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Kromagnsss July 1, 2010 03:06

Simulating a high pressure flow through a valve
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 180C

output : pressure outlet
gauge pressure 100 bar
temperature 140C

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...:mad:

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. ;)

-mAx- July 2, 2010 02:05

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

Kromagnsss July 2, 2010 02:38

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?


-mAx- July 2, 2010 03:44

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).

Kromagnsss July 2, 2010 03:50

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!

-mAx- July 2, 2010 04:16

For the compressible side of your project, check tutorial about "Modeling external compressible flow"

Kromagnsss July 2, 2010 04:34

No matter that my project is internal flow?

-mAx- July 2, 2010 05:18

I don't think there is huge difference.
You may also check tutorial "Modeling Unsteady Compressible flow" (internal)

Kromagnsss July 2, 2010 05:20

Ok thank you a lot i will say if that worked or not and post some results ^^

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