# Centrifugal pump query

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 May 16, 2022, 13:49 Centrifugal pump query #1 Member   Vivek MJ Join Date: Oct 2020 Location: India Posts: 50 Rep Power: 3 Hi, i am running a centrifugal pump simulation in 2d in Ansys fluent 19. It is a steady state frozen rotor simulation with water as the working fluid. No cavitation is being considered, no slip. The impeller rotates at 2800 rpm. The boundary condition for inlet is Mass flow rate and the BC for outlet is pressure outlet. The pump has 7 blades with vaneless diffuser. Here is a list of boundary conditions- Mass flow rate Pressure 0.00001 176325 0.3846 161325 0.667 141325 1.0345 111325 After completing the simulation, i have found the head of the pump for different boundary conditions from the formula: Head = (Total pressure outlet - Total pressure inlet)/ (density of liquid* g) I have found that the value of the head starts at 11 (mflow = 0.00001) increases till 16 (mflow = 1.0345 as the mass flow rate increases. Is this correct? My other results like the contour and vectors are coming as expected. if not then what can i do?

 May 17, 2022, 01:29 Bump #2 Member   Vivek MJ Join Date: Oct 2020 Location: India Posts: 50 Rep Power: 3 ***bump***

 May 17, 2022, 22:58 help please #3 Member   Vivek MJ Join Date: Oct 2020 Location: India Posts: 50 Rep Power: 3 help please

 May 18, 2022, 03:39 #4 New Member   Apoorv Shukla Join Date: Jul 2019 Location: Bengaluru Posts: 8 Rep Power: 5 Hi, Head should decrease with mass flow rate. Since you are considering no cavitation, try using velocity inlet and pressure outlet boundary condition as that us more compatible with incompressible flow. Apoorv

May 18, 2022, 11:42
#5
Member

Vivek MJ
Join Date: Oct 2020
Location: India
Posts: 50
Rep Power: 3
Quote:
 Originally Posted by apoorvs01 Hi, Head should decrease with mass flow rate. Since you are considering no cavitation, try using velocity inlet and pressure outlet boundary condition as that us more compatible with incompressible flow. Apoorv
Ok thank you, will try

 May 22, 2022, 11:38 Did not exactly work for me #6 Member   Vivek MJ Join Date: Oct 2020 Location: India Posts: 50 Rep Power: 3 Hi, the Boundary conditions did not exactly work for me as my journal has used mass flow inlet and pressure outlet for frozen rotor approach and the authors have gotten result. Any other suggestions are welcome.

 May 22, 2022, 23:54 Update to the problem #7 Member   Vivek MJ Join Date: Oct 2020 Location: India Posts: 50 Rep Power: 3 I discovered this page from fluent manual and decided to try increasing the rpm from 280 to 560 and to 1120 and finally to 2800 in a single case file. Doing so didnt help me much. i got the idea from this link. dropping it here, incase if anyone needs it for their simulation. https://www.afs.enea.it/project/nept...ug/node378.htm I am going to try running the simulation in high mass flow rate--> medium mass flow rate ---> low mass flow rate in the same case file and see if it helps me or not. If anyone has any ideas please give feel free to add.

 Tags centrifugal pump, cfd, fluent, head drop, parallel