Flow Control Over a Circular Arc Airfoil by Periodic Blowing

Abstract

The flow over sharp-edged wings is almost always separated. The control of separated flows is possible and benefits can be achieved but only in a time average sense. A new design of an actuator was designed and tested which can achieve a wide range velocity of without frequency dependence, is free of oscillating components as well as free of secondary frequencies and therefore can be scaled up easily, unlike a traditional synthetic jet. The actuator can achieve a considerable amount of jet vectoring, thus aligning the disturbance with the leading edge shear layer. Results indicate that unsteady mini-jet actuation is an effective actuation device capable of increasing the lift in the stall region of the airfoil. Moreover, pressure measurements showed that two parameters could be altered to maximize the lift. The momentum coefficient needed a minimum value to exert influence and the actuating frequency need not be at exact the natural shedding frequency to improve the lift and can be operated at harmonics of the natural shedding frequency and obtain improvements.