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-   -   Exporting Outlet Conditions to Inlet (http://www.cfd-online.com/Forums/cfx/98496-exporting-outlet-conditions-inlet.html)

viggi90 March 12, 2012 13:12

Exporting Outlet Conditions to Inlet
 
I am analysing a combustor running on producer gas as a part of my engineering project and have run into a slight problem

My combustor is finalised but the problem is i am getting huge variations in temperature at the outlet of it

So i would like to attach a device at the outlet of this combustor to reduce this temperature difference

The problem that i am facing now is in exporting and importing this data

I would like to export the outlet conditions of my combustor and import it as the inlet to my device.
Any help on how to do this will be greatly appreciated
Please provide me a detailed procedure since all my attempts on exporting the conditions and importing them seemed to have failed :(

I tried exporting CH4 mass fraction and a few others along with vel , temp , mass flow .

I also want to know whether a coordinate frame has to be created
http://www.edr.se/blogg/blogg/ansys_...ary_conditions
i referred to the above link but it hasn't helped me a lot

ghorrocks March 12, 2012 17:22

Sounds like you should use a periodic interface.

viggi90 March 13, 2012 00:42

Dear Ghorrocks
Please can you guide me on how to go about that ?

ghorrocks March 13, 2012 05:48

Use of periodic boundaries is described in the CFX tutorials. A number of them use periodic boundaries.

mescalito March 19, 2012 13:01

Hi viggi90,

I'm trying to do the same thing that you are interested. Please, if you make this procedure, could you describe it to me? I am trying to write a Fortran routine to make this periodic condition by Junction Box. Because the periodic condition available in CFX only accept constant properties. If i get this i'll tell you.

Regards.

ghorrocks March 19, 2012 19:38

Quote:

Because the periodic condition available in CFX only accept constant properties.
What do you mean? The CFX periodic boundary works fine with variable material properties. Or do you mean some other property?

mescalito March 20, 2012 08:18

Quote:
What do you mean? The CFX periodic boundary works fine with variable material properties. Or do you mean some other property?
ghorrocks,

Sorry, I agree with you, the CFX periodic boundary works fine with variable material properties. But, when I set the periodic condition with a source momentum, like mass flow or pressure drop, there is an error in CFX-Pre saying that the material properties have to be constant. Do you know how i can vary the material properties in this situation?

Regards!

ghorrocks March 20, 2012 17:15

Your comment is very strange. The periodic boundary settings have nothing to do with material properties. Can you post the CCL which is generating the error?

mescalito March 21, 2012 14:28

1 Attachment(s)
I don't know if all properties have to be constant, but there is a message in CFX-Pre saying that:

In Analysis 'Flow Analysis 1' - Domain Interface 'periodic': A Mass and Momentum model is only valid for periodic interfaces if all fluids have constant density.

Here is the ccl.

ghorrocks March 21, 2012 17:50

It is not the periodic interface which is the problem, it is the pressure jump you have specified at the periodic interface. It appears this is not compatible with variable density fluids.

I would remove the pressure jump at the periodic interface and define your own momentum source term to do it. Then you can specify the density/temperature effects across the source term and get around the limitation giving you the error message.


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