Interface between a stator-rotor with sudden change in flowpath of the turbine

mitra22 · May 18, 2015, 14:04

Hi ! Every one.. I have so far successfully carried a good number of single stage and multistage turbine simulations using the stage interface option.

Now I have a problem in which the flow path is not continuous i.e. there is a sudden step in the flow-path hub and shroud radii from stator to rotor domain.There are 10 stator blades and 27 rotor blades.

Usage of stage interface gives a different mass flow rate at the stator outlet and rotor outlet domains (flux is conserved as it should be) but i want to avoid this flux scaling. Mass flow in stator and rotor domains should be equal.

Kindly suggest an option where such sudden changes in area can be handled along with frame change(stationary to rotational domains). I have the flexibility to alter the geometry slightly by displacing the rotor a little downstream.

Thanks in Advance.

Opaque · May 18, 2015, 21:56

I do not understand your requirement than the mass flow through the stator must be equal to the mass flow through the rotor.

That can only happens if your model is the full stator with the full rotor, or the pitch of both the stator and the rotor is the same.

If you are modeling a reduced number of passages on both components, the mass flow through each component must be different; otherwise, you will violate conservation of mass.

Thomas MADELEINE · May 19, 2015, 05:07

We already discuss on subjects like that on this thread. I agree with Opaque, you should always keep the massflow constant on your physical domain, not always on your mathematical one...

http://www.cfd-online.com/Forums/cfx...t-details.html

May 18, 2015, 14:04	Interface between a stator-rotor with sudden change in flowpath of the turbine	#1
mitra22 New Member AGNIMITRA Join Date: Jan 2013 Posts: 8 Rep Power: 13	Hi ! Every one.. I have so far successfully carried a good number of single stage and multistage turbine simulations using the stage interface option. Now I have a problem in which the flow path is not continuous i.e. there is a sudden step in the flow-path hub and shroud radii from stator to rotor domain.There are 10 stator blades and 27 rotor blades. Usage of stage interface gives a different mass flow rate at the stator outlet and rotor outlet domains (flux is conserved as it should be) but i want to avoid this flux scaling. Mass flow in stator and rotor domains should be equal. Kindly suggest an option where such sudden changes in area can be handled along with frame change(stationary to rotational domains). I have the flexibility to alter the geometry slightly by displacing the rotor a little downstream. Thanks in Advance.

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May 18, 2015, 21:56		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,873 Rep Power: 33	I do not understand your requirement than the mass flow through the stator must be equal to the mass flow through the rotor. That can only happens if your model is the full stator with the full rotor, or the pitch of both the stator and the rotor is the same. If you are modeling a reduced number of passages on both components, the mass flow through each component must be different; otherwise, you will violate conservation of mass.

May 19, 2015, 05:07		#3
Thomas MADELEINE Senior Member Thomas MADELEINE Join Date: Oct 2014 Posts: 126 Rep Power: 12	We already discuss on subjects like that on this thread. I agree with Opaque, you should always keep the massflow constant on your physical domain, not always on your mathematical one... http://www.cfd-online.com/Forums/cfx...t-details.html