Hi All, I am interested in simulating flow in a centrigufal compressor using CFX-TASCFLOW. Following are the conditions, what I applied for initial run. 1. rfr with specified omega 2. Walls stationary with relative frame of reference 3. Inlet with total pressure 4. Outlet with mass flow specified. I started with incompressible , turbulent flow, air is the fluid. I am not getting rise in pressure from inlet to outlet. What could be the casues ?

Thanks for your time. Veebs

Is your guess appropriate? Did it converge? What interface is it frozen or? What time step?

Veebs,

How have you defined the inlet direction components?

Robin

Hi Erich /Robin, Thanks for your time. simulation aimed for only the impeller.So have one doimain defined as rotating. Solution is converged. But it shows decrease in pressure / total pressure from inlet to outlet. (no pressure rise). At the inlet, total pressure normal to the surface is defined. Thanks again Veebs

Hi Veebs,

Defining the direction vector to be normal to the inlet face results in a vector which is normal to the face relative to the rotating frame, thus resulting in a high degree of pre-whirl and corresponding drop in pressure rise.

Re-define your inlet velocity components to be axial and you will get the pressure rise you expect.

Best regards, Robin

What about the direction of rotation? If you rotate it in wrong direction, you could get this problem. Give it a try.

Drona