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-   -   Why is the pressure larger than the total pressure (http://www.cfd-online.com/Forums/cfx/109103-why-pressure-larger-than-total-pressure.html)

greatwall November 9, 2012 04:41

Why is the pressure larger than the total pressure
 
I am simulating a gas flow through a rotating multi-channels with CFX, both the inlet and outlet are the Opening boundary condition. While the inlet has a reletive pressure of 4atm, and the outlet of 2atm, rotation speed is 10000r/min. When I look the result of my computation, at the inlet plane, the pressure is larger than the total pressure, how could this happened?

ghorrocks November 9, 2012 05:30

Can you show some images of what you are seeing?

greatwall November 9, 2012 06:07

http://b310.photo.store.qq.com/psb?/...ORAQAAAAADADI!

[IMG]
These are the inlets, the range of the contour is local, from the picture we can see that the pressure is larger than the total pressure in the inlets plane, I don't know why.

ghorrocks November 9, 2012 06:09

Sorry, I do not download files from other websites. Please post them as attachments to this post (using "Go Advanced").

greatwall November 9, 2012 06:12

[IMG]http://b323.photo.store.qq.com/psb?/V13rxVKa3rhjqK/dwmy9NgB8guQ2FZrPtVmGUFOOzoOhbMyE*ps3QsggBA!/b/dGl*isCnAAAA&bo=hAOAAQAAAAADACM![/IMG]

greatwall November 9, 2012 06:24

2 Attachment(s)
Attachment 16781

Attachment 16782

ghorrocks November 9, 2012 06:36

We will need to see a bit more of the geometry to make any sense of it. Can you post an image which shows what the flow is actually doing?

Also, is this boundary on a rotating frame of reference? Multiphase? Does it have reverse flow?

greatwall November 9, 2012 06:51

1 Attachment(s)
This boundary is on a rotating frame of reference, no multiphase. The geometry is a turbine blade internal cooling channel, in the computation, the trailing edges did have reverse flow.
Attachment 16788

ghorrocks November 9, 2012 16:22

Where is the axis of rotation for the domain?

greatwall November 9, 2012 21:36

The axis of the rotation is on the negative y direction

ghorrocks November 11, 2012 06:10

I see. I cannot explain what you are seeing.

What does the total pressure in the stationary frame of reference look like?

greatwall November 12, 2012 21:49

The problem has been solved. Thank you! When I put the total pressure in the stationary frame of reference, the result is correct.


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