Contrôle des structures tourbillonnaires longitudinales dans le sillage d'une géométrie simplifiée de véhicule automobile : approche expérimentale
Résumé
Control of longitudinal vortices in the wake of a simplified car geometry: experimental approach. The control by blowing techniques of longitudinal vortices originating at the rear pillars of a simplified automobile vehicle are analyzed by an experimental approach on the Ahmed body having a rear window angle of 25 ◦. The experimental measurements are conducted according to stereoscopic Particle Image Velocimetry (Stereo-PIV). The results show that the blowing technique is associated to an increase of vorticity inside the vortex core on the upper part of the rear window and a decrease of vorticity on the lower part of the window. This vorticity drop is related to the onset of a recirculation zone (negative longitudinal velocities) in the vortex core which characterizes the vortex breakdown. The analysis of the azimuthal and longitudinal velocities allows to identify the increase of the Swirl number up to the critical point of vortex breakdown noted for high blowing velocities.