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good Cold Flow Results but problem with Hot Flow |
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June 12, 2006, 11:17 |
good Cold Flow Results but problem with Hot Flow
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#1 |
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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 |
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June 13, 2006, 00:31 |
Re: good Cold Flow Results but problem with Hot Fl
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#2 |
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I presume it is a pretty weak constraint on the sytem With pressure condition at the inlet and at the outlet.
Are you sure the results have converged for this case. Try to calculate the velocity at the inlet and change the inlet condition to the same. Regards Rajit |
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June 13, 2006, 04:30 |
Re: good Cold Flow Results but problem with Hot Fl
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#3 |
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Hello Sir,...
My results are not converged but after around some 1000 or 1500 iterations the when i check the pressure,.. there is negative pressure at the throat of the inlet and outlet nozzle,............... if am continuing iterations the whole pressuree in the combustion chamber is becoming negative,................ I'll try what eveer suggestions u have made,.. thanks,... regards, Rams |
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