overpredicted lift and stall angle

student123a · November 15, 2009, 09:06

hi everyone!
im conducting a CFD experiment for my thesis and have some errors in my results.
Im comparing wind tunnel results and Fluent results for a Naca airfoil. In the wind tunnel, the airfoil (infinite test) was stalling at 14 degrees and max Cl 1.5 . however, fluent is over prediciting these values....giving stalling angle of 17 degrees and max cl of 1.9. im preforming the test at low Reynolds numbers (1.5 million)

Is there any reason for the over-predicted values from fluent? i have a very good mesh constructed by an experienced fluent user so i know that is not causing the problem.
(model used: K-E, RNG)

many thanks

Figd84 · November 16, 2009, 12:12

Try using LES turbulence model if there is any change.

Often that kind of problem respond to turbulence model issues.

Also, check the turbulence boundary conditions.

November 15, 2009, 09:06	overpredicted lift and stall angle	#1
student123a New Member s.k Join Date: Sep 2009 Posts: 7 Rep Power: 16	hi everyone! im conducting a CFD experiment for my thesis and have some errors in my results. Im comparing wind tunnel results and Fluent results for a Naca airfoil. In the wind tunnel, the airfoil (infinite test) was stalling at 14 degrees and max Cl 1.5 . however, fluent is over prediciting these values....giving stalling angle of 17 degrees and max cl of 1.9. im preforming the test at low Reynolds numbers (1.5 million) Is there any reason for the over-predicted values from fluent? i have a very good mesh constructed by an experienced fluent user so i know that is not causing the problem. (model used: K-E, RNG) many thanks

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November 16, 2009, 12:12		#2
Figd84 Member Felipe Gutiérrez Donoso Join Date: Mar 2009 Posts: 31 Rep Power: 17	Try using LES turbulence model if there is any change. Often that kind of problem respond to turbulence model issues. Also, check the turbulence boundary conditions.