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compressor problem.

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Old   September 26, 2008, 05:43
Default compressor problem.
  #1
john
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Hi friends,

I ran a case of centifugal compressor rotating at 1,00,000 rpm. I specified mass flow at inlet and pressure at outlet (2.5 bar). but I am really shocked wht i got. I got 2.7 bar inlet pressure (instead 1.012bar.) Was I wrong to put mass flow at inlet? Should I use pressure at inlet and pressure at outlet.But if I am using pressure bcs, how can I achieve mass flow rate??? pls clarify. thanks a lot.
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Old   September 26, 2008, 18:09
Default Re: compressor problem.
  #2
Clifford Arnold
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When I solve a problem like this I use Total pressure at inlet and static pressure at outlet. I believe this is preferable to other options. The solver should generate the appropriate massflow for the pressure head it is working against.

When you provide a massflow at the inlet this is ill-posed. The massflow is governed by the rpm and blade profile of the impeller and the resistance of the static pressure at the outlet.
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