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-   -   Steam-Water Vertical Cyclone Separator (http://www.cfd-online.com/Forums/fluent/97486-steam-water-vertical-cyclone-separator.html)

Munggang February 18, 2012 01:09

Steam-Water Vertical Cyclone Separator
 
Hi,

I've seen interesting discussions on the cyclone separator in this forum. However, I still encounter some problems with my cyclone modelling. Hence, I'd be glad if somone can help me finding what's wrong with my set up parameters.

I'm working with cyclone separator commonly used in geothermal power station to separate steam and water from two phase fluid. The design is quite similar with cyclone separator used to separate gas and solid. The different is in the shape geometry and the directin of the inner pipe which goes into the bottom instead of the top (refer to this drawing http://postimage.org/image/mp5qddn2r/).

I use tetrahedrons for meshing.

I define the inlet as velocity inlet, the steam outlet as pressure outlet and the water outlet as pressure outlet. I use RSM model (mixture, slip velocity, number of eulerian phase: 2, reynolds stress, linear pressure-strain, wall reflection effects, standard wall functions).

For disretization, I use Simple, Green-Gauss Node Based, Presto!, 2nd order upwind, Quick, 2nd order upwind, 2nd order upwind.

The problem is the iteration never converges below 0.01 (I expect it to be as low as 0.0001). Besides, the result never indicates that the steam will move up the vessel, entering the inner vessel. It seems that the two phase fluid just go directly into the water outlet, without any swirling or cyclone movement.

Does anybody have any suggestion on this?

Thanks in advanced.

antu April 28, 2014 15:23

Hi,

I'm doing simulation of cyclone separator with different inlet tube angle. I've used steady-state solver with RSM model and inlet as velocity inlet, overflow at outlet and no-slip BC on wall. The problem is that after some iteration it got diverged and shows some error called Divergence detected in AMG solver: epsilon. I tried to fix the URF, but it does not work. I think its the meshing problem. I have used the hex mesh with 124314 nodes. Can anyone help me with the meshing??How could I fix the problem??

Munggang April 28, 2014 23:51

Hi Antu,

Try to refine the mesh. Try to use tetra instead of hex. You can also try to increase the number of nodes.


Cheers,
Munggang

Quote:

Originally Posted by antu (Post 488743)
Hi,

I'm doing simulation of cyclone separator with different inlet tube angle. I've used steady-state solver with RSM model and inlet as velocity inlet, overflow at outlet and no-slip BC on wall. The problem is that after some iteration it got diverged and shows some error called Divergence detected in AMG solver: epsilon. I tried to fix the URF, but it does not work. I think its the meshing problem. I have used the hex mesh with 124314 nodes. Can anyone help me with the meshing??How could I fix the problem??


antu April 29, 2014 13:38

Thanks Muggang for your reply.
I tried with tetra mesh as you suggested. But it didn't work. Do you have any suggestion on meshing?? I really need to know that. Any suggestion would be highly appreciated.

Regards,
Antu


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