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William Blake February 20, 2000 03:29

CFD for temerature measurement
 
I have proble in calculating temperatures on the surface of vehicle at hyperonic mach numbers. At subsonic mach numbers, it is a practice to cosider body as an adiabatic surface. This is certainly not valid at hypersonic Mach #. Can any one has successfully done these calculations. Any refence would be of immense help.

Bob Anderson February 20, 2000 03:51

Re: CFD for temerature measurement
 
Sounds like you don't have enough information to solve the problem yet. Is your vehicle reaching thermal steady state? If so, where is the heat being drawn off to if it is not essentially an adiabatic surface?

Bob

clifford bradford February 20, 2000 17:32

Re: CFD for temerature measurement
 
if you assume the body is heat soaked then can't we use the adiabatic bc as a best guess. otherwise there is no reasonable way to specify thermal bc without doing conjugate heat transfer. i guess you'd need some first guess on a heat transfer distribution.

John C. Chien February 22, 2000 13:16

Re: CFD for temerature measurement
 
(1). The adiabatic condition certainly can be used in the analysis, unless one is concern about the real condition. (2). Depending upon the Mach number, (at Mach 4, things would be all right), the viscous heating eventually will exceed the melting point of the material at much higher Mach number. (3). At Mach 8, the real gas effect will set in, and at even higher Mach number, the chemical reactions in the boundary layer must be included. (4). At extreme Mach number, special silicon tiles must be used, like those used on the space shuttle. (5). Or, very thick carbon composite material can be used by releasing the heat through burning of the material. In that case, mass transfer in boundary layer will have to be considered. There was a book on hypersonic viscous boundary layer published in 60's. There are also more recent books on hypersonic flows, by Anderson? Look into AIAA journals, you should be able to find the right information you need.


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