# X-Foil Airfoil with gurney?

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

 August 26, 2011, 11:33 X-Foil Airfoil with gurney? #1 New Member   Join Date: Aug 2011 Posts: 17 Rep Power: 7 Dear forum members, I'm working on a double element wing, and I would like to know if there is a way to get reliable results for a wing with a gurney? As I know that it's not possible to simulate multi element airfoils in X-Foil, I separate them and also simulate separatly, but on some way, X-Foil doesn't get the right chord lenght. So the simulation totally fails. I organize all coordinates in Excel, so maybe there are some tricks to do it better. Thanks.

 August 26, 2011, 13:32 #2 Senior Member     Join Date: Jan 2011 Posts: 246 Blog Entries: 5 Rep Power: 9 Why do not you fix the chord lenghth of each airfoil and change reynolds number instead? What problem are you solving exactly? Is it a gurney flap which is separated from main airfoil? X-foil could be not a good choise for such kind of problems. Truffaldino

 August 27, 2011, 04:23 #3 New Member   Join Date: Aug 2011 Posts: 17 Rep Power: 7 Well is there a way to change the chord length in X-Foil? The gurney is attached to the foil, so there are no gaps. The problem is that X-Foil thinks that the gurney flap, is the chord length and doesn't recognize the LE. The thing I would like to know is, if there's a proper way to put in the coordinates in Excel to let X-Foil recognize the right LE and TE. Thanks.

August 27, 2011, 05:26
#4
Senior Member

Join Date: Jan 2011
Posts: 246
Blog Entries: 5
Rep Power: 9
Quote:
 Originally Posted by Yur The problem is that X-Foil thinks that the gurney flap, is the chord length and doesn't recognize the LE. Thanks.
I have just added a 2% gurney flap to naca0012 and loaded it to x-foil: everything seems to work. Xfoil recognizes LE and TE.

Bad panelling coul be also eliminated by tiny rounding the right angle.

For sure, your coordinate loading problem can be easily fixed, but it is not the main problem with x-foil. The real problem is more fundamental: the methods X-foil uses are not fitted for analyzing gurney flaps, and results you will get could have nothing to do with reality.

X-foil is based on integral boundary methods that do not handle vorticity regions that you have at gurney flaps, corners, steps etc.

Truffaldino
Attached Images
 gurney.jpg (71.3 KB, 49 views)

January 17, 2014, 06:32
#5
New Member

Jose
Join Date: Jan 2014
Posts: 1
Rep Power: 0
Quote:
 Originally Posted by truffaldino I have just added a 2% gurney flap to naca0012 and loaded it to x-foil: everything seems to work. Xfoil recognizes LE and TE. Bad panelling coul be also eliminated by tiny rounding the right angle. For sure, your coordinate loading problem can be easily fixed, but it is not the main problem with x-foil. The real problem is more fundamental: the methods X-foil uses are not fitted for analyzing gurney flaps, and results you will get could have nothing to do with reality. X-foil is based on integral boundary methods that do not handle vorticity regions that you have at gurney flaps, corners, steps etc. Truffaldino
Can you share the dat file?

January 17, 2014, 14:44
#6
Senior Member

Join Date: Jan 2011
Posts: 246
Blog Entries: 5
Rep Power: 9
Quote:
 Originally Posted by jemo Can you share the dat file?
Here it is. you could do fine repanelling (using standard x-foil/xflr procedures) closer to the flap
Attached Files
 naca0012_gurney02.txt (3.2 KB, 21 views)

Last edited by truffaldino; January 17, 2014 at 14:57. Reason: wrong attached file

 January 17, 2014, 15:13 #7 Senior Member   lore Join Date: Mar 2010 Location: Italy Posts: 464 Rep Power: 10 I agree with truffaldino, what you are doing cannot be done with x-foil for two reasons: 1. It cannot handle multi element wings and the behavior of a main plane + flap all together is totally different from the behavior of each one of them alone since they influence each other. 2. A gurney tab works because of the flow separation it creates and this is not handled by X-foil

 Tags airfoils, element, multo, wings, x-foil

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Mancusi FLUENT 7 April 3, 2014 06:11 creggie ANSYS Meshing & Geometry 10 June 27, 2010 19:24 alastormoody11 FLUENT 0 October 24, 2009 07:22 Josh CFX 9 August 18, 2009 11:31 Frank Main CFD Forum 1 April 21, 2008 18:36

All times are GMT -4. The time now is 12:35.