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TRANSIENT CONTROL OF THE SEPARATING FLOW OVER AN AIRFOIL

George Tak Kwong Woo
George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332, USA

Ari Glezer
George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, Georgia 30332, USA

Sinopsis

The effects of pulsed actuation on stalled NACA 4415 airfoil is investigated in wind tunnel experiments. The actuation results in transitory flow attachment that is manifested by rapid changes in the global circulation and aerodynamic forces. Actuation is applied by a momentary [Ο(1 msec)] jet produced by a combustion-based actuator such that the characteristic duration of the impulse is an order of magnitude shorter than the characteristic convective time over the airfoil. The present work has shown that large-scale changes in vorticity accumulation and flux can be effected by successive repetitions of a single actuation pulse and are accompanied by significant shedding of CCW vorticity concentrations on the pressure side coincidently with the trapping of CW vorticity concentrations, hence extending the streamwise domain of the attached vorticity layer towards the trailing edge.