Determining Stall Angle of 2D Airfoil

Active.Aero.Fiero · October 25, 2010, 17:46

Hi Guys,

I am fairly new to the FLUENT software. I have a GAMBIT 2D Mesh using Quad Map and I have successfully imported it into FLUENT. It has recognized my boundary conditions that I had set in GAMBIT.

My question is; is there a simple way (simple is probably the wrong word) but is there a way to determine the airfoil's stall angle without having to simulate the flow for every degree and then just picking the highest. Or is there a way to tell FLUENT to test all angles between a range of lets say 0degrees to 25 degrees?

A second question I have is that I tried a variety of angles by setting the flow to have x and y components, but my coefficient of lift kept increasing. From another software (Xfoil) we have previously determined that the stall angle was around 12 degrees. With Fluent I tried 0, 5, 10, 15, 20 and the coefficient of Lift kept increasing between each degree. I am not entirely sure how it could have, so test it I tried 30 degree KNOWING that the coefficient should have gone back down, but I got an even BIGGER answer. I was wondering if anyone knew what sort of model I should be running this through? I tried reading the User's Guide and the Theory Guide and I chose my models based on that. The airfoil is a LOW speed airfoil <300km/h so I couldn't use inviscid modelling...

Any help for both of these questions would be greatly appreciated!

Thanks in advance,

A.A.F.

kdrbrk · October 26, 2010, 02:01

Maybe you should try k-omega models for flow sweperation.

samcool · October 27, 2010, 02:42

There are many methods to predict the stall angle of a foil section. For some particular sections, some test results can be used, such as NACA series. Wing Section Theory by Abbot is a best reference book with many test results. Also there are some reference books or reports for foil sections.

Active.Aero.Fiero · October 27, 2010, 10:07

Thanks for your help, so you are saying that FLUENT the software itself cannot simply run a test where it tries each and every angle as a sweep from lets say -30 to +30 degrees and then determines the stall angle based on the output comparison from each angle.

So if I were to find an outsiders information about the stall angle of a certain wing, then I could use FLUENT to test the results for set angle. Ok

Thanks again guys,

October 25, 2010, 17:46	Determining Stall Angle of 2D Airfoil	#1
Active.Aero.Fiero New Member Active Aero Join Date: Oct 2010 Posts: 5 Rep Power: 16	Hi Guys, I am fairly new to the FLUENT software. I have a GAMBIT 2D Mesh using Quad Map and I have successfully imported it into FLUENT. It has recognized my boundary conditions that I had set in GAMBIT. My question is; is there a simple way (simple is probably the wrong word) but is there a way to determine the airfoil's stall angle without having to simulate the flow for every degree and then just picking the highest. Or is there a way to tell FLUENT to test all angles between a range of lets say 0degrees to 25 degrees? A second question I have is that I tried a variety of angles by setting the flow to have x and y components, but my coefficient of lift kept increasing. From another software (Xfoil) we have previously determined that the stall angle was around 12 degrees. With Fluent I tried 0, 5, 10, 15, 20 and the coefficient of Lift kept increasing between each degree. I am not entirely sure how it could have, so test it I tried 30 degree KNOWING that the coefficient should have gone back down, but I got an even BIGGER answer. I was wondering if anyone knew what sort of model I should be running this through? I tried reading the User's Guide and the Theory Guide and I chose my models based on that. The airfoil is a LOW speed airfoil <300km/h so I couldn't use inviscid modelling... Any help for both of these questions would be greatly appreciated! Thanks in advance, A.A.F.

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October 26, 2010, 02:01		#2
kdrbrk Member Burak Join Date: May 2009 Posts: 90 Rep Power: 17	Maybe you should try k-omega models for flow sweperation.

October 27, 2010, 02:42		#3
samcool New Member Zone Wei Join Date: Sep 2009 Posts: 1 Rep Power: 0	There are many methods to predict the stall angle of a foil section. For some particular sections, some test results can be used, such as NACA series. Wing Section Theory by Abbot is a best reference book with many test results. Also there are some reference books or reports for foil sections.

October 27, 2010, 10:07		#4
Active.Aero.Fiero New Member Active Aero Join Date: Oct 2010 Posts: 5 Rep Power: 16	Thanks for your help, so you are saying that FLUENT the software itself cannot simply run a test where it tries each and every angle as a sweep from lets say -30 to +30 degrees and then determines the stall angle based on the output comparison from each angle. So if I were to find an outsiders information about the stall angle of a certain wing, then I could use FLUENT to test the results for set angle. Ok Thanks again guys,