[Roose28]

Good day Sirs!

I am simulating a multiphase cross flow turbine and I uploaded 2 pictures as a reference for my 2 questions. One is a picture of my old model and the other is the new one.

I have three domains now (see reference picture). The brown one is the "CASING". The green one is the "BLADES". The blue one is the "INNER PART". Initially I only had two domains which is the CASING and the "Whole Rotor", but i separated the Whole Rotor to 2 parts as BLADES and INNER PART for meshing purposes.


Question on Domain Motion:
The CASING domain is set as stationary. The BLADES domain is set as rotating. should I set the INNER PART as rotating? or i should leave it as stationary?

Question on Interfaces:
2. the CASING and BLADES are connected via "Frozen Rotor" frame change setting. What should be my frame change setting on the interface between BLADES and INNER PART? Is it also Frozen Rotor?

Thank you very much sirs I got a bit confused as I separated the Whole Rotor domain to two parts.

[ghorrocks]

I would make it a rotating frame of reference because then you do not need a frame of reference change at the GGI.

[turbo]

At first, you will need small extensions upstream and downstream of the blade domain to ensure a good interfacing. If you want to get performance far downstream of the turbine blade, you will need to go with a separate stationary domain like you did for the new model. Since you have a 360 deg blade domain, no choices but to apply the frozen rotor if steady state solution is wanted. BTW what is the application and working fluid? Curious 'cause you said of multiphase.

[Roose28]

Originally Posted by turbo

At first, you will need small extensions upstream and downstream of the blade domain to ensure a good interfacing. If you want to get performance far downstream of the turbine blade, you will need to go with a separate stationary domain like you did for the new model. Since you have a 360 deg blade domain, no choices but to apply the frozen rotor if steady state solution is wanted. BTW what is the application and working fluid? Curious 'cause you said of multiphase.

Hi turbo, thank you very much for the help! i am simulating a cross flow turbine with air and water on it, i inputted them as standard homogeneous free surface model. I am still refining my settings. I left the Advanced Settings Tab of the Solver Control untouched; would you think changing the settings below would help? :

Body forces -> Volume-Weighted
Velocity Pressure Coupling -> Rhie Chow 4th
Multiphase Control -> Volume Fraction coupling

I did not have formal training on CFX and i cannot fully grasp the CFX guides.
Thanks turbo.

[Roose28]

Originally Posted by ghorrocks

I would make it a rotating frame of reference because then you do not need a frame of reference change at the GGI.

Thanks for the help Sir!

I am still refining my simulation, Should I include the following settings below? (for the Advanced Settings Tab of Solver Control):

Velocity Pressure Coupling -------> Rhie Chow 4th order
Multiphase Control --------> Volume Fraction coupling
Body forces --------> Volume-Weighted

I am using the default setting, wherein none of those three are set.
I cannot fully grasp their definitions in the CFX guide.