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Heat Transfer From Radiatively Heated Material in a Low Reynolds Number Microgravity Environment.


pdf icon Heat Transfer From Radiatively Heated Material in a Low Reynolds Number Microgravity Environment. (851 K)
Yamashita, H.; Baum, H. R.; Kushida, G.; Nakabe, K.; Kashiwagi, T.

Journal of Heat Transfer, Vol. 115, 418-425, May 1993.

Sponsor:

National Aeronautics and Space Administration, Washington, DC

Keywords:

heat transfer; reynolds number; microgravity; mathematical models; vapor phases; equations; fluid flow

Abstract:

A mathematical model of the transient three-dimensional heat transfer between a slowly moving ambient gas stream and a thermally thick or thin flat surface heated by external radiation in a microgravity environment is presented. The problem is motivated in part by fire safety issues in spacecraft. The gas phase is represented by variable property convection-diffusion energy and mass conservation equations valid at low Reynolds numbers. The absence of gravity and low Reynolds number together permit the flow to be represented by a self-consistent velocity potential determined by the ambient velocity and the thermal expansion in the gas. The solid exchanges energy with the gas by conduction/convection and with the surroundings by surface absorption and re-emission of radiation. Heat conduction in the solid is assumed to be one dimensional at each point on the surface as a consequence of the limited times (of order of 10 seconds) of interest in these simulations. Despite the apparent simplicity of the model, the results show a complex thermally induced flow near the heated surface. The thermal exchange between the gas and solid produces an outward sourcelike flow upstream of the center of the irradiated area and a sinklike flow downstream. The responses of the temperature fields and the associated flows to changes in the intensity of the external radiation and the ambient velocity are discussed.