||November 19, 2004 14:17
PDF with Compressibilty Effects
I have a debate here with a collegue. We are conducting a first time CFD study here dealing with a gas turbine combustor connected to the high pressure turbine nozzle. The fast is that one of the guys here states that Fluent does not correctly predict compressibility results from the Partially Premixed PDF model within the high pressure nozzle due to the fact that the PDF was created using one pressure. I disagree with him since Fluent updates the values from the PDF table to account for the varying pressure difference within the combustor and HPT nozzle. I mean this is stated in the manual. My collegue assumes that there will be large pressure differences between a model using pure air and using the ideal-gas law turned on compared to the model that used the partially premixed PDF with compressibility effects, so he wants to turn off compressibilty effects. But the fact is that the HPT nozzle creates compressible flow and it would be computationally incorrect to model this case as a incompressible flow. I would like to know if anyone out in the Fluent forum can give their feedback about this or perhaps has done this experimentally or numerically.