A Study of Pulsed Blowing Effect on Flow Separation over Flap

With the development of the modern aircraft, such as tailless flying configuration, traditional flaps are also the main control surfaces for flight controlling. However, the efficiency of the flap is not only descent quickly due to flow separation over itself under higher deflection angle of flap, but also is evidently influenced by the flow coming down from the upstream wing. A novel flow control technique to improve the flow separation over the flap by pulsed blowing is investigated in this paper by wind tunnel test under Reynolds number of 0.6*10E6 2.4*10E6. To begin with, the control performance for flow separation over the flap is very sensitive to the blowing position and direction and the flow separation can be recovered by the pulsed blowing evidently. Secondly, the pulsed blowing efficiency is 30{\%} higher than that of continuous blowing with the same consumption. In addition, the pulsed blowing efficiency increases quickly with the increasing of pulsed blowing frequency and keep constant gradually when the pulsed blowing Stroul number is bigger than 0.6.