CFD vs Experimetal Results for Aerofoil

owhelan · March 25, 2010, 08:05

Hi, I'm comparing experimental results obtained for a NACA 0012 aerofoil in a wind tunnel with CFD results ran on Fluent.

The CFD model was a very simple 2D, steady time, incompressible model using k-epsilon and standard wall functions. BC's were a pressure inlet and outlet and symmetry on upper/lower surfaces or fluid domain.

Despite the low inlet gauge pressure of 215pa, I'm getting pressure readings on the surface of the aerofoil that lead to pressure coefficients greater than +ve 1 on the pressure surface at 9 deg and 12 deg incidence.

Can anyone explain why this may be happening? Is it a problem with the wall function?

Thanks
Osh

Karatix · March 25, 2010, 10:12

What CFD Package and mesh generator do you use?

owhelan · March 25, 2010, 10:15

I an using GAMBIT to generate the mesh and FLUENT to run the simulation.

Karatix · March 25, 2010, 11:54

Unfortuntately I am not using Gambit and Fluent anymore and cannot remember whether I had similar problems. I think I used a structured grid without a wall function. The turbulence model was Spalart Allmares and worked pretty well.

Have you got subsonic, transonic or supersonic flow?

Does it have a great difference between the value and +1?

March 25, 2010, 08:05	CFD vs Experimetal Results for Aerofoil	#1
owhelan New Member owhelan Join Date: Mar 2010 Posts: 3 Rep Power: 16	Hi, I'm comparing experimental results obtained for a NACA 0012 aerofoil in a wind tunnel with CFD results ran on Fluent. The CFD model was a very simple 2D, steady time, incompressible model using k-epsilon and standard wall functions. BC's were a pressure inlet and outlet and symmetry on upper/lower surfaces or fluid domain. Despite the low inlet gauge pressure of 215pa, I'm getting pressure readings on the surface of the aerofoil that lead to pressure coefficients greater than +ve 1 on the pressure surface at 9 deg and 12 deg incidence. Can anyone explain why this may be happening? Is it a problem with the wall function? Thanks Osh

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March 25, 2010, 10:12		#2
Karatix New Member Karatix Join Date: Sep 2009 Posts: 22 Rep Power: 17	What CFD Package and mesh generator do you use?

March 25, 2010, 10:15		#3
owhelan New Member owhelan Join Date: Mar 2010 Posts: 3 Rep Power: 16	I an using GAMBIT to generate the mesh and FLUENT to run the simulation.

March 25, 2010, 11:54		#4
Karatix New Member Karatix Join Date: Sep 2009 Posts: 22 Rep Power: 17	Unfortuntately I am not using Gambit and Fluent anymore and cannot remember whether I had similar problems. I think I used a structured grid without a wall function. The turbulence model was Spalart Allmares and worked pretty well. Have you got subsonic, transonic or supersonic flow? Does it have a great difference between the value and +1?