Labyrinth Seal (Axisymetric swirl flow)
 

Hi everyone,

I'm trying to solve sudden constricted channel flow with air, whose height and pressure differences are 0.15 mm and 5 to 3~10 bar for the general labyrinth seal. The diameter of a rotating shaft is 400mm and its speed is about 30000 rpm.

I applied pressure based 2D Axisymetric swirl to this problem and it converged very well up to about dp 1 bar between the inlet and exit. But, it does not work any more as dp inceases over 1.5 bar even with density based solution. I understand that flow would be chocked and has highly increased Mach number and has lots of discontiuity at throat (or constricted channel) in physics, and it causes the problem diverged directly.

Please advice me how to sep up the modeling and any tutorials related.
Thanks,