Surface flow and wake characteristics of automotive external rear-view mirror

Abstract

To observe surface flow and wake structure around an automotive external rear-view mirror, the pressure distribution over the mirror skin and the velocity vector fields in the cross-sectional planes were measured using a pressure scanning system and hot-wire anemometry in a blow-down wind tunnel. Surface flow visualization was also used to investigate boundary layer flow over the mirror surface. It was found that the pressure coefficient became negative over the whole of the surface area, with the exception of the proximity of the stagnation point of the mirror housing, implying the surface flow acceleration along the curved mirror contour. The minimum pressure on the surface of the mirror glass appeared near the outside edge region, which seemed to be the origin of the vortex envelope. Velocity vector fields showed that a conical envelope of the vortex sheet developed with its centre trailing toward the body frame. It was also demonstrated that visualizations over the mirror housing surface and the driver side vehicle skin show good agreement with the pressure distribution of the mirror housing surface and the trail of the vortex sheet in the mirror wake.