Control of Separated Flow over a Thick Airfoil using Fluidic Actuators


The apparent modification of the surface shape of an unconventional airfoil by surface mounted synthetic (zero mass flux) jet actuators is exploited for dynamic control of flow reattachment and separation. In the absence of control, the airfoil stalls at angles of attack exceeding 5^o for which the dimensionless shedding frequency is F^+=0.7. The effect of the actuation is investigated at two ranges of jet formation frequencies of the order of or well above the natural shedding frequency [i.e., F^+ of O(1) and O(10), respectively]. At either frequency range, the collapse of the separated flow region is associated with a strong lift transient that is followed by a partial or full reattachment and recovery of the mean lift. These transients are exploited to improve the effectiveness of the jet actuators by using pulsed modulated excitation which helps to reorganize the vorticity produced during the initial stages of the separation process and thus to increase the lift force. The evolution of these flow transients is measured using particle image velocimetry. 

Amitay, M., Lal, M., and Glezar, A., "Control of Separated Flow over a Thick Airfoil using Fluidic Actuators."

52nd Annual Meeting of the APS Division of Fluid Dynamics, New Orleans, LA, November 21-23, 1999