Pitching moment calculation (PM vs VLM)
Gennaro Barbato
Hi everyone,
I'm currently trying to compute the pitching moment (Xref=1.751, Yref=Zref=0) for a BWB (Blended Wing Body) configuration using both the Panel Method (PM) and the Vortex Lattice Method (VLM), but I'm getting completely opposite results from the two approaches (Mach=0.2, ReCref=70k).
With the PM, the configuration appears stable (negative CMy derivative) and trimmable (CMy crosses zero within an incidence range of 0° to 8°).
However, with the VLM, the configuration comes out as unstable (positive CMy derivative) and not trimmable.
I've attached the geometry file I'm using in case anyone wants to take a look (if it's necessary, I can attached also the custom airfoil files).
Any help or insights would be greatly appreciated—thank you in advance!
Li Zhikai
According to my experience, calculating pitch moment is difficult for both methods and even for RANS. The result means that the precision of Cp is not enough to calculate Cm precisely. I've calculated flying wing's Cm and have met the same problem. At last I did some flights... The tendency is the same as VLM method's result, but I don't know if the tendency is the same for your case.
Mike Novikov
I hope it will help you.