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 pump_passion March 31, 2010 04:35

Dear All,

I am trying to calculate the radial load on a volute of a centrifugal pump using the function FORCE of CFX_Post.

I have obtained too high results for the forces:
Fx=5030N
Fy=7032N
Fz=negligible

My pumps makes an head of 177m, SG=1, D2=580m, b2=34mm (disks included), running speed=1740 rpm, NS=382

If I use the empirical formula (Lobanof & Ross) for the calculation of radial load, I obtain a total radial force of about 750N... which is far from the results calculated with CFX.

I need to calculate the pressure resultant on volute in radial direction (radial thrust). I think that the proble is the function FORCE of CFX doesn't consider only pressure forces.

Could anyone help me???

Thanks a lot.

Regards.

 ghorrocks March 31, 2010 07:02

The force function includes both pressure and wall shear forces.

The pressure force is worked out relative to the reference pressure. Have you taken that into account?

 pump_passion March 31, 2010 07:26

No problem for the refence pressure, I have an axial symmetric surface. I made also some test changing the reference pressure and results doesn't change. What should I set to take in account only pressure forces and not shear stress forces.