Investigation of the statistical properties of pressure loadings on real automotive side glasses

In modern vehicle, aerodynamic noise is now the major source of annoyance at highway speeds and for frequencies higher than 400 Hz. The origin of the aerodynamic noise in the cabin is the flow around the vehicle particularly in the neighborhood of the side glass. A complex and unsteady pressure field excites the glass panels which vibrates and radiates noise inside the cabin. The development of numerical methods related to wind noise prediction is closely associated to the understanding of the pressure field properties. Some quantities like local fluctuating pressure can be measured but other quantities like two points correlation are much more complicated to obtain. In this paper are presented one point pressure measurements performed on the side glass of a Sedan vehicle at two yaw angles. The experimental method is described and the results are analyzed and compared to unsteady CFD simulations. This study depicts general properties of the side glass loading and validates the numerical approach. The numerical results are then used to study two point statistics and are compared to semi-empirical models of the literature. The strong inhomogeneous and spatial dependency of the pressure field is underlined and detailed.