PSP and PIV investigations on the VFE-2 configuration in sub- and transonic flow

Abstract

An overview is given about investigations on a 65° delta wing using the Pressure Sensitive Paint (PSP) and Particle Image Velocimetry (PIV) techniques which took place as part of the International Vortex Flow Experiment 2 (VFE-2). For the delta wing with rounded leading edges and subsonic flow, the occurrence of a flat vortical structure as well as the onset of the primary vortex and the development of a vortex system consisting of an inner and outer vortex is described in dependency of the angle of attack and the Reynolds number. The Qcriterion is applied to the measured velocity data to estimate the circulation strength of individual vortices allowing for a quantitative description of the vortex developments and interactions. Furthermore, a case at transonic flow speeds (M = 0.8) is described, showing a sudden occurrence of vortex breakdown above the delta wing, most probably induced by a shock wave.