Pressure singularities using supercritical airfoils

[François DUNOYER]

Hello,

I'm trying to make a wing with winglets with supercritical profiles, but when I use the panel Method I end up with singularities in the angles and trailing edges, with several thousand Cp, Cl and Cd values. (VLM method works perfectly however).

Since the results are accurate with an equivalent NACA profile, I suspect that the supercritical profile (taken from Airfoiltools) is the cause. Since the trailing edge has a gap, I used the close function to close that gap. With this difference the solver crashes.

In your opinion, is it the airfoil that poses a problem, the refinement of the mesh at the trailing edge or the too brutal dihedral? I have tried several parameters of refinement but none have helped me fix this problem.

You can find attached the file, airfoils and images

Thanks in advance,

François Dunoyer

[François DUNOYER]

Clarification: In the 2nd paragraph, it is with the gap that the solver crashes, if i sharpened the LE the solver works but with the singularities.

[Rob McDonald]

I don't have a great answer for you.

I've brought these kinds of issues up to the VSPAERO developer and they are on his list to work on.  It seems to be a combination of cusp-like behavior at the TE and also the very thin triangles that come together at the wingtip TE.

Certainly using the thin-surface VLM mode is a good work around.  Avoiding problems like this is one of the reasons I like the thin-surface mode so much.

Rob

[François DUNOYER]

Thank you for your quick reply

Yes I have already done the VLM calculations and the results are convincing. However, I want to add a lifting body and I think the panel method is more suitable for this case.

I will try to modify the trailing edge of the airfoil or take a NACA equivalent.

I will keep you posted if I find a better solution.

François