Learning Forum

[kiran.chikkamath]

I would like to know if we can specify impeller torque as an input in CFX-Pre and then measure the pump H-Q curve.

Background: In a "Pump A" If I maintain same RPM for pump and same Flow at outlet and suppose If I run the same Pump A with 2 different motor (2 different Power ratings) then I get 2 different H-Q curve for pump.

So how can I consider this input power as a variable in my impeller CFD simulation.

[C N]

Hello Kirankumar,

I would recommend you using vista cpd - for you . You just have to specify the  following inputs which is mentioned in the screenshot below , the vista cpd will automatically calculate the power from which you can adjust the torque because power is equal to torque * angular velocity . The angular velocity is radius of rotor *linear velocity. The linear velocity can be calculated from the speed of rotor ie.. pi*dia*N/60 for m/s and N in RPM. So by this way you can give torque as input and create a blade design accordingly so that you achieve the target  power in the results tab . Then use turbogrid for meshing and then use cfx pre and set the boundary conditions and perform a speedline analysis. I am attaching the how to do video link for your reference . Kindly follow this best practice for designing your centrifugal impeller.

(548) ANSYS CFX: Design and Analysis of a Pump Impeller - Part 1 - YouTube

(548) ANSYS CFX: Design and Analysis of a Pump Impeller - Part 2 - YouTube

I hope this helps you in your simualation.

Thanks,

Chaitanya Natraj

[kiran.chikkamath]

I have tried the Vista CPD for new impeller design. However here I am interested to input Power/torque as one of the CFX inputs. Scenario is If I have one set of impeller and volute and 3 different electrical motors to run the pump, impeller geometry remains same in all 3 configurations and 3 motors have different rotor ( winding) configuration. thus varying the power input to pump. If i maintain same speed in 3 different motor I get 3 different H-Q curves in these 3 cases. so in CFD how do i consider this power input change with same speed?