CFX - Compressor Impeller
 

Hi, I'm studing a centrifugal compressor impeller and I found some problems about BCs:

1 - Turbogrid define 2 surface, Inlet e Outlet surface; I think these surface serve to CFX-Pre for define the BCs. Unfortunately if I move the Outlet surface the solution change. Is better to fix outlet domain close o far from trailing edge?

2 - I know that "inlet pressure/outlet mass flow rate" and "outlet pressure/inlet mass flow rate" are most robust BCs, but my model converge only with "pressure inlet/pressure outlet".

3 - CFX-Post report a summary table with many variables @Inlet,@LE,@TE,@Outlet. I've noticed that Ttotal@TE<Ttotal@Outlet. Ttotal must change only inside the impeller...

many thanks for replyes

Re: CFX - Compressor Impeller
 

Errata corrige: 3 - CFX-Post report a summary table with many variables @Inlet,@LE,@TE,@Outlet. I've noticed that Ttotal@TE < Ttotal@Outlet. Ttotal must change only inside the impeller...

hi it' s better to place the outlet surface away from trailin edge.,to avoid any variations in results (due to flow fluctuations)

If u want that extende surface to be excluded from rotating domain...
u can use primitive region and select that patch alone (give th BC as Counter rotating wall) --- this will be to prevent that extra patch from addin additional momentum to fluid..