Numerical Study of Active Aerodynamic Control via Flow Discharge on a High-Camber Rear Spoiler of a Road Vehicle

In this study, a numerical investigation of the active aerodynamic control via flow discharge was performed on a two-dimensional simplified vehicle with a spoiler. The analysis was performed using computational fluid dynamics techniques based on the unsteady Reynolds averaged Navier–Stokes equations. Unlike the conventional aerodynamic control methods, in which the control flow is forcibly injected to increase the lift or reduce the drag, the flow discharge method uses the ram air flow to reduce both the downforce and aerodynamic drag of a road vehicle. The technique of aerodynamic control via the flow discharge is applied to a simplified vehicle with a rear spoiler. For the isolated spoiler, at a discharge speed of 40% of the vehicle driving speed, the flow discharge at 75% of the chord exhibited a reduction of 4.5% and 1.8% in the aerodynamic drag and downforce reduction, respectively. For the vehicle with a spoiler, the drag and downforce were respectively reduced, on average, by 3.4% and 19.3% for a vehicle velocity range of 100–300 km/h; in this case, the discharge speed was 40% of the vehicle driving speed, and the discharge position was 75% of the chord owing to the interaction between the spoiler separation flow and vehicle wake.