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-   -   Fluent Reversed Flow for a cascade simulation (http://www.cfd-online.com/Forums/fluent/111108-fluent-reversed-flow-cascade-simulation.html)

manukamin December 27, 2012 11:51

Fluent Reversed Flow for a cascade simulation
 
1 Attachment(s)
Hey guys,

I need to study flow properties for a particular cascade that I've designed. I tried out first with the simplest conditions using ANSYS FLUENT.

My fluid model in inviscid, incompressible(Euler) and subsonic. It is a compressor cascade configuration. Inlet condition is given to be velocity inlet and exit as outflow. The top and bottom surfaces are periodic (translational). I have attached an image of my geometry .

For this simple configuration, Fluent says there's reverse flow occuring on outlet face.
Would anyone happen to know what could be the possible reason?

msaeedsadeghi December 28, 2012 12:20

You may need to add a free channel to outlet.

itsqi7 January 24, 2013 23:15

Quote:

Originally Posted by msaeedsadeghi (Post 399330)
You may need to add a free channel to outlet.

Hi, could you pls specify how to add that? Thanks!

msaeedsadeghi January 25, 2013 01:18

Quote:

Originally Posted by itsqi7 (Post 403921)
Hi, could you pls specify how to add that? Thanks!

Add it in Gambit. Add a straight channel to it. Reverse flow will be disappeared if the length was enough.

itsqi7 January 25, 2013 01:20

Quote:

Originally Posted by msaeedsadeghi (Post 403928)
Add it in Gambit. Add a straight channel to it. Reverse flow will be disappeared if the length was enough.

Thanks for ur reply. It seems different from my problem. Could you pls explain my question?
http://www.cfd-online.com/Forums/flu...ow-output.html
Thank you.

msaeedsadeghi January 25, 2013 01:24

Which forces makes the oscillating flow? inlet or outlet condition causes it?

itsqi7 January 25, 2013 05:42

Quote:

Originally Posted by msaeedsadeghi (Post 403931)
Which forces makes the oscillating flow? inlet or outlet condition causes it?

actually it's the diaphragm between inlet and outlet causes the oscillating flow. Thanks.

msaeedsadeghi January 25, 2013 05:59

so both inlet and outlet do the same, at some time inlet and at the other time does as outlet. correct? Is your case unsteady?

itsqi7 January 25, 2013 16:41

Quote:

Originally Posted by msaeedsadeghi (Post 403972)
so both inlet and outlet do the same, at some time inlet and at the other time does as outlet. correct? Is your case unsteady?

Exactly,they r unsteady. In the first pi phase, there is inflow from the inlet and outflow at the outlet, and in the last pi phase, reversed flow comes from both of them.
Thanks.

msaeedsadeghi January 26, 2013 03:29

You should use pressure inlet for both outlet and inlet. For more configuration you should use a DEFINE_PROFILE udf.


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