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-   -   Impact temperature on an aircraft (http://www.cfd-online.com/Forums/fluent/91632-impact-temperature-aircraft.html)

Santos-Dumont August 17, 2011 12:01

Impact temperature on an aircraft
 
Hi,

I would like to simulate the temperature of the surface of a flying aircraft. The main point of interest is the impact temperature on the leading edges to determine icing datas.
I didn't succeed in modeling it with Fluent. I used different models (Laminar, Spalart Allmart, k-Espilon) with a coupled solver but I get unsatisfying results.
The thing is quite disturbing because after like 20 iterations I get a result that looks pretty good with a higher temperature on the leading edges. But when I iterate more the aircraft surface temperature become constant except for some small hot and randomly located zones.
I activated the viscous heating, and I set the wall and the external temperature at the same value (240 K). The flow speed is 180 m/s and the air density 0.5 kg/m3.

What would you do to solve such a case in terms of model, boundary settings....? There is no tutorial that is about the impact temperature.

Santos-Dumont August 17, 2011 18:44

I made some extra tests on a simple cube but I get divergent results after 200 iterations, no matter which solver I chose.
Do somebody have some pieces of advice to share about this viscous heating on a wall ?

Santos-Dumont August 18, 2011 12:01

My test on the cube finally succeed with the Coupled k-epsilon solver.
Still, when I try it on the real geometry, I get the message "Time step reduced for xx cells" after like 200 iterations, and the residuals are diverging a few iterations later...

I read that it's due of sudden changes of temperature between iterations and that it could be caused by wrong solver setup...

Can someone help me out ?


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