Radial Load calculation

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.

Many thanks for your quick reply.

Regards

ghorrocks · March 31, 2010, 17:51

Then do a surface integral of pressure.

March 31, 2010, 04:35	Radial Load calculation	#1
pump_passion New Member NA Join Date: Jul 2009 Posts: 11 Rep Power: 16	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.

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March 31, 2010, 07:02		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	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?

March 31, 2010, 07:26		#3
pump_passion New Member NA Join Date: Jul 2009 Posts: 11 Rep Power: 16	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. Many thanks for your quick reply. Regards

March 31, 2010, 17:51		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Then do a surface integral of pressure.