Unsteady Gust Response of Road Vehicles

Abstract

A theoretical model based on an indicial method is proposed to simulate the unsteady response of a series of road vehicles, including high-speed trains, sports utility vehicles, sports cars, caravans, and pick-up trucks. The response is described in the frequency domain by the aerodynamic admittance for both side force and yawing moment. The properties of the admittance function are discussed for basic two-dimensional geometries, and the existence of critical damping is shown for a number of cases. The vehicles are undergoing aerodynamic forcing in the form of a gust. Systems with one degree-of-freedom were considered. The results show that the main parameters affecting the vehicle’s aerodynamic response are the mean vehicle length compared to the wave length of the gust, and the inclination of the nose.