Investigating the Impact of Flow Control Devices on the Low-Speed Performance of a Blended-Wing-Body UAV

This study investigates the effect of active and passive flow control devices on the aerodynamic behavior and stability of a Blended-Wing-Body (BWB) Unmanned Air Vehicle (UAV), emphasizing the low-speed segments of a typical flight. Vortilons, which are small fins placed on the leading edge of the wing, generate vortices that delay the appearance of spanwise flow and consequently the appearance of pitch break. Belly flaps are located on the underside of the UAV and can enhance the lift, while they produce a nose-up pitching moment. Seven different configurations are examined using high-fidelity Computational Fluid Dynamics (CFD) over a range of angles of attack to address the effect of each device on the lift and drag forces and the pitching moment of the UAV. Based on these results, the low-speed performance of the platform is evaluated by calculating the minimum speed, the take-off distance, and the maximum lift to drag ratio, while the elevon deflection required for the take-off rotation of the UAV is also assessed.