Centrifugal Compressor BC

Tobi

Hello, I`am simulating a Centrifugal Compressor Stage with StarCD 3.26.

I use the MRF implicit steady state approach with only one mesh passage region. The grid structure is

Upstream H-Block (UH)-> Blade O-Block (OB) -> Downstream H-Block (DH) with surrounding cyclic periodics.

UH and DH have spin index with zero rotation speed, OB a spin index with nonzero rotation speed.

Because am going to compare the calculation results with experimental data following BC must be applied:

Inlet: absolute Totalpressure, absolute Totaltemperature, velocity direction

Outlet: mean static Pressure

Until now I tried BC combination Inlet+Pressure (1), Pressure+Pressure (2) and Stagnation+Pressure (3) for Inlet and Outlet Region. Unfortunately the following problems/ questions occur:

- How to set known Total Inlet BC (1) ? - How to avoid disorientated flow field after initialisation with low inlet and high outlet static pressure (2) ?

- How to set up stagnation BC right (I received a somewhat error message: difference between static and total pressure is lower than zero with calculation breakup before first iteration ) (3) ?

Perhaps anybody is able to help me with the prescribed problems. Thanks Tobi.