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

Influence of riblets on airfoils

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 6, 2000, 12:20
Default Influence of riblets on airfoils
  #1
Ron Barer
Guest
 
Posts: n/a
Hi,

does anybody know any references on the usage of riblets on airfoils ?

Could it be possible, that beside reduction of friction drag riblets could have a positive influence on stall angle ? (increasing it)

Any opinions on that topic ?

Ron
  Reply With Quote

Old   November 6, 2000, 12:45
Default Re: Influence of riblets on airfoils
  #2
Patrick Godon
Guest
 
Posts: n/a
Riblets would make the surface non-smooth and induce turbulence in the boundary layer at an earlier stage. A turbulent boundary layer would detach itself later than a non-turbulent boundary layer, therefore making it possible to increase the angle of attack. So the stall angle would be increased. I am not an aeronautical engineer, but I am familiar with boundary layers, so that's a guess.

Any comment and/or addition from the aeronautical engineers?

Cheers, Patrick
  Reply With Quote

Old   November 6, 2000, 13:05
Default Re: Influence of riblets on airfoils
  #3
frederic felten
Guest
 
Posts: n/a
Hi,

You can check the following articles:

"Direct Numerical Simulation of turbulent flow over riblets" Choi, H., Moin, P. and Kim. J. J. Fluid Mech., Vol 225, 1993, pp 503-539.

"DRAG REDUCTION DUE TO RIBLETS ON A GAW(2) AIRFOIL". Subaschandar, N.; Kumar, Rajeev; Sundaram, S. Journal of Aircraft v36 n5 1999, pp 890-892

"VISCOUS DRAG REDUCTION USING RIBLETS ON A SWEPT WING". Sundaram, S.; Viswanath, P.R.; Subaschandar, N. AIAA Journal v 37 n 7 Jul 1999, pp 851-856

"BASE DRAG REDUCTION CAUSED BY RIBLETS ON A GAW(2) AIRFOIL". Raju, Channa; Viswanath, P.R. Journal of Aircraft v 35 n 6 Nov-Dec 1998, pp 988-991

"EFFECTS OF SURFACE RIBLETS AND FREE-STREAM TURBULENCE ON HEAT TRANSFER IN A LINEAR TURBINE CASCADE". Maciejewski, Paul K.; Rivir, Richard B. American Society of Mechanical Engineers (Paper) Proceedings of the International Gas Turbine and Aeroengine Congress and Exposition Jun 13-16 1994 Hague Publ by ASME New York NY USA p 1-9 Paper : 94-GT-245

"EFFECT OF RIBLETS ON AXISYMMETRIC BASE PRESSURE". Krishnan, V.; Viswanath, P.R.; Rudrakumar, S.; Journal of Spacecraft and Rockets v 34 n 2 Mar-Apr 1997, pp 256-258

"DEVELOPMENT OF THE WAKE OF AN AIRFOIL WITH RIBLETS". Caram, J.M.; Ahmed, A. AIAA Journal v 30 n 12 Dec 1992, pp 2817-2818

"EFFECT OF RIBLETS ON SAILS". Alving, A.E.; Freeberg, P. Experiments in Fluids v19 n6 Oct 1995, pp 397-404

"EFFECT OF RIBLETS ON TURBULENCE IN THE WAKE OF AN AIRFOIL". Caram, J.M.; Ahmed, A. AIAA Journal v 29 n 11 Nov 1991, pp 1769-1770

"TURBULENT DRAG REDUCTION USING RIBLETS ON A SUPERCRITICAL AIRFOIL AT TRANSONIC SPEEDS". Viswanath, P.R.; Mukund, R. AIAA Journal v33 n5 May 1995, pp 945-947

"EXPERIMENTAL INVESTIGATION OF LOSS REDUCTION WITH RIBLETS ON CASCADE BLADE SURFACES AND ISOLATED AIRFOILS". Fang, Chen; Yan-Ping, Tang; Mao-Zhang, Chen American Society of Mechanical Engineers (Paper) International Gas Turbine and Aeroengine Congress and Exposition Jun 11-14 1990 1990 Brussels.

I hope this will help.

Sincerely,

Frederic Felten CFD Laboratory UT Arlington, TX, USA. http://utacfdb.uta.edu/
  Reply With Quote

Old   November 7, 2000, 04:44
Default Re: Influence of riblets on airfoils
  #4
Ron Barer
Guest
 
Posts: n/a
Hi,

thanks for your comments.

Patrick, you talked about transition to turbulence and delaying of separation by that fact. What do you think about the following. If you assume that the boundary layer is turbulent at an early stage due to by-pass transition. So the riblets are not necessary to cause transition. If I remember my fluid mechanics lessons right separation is caused by the fact that the boundary looses too much kinetic energy due to wall friction to overcome the positive pressure gradient on the upper side of the airfoil. But if the riblets reduce the wall friction the energy loss is reduced and so the separation is delayed as well.

Do these thoughts make sense in your opinion ?

Ron
  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
Gravity (g) Influence on Simulation Results Colin FLUENT 12 September 23, 2015 10:45
multiple airfoils at once, are they affected? kdrbrk FLUENT 0 October 18, 2010 06:31
MOdelling a 3-D structure of a fan blade using NACA airfoils ashu.feb28 Main CFD Forum 0 February 2, 2010 11:19
Where to find airfoils with more coordinates pts? KB Main CFD Forum 2 March 24, 2008 00:18
Gravity g's influence on Simulation Results Colin Main CFD Forum 6 November 2, 2003 15:13


All times are GMT -4. The time now is 05:18.