Heat Transfer From Radiatively Heated Material in a Low Reynolds Number Microgravity Environment.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899