CFX - Compressor Impeller

September 3, 2007, 06:53

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

September 3, 2007, 06:56

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...

cool_dude · August 8, 2009, 08:44

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..

September 3, 2007, 06:53	CFX - Compressor Impeller	#1
Dothan Guest Posts: n/a	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

September 3, 2007, 06:56	Re: CFX - Compressor Impeller	#2
Dothan Guest Posts: n/a	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...

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August 8, 2009, 08:44		#3
cool_dude New Member cool_dude Join Date: Aug 2009 Posts: 1 Rep Power: 0	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..