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-   -   good Cold Flow Results but problem with Hot Flow (http://www.cfd-online.com/Forums/fluent/41356-good-cold-flow-results-but-problem-hot-flow.html)

Rams June 12, 2006 10:14

good Cold Flow Results but problem with Hot Flow
 
Hello Friends,..

i have got good results in agreement with the experimental values for cold flow analyis,... but when am starting combustion on the same geometry,... am getting negative pressures at the throat of the inlet and oulet nozzles of the combustion chamber,... this negetive pressures is not dying down but going on increasing,...

am doing non-premixed combustion using mixture fraction/pdf model,...

am unable to locate where the problem lies,.. is it in the pre-pdf or any where else,...

My inlet boundry conditions for hotflow are

Pressure inlet : 60bar at inlet nozzle

Pressure oulet : 0bar (i.e atmospheric pressure ) at outlet nozzle

Wall Temperature : 500K

Operating pressure is 0 pa

Please help me in solving my problem,..

Thanks regards,..

Rams

Elteyeb June 18, 2006 19:59

Re: good Cold Flow Results but problem with Hot Fl
 
hello,

I did the same problem several years ago, I had the same problem, this problem arise from the jet back flow, apply negative pressure at the outlet, another solution is to make the out let geometry converge, i.e. reduse the cross sectional area of the burner far downstream.

Good luck!

Elteyeb


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