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-   -   How to set BCs for 3D double inlet centrifugal fan (http://www.cfd-online.com/Forums/fluent/28649-how-set-bcs-3d-double-inlet-centrifugal-fan.html)

siswara June 28, 2001 00:20

How to set BCs for 3D double inlet centrifugal fan
 
I am modelling 3D double inlet centrifugal fan, and the problems is how to set the correct BCs (interface) & MRF. Is there any tutorial online about this??

Lanre June 28, 2001 10:00

Re: How to set BCs for 3D double inlet centrifugal
 
http://www.fluentusers.com/fluent5/d...ml/node223.htm

Chetan Kadakia July 1, 2001 01:52

Re: How to set BCs for 3D double inlet centrifugal
 
Could you give a little more decscription to your problem? I'm guessing you'll need two pressure inlets, one pressure outlet, and two interface b.c.'s.

siswara July 2, 2001 05:40

Re: How to set BCs for 3D double inlet centrifugal
 
Thanks before to Mr Chetan and Mr Lanre, Here is my problem descriptions : 1. My model consists of inlet duct(45 deg),impeller

and scroll housing. Since my model is symmetry in y-direction, I plan to make a half from the model, but is it allowed/valid? 2. Which MRF should I use ? single rotating reference,

mixing planes or sliding mesh ? 3. Where should I put BCs for interface, is it in the

input and outlet of impleller? 4. My colleague suggested me to use tfilter to combine

two meshes , is it right ? 5. I have tried many times to iterate it, but

the results is always divergence, eventhough

I have reduced relaxation number.How do I solve it?

I need desperately your help, I'll appreciate any help

Chetan Kadakia July 2, 2001 22:23

Re: How to set BCs for 3D double inlet centrifugal
 
I am not an expert, but I am working on similar things. First tell me what are you trying to find? Is your flow steady or unsteady? You are allowed to make only half a mesh if it is symmetrical, but you have to use a symmetry boundary condition. But I think your mesh may work better if you use periodic boundary conditions instead because a turbomachine cut is like a piece of pie. i think your bc's for your interface boundaries should be 'interface'. I suggest that you see Fluent tutorial 18 and Fluent tutorial 16. Do you have access to these tutorials and their meshes? Look through those, develop confidence in your set up and then lets talk about convergence.


siswara July 5, 2001 01:41

Re: How to set BCs for 3D double inlet centrifugal
 
Thanks for the reply, My model is steady flow, and I want to make flow simulation inside the fan. I do have access to those tutorials, but when I tried tutorial 15, the result was not converge. I have followed all the step in those tutorials except the dimension which I create myself ( but still similar).

Could you tell me, are there any other tutorial online, especially that discuss Rotating problems.

Chetan Kadakia July 5, 2001 01:47

Re: How to set BCs for 3D double inlet centrifugal
 
How about the other tutorials (16, 17, and 18)? Did you try them? Try the tutorial 15 again but with their dimensions just to make sure your approach was right.

And too many people in this forum ask for help and say it doesn't converge but they never give greater details or talk of there procedure.

So give us full details and then we can help you better.


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