NUMERICAL INVESTIGATION OF HIGH-INCIDENCE FLOW OVER A DOUBLE-DELTA WING

The vortical flowfield over a double-delta wing configuration, consisting of a sharp leading-edge 76-deg sweep strake and a 40-deg sweep wing section is investigated numerically. The governing equations are solved with a partially upwind, finite difference, two-factor algorithm. The leeward-side vortex system resulting from the strake and wing vortices is investigated for a subsonic freestream speed of M(infinity) = 0.22, high Reynolds number turbulent flow at various angles of incidence. At low angles of attack the strake and wing vortices remain separate over the wing section, whereas for flows at higher angles of attack the two vortices merge and vortex breakdown develops. Vortex breakdown appears initially in the trailing-edge region of the wing section. As the angle of attack increases, bursting occurs further upstream closer to the strake section. The effect of numerical grid density is investigated, and the solutions are compared with available experimental data. The computed surface pressures are in good agreement with the experimental measurements for the lower angles of attack, but the agreement deteriorates as the angle of attack increases.