Enhancing the aerodynamic performance of diffusers in high-performance vehicles using trapped vortex cavities

Abstract

Motivated by the inclusion of active flow control provisions in the 2026 Formula One regulations, and building upon previous studies of Trapped Vortex Cavity (TVC) implementation in inverted front wings, this paper investigates the effectiveness of TVC as a flow control mechanism applied to vehicle diffusers. Both active and passive configurations were considered for three diffuser geometries: a base straight-line diffuser, an inverted airfoil-shaped diffuser, and a diffuser inspired by a Formula One car. The study employed numerical simulations to evaluate the aerodynamic performance and the potential benefits of integrating TVC systems. Across all types of diffusers, the implementation of a circular TVC cavity resulted in a significant improvement in the lift-to-drag ratio (CL/CD). In the active flow control configuration, a 10% improvement was observed in the straight diffuser under a limited mass-flow rate. With optimized cavity positioning and radius, the airfoil-shaped and Formula One-inspired diffusers achieved improvements of 38.9% and 54.6%, respectively, under the same flow conditions. Passive flow control also demonstrated notable aerodynamic benefits without additional energy input. Compared to the original diffuser configurations, performance gains of 8%, 23.6%, and 12.9% were recorded for the straight, airfoil-shaped, and Formula One-inspired diffusers, respectively. The results suggest that the integration of a TVC system in the diffuser could effectively enhance aerodynamic performance by strengthening suction effects and promoting secondary pressure recovery, regardless of diffuser geometry.