Effectiveness of Dynamically Deflected Tab Control of a Tip Vortex

Abstract

The control of the tip vortex generated by an oscillating NACA 0015 wing via a dynamically deflected trailing-edge tab, actuated at 29 different start times, amplitudes, and ramp-up rates, was investigated. The upward tab deflection was found to be more effective in weakening the peak tangential velocity and vortex strength than the downward deflection, regardless of the start time and ramp-up rate. A pair of corotating vortices was persistently noticed during pitch-up. An earlier and faster tab deflection (actuated during pitch-up) led to a larger reduction in the core vortex flow quantities. The downward tab deflection was, however, more effective in displacing the vortex position and in diffusing the vortex. The later and slower the downward tab actuation, the larger the vortex displacement and diffusion that took place. The largest reduction in the vortex strength was obtained with a start time at the beginning of pitch-down. The effectiveness of the tab control was also evaluated via the hysteretic behavior of the vortex core flow quantity and the potential suppression of the blade-vortex-interaction noise.