Computational Analysis of Flap Camber and Ground Clearance in Double-Element Inverted Airfoils

Drag and lift are the primary aerodynamic forces experienced by automobiles. In competitive automotive racing, the design of inverted wings has been the subject of much research aimed at improving the performance of vehicles. In this direction, the aerodynamic impact of change in maximum camber of the flap element and ground effect in a double-element inverted airfoil was studied. The National Advisory Committee for Aeronautics (NACA) 4412 airfoil was taken as the constant main element. The camber of the flap element was varied from 0% to 9%, while ground clearance was varied from 0.1c to 1.0c. A two-dimensional (2D) Computational Fluid Dynamics (CFD) study was performed using the realizable k-ε turbulence model in ANSYS Fluent 18.2 to analyze the aerodynamic characteristics of the airfoil. Parameters such as drag coefficient, lift coefficient, pressure distribution, and wake flow field were investigated to present the optimum airfoil configuration for high downforce and low drag. It was observed that while an increase in flap camber improves the lift coefficient substantially, this change is dependent on the angle of attack as well as the ground clearance. The critical ground clearance below which lift force begins to decrease was also observed to be dependent on the angle of attack. An optimum configuration of 9% maximum flap camber, 0.8-1.0c ground clearance, and -3° to 0° angle of attack was hence obtained for the given double-element airfoil.