CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Why am I getting negative pressure head of the Centrifugal Pump through CFD?

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 17, 2021, 21:14
Default Why am I getting negative pressure head of the Centrifugal Pump through CFD?
  #1
New Member
 
Muhammad Ahmad Raza
Join Date: Jan 2021
Posts: 1
Rep Power: 0
raza48919 is on a distinguished road
Hello,

I'm working on the CFD analysis of a centrifugal pump (basically a left ventricular device, LVAD) having an impeller diameter of 31 mm only.

I've modelled the problem on Fluent and using k-epsilon (realizable) turbulence model. Moreover, I am employing the MRF (multiple reference frame) technique to give a rotation to the impeller of the pump. I'm using following conditions:

1) Inlet: mass flow inlet (0.04375 kg/sec)

2) Outlet: Pressure outlet (0 Pa)

3) Impeller Speed: 1000 RPM (Given to the impeller zone and walls)

Moreover, I've also tried moving mesh technique and checked the model for transients analysis as well but the resulting pressure head of the pump is negative (the pressure at the inlet of the pump is higher than that at the outlet). Hence, the pump is not creating the suction. I've tried different set of boundary conditions and different turbulence models, but I am getting the same problem again and again.

The results of the simulation with 0.04375 kg/sec flowrate (mass flow inlet), outflow outlet and the impeller speed of 1000 RPM are given below.
I am achieving a good convergence:

The mass flow at the outlet is:

The pressure at the inlet is:

The pressure at the outlet is:


Hence, the resulting differential pressure head is -1697-19=1716 Pa (which is against my expectation of getting the suction at the inlet). The model is doing good at higher speeds but at the impeller speed less than or equal to 1000 RPM it doesn't produce any suction. I've checked many times for the possible errors and everything seems fine.

If anyone can identify the cause of the problem and provide any assistance regarding its solution, it would of a great help for me.

Thank you!



Regards,

Ahmad
raza48919 is offline   Reply With Quote

Old   June 11, 2021, 14:23
Default Negative outlet pressure
  #2
New Member
 
Lamp
Join Date: Sep 2020
Posts: 10
Rep Power: 4
lampfall90@icloud.com is on a distinguished road
Hello dear, Did you find why you outlet pressure was negative? If yes , please heal me out I am facing the same problem. Thanks so much in advance
lampfall90@icloud.com is offline   Reply With Quote

Old   June 12, 2021, 04:23
Default
  #3
Senior Member
 
Join Date: Nov 2013
Posts: 1,965
Rep Power: 24
pakk will become famous soon enough
Flow goes from high pressure to low pressure, so it is completely normal that the pressure at the inlet is higher than at the outlet...
__________________
"The UDF library you are trying to load (libudf) is not compiled for parallel use on the current platform" is NOT the error after compiling. It is the error after loading. To see compiler errors, look at your screen after you click "build".
pakk is offline   Reply With Quote

Old   June 12, 2021, 05:15
Default
  #4
New Member
 
Lamp
Join Date: Sep 2020
Posts: 10
Rep Power: 4
lampfall90@icloud.com is on a distinguished road
Quote:
Originally Posted by pakk View Post
Flow goes from high pressure to low pressure, so it is completely normal that the pressure at the inlet is higher than at the outlet...
Thanks my Dear, But in pump we need to gain pressure like low pressure to high pressure to gain head
lampfall90@icloud.com is offline   Reply With Quote

Old   June 13, 2021, 06:28
Default
  #5
Senior Member
 
Join Date: Nov 2013
Posts: 1,965
Rep Power: 24
pakk will become famous soon enough
O I see, this is the inside of a pump. I thought it was about the outside effects of a pump.

(don't call people "dear" on the Internet. It sounds belittling and insulting. I assume you were not aware and did not mean to.)
__________________
"The UDF library you are trying to load (libudf) is not compiled for parallel use on the current platform" is NOT the error after compiling. It is the error after loading. To see compiler errors, look at your screen after you click "build".
pakk is offline   Reply With Quote

Old   June 16, 2021, 04:37
Default
  #6
Member
 
Vestdam
Join Date: Nov 2017
Posts: 41
Rep Power: 6
Vestdam is on a distinguished road
Hi,
Can you post some figures of contours through the pump? Like pressure and velocity? Do you have backflow? Is the impeller turning the right direction? Is it the static pressure, you are monitoring? In that case, the outlet should be 0 Pa and this indicates that it has not yet converged.
Vestdam is offline   Reply With Quote

Reply

Tags
blood flow, centrifugal blood pump, fluent cfd, moving reference frame, pressure head

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Centrifugal pump Simulation in Cfx ; Head capacity curve not matching dileeps ANSYS 0 December 6, 2017 22:01
[blockMesh] error message with modeling a cube with a hold at the center hsingtzu OpenFOAM Meshing & Mesh Conversion 2 March 14, 2012 09:56
Centrifugal Pump Cavitation problem or not. ismael.s CFX 13 February 27, 2012 08:00
CFD analysis of centrifugal pump saurabh9978 FLUENT 1 April 6, 2010 05:40
pressure measure in centrifugal pump vanes Patricio Torrejon FLUENT 1 December 16, 2005 17:10


All times are GMT -4. The time now is 05:06.