Fan Boundary Condition In CFX
 

Hi,


I am simulating a cooling process according to the following Model. This model has two centrifugal fan. Blades are not designed in the fans and so I want to apply a Fan BC in these Fans. How can I do it in CFX?

Is it possible to create a circular face inside the fans to apply this BC?


http://uupload.ir/files/52oq_111.png




http://uupload.ir/files/kfw6_222.png

If you want to simulate a simplified model of the flow generated by the fan, but not actually model the fan itself then use a momentum source term.

Yes you are right.

Your mean is: I should create a circular zone(cell volume or cell zone) inside the Fans and the Circular zone rotated by a rotational velocity. Yes?

The source term approach can be considered a lumped approach. This means that the entire pump device can be just replaced by a box with a source term in it which generates a flow to approximate the pump. So you don't model the pump motion such as the rotation of the impeller; you just model the inlet and outlets, connected with a duct with the source term applied to it.

Thanks your reply.


Could you please explain me how to apply monument source in CFX for above problem?

The CFX tutorial examples have examples of this. I think they use a heat source term in the heating coil example. The concept is to the same for a momentum source.

I have also removed a portion of the model, and use an outlet and inlet pair on the faces of the void. Inlet would have its flow properties equal to the corresponding outlets. For example Temperature definition of Inlet would be massFlowAve(T)@Outlet + something if you wanted to include any additional heat from the fan. Same goes for turbulence, species etc.
Momentum Source is probably more accurate than the simplified inlet/outlet approach though.

Thanks your reply.




For my case, How can I remove a portion of the model to create inlet and outlet in the fan?


I think that I can't remove a portion of the model in my case...

Hi,


How can I set "total fluid mass source" and "total mass source pressure coefficient" and cylindrical velocity components" in the following picture?




http://uupload.ir/files/kino_44.png




http://uupload.ir/files/ttcq_22.png




http://uupload.ir/files/1e45_33.png



http://uupload.ir/files/o8uh_222.png


I am grateful that guide me in these cases....


Thanks.

Can I use "source point" for the fans?

Your previous post suggests you don't have much of an idea about source terms. This is because you have selected the option to do a continuity source term (ie, to generate or destroy mass), not the option to apply momentum to it.

You should not apply a concept you do not understand to your complex model. I recommend you do a simple test model, where the geometry is just a box and the source term is just applied to a box subdomain inside that, and apply the different options and start learning how source terms work, and what the various options mean.

The first thing you will find out is that you will want to apply a momentum source term, not a continuity source term :)