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Russ June 15, 2006 11:58

Axial Fan
Hi all,

Im after some help. Im trying to analysis a 3D axial fan, but its diverging after around 100 iterations and I can not seem to solve why.

I have modeled the fan with a static volume for inlet (volume 3) a static volume for the outlet (volume 4) and then a seperate volume that is the rotating reference frame around the fan (volume 2). The faces between the volumes have been connected. The mesh in the inlet and out let are resonable fine-course while the mesh around the fan is very fine.

I have applied pressure inlet and pressure outlet to the in and out flow boundaries. The set the rotational speed of the reference frame and applied relative speeds to adjactent cells for the fan surfaces, etc.

I have set Pisto for the Pressure solver, and second order for the other 3 models. I am using the KE turbulence model with realization.

I have set the operation pressure reference at the centre of the inlet.

I have initialised the solution from the inlet surface.

However, I am struggling to solve this solution, even with changing a number of parameter.

I was wondering if anyone has any tips when it comes to axial fans or solutions to my problem.

Many thanks in advance


Anonymous June 18, 2006 18:33

Re: Axial Fan
Do you need to model the fan explicitly? If not, why not try the fan boundary condition.

I use the fan boundary condition with a piecewise linear input derived from the manufacturer fan curve, and it performs reasonably.

sam June 21, 2006 01:20

Re: Axial Fan
wats difference between fan boundary condtion and solving it with MRF and mixing plane

Russ July 5, 2006 03:57

Re: Axial Fan
Hi Guys,

No I want to model the fan directly to analyse blade performance etc.

Can anyone help with this, Im really struggling to get it to work correctly?

Many thanks


sam July 5, 2006 06:45

Re: Axial Fan
can u desrbe ur fan . is this internal flow or wind turbine.

Russ July 5, 2006 09:18

Re: Axial Fan
Hi Sam,

Its a standard axial fan, check out the link below

I have removed the housing and created the MRF domind around the blade with the same venturi shape. I have discarded the hub supports.

any ideas?

Many thanks for your help


sam July 6, 2006 02:00

Re: Axial Fan
Dear Sir

So you have used the periodic boundary condtion and MRF . Thats nice, still u need some help! and in which direction. I will be glad to discuss with u some knowledge i have.


Russ July 6, 2006 05:14

Re: Axial Fan
Hey Sam,

Thanks for helping out, I am very grateful.

I chose not to use periodic BC in the end as I ran the model as a full 360 degree model.

I have having problems with divergence and also the results just do not look correct.

Do you have MSN so you can prehaps shed some of your knowledge to me in real time while I have fluent up and running??

many thanks


sam July 7, 2006 13:59

Re: Axial Fan
yes it is

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