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 Marcos October 7, 2008 11:03

axisymmetric nozzle analysis

I am doing an air compressible nozzle simulation. I know that I have to draw a 5 degrees part of the nozzle. I already did it in solidworks. What to do next? I have done this simulation in 3D, but using half of the nozzle drawing and assuming a symmetry plane. In this case the solution is taking to much time to converge. Many thanks in advance.

 Glenn Horrocks October 7, 2008 20:19

Re: axisymmetric nozzle analysis

Hi,

CFX cannot do true 2D axisymmetric simulations. This is one of the biggest short comings of the software against its competitors, so what you have done is the correct approach.

Make sure the wedge has only one element in the thickness. Otherwise that's all you can do in CFX. If you are going to do a lot of 2D simulations I would consider going to another code which supports true 2D and they will run much faster.

Glenn Horrocks

 Marcos October 8, 2008 07:11

Re: axisymmetric nozzle analysis

Thanks for the answer. When I did half of nozzle, I choose a SYMMETRY plane for the problem in order to calculate the flow, pressure, MACH and so on. Now with 5 degrees nozzle, what condition on the lateral faces (not inlet or outlet OK) I must choose to properly represent the problem (360 degrees)? Is it a must condition to fix one element in the thickness or I could divide the thickness in more elements (it will increase precision calculations even if needs more computational time)? I see a figure on CFX site of a similar problem, but applied to mechanical problem, and it shows more elements in the thickness. Again many thanks for your time in giving me this help. Marcos Theiss Neves

 rohit October 8, 2008 07:23

Re: axisymmetric nozzle analysis