Experimental Study on the Utilization of Synthetic Jet to Modulate the Leading-Edge Vortex of a Flapping Wing

Biological flapping wing flyers depend upon the leading-edge vortices for their sustained flight. The leading-edge are the vortices formed when the airfoil impulsively started in a fluid with an angle of attack (AOA) > 15°. This leading-edge vortex creates a negative pressure over the wing surface and is the main reason behind the sustained flight in birds and insects at low Reynolds number \(\sim {10}^{4}\) . This paper adopts an active flow control technique (synthetic jet) to modulate the leading-edge vortex’s strength. The experimental setup comprises a 4-bar flapping wing robotic model and the reciprocating slider crank synthetic. The Arduino AT-mega 2560 microcontroller digitally controlled the robotic flapping model and the synthetic jet. Semi-elliptical wing profile, close to the wing morphology of biological flapping wing flyers with AR 1.5 was selected. The leading-edge along the span was provided fourteen 2 mm orifices to accommodate the span-wise blowing. A constant temperature anemometer (CTA) was used for the characterization of the synthetic jet. Then instantaneous PIV images were acquired at 85% of the span for the free stream wind speed of 0.6 m/s. The PIV results showed that periodic blowing at 5 Hz, along with 2.5 Hz flapping along the chordwise direction, influenced the shape of the leading-edge vortex (LEV) structure and altered its magnitudes of induced velocity and vorticity.