Numerical investigation of the aerodynamics of an inverted three-element airfoil in ground effect for race car application

In this paper, a new concept of inverted three-element wing in ground effect is presented in order to provide more down-force and less drag for race cars during rapid runs and fast turns. The Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with Shear Stress Transport (SST) k-ω turbulence model are solved by the finite volume method to simulate the flow around an inverted 30P30N three-element airfoil at various ground clearances. Compared to the two-element airfoils widely used for race cars, the threeelement airfoil can produce more down-force and less drag. As the ground clearance reduces, the down-force of the three-element airfoil first increases slowly and then rapidly to a peak value at some ground clearance; after reaching the peak value it sharply decreases as the ground clearance further decreases. At very small ground clearances in which the downforce decreases, the separation vortex within the slat cove enlarges to block the slat gap flow; meanwhile, the fast airflow from the flap gap and the slow airflow from the Venturi tube forming between the downside of the airfoil and the ground meet and generate a strong shear separation vortex. These two separated flows together affect the pressure distribution on the airfoil resulting in a reduced down-force.