Aerodynamic characteristics of two slipstreaming race cars

Abstract

A computational model was developed to study aerodynamic forces acting on two closed-wheel race cars in the slipstreaming (drafting) arrangement, i.e., when the cars are characterized by the same driving speed and situated one directly behind the other one. A particular focus was on the influence of a distance between the two cars on flow characteristics and aerodynamic loads experienced by the cars. Computational fluid dynamics (CFD) simulations were performed for a steady viscous fluid flow using the realizable k-ε turbulence model and non-equilibrium wall functions. The results indicate some important findings. The leading car experiences the smaller drag force coefficient for all studied distances when compared to the single car case. For larger distances between the cars, the drag force coefficient of the trailing car is generally larger than for a single car due to a complex turbulent wake flow of the leading car (drag bubble) that impinges the trailing car. The drag force coefficient of the trailing car decreases when decreasing a distance from the leading car. The modifications of the lift force coefficient are more pronounced for the trailing car as there is a decrease in the negative lift force (downforce). The downforce coefficient is significantly smaller for the trailing car than for the single car configuration at all studied distances. A slight decrease in the downforce coefficient is present for the leading car as well.