[vivjk94]

i am trying to simulate a steady state simulation (moving reference frame) of centrifugal pump using fluent. The centrifugal pump is pumping water and its impeller has 7 blades rotating at 2800 rpm. The inlet of the pump is pressure inlet at 0 Pa and the outlet of the pump is mass flow rate of 1.0345 kg/s. i would like to plot head vs flow curve. I figured out how to find the head of the pump from fluent post. i would like to find the volumetric flow rate of the pump. i am no expert in cfd.
My question is -
1. will it be viable if i convert the mass flow rate outlet (kg/s) to m^3/s by multiplying density? like divide 1.0345 /1000 .
2. should i find out the mass flow rate from post and convert it to m^3/s?
3. is there any better way of finding the volumetric flow rate of the centrifugal pump?

Kindly help

[LuckyTran]

1. yes
2. isn't this the same as 1?
3. You can also integrate the velocity over the outlet boundary but that should give you the same result as 1 unless you made a mistake

P.S. Due to the way boundary conditions work , a mass flow constraint is usually applied to a pressure outlet BC template and the actual mass flow rate you get from CFD may be a slightly different number. If the solution is well converged they should be close but it is not unthinkable for you to end up with a massflow of 1.0342 for example.

P.P.S. for a fixed rotational speed, a centrifugal fan/pump is a fixed displacement device and has a nominally constant volumetric flowrate. In order to get the fan curve you have to simulate various rotational speeds and this curve is only useful if the fan/pump has a variable speed drive attached to it.

[vivjk94]

Originally Posted by LuckyTran

1. yes
2. isn't this the same as 1?
3. You can also integrate the velocity over the outlet boundary but that should give you the same result as 1 unless you made a mistake

P.S. Due to the way boundary conditions work , a mass flow constraint is usually applied to a pressure outlet BC template and the actual mass flow rate you get from CFD may be a slightly different number. If the solution is well converged they should be close but it is not unthinkable for you to end up with a massflow of 1.0342 for example.

P.P.S. for a fixed rotational speed, a centrifugal fan/pump is a fixed displacement device and has a nominally constant volumetric flowrate. In order to get the fan curve you have to simulate various rotational speeds and this curve is only useful if the fan/pump has a variable speed drive attached to it.

Thank you for your response. I used report definitions and i got -1.0345 kg/s at outlet. i will convert it to m3/s. i would also like to know how does one extract meridional velocity at impeller? can you help me with that?