Strange lift coefficients for NACA 0012

dss1092 · July 15, 2009, 10:06

I'm running some tests on a NACA 0012 airfoil with Re = 9e6 and I've been getting some strange values for the lift coefficient. For a 4 degree angle of attack, I'm getting a lift coefficient of 0.1, which is far too low. For zero angle of attack, I'm getting 0.007. I'm using a velocity inlet and the outflow bc for the outlet. I've tried using equivalent pressure boundary conditions and got very similar results. I also check the reference values and I think they're ok. The velocity reference is set to the inlet velocity, and the area is the length of the airfoil. Any thoughts as to why my results are not good would be greatly appreciated. Thanks!

jortega · July 20, 2009, 11:49

Hello,

I am working with the naca0012 airfoil, too. I am doing some preliminary simulations with an angle of attack of 9 degree and Re=50000 and the Cl and Cd seems rights.

Are you using a turbulent model?

nvtrieu · August 27, 2009, 12:02

Hi all,

I'm simulating NACA 0012 too (chord =4m) in Star-CCM+. I use turbulent model like K-ep and K-w. The fuid is H2O. Velocity =1~10 m/s. Attack angle =2~16deg. I got the incorrect lift coef. and drag coef. because the lift coef. is so small.
Who have experience on this problem please help me!
Thanks alot!

July 15, 2009, 10:06	Strange lift coefficients for NACA 0012	#1
dss1092 New Member Dan Join Date: Mar 2009 Posts: 3 Rep Power: 17	I'm running some tests on a NACA 0012 airfoil with Re = 9e6 and I've been getting some strange values for the lift coefficient. For a 4 degree angle of attack, I'm getting a lift coefficient of 0.1, which is far too low. For zero angle of attack, I'm getting 0.007. I'm using a velocity inlet and the outflow bc for the outlet. I've tried using equivalent pressure boundary conditions and got very similar results. I also check the reference values and I think they're ok. The velocity reference is set to the inlet velocity, and the area is the length of the airfoil. Any thoughts as to why my results are not good would be greatly appreciated. Thanks!

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July 20, 2009, 11:49		#2
jortega New Member Joaquin Join Date: Mar 2009 Location: Málaga, Andalusia, Spain Posts: 6 Rep Power: 17	Hello, I am working with the naca0012 airfoil, too. I am doing some preliminary simulations with an angle of attack of 9 degree and Re=50000 and the Cl and Cd seems rights. Are you using a turbulent model?

August 27, 2009, 12:02		#3
nvtrieu Member Join Date: Jul 2009 Posts: 70 Rep Power: 17	Hi all, I'm simulating NACA 0012 too (chord =4m) in Star-CCM+. I use turbulent model like K-ep and K-w. The fuid is H2O. Velocity =1~10 m/s. Attack angle =2~16deg. I got the incorrect lift coef. and drag coef. because the lift coef. is so small. Who have experience on this problem please help me! Thanks alot!