Vortical Flows on the Lee Surface of Delta Wings

Abstract

In the more than three decades of research on the lee surface flow of delta wings, starting from the identification of a single pair of counter-rotating vortices springing from the leading edges, multiple vortices (secondary, tertiary), “squashed” vortices, vortices embedded in boundary layers, shock waves on the wing, on, underneath and in between the vortices, shock wave boundary layer interaction, shock-induced separation, vortex bursting, asymmetric flow behaviour and so on have been progressively “discovered”. In a gross sense, the geometric and free stream conditions under which each of these flow phenomena occurs are reasonably well understood. However, the physical mechanisms underlying some of the flow phenomena remain far from clear. Significant progress has been made in recent times in the computation of the complex three-dimensional flows on delta wings; however, solutions for even the simplest flow type (flow with a pair of leading edge vortices) tax the resources of the largest available computer. Solutions for the more complex flow types including multiple separations, shocks, etc., appear to be realisable only in the distant future.