On the Influence of Ground Movement and Wheel Rotation in Tests on Modern Car Shapes

Wind tunnel force-balance and wake-traverse tests were carried out on 0.154-scale model cars with various degrees of streamlining to determine the significance of ground treatment for increasing levels of aerodynamic cleanness. The wake-traverse analysis included investigations of spanwise distributions of vortex and viscous drag. Wake measurements for a configuration with rolling wheels showed further reductions in wake width, relative to a comparable stationary, flat-bottom-wheels case tested over moving ground. This effect was less significant than the effect of ground motion itself. For the covering abstract see IRRD 819832.