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Boundary Condition for 2D simulation of Turbo-machinery

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Old   January 16, 2017, 07:33
Exclamation Boundary Condition for 2D simulation of Turbo-machinery
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Vishal
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Dear users,
This is first time i am doing a 2D analysis, since 3D un-steady analysis will involve huge computational time.
I am planning to do a 2D un-steady analysis to simulate the effect of on-coming wakes on LPT Vane boundary layer and blade loading by using Fluent. For simulating wakes I am using cylinder upstream of LPT Vane(picture enclosed).I have the following queries

1. What should be the boundary condition for LPT Vane Edges which I have marked with red line, if I am doing a 2D analysis how does I specify periodicity (rotational) or does it is required.Edges with black line are for inlet and outlet.
2. Same is for the hole mesh.
3. Does I have to do a axi-symmetric analysis or 2D planar.

I have attached two mesh pics one that of hole and other one for LPT Vane.
Thanks in advance for your valuable input.
Attached Images
File Type: png vane.PNG (19.6 KB, 3 views)
File Type: png hole for wake.PNG (13.2 KB, 3 views)
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Old   January 17, 2017, 19:07
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Lucky Tran
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If I understand correctly, I guess you will do a sliding mesh and have a moving wake pass through?

You would not be able to do this in an axissymmetric simulation. This looks to be 2D-planar. I wonder if there is some cute transform or option to make it 2D-curvillear but I do not know off the top of my head.

  • Vane walls should be no-slip but moving walls. Remember to set the wall velocity.
  • Between vanes, edges of mesh should be periodic BC's with 0 pressure gradient.
  • And then inlets and outlets.
Are you sure you cannot afford it in 3D? You only need to resolve the wake passing frequency so the computational expense is not too bad in my opinion. But experience with the 2D case would be helpful.
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