Abstract
KEYWORDS
Passing manoeuvres, transient aerodynamics, automotive vehicles, shape, aspect ratio
ABSTRACT
Passing manoeuvres and crosswind have significant effects on vehicle stability. When vehicles overtake or cross, they mutually influence the flow-field around each other and under certain conditions can generate severe gust loads that act as additional forces on both vehicles. These transient forces result from rapidly varying flow patterns which are influenced by various basic parameters such as lateral spacing, relative velocity between the vehicles, crosswind and vehicle shapes. Experiments were conducted in one of the automotive wind tunnels of the Institut Aérotechnique of Saint-Cyr l’École to simulate the transient overtaking process between two models of a simplified automobile shape. Previous work studied the effects of various parameters such as the lateral spacing, the relative velocity and the crosswind on the aerodynamic forces and moments generated on the overtaken and overtaking vehicles. The present study focused on the influence of the vehicle shapes and aspect ratios on the transient aerodynamic side-force and the yawing moment coefficients acting on an overtaken vehicle.