Hingeless flow control over an airfoil via distributed actuation

摘要

An experimental investigation was undertaken to test the effectiveness of a novel designfor controlling the aerodynamics of an airfoil. A synthetic jet actuator (SJA) was placedinside a NACA 0015 airfoil with its jet at 12.5% of the chord length, hereby referred toas the leading edge actuator. Four centrifugal fans across the span were mounted at 70%of the chord and the jet formed by them was located at 99% of the chord, hereby referredto as the trailing edge actuator. The effects of these actuators on the aerodynamicproperties were studied, separately and then in conjunction, with varying angles ofattack.The leading edge actuator delays the onset of stall up to 24 degrees, the maximum angleof attack that could be attained. The control of the aerodynamics was achieved bycontrolling the amount of separated region. There was no effect of the actuation at lowerangles of attack.The trailing edge actuator provides aerodynamic control at both low and high angles ofattack. The study investigated the effect of jet momentum coefficient on the aerodynamic properties for various angles of attack. The data obtained shows that liftcontrol (in both positive and negative direction) was achieved even at low angles. Theactuator enhances the aerodynamic properties by changing the pressure distribution aswell as by delaying flow separation.Study of the combined actuation shows that the synthetic jet actuator was very effectivein delaying stall when the trailing edge jet was ejected from the upper surface. For thecase when the jet is ejected from the lower surface, there is less control. This can beaccounted for by the difference in aerodynamic loading for both cases.