Turbine stage mixing plane calculation

Knut

Hi,

I am trying to run a mixing plane calculation on a 50% reaction low speed turbine stage (stator-rotor). Since the first iterations I have noticed that the static pressure in the mixing plane is oszillating and not settling down. Does anyone have some good suggestions how to solve this?

The stage is modelled with 10mio cells, unstructured, prismatic b.l. I'm running Fluent6.3 pressure based solver incompressible with a ke turbulence model. The flow does not settle in the rotor domain because the rotor inlet(mixing plane) pressure oszillates from -400 to -800 Pa when I am expection a pressure of -600 Pa from experiments. The oszilations are almost perfectly sinusodial with periodicity on about 150 iterations. I have already tried to decrease under relaxation value for the mixing plane but even if I put that to 0, amplitude and periodicity remain unchanged. That makes me think there is something fundamentally wrong in the case setup.

I would be very happy about suggestions that might solve the problem.

Cheers ... Knut