Vortices in the Wake Past Adjustable Car Spoiler in Open and Closed Configuration Studied Experimentally by PIV

Abstract

A complex adjustable car spoiler opens or closes in dependence on ride properties: the closed state increases negative lift (better for curves), while the open state ensures lower drag (better for straight segments of the road). Both these configurations are studied by using Particle Image Velocimetry method in a wind tunnel at model scale. The three measured planes are perpendicular to the main flow. The wake is characterised by upwind (stronger past the closed variant) and by a pair of wing-tip vortices, although the spoiler wing has no end, it is rounded downwards instead. These vortices are stronger past the closed variant, they migrate towards each other, while their positions correlate by about 30 %. The circulations of both vortices are strongly correlated by about 90 % for the closed case, while this correlations is much smaller (∼ 25 %) for the open case.