Green`s function and two-flux analysis for transient radiative transfer in a composite layer
- NASA Lewis Research Center, Cleveland, OH (United States)
A method is developed for obtaining transient temperatures in a two-layer semitransparent gray composite. Each boundary of the composite is exposed to a hot or cold radiative environment, and is heated or cooled by convection. A Green`s function solution is derived for the two-flux radiative transfer equations, and this solution is coupled with the transient energy equation. The refractive indices of the layers are larger than one, and the analysis includes internal reflections at the boundaries and the internal interface that are assumed diffuse. Internal emission, absorption, heat conduction, and isotropic scattering are included. An advantage of the method is that it incorporates isotropic scattering without additional complexity. Typical results using the Green`s function method are verified by comparison with finite-difference solutions using the exact radiative transfer equations; very good agreement is obtained. Transient temperature distributions are given to illustrate the effect of radiative heating on one side of a composite with cooling on only the other side, and the protection of a material by placing a layer with various amounts of scattering between it and a radiative source. The effect on transient temperatures is demonstrated when using a layer with a higher or lower refractive index than that of the protected material. Heat capacity in a coating can be evaluated for its effect on delaying the thermal response within a composite suddenly subjected to radiation.
- OSTI ID:
- 395260
- Report Number(s):
- CONF-960815--; ISBN 0-7918-1507-2
- Country of Publication:
- United States
- Language:
- English
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