[MarcoC501]

Dear all,

I am a newbie in foam-extend 5.0 and I would like to simulate the NASA 37 stage (rotor + stator), which I attach here for those who might not be familiar with that.

As standard practice to solve this steady-state problem, we can model only one blade passage and apply an interface treatment (e.g. mixing plane) between rotor and stator (to notice that the interface does not have the same area). In CFX, with the geometry attached and a good mesh the solution is well-converging and it leads to reasonable results. It is also important to point out that the stage is transonic and highly turbulent.

I wanted to simulate the same problem in OpenFOAM: after successfully simulating only the rotor, I now would like to add the stator and I tried several methods (all are using k-epsilon method and a robust PISO algorithm):
- steadyCompressibleMRFFoam with ggi interface: it diverges after around 100 iterations and the source of divergence seems to be the interface itself;
- steadyCompressibleMRFFoam with MixingPlane: it is crashing very fast, i also tried very low / 0 rotational speed but no improvement.

Have you ever had experience with that solver? What the problem might be in your experience?
If needed I could attach my BCs and the other files.

Thank you so much for your help :=)

[MarcoC501]

Apparently the source of all my problems is the pitch difference between stator and rotor. In fact I tried a simulation with the full annulus and both interface modeling approaches are woking.
It apprears strange to me that this problem does exist not only for the ggi interface but also for the mixing plane.
According to your experience, do you confirm that the mixing plane does not work with different pitches / number of blades?
Thanks a lot for your help and support