Steady blowing control for tail stall flutter at large angle of attack

Stall flutter poses great challenges to flight safety. To alleviate this problem, a steady blowing control considering the perturbation and wake-induced vibration at a large angle of attack is developed in this paper, where two blowings are configured on upper and lower tail surfaces to suppress the stall flutter. The stall flutter with one-degree-of-freedom is first evaluated by numerical simulation. The equation of motion for stall flutter is solved by the Newmark-β method. Then, the stall flutter responses for five blowing speeds, i.e., 0, 4, 12, 20, and 28 m/s under the airspeed range of 3–9 m/s, are studied in detail. The stall flutter suppression mechanism can be summarized as follows: a large blowing speed can inject energy into the boundary layer and enhance the high-pressure zone, which delays the flow separation on the suction surface. In this way, the formation of the leading-edge separation vortex is suppressed. Thus, the dynamic stall vortex is weakened and accelerates shedding. In addition, the driving moment is reduced, which leads to a decrement in the stall flutter amplitude. When the blowing speed is 28 m/s (stall flutter amplitude = 0.135 7 rad), compared with uncontrolled case (stall flutter amplitude = 0.600 2 rad), the amplitude can decrease by 77.39%, which demonstrates the effectiveness of the proposed steady blowing based active control strategy.