Hello erwin, apologies for bringing up an an already resolved topic but may I ask how you were able to resolve yours? I'm running a similar simulation with another type of spiral turbine and have run into this same issue.
I'm just doing a transient analysis. I set the rotating domain to dead zone and kept the turbine and outer domain as fluids as per this guide [CFD ANSYS Tutorial - Wind Turbine Simulation Using Dynamic Mesh and 6 DOF - YouTube] at about 53:08.
The construction of the geometry was a turbine made in solidworks, then brought to design modeler for creating a cylindrical rotating enclosure and a larger rectangular stationary enclosure. I did the meshing in fluent in accordance with the guide above (used face sizing on the inner rotating domain, generated surface mesh with some tweaking, no inflation layer, shared topology, polyhedral with growth of 1.4 instead of tetrahedral).
What could I be doing wrong?