(Dr. Ari Glezer, advisor)

"Virtual Aero-Shaping of a Clark Y Airfoil at Low Angles of Attack"

Abstract

The pressure drag of lifting surfaces at low angles of attack is reduced with minimal lift penalty by fluidic modification of the apparent aerodynamic shape of the surface.  The pressure distribution on the surface is modified when the baseline flow is fully attached by the formation of a small stationary recirculating flow domain next to the surface, which displaces the local streamlines sufficiently to modify the local pressure distribution.  In the present work, the recirculating flow domain is formed on the surface of a Clark-Y airfoil by combining the activation of a high-frequency synthetic jet actuator placed downstream from a miniature surface-mounted passive obstruction.  The alteration of the pressure distribution around the airfoil results in a significant reduction in pressure drag that is comparable to the magnitude of the pressure drag of the baseline configuration with minimal loss of lift.  Effects of the obstruction location, obstruction size, jet location, jet strength, angle of attack and chord based Reynolds number on the pressure distribution and aerodynamic performance characteristics are investigated.  The flow structure in the vicinity of the recirculation domain and its scaling is investigated using particle image velocimetry (PIV).  It is also shown that replacing the recirculation domain with a solid surface extension having the same shape results in complete flow separation.