 percent above the base case. Adding up to five more rows caused no increase or decrease in heat transfer. Adding rows in the staggered array cases resulted in average increases in heat transfer of 21, 64, 58, 46, and 46 percent for one to five upstream rows, respectively. Previously announced in STAR as N82-19493

Simoneau, R. J.↗
NASA NTRS1992

The program FANS-3D (finite analytic numerical simulation 3-dimensional) and its applications

In this study, the program named FANS-3D (Finite Analytic Numerical Simulation-3 Dimensional) is presented. FANS-3D was designed to solve problems of incompressible fluid flow and combined modes of heat transfer. It solves problems with conduction and convection modes of heat transfer in laminar flow, with provisions for radiation and turbulent flows. It can solve singular or conjugate modes of heat transfer. It also solves problems in natural convection, using the Boussinesq approximation. FANS-3D was designed to solve heat transfer problems inside one, two and three dimensional geometries that can be represented by orthogonal planes in a Cartesian coordinate system. It can solve internal and external flows using appropriate boundary conditions such as symmetric, periodic and user specified.

Bravo, Ramiro H.↗
NASA NTRS2019

A Finite Volume Procedure for Thermo-Fluid System Analysis in a Flow Network

This paper describes a finite volume procedure for network flow analysis in a thermofluid system. A flow network is defined as a group of inter-connected control volumes called “nodes” that are connected by “branches”. The mass and energy conservation equations are solved at the nodes and momentum conservation equations are solved at the branches. The flow network also includes solid nodes to account for fluid to solid heat transfer. The heat conduction equation is solved at the solid nodes in conjunction with the flow equations. The properties of a real fluid are calculated using a thermodynamic property program and used in the conservation equations. The system of equations describing the fluid-solid network is solved by a hybrid numerical method that is a combination of the Newton-Raphson and successive substitution method. This procedure has been incorporated into a general-purpose computer program, the Generalized Fluid System Simulation Program, GFSSP. This paper also presents the application and verification of the method by comparison with test data for several applications that include (a) internal flow in a rocket engine turbo-pump, (b) pressurization and loading of a cryogenic propellant tank, (c) fluid transient during sudden opening of valve for priming of an evacuated feed line, and (d) chill down of a cryogenic transfer line with phase change and two phase flows.

Majumdar, Alok↗
NASA NTRS1950

Correlation of Forced-convection Heat-transfer Data for Air Flowing in Smooth Platinum Tube with Long-approach Entrance at High Surface and Inlet-air Temperatures

A heat-transfer investigation was conducted with air in an electrically heated platinum tube with long-approach entrance, inside diameter of 0.525 inch, and effective heat-transfer length of 24 inches over ranges of Reynolds number up to 320,000, average inside-tube-wall temperature up to 3053 degrees R, and inlet-air temperature up to 1165 degrees R. Correlation of data by the conventional Nusselt relation resulted in separation of data with tube-wall temperature. Good correlation was obtained, however, by use of a modified Reynolds number.

Desmon, Leland G↗