Some Experiments with Vortex Breakdown

Abstract

Summary Water tunnel flow visualisation experiments on a slender delta wing have revealed some new phenomena connected with vortex breakdown. Vortex breakdown hysteresis has been found, there being two steady flow states at some incidences, one with breakdown on the wing and one without. The formation of vortex breakdown has been studied and found to be a non-axisymmetric instability. It is suggested that pressure gradient plays a more general part in the phenomenon than has been thought hitherto.