Increasing the aerodynamic performance of a Formula Student race car by means of active flow control 2019-01-0652

This article involves an experimental study regarding the capability of fluidic actuators to increase the aerodynamic performance of a four-element race car rear wing. Sweeping jet actuators are integrated in the upper flap, of which the angle of attack is increased by up to Δα_F3=40° with reference to a passively optimized setup. Different velocities of the emitted sweeping jets are applied to study the influence of momentum coefficients c_μ=0.04,…,0.98 %. To prove the general feasibility of the approach, the separate rear wing is assessed first before implications on a realistic race car model are investigated inside a large-scale wind tunnel. Employing particle image velocimetry, flow visualization techniques as well as pressure and force measurements, we show that the velocity field on the suction side of the upper flap is characterized by flow separation of different degrees when the angle of attack is increased beyond Δα_F3=20° (rear wing only) and Δα_F3=30° (complete race car). Generally, the employed fluidic devices have a positive impact for all of the investigated angle of attack modifications in terms of the aerodynamic performance, as significant overall downforce increases by up to 22 % are feasible, however, accompanied by greater drag coefficients. Nonetheless, an in-house simulation determines a potential laptime reduction of 0.17 % at the Formula Student endurance race circuit at Hockenheim with even greater gains to be expected for skidpad and acceleration competitions.