# PUPM calculation

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 April 13, 2009, 06:56 PUMP calculation #1 New Member   Zvonko Kostovski Join Date: Apr 2009 Location: Skopje, Macedonia Posts: 13 Rep Power: 8 I'm having a problem calculating a pump (spiral pump inlet-impeller-pump spiral (outlet)) I'm using only frosen rotor (someone thold me that this is OK for calculating pump Q-H curve and efficiency) the problem is that I allvays get efficincy to be 3-6 %% less that is should be (in optimal point) an the q-h curve is not as expected in lower q than otimal it has lower H and for greater Q i get higher H than the expected curve this is what i do after starting CFX pre import meshes (gtm) (inlet-impeller-pump) for inlet I have mass flow (for example 300 kg/s) and for outlet preasure (0 Pa), what is the reference preasure ? (also 0 Pa or atmosphere preasure) and after the solver in CXF post, when I go to MAcro Calculator - > Liquid Pump Performance , what Reference Radius and Reference High mean (diameter of impeller / 2 and hight difference between inlet and outlet) Please someone help, I was traying to find tutorial for similar problem but only found one tutorial for axial turbine and that is very different I'm willing to give the files to someone who wants to help me solve this kind of problem Last edited by zona; April 13, 2009 at 12:38.

 April 14, 2009, 03:06 #2 Member   SanS Join Date: Mar 2009 Posts: 42 Rep Power: 8 Hi, Rather than using the macro, you would be better off to calculate the way you would do in a test rig. Determine the pressure head, velocity head, torque from POST and then calculate efficiency. Also read thru the ANSYS CFX Best Practices mentioned in the manual.

 April 14, 2009, 08:53 #3 New Member   Zvonko Kostovski Join Date: Apr 2009 Location: Skopje, Macedonia Posts: 13 Rep Power: 8 thanks, I'll tray it what is reference radius and hight I can't find definition in manuals

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