Front Wing Interactions on a Racecar

Abstract

A multi-element front wing of a formula student car was analyzed using the Computational Fluid Dynamics (CFD) software STAR-CCM+. A number of cases were simulated in steady state to get an understanding of the interaction between the wing, the front wheels, the car body (monocoque) and the ground. Three different flap settings were simulated in three different heights in combinations with and without the following elements: Front wheels, monocoque, ground, front wing. The SST k-omega turbulence model was used with a polyhedral mesh. Chord Reynolds numbers were between 545 000--600 000.It was found that both the front wing operating isolated from other components and the wing operating in interaction with the front wheels and the monocoque responded with increased downforce in ground effect. Optimal ground height was dependent on flap setting: The mild configuration did not stall at any of the simulated heights, while the flaps on the aggressive configuration stalled close to the ground in the isolated case. Ground effect improved the downforce produced by the wing in free stream by up to 50.7%.Comparisons of the wing in mild and high downforce settings were done with and without the wheels. The wing-wheel interaction reduced the downforce produced in the mild flap angle setting by 20.5% by obstructing the flow, but increased the downforce of the high flap angle setting by 2.2% by introducing surface normal adverse pressure gradients, preventing boundary layer separation. The wing-monocoque interaction increased downforce in all simulated cases. The monocoque caused increased velocity and suction on the bottom of the symmetric center section, thus reducing the 3D effects across the span toward the high-downforce section. This contributed to enhanced sectional lift coefficient along the complete span, increasing downforce produced by the wing with low flap angles and wheels behind by 14.3% and correspondingly for the high flap angle an increase of 10.8%.