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Simulating a high pressure flow through a valve

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Old   July 1, 2010, 03:06
Arrow Simulating a high pressure flow through a valve
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Hi all!
I'm new on this forum and i request your help in simuling a fluid flow through a valve.
The simulations i tried until today where not satisfying.

Little sum up :
The valve aim is to make a detent from 229 to 100 bar nearly.
This is this kind of cage choke.
Choke Photo

I want to modelise air flow and then water flow, given that the valve is made to work on both of them.
For air flow i take these boundary conditions :
input : pressure inlet
gauge pressure 229 bar
initial / supersonic gauge pressure 220 bar
temperature 180°C

output : pressure outlet
gauge pressure 100 bar
temperature 140°C

I don't know if these parameters are correct for you?
Because with these pressures, when i simulate, at the second iterations the solver always send back error in AMG solver : temperature...

I'm not a pro in fluent and need perhaps a good tutorial in how to modelise the reality in the soft... do you know one?

Thank you for advance.
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Old   July 2, 2010, 02:05
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Maxime Perelli
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I would start with water flow and without energy equation.
Just a simple incompressible flowfield.
If you get correct results, then enable energy equation.

Then you may try with air flow, but I guess you will have to treat your problem as compressible
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Old   July 2, 2010, 02:38
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Hi -mAx-
Thx for your help!
Never tried water flow, i will try this evening!
Yesterday, with energy equation enabled and these parameters i get 1e+19 Pa in my results and 1e+5 in velocity... Something's wrong with my parameters...

Do you think i must add a pressure farfield before and after the valve?
Or a pressure/velocity inlet in a face is good?

Kro
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Old   July 2, 2010, 03:44
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If you know the massflow rate passing through your valve, I would work with velocity-inlet and pressure outlet combination.
But as I said, check first water flow (basic flowfield).
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Last edited by -mAx-; July 2, 2010 at 04:13.
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Old   July 2, 2010, 03:50
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Yes i will try this way, but is it possible (for the air or gas test) use the velocity inlet given that i will study a compressible fluid problem? Fluent says it's not possible!
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Old   July 2, 2010, 04:16
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For the compressible side of your project, check tutorial about "Modeling external compressible flow"
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Old   July 2, 2010, 04:34
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No matter that my project is internal flow?
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Old   July 2, 2010, 05:18
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I don't think there is huge difference.
You may also check tutorial "Modeling Unsteady Compressible flow" (internal)
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Old   July 2, 2010, 05:20
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Ok thank you a lot i will say if that worked or not and post some results ^^
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