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Kevin Lamers December 28, 2008 19:08

stall simulation

I'm doing some research on airfoils using Floworks and Xfoil. There is something I can't figure out. I have a airfoil which will stall at 9 degrees according to Xfoil (2d, infinite wing). Whatever I try in Floworks (even an angle of attack of 45 degrees), the wing (3d) won't stall. Sounds great, but not really realistic. If I draw the streamlines of such a case, I see clearly large separation areas, which indicate stalling behavior. The drag polars look good, they are about the same as the one from Xfoil, with accordances to the down wash. The first part of the lift polar also looks good, except that after the stall point, the lift keeps increasing linear.

I set the angle of attack by changing the components of the flow in x and y direction. With global goals, I calculate the X and Y force which are normal and parallel forces with respect to the wing. From this I calculate the CL and CD using cos and sin equations.

I think there is something going wrong with the calculation of the angles. I probably just miss something.

If someone could help me, I would be very thankful.

Kind regards,

Kevin Lamers

Ive January 29, 2009 07:24

Re: stall simulation
1. Try the 2D simulation in Floworks and compare the results with XFoil.

2. Try to use Surface parameters to calculate the forces. Try to use Surface goals. Compare the results with each other and with global goals.

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