Modern high-speed aircraft, especially military, are
very often equipped with single or compound delta
wings. When such aircraft operate at high
angles-of-attack, the major portion of the lift is
sustained by streamwise vortices generated at the
leading edges of the wing. This vortex-dominated
flow field can breakdown, leading not only to loss
of lift but also to adverse interactions with other
airframe components such as the fin or horizontal
tail. The wind tunnel and water studies described
herein attempt to clarify the fluid mechanics of
interaction between the strake and wing vortices of
a generic 76°/40° double-delta wing leading to
vortex breakdown. Some studies of passive control
using fences at the apex and kink region are also
described. Various diagnostic methods-laser sheet
flow visualisation, fluorescent dyes, and pressure
sensitive paints have been used.