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-   -   MRF Solver fan simulation - problem (http://www.cfd-online.com/Forums/fluent/113221-mrf-solver-fan-simulation-problem.html)

sivakumar February 15, 2013 04:26

MRF Solver fan simulation - problem
 
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Hi Guys,

Good morning to every one,

I am OpenFOAM user, I am working on axial flow fan. To check the OF result, I am trying to simulate the case in Fluent (This is my first case in Fluent for ever).

I am using MRF - steady state solver in Fluent,
First I tried a passage of a fan (see fig-1 pdf), I got good torque and fluxes but I didnt check the pressure raise. I got good agreement with experimental torque (79 N-m).
I thought the simulation is right, now I am not sure about it.

Secondly, I tried 2 blade with quarter of the cylinder (see fig-2 pdf), I ran the case with same setup, but the torque is strange I got twice of the passage case (168 N-m).

expected torque is 70-80 N-m

I am totally confused, please help guys

Fluent case setup is as follows:

i) Mesh --> check --ok

ii) General --> type - Pressure Based, absolute, and time--> Steady

iii) Material --> air (I didn’t change the properties)

iv) Cell Zone Conditions --> I have 3 zones namely IV - Inlet Volume, FV - Fan Volume and OV - Outlet Volume. here I have selected the Fan Volume --> Frame motion, rotation axis origin - (0 0 0),
rotation axis direction (0 0 1),
rotational velocity (78.54 rad/s)

v) BC's
All periodic I have given Rotational (It was Translational)

Fan

wall motion -->Moving wall
motion --> Relative to adjacent Cell Zone and Rotational
speed --> 0 rad/s
rotation Axis Origin --> (0 0 0)
Rotation axis Direction (0 0 1)

Is the settings are correct? if not what should I change?
please give me some hit, what is going wrong.

Thanks for your time and help,
Sivakumar


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