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-   -   Determining Stall Angle of 2D Airfoil (http://www.cfd-online.com/Forums/fluent/81382-determining-stall-angle-2d-airfoil.html)

Active.Aero.Fiero October 25, 2010 16:46

Determining Stall Angle of 2D Airfoil
 
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 01:01

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

samcool October 27, 2010 01:42

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 09:07

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,


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