CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Problem with centrifugal pump calculation

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 23, 2009, 06:12
Question Problem with centrifugal pump calculation
  #1
Member
 
Michiel
Join Date: Jul 2009
Location: The Netherlands
Posts: 42
Rep Power: 17
Michiel is on a distinguished road
The idea is to create a predicted pump curve which gives information about the maximum pressure at a fixed flow and a fixed inlet pressure. Based on this information I like to calculate the pump power (mechanic and hydraulic), and the efficiency.

I use Floworks to perform the analysis. The medium is water (pre defined in floworks). First I like to set up a basic calculation method, and then I can analyze some pumps and compare results tot actual test data.



For calculating the maximum outlet pressure at fixed flow and inlet pressure I set the following boundary conditions:
-At inlet a total pressure of 1 bar
-At oulet a outlet volume flow of 2 m3/sec
-The impeller walls which are in contact with the fluid are defined as ideal wall
-The pump casing and the inlet pipe are defined as real wall

I have set the following goals:
-Bulk av static pressure at inlet and outlet
-Equation goal to calculate the pressure drop (used for convergence)
-Inlet volume flow (used for convergence)
-Outlet volume flow (used for convergence)


When I run the calculation I can’t get a good result. The most strange is that the inlet flow is not the same as the outlet flow. During the calculation the inlet flow varies from -8 m3/sec up to 12 m3/sec. After 400+ iterations the inlet flow keeps bouncing up and down. This indicates there is something wrong. The inlet and outlet flow should be exactly the same.

When I use the same model to solve the volume flow at fixed inlet and outlet pressure, there is no problem. Also when I solve the inlet pressure at fixed outlet pressure and fixed inlet volume flow, there is no problem.

Does anyone has an idea what is going wrong over here?
Michiel is offline   Reply With Quote

Old   September 23, 2009, 06:22
Default
  #2
Member
 
Michiel
Join Date: Jul 2009
Location: The Netherlands
Posts: 42
Rep Power: 17
Michiel is on a distinguished road
Ow sorry.... I see I forgot to mention some more information.

I use the local rotating region for the impeller. Angular velocity will be around 325 rpm. The numbers i use are normal for this type of pumps, so i am not analyzing something far away from the actual duty point.
Michiel is offline   Reply With Quote

Old   June 17, 2012, 22:32
Default
  #3
New Member
 
Wang Yuchuan
Join Date: May 2012
Posts: 1
Rep Power: 0
yuchuan19831021 is on a distinguished road
I have met the such problem, when i generate the finer grids, the convegence shows good.
yuchuan19831021 is offline   Reply With Quote

Reply

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 boundary conditions Peter FLUENT 6 January 5, 2010 10:59
Centrifugal pump CFD problem...pls help Peter Main CFD Forum 4 June 25, 2008 12:39
pressure measure in centrifugal pump vanes Patricio Torrejon FLUENT 1 December 16, 2005 18:10
BC for centrifugal pump Shiju G.Thomas FLUENT 1 March 18, 2005 03:01
centrifugal pump novice Siemens 2 October 11, 2004 05:29


All times are GMT -4. The time now is 18:39.