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

Some help with the results, please

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 5, 2010, 16:53
Default Some help with the results, please
  #1
New Member
 
Zvonko Kostovski
Join Date: Apr 2009
Location: Skopje, Macedonia
Posts: 13
Rep Power: 8
zona is on a distinguished road
Send a message via Skype™ to zona
Hi, I've been working on a CFD simulation on a pumps for some time now, but I have some doubts about the results I'm getting from it.
This is my process of calculation
1. make 3D model is SolidWorks
2. create the mesh in ANSYS
3. make a simulation boundary conditions ShearStress, MassFlow in, Static Preasure outlet (I put hier 0bar is this OK or shoul I put normal preasure???), and I use frozen rotor
4.finally after the calculations I use turbo macro Liquid Pump Performance to calculate the head and efficiency, (I get strange result for the efficiency anny ideas why????)
5. I repeat the calculations for 5-6 different flows and get head and efficiency and make Q-H and Q-eta diagrams in EXCEL
.
is this a good way to works
is there an automated way to calculate more than one point at once and to get an automated Q-H diagram...
- what is better for pumps Shear Stress or K-epsilon (turbulence model)
what is reference radius and reference height in the Liquid Pump Performance calculation (I change them but nothing happends!)
Attached Images
File Type: jpg 05.02.jpg (48.8 KB, 18 views)
zona is offline   Reply With Quote

Old   February 7, 2010, 17:25
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,651
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Unless you know what the wall shear stress is then do not use it. Almost always you don't know the wall shear stress so let the turbulence model calculate it for you. Also consider the SST turbulence model over the k-e model. It is better in just about all respects.

Yes, you can automate your curve generation. Have a look in the workbench tutorials about how to get WB to do this.

As for if your method is good - the devil is in the detail. But if you have not done a mesh and convergence sensitivity study and checked your boundaries are appropriate and the physics models are good then you are just guessing.
ghorrocks is offline   Reply With Quote

Old   February 8, 2010, 04:01
Default
  #3
New Member
 
Zvonko Kostovski
Join Date: Apr 2009
Location: Skopje, Macedonia
Posts: 13
Rep Power: 8
zona is on a distinguished road
Send a message via Skype™ to zona
Hi thanks for the tips, can You, please be a little bit more specific about this
Quote:
Originally Posted by ghorrocks View Post
...
Yes, you can automate your curve generation. Have a look in the workbench tutorials about how to get WB to do this.
...
I was searchif the PDF files but with no luck
zona is offline   Reply With Quote

Old   June 6, 2013, 01:28
Default Hi I am facing the same problem
  #4
New Member
 
Join Date: Jun 2013
Posts: 1
Rep Power: 0
ccs_2v is on a distinguished road
Hi I am facing problems in getting Efficiency Values which make sense for a pump.
I am new to CFX ,Did you find any Solution, i have browsed thru the forum but cant make a clear direction, if the above was solved can you share the solution to get proper efficiency in CFX.
Thank for Help in advance.
ccs_2v is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
OpenFOAM - Validation of Results Ahmed OpenFOAM Running, Solving & CFD 9 June 22, 2011 18:59
Different Results from Fluent 5.5 and Fluent 6.0 Rajeev Kumar Singh FLUENT 6 December 19, 2010 12:33
wind tunnel results vs fluent pixie Main CFD Forum 1 August 20, 2009 08:02
validation of CFD results andy FLUENT 0 June 13, 2007 13:55
Problems with repeating results Lee CD-adapco 4 May 26, 2006 03:39


All times are GMT -4. The time now is 15:28.