# How to set up the runner rotation?

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 March 19, 2011, 02:59 How to set up the runner rotation? #1 New Member   Kooky Join Date: Mar 2011 Location: Thailand Posts: 20 Rep Power: 8 Dear All, I have a mini hydro system that consist of runner and giude vane. I would like to simlulate by using ANSYS CFX. The problem is how to set up the runner rotatation and fix the giude vane (stationary). Many thanks, Last edited by Kiat110616; March 19, 2011 at 03:15.

 March 19, 2011, 03:20 #2 New Member   Kooky Join Date: Mar 2011 Location: Thailand Posts: 20 Rep Power: 8 It should be split into three domain: runner domain, fluid domain, and guide vane domain. I have set up the fluid and guide vane domain as stationary and the runner domain as rotation. The results show that the streamline did not go through all domains. How to solve this problem? Thanks

 March 20, 2011, 21:57 #3 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,307 Rep Power: 110 Can you post an image?

 March 23, 2011, 09:15 #4 New Member   Kooky Join Date: Mar 2011 Location: Thailand Posts: 20 Rep Power: 8 Meshing of two fluid volume Meshing.jpg Set up the boundary condition - Runner domain is rotated - Guide vane domain is fixed (stationary) Setup BC.jpg Streamline plot Results.jpg Is this condition correct? Last edited by Kiat110616; March 23, 2011 at 09:53.

 March 23, 2011, 18:52 #5 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,307 Rep Power: 110 So what is your question? It looks like the streamlines are going through all domains to me.

 March 23, 2011, 22:29 #6 New Member   Kooky Join Date: Mar 2011 Location: Thailand Posts: 20 Rep Power: 8 I assigned the runner surface to rotate in the fluid domain with stationary condition at inlet, outlet, and fluid wall. The software cannot solve for result. It showed the message " The ANSYS CFX slover exited with return code 1. No results file has been created". So, I tried to modify fluid domain by separating the guide vane and runner domain as shown in the picture. I'm not sure it is correct because the streamline at interfaces of both domain it should be continuous curve. It should not be sharp. What do you think about that? Thanks Last edited by Kiat110616; March 24, 2011 at 10:01.

March 24, 2011, 09:23
#7
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Attesz
Join Date: Mar 2009
Location: Munich
Posts: 367
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Quote:
 I'm not sure it is correct because the streamline at interfaces of both domain it should be continuous curve. It should not sharp.
It is not all the same that you plot the streamline in stationary or rotating frame: if you can get sharp connections there, because you "loose" the circumferential component.

On the other hand, you have the slice the domain near the inlet and outlet regions of the rotor, so you get 3 domains as you have written above. Did you do so?

 March 24, 2011, 10:06 Dear Attesz, #8 New Member   Kooky Join Date: Mar 2011 Location: Thailand Posts: 20 Rep Power: 8 "It is not all the same that you plot the streamline in stationary or rotating frame: if you can get sharp connections there, because you "loose" the circumferential component." I'm a little confused. What do you mean by loose? Thanks

 March 24, 2011, 21:40 #9 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,307 Rep Power: 110 The sharp kink in the streamline is because you are using the variable "Velocity" for the streamlines, which is relative to the local frame of reference. At a change of frame of reference the velocity will not be continuous. If you use "Velocity in stationary frame" all the velocities will be relative to the stationary frame and your streamlines will be smooth.

 March 25, 2011, 13:20 Dear Ghorrocks, #10 New Member   Kooky Join Date: Mar 2011 Location: Thailand Posts: 20 Rep Power: 8 Thank you for your advice. I will try that and will let you know how it goes.

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