EVOLUTION OF FOREBODY VORTICES OVER SLENDER BODIES AT HIGH ANGLES OF ATTACK

摘要

From numerous experiments we know that a pair of vortices in the wake of a slender body at angle of attack becomes asymmetric as the angle of attack increases above a certain value. This asymmetry is believed to be a consequence of the vortex instability to asymmetric disturbances at the body nose. In this study we adopt an analytical approach to demonstrate that in an inviscid fluid, a pair of vortices in the wake of a slender cone is unstable to antisymmetric disturbances at high angles-of-attack and stable to both symmetric and antisymmetric disturbances at low angles-of-attack. Inviscid numerical simulations performed at similar conditions support this conjecture. The ratio K of tangents of the semi-apex angle and the angle-of-attack (the reciprocal of 'Sychev parameter') was identified as the parameter that determines the stability of the vortices.