On Numerical Simulations of Turbulent Flows Over a Bluff-Body with Aerodynamic Flow Control Based on Trapped Vortex Cells: Effects of Compressibility

This study presents numerical simulations of turbulent flow over a thick airfoil, modeled here as a semicircular cylinder, incorporating aerodynamic flow control (AFC) based on trapped vortex cells. Building upon previous work that focused on viscous effects, we now examine the influence of compressibility at various Mach numbers (M = 0.1, 0.2, and 0.3), corresponding to a diameterbased Reynolds number of 130, 000. The simulations employ a conventional RANS methodology, coupled with the Spalart-Allmaras and realizable k-ϵ turbulence models. To reinforce the validity of the results, cross-platform validation is performed using multiple numerical solvers, including pressure-based, density-based, and hybrid approaches (combining PISO/SIMPLE algorithms with the Kurganov-Noelle-Petrova scheme). Under the investigated conditions, the flow over the AFCintegrated configuration remains fully unseparated and exhibits outstanding lift performance. At Mach 0.2 (cruise conditions), the concept achieves a lift coefficient of approximately 6, about 95% of the theoretical maximum for a half-circular airfoil (2π), with a corresponding lift-to-drag ratio of around 24. As the Mach number increases to 0.3, the accelerated flow over the upper surface of the airfoil becomes locally transonic. Further analysis across a range of angles of attack (±150) at Mach 0.2 confirms the concept’s ability to maintain high lift and unseparated flow behavior, underscoring the effectiveness of the AFC system in enhancing aerodynamic performance.