G0510203 Configuration parameters and aerodynamic characteristics of cars

Abstract

Aerodynamic characteristics have great influences on vehicle performance. The aim of this research is to analyze the influence of configurations of road vehicles on aerodynamic characteristics. As configuration parameters, not only the rear window angle but also the side-window angle are adopted, and totally 55 patterns of configurations changing from box type through fastback to notchback types are investigated by wind-tunnel experiments. As results, in the cases of side angles less than 30°, the drag increases steeply at rear angle from 20° to 35°, while in the case of side angle 30° this tendency was not detected. It was shown that as the side window is slanted, increase of drag occurs gradually at larger rear angle, and the drag increment becomes smaller. In the whole cases the larger the side angle is, the less the drag is. The factor is that as the inclination of the side window is larger, the angle between the rear and side surfaces becomes more obtuse, and the formation of longitudinal vortices is restrained. The flow visualization confirmed the factor.