Modeling a centrifugal fan
 

Can some one please tell me how to simulate a Centrifugal fan in CFX ?

Have a look at the tutorial examples, there are a few which use rotating frames of reference. Also look at the best practises guide for turbomachinery.

Hii I am also working on same domain.

Simulation has to be done with RFR (Rotating Frame of Reference). i.e, u need to select a domain (only rotating domain) and give that domain is rotating with desired RPM in Cfx-Pre. u can go through the help manual for robust bc`s.

If possible, Elaborate your problem description in detail, so that i can add some more points.