Vehicle Wind Noise Measurements in a Wind Tunnel with a Contoured Top Profile

A 1/4 scale model vehicle profile has been tested in a wind tunnel with speeds up to 360 km/h. In order to simulate the free field flow over the vehicle, the top surface of the wind tunnel is contoured. A CFD simulation of the free field flow at various speeds is used to identify the desired top streamline. Then the boundary layer growth on the top surface is calculated and the top contour is adjusted accordingly. Since this contour changes very little with flow speeds of interest, an average contour is used for a fixed top surface of the wind tunnel. Pressure drop measurements are used to verify the flow similarity to the CFD model. Wind noise measurements using surface mounted pressure transducer arrays are used to determine the acoustic loads on the vehicle surfaces.