Optimization of Synthetic jet to enhance the aerodynamic performance of a VTOL aircraft at real flight conditions

The study presented in this paper has been carried out in the context of the European funded CleanSky2 project Active Flow Control for Tilt Rotor aircraft (AFC4TR), Grant Agreement 886718. The physical dynamics of the use of the Active Flow Control (AFC) actuators embedded in a Vertical Take-Off and Landing (VTOL) aircraft is discussed. Different approaches of AFC are proposed to suppress the flow separation at near stall conditions by using High-Fidelity numerical simulations. First the flow around the Next Generation Civil Tilt Rotor (NGCTR) VTOL aircraft at high angle of attack in the take-off and landing configurations was studied at high Reynolds numbers. At these flow conditions, the study showed that a flow separation travels along the spanwise direction in the near trailing-edge region of the wing with additional corner vortices between the wing-nacelle and the wing-fuselage junctions. This was followed by the investigation of different flow control strategies. Zero Net Mass Flux (ZNMF) actuators, also called synthetic jets, were then used for Active Flow Control. It was found that these ZNMF devices, when operating at the optimal blowing velocity and activation frequency, and when placed at the correct location enable the flow to re-attach and to delay the flow separation, resulting in an increase in aerodynamic efficiency of the aircraft.