4 Replies Latest reply on Dec 2, 2015 7:59 AM by Alexandre Bourrieau

Problem with flow simulation / propeller global rotation at high RPM

Alexandre Bourrieau Nov 24, 2015 1:07 PM

Hi,

I am trying to simulate a litle propeler rotation in air: I wan to get the Fy force :

The results are OK with my experiment at slow angular frequency but when w>3000 rad/s there are some errors (see below).

I have a warning saying that "there is a lot of supersonics cells... Try to use manual criterium" .... Is that the problem ?

Can you help me to avoid this problem please ? (perhaps by adding some initials conditions ??)

I have add a criterium (F <0.1N) but simulation is very long... and still do not converge to my experiment value...

Thanks you very much for you help.

Regards.

Alexandre.

Re: Problem with flow simulation / propeller global rotation at high RPM

Amit Katz Nov 25, 2015 11:12 AM (in response to Alexandre Bourrieau)

What type of rotating model are you using? (global rotating, local regions, sliding mesh?)
Like Show 0 Likes(0)

Actions
- Re: Problem with flow simulation / propeller global rotation at high RPM
  
  Alexandre Bourrieau Nov 25, 2015 5:29 PM (in response to Amit Katz)
  
  Hi,
  
  I am using global rotating option :
  
  Regards.
  
  Like Show 0 Likes(0)
  
  Actions
  - Re: Problem with flow simulation / propeller global rotation at high RPM
    
    Amit Katz Dec 1, 2015 4:27 PM (in response to Alexandre Bourrieau)
    
    Global rotation causes every fluid cell in your domain to rotate about the specified axis. If your domain is too large, and the spin is too rapid, then the fluid cells may reach supersonic speeds. In particularly at 3000 rad/s you would need less than 1 meter of distance from your axis to reach Mach 1. I recommend using a local rotating region about the propeller.
    
    Like Show 0 Likes(0)
    
    Actions
    - Re: Problem with flow simulation / propeller global rotation at high RPM
      
      Alexandre Bourrieau Dec 2, 2015 7:59 AM (in response to Amit Katz)
      
      Hi !
      
      Thanks you very much it works great now with sliding mesh or local rotating !!
      
      Regards.
      
      Like Show 0 Likes(0)
      
      Actions