Elucidation of Aerodynamic Drag Reduction Mechanism Due to Air-dam Spoiler

Abstract

An air-dam spoiler, which is widely equipped under the front bumper, is known to be one of the most effective aerodynamic devices to improve vehicle aerodynamic performances. However, the mechanism to control the aerodynamic characteristics has not clarified completely. This paper revealed fluid dynamic mechanism of the aerodynamic drag reduction regarding a small hatchback type passenger car. In this research, we investigated the mechanism by comparing the drag change to the flow structure change of the wake by PIV measurement. Finally, we explained clearly the mechanism of the drag reduction from the point of view of the wake structure change.