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-   -   [Other] TurboGrid - problem with trailing edges ending with hub/shroud curve (http://www.cfd-online.com/Forums/ansys-meshing/96548-turbogrid-problem-trailing-edges-ending-hub-shroud-curve.html)

TTM January 25, 2012 11:47

TurboGrid - problem with trailing edges ending with hub/shroud curve
 
Dear cfd-online community

I am currently trying to create a mesh for a centrifugal pump impeller using TurboGrid:

sketch
http://www7.pic-upload.de/25.01.12/tfn9jdb4cgib.jpg

My problem is that the trailing edges of the impeller end on the same radial coordinates as the hub an shroud curves (please see sketch).
Furthermore I need an outlet domain where I can define interfaces to the volute and the side wall gaps (like on the sketch).
TurboGrid creates a valid geometry (including the outlet domain) with the curves I provide but when it comes to meshing TurboGrid meshes the outlet domain as an extension of hub and shroud (so I have no domain in which I can set up the interfaces to the side wall domains).
If I move the outlet domain marker (the white diamonds) so that the outlet domain begins immediately after the trailing edges TurboGrid creates inverted elements on the surface between the trailing edges.

None of the tutorials or thesis I found in which TurboGrid was used included such an impeller geometry.
Is it even possible to create a mesh with TurboGrid where the hub/shroud end the way they do in my case? Is there any error source I am overlooking?

Thanks in advance

Far January 25, 2012 12:20

please post pics of turbogrid where you are getting problem

TTM January 26, 2012 04:35

Thanks for your quick reply.

Here is a picture showing the inverted elements near the trailing edges:

http://www7.pic-upload.de/26.01.12/xk91s6ydbdoc.jpg

Far January 26, 2012 10:50

1) Extend your hub/domain few percents (atleast, but ideally should be mid way between two components and shall be used as interface) of chord to provide room to turbo-grid for its proper working.

2) You need to provide special instructions in turbogrid and turbogrid file for treating the flat trailing edge. Have you done this?

TTM January 26, 2012 20:11

I found a solution to this matter.

I had to change the hub/shroud curve approximation from bspline to piece wise linear and then check "line of rotation on hub and shroud" at the trailing edge definition field.


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