Airfoil drag elimination and stall suppression via piezoelectric dynamic tangential synthetic jet actuators

This paper describes a new method for drag elimination and stall suppression via tangential synthetic jet actuators. This boundary layer control (BLC) method is shown to perform as well as continuous and normal synthetic jet BLC methods but without fouling difficulties, system-level complexity or extreme sensitivity to Reynolds number. Classical laminated plate theory (CLPT) models of the piezoelectric actuators were used to estimate diaphragm deflections and volume per stroke. A 12” (30.5cm) chord, 6” (15.3cm) span NACA 0012 profile wing section was designed with three unimorph 10 mil (254μm) thick, 3.25” (8.23cm) square piezoelectric diaphragm plenums and five 1 mil (25μm) thick stainless steel valves spaced from 15%c to the trailing edge of the airfoil. Static bench testing showed good correlation between CLPT and experiment. Plenum volume per stroke ranged up to 5cc at 500 V/mm field strength. Dynamic testing showed resonance peaks near 270 Hz, leading to flux rates of more than 60 cu in/s (1 l/s) through the dynamic valves. Wind tunnel testing was conducted at speeds up through 13.1 ft/s (4 m/s) showing more than doubling of Clmax. At low angles of attack and high flux rates, the airfoil produced net thrust for less than 4.1W of electrical power consumption.