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

Modelling of a foil and comparison with NACA data

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 7, 2006, 07:39
Default Modelling of a foil and comparison with NACA data
  #1
Tom
Guest
 
Posts: n/a
Hi, i have designed and modelled a NACA 642-015 foil in ansys at 2 degrees and 14 degrees. the results for 2 degrees match up well for lift coefficient but not for drag? and again for the 14 degree foil lift and drag do match up to NACA values.

why is this, what floors are there in Ansys modelling such as modelling through seperated flow and turbulence effects. also does the program have difficulty calculating drag.

thaks alot for any responses!!!
  Reply With Quote

Old   December 7, 2006, 12:55
Default Re: Modelling of a foil and comparison with NACA d
  #2
Joe
Guest
 
Posts: n/a
Grid independance study?

Massive separation may make a RANS approach wobble at the knees.
  Reply With Quote

Old   December 7, 2006, 17:24
Default Re: Modelling of a foil and comparison with NACA d
  #3
Glenn Horrocks
Guest
 
Posts: n/a
Hi,

Also add to the list of things to check:

Laminar to turbulent transition, upstream effects, blockage factor, correct modelling of surface roughness, transient effects around the stall point, etc etc.

There are a lot of things which have to be right before you get an accurate airfoil simulation.

Glenn Horrocks
  Reply With Quote

Old   December 8, 2006, 13:25
Default Re: Modelling of a foil and comparison with NACA d
  #4
Tom
Guest
 
Posts: n/a
i was sort of wondering what were the differences between K-epsilon modeling, SST modeling and K-omega modelling and what were the advantages and disadvantages of using the different techniques.....

cheers again
  Reply With Quote

Old   December 9, 2006, 15:07
Default Re: Modelling of a foil and comparison with NACA d *NM*
  #5
Jonas Pedro Caumo
Guest
 
Posts: n/a
  Reply With Quote

Old   December 9, 2006, 15:10
Default Re: Modelling of a foil and comparison with NACA d
  #6
Jonas Pedro Caumo
Guest
 
Posts: n/a
you need to improve your mesh near the airfoil to get a good boundary layer calculation, because near the airfoil the gradient of velocity is very high, an O-grid is a good type of mesh, your turbulence model need to be good, have you ever tried sparlat-almaras ? Do you calculate y+ ? these things help to get accuracy. 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 04:42.