Flow Past Nonconical Wings with Separation

Abstract

The Brown and Michael (1954) method is extended to evaluate the effect of flow separation on wings of nonconical planform. It is assumed that the spiral vortex sheets that separate from the leading edges can be replaced by two isolated vortices at the cores of the vortex sheets. The boundary conditions on the wing are such that (1) the normal velocity is zero; (2) the velocity is finite at the leading edge; and (3) the conditions in the field are that the disturbances vanish at infinity and the fluid pressure is continuous. The vortex strength increases in the downstream direction, and the increase in vorticity is achieved in this model by a feeding sheet of vorticity in order to satisfy Kelvin's theorem. Although this approximation method yields higher values for the lift coefficient than those obtained from experiments on delta wings, it gives a first approximation for evaluating the vortex lift.