Understanding of Pitch Change
 

Hi everyone,

I know there is a lot of tutorial material from ANSYS that deals with rotor stator problems and I went through it, but it is most often just telling me what to click and not what that really means. So even though I can set up similar problems I do not understand it in a way that would be helpful for "transfer problems".

That being said, I'll get to my problem straight away. I'm interested in the transient flow behaviour produced by a impeller rotating in a water filled tank.
I have a mesh containing a bit of the fluid region and the impeller and a second mesh containing the tank except for the part the first mesh consists of.
To reduce effort, I just modelled 90° of tank and impeller since it is four blade rotational symmetric.
Now I want to set it up as a transient rotor stator problem with the impeller containing mesh rotating in the tank mesh. I create periodic interfaces connecting the sides resulting from the 90° simplification and also three interfaces for the top bottom and front region where the two meshes touch and slide away from another(the rotating one rotates out of the other)

No here starts my confusion. Can i only use transient rotor stator appriach if I have the full 360°? Because I don't know how to set the pitch change. With 360° i could just say pitch change "none" right? But now i have to compute it somehow... The documentation says it is something like (360/#bladesRotor):(360/#bladesStator) but my stator doesn't have any blades. That was okay for the turbo tutorials. But is there a way to simulate rotor stator when the stator is just a tank without blades? Maybe my confusion already originates from the fact that i'm obviously not native english speaker and until now i thought a change in pitch has something to do with the frequency of sound... what actually is the pitch change here? Sorry if this question is super stupid....

I hope you can help me again, thanks for the effort!