Separated Flow Around Dragonfly Inspired Corrugated Airfoil at Large Angle of Attack in Freestream Turbulence

An experimental study has been undertaken to explore the effect of externally induced free stream turbulence on a bio-inspired corrugated airfoil. Flow visualization is undertaken at Re = 960, 2100, 6760 and 11,700 and angle of attacks (AOA) of ±15°. The free stream turbulence is observed to significantly alter the flow behavior around the corrugated surface. Formation of vortices is seen at all the four Reynolds numbers covered in the study. However, the non-uniform sizes of vortices formed over the airfoil surface preclude the formation of smooth streamlined virtual airfoil as reported earlier in the literature for flows without external turbulence. The time averaged and instantaneous velocity and vorticity plots are discussed to provide better insight into flow behavior. This is perhaps a maiden study in the literature exploring the flow behavior around corrugated surfaces under external turbulence at higher angle of attacks.