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

Rotor Stator Instability

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 30, 2007, 01:52
Default Rotor Stator Instability
  #1
Jack Ling
Guest
 
Posts: n/a
Hi! Everyone, I am quite new to CFX. For those who are playing with turbomachineries, can anyone tell me if there is a way to avoid the transient effects which cause the residuals to fluctuate after converved to a certain value (magnitude of 1e-4s). I am trying to avoid transient simulation because I am only intereted in the overall performance of the pair. But even if I use transient simulation, the residuals dont go down far enough to make me happy, they will stay almost flat. Also, If i have to use transient simulations, How am I going to average the the quantities over a period? Thanks

  Reply With Quote

Old   May 30, 2007, 02:17
Default Re: Rotor Stator Instability
  #2
Jack Ling
Guest
 
Posts: n/a
Hi! is me again. Also I like to ask: if I got message as follwed in the process of iteration, is that normal? Is this the source of residual fluctuations?

"A wall has been placed at portion(s) of an OUTLET boundary condition (at 23.6% of the faces, 2.9% of the area) to prevent fluid from flowing into the domain. The boundary condition name is: S1 Outlet. The fluid name is: Air Ideal Gas. If this situation persists, consider switching to an Opening type boundary condition instead."

Thanks
  Reply With Quote

Old   May 30, 2007, 06:22
Default Re: Rotor Stator Instability
  #3
Phil
Guest
 
Posts: n/a
Your BCs are of an inappropriate type and/or position.
  Reply With Quote

Old   May 30, 2007, 08:05
Default Re: Rotor Stator Instability
  #4
Gert-Jan
Guest
 
Posts: n/a
Can you put your outlet further downstream?
  Reply With Quote

Old   May 31, 2007, 05:46
Default Re: Rotor Stator Instability
  #5
Jack
Guest
 
Posts: n/a
Hi! Thank you very much for the help. So what is the next strategy after discovering extending the outlet does not help much? Do you think SST model will be better than k-e turbulent model in high speed turbomachines? Thanks

  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



All times are GMT -4. The time now is 14:25.