Efficiency prediction of centrifugal pumps in CFX
 

Dear all,
I have done a lot of simulations for centrifugal pumps in CFX, and I found that the efficiency prediction (ρgQH/Mω) is not accurate, especially for a centrifugal pump with very large flow rate as design point, for example, 10000 cubic meter per hour. At design point, the head result is acceptable, but the efficiency result is obviously lower than the test data. Does anybody have the experience about this? I will be very appreciated if you can explain to me.
Thanks a lot!
Ji

I have the same problem. Did you get any solution?

How are you computing the Moment ? I assume you use the torque variable in Post of blade, hub and shroud ? Are you modeling the side chambers ? This is obviously a simplification which will result in a difference in test data and simulation data. But, in my experience, the Efficiency would be higher then (without side chambers).
By which magnitude do the test data and CFD result differ ?
Convergence was reached, correct ? Is the mesh accurate enough ?
Are you evaluating your hydraulic data at a similar position like the test data, e.g. suction and discharge pipe position ?