Research on the lift-enhancement and roll control characteristics of a circulation control wing

As an efficient active flow control technique, the circulation control has a great potential for aerodynamic improvement and performance enhancement of aircraft. Therefore, a set of circulation control devices that can blow downward are designed, and appllied for aerodynamic control of aircrafts. First of all, parametric analyses of aerodynamic characteristics of a two-dimensional airfoil are conducted by numerical simulations. Then, the aerodynamic force and moment of a conventional rudder wing and a circulation control wing of the same size are analyzed by wind tunnel experiments. Based on these results, the particle image velocimetry (PIV) is further used to reveal the mechanism of circulation control by characterizing the flow fields around circulation control devices. Wind tunnel experiments shows that, when the blowing coefficient equals to is 0.04, the lift coefficient and the roll moment coefficient increases by 32.4% and 60.3%, respectively. PIV results suggest that high-velocity jets deflects the airflow at the trailing edge of the wing, which consequently increases the amount of circulations and changes the force on the wing. The blowing efficiency of the circulation control wing is comprehensively analyzed by introducing the "effective lift-to-drag ratio". Results indicate that the largest effective lift-to-drag ratio and the highest blowing efficiency for a circulation control wing can be achieved with the blowing coefficient equals to 0.02.