Modeling of centrifugal fan in CFD

Simon Williams

Hello,

I am trying to optimize a centrifugal fan impeller in CFD with a set inner radius, outer radius and angular velocity. I am dubious to include any form of volute or casing in my model as I do not want to influence the performance of the impeller as much as possible. My understanding is that the following equation can be used to evaluate the performance of the fan design.

Efficiency = Q Î"P/W

Q = Volumetric flow rate (m/&rho Î"P = Total pressure increase across the fan (P2-P1) W = Work (ωT)

My question is where exactly upstream and how far down stream should the pressures be measured? I am curious because I am currently measuring just up stream of the impeller leading edge and directly aft of the impeller trailing edge. I am worried that measuring the total pressures at these locations is over predicting fan performance. My models are suggesting forward-curved blades are superior to backward-curved blades which is not the case according to literature.

I would really appreciate some guidance as to how the optimization process of an impeller design should be conducted.

Thank you,

Simon