Force and moment measurements for a generic car model in proximity to a side wall

摘要

Force and moment data are presented for an Ahmed reference model with backlight angles of 10°, 25° and 40° at various distances from a side wall. Tests were run at a freestream velocity of 25 m/s and a rolling road provided ground simulation. Six-component force data were recorded and compared with previous experimental data. It is found that the proximity of the side wall causes a general increase in both the lift coefficient and the pitching moment for the Ahmed model, with the increase in the pitching moment becoming more rapid with decreasing wall distance. Increasing the proximity to the wall is further found to increase the overall Ahmed model drag. Furthermore, there is evidence of the breakdown of longitudinal vortices on the near-wall side of the model as the wall-to-model distance decreases, and a large pressure drop on the near-wall model side. This pressure drop increases in magnitude as the wall-to-model distance decreases, before dissipating at wall distances where the boundary layer restricts the flow.