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TSFP DL Home Архив Исполнительный Комитет

TRANSITORY CONTROL OF DYNAMIC STALL

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

Аннотация

The flow transients associated with controlled attachment and separation of the flow over a dynamically stalled airfoil are investigated with the objective of enhancing aerodynamic forces and moments. Transitory response to pulsed actuation on time scales that are an order of magnitude shorter than the characteristic convective time scale is assessed. Actuation is effected by time-periodic bursts of momentary [O(1 msec)] pulsed jets that are generated by a spanwise array (0.2 span) of combustion-based actuators integrated into the airfoil. The flow field in the cross stream plane above the airfoil and in its near wake is measured using high-resolution PIV images that are obtained phase-locked to the oscillatory pitch motion of the airfoil, and allow for continuous tracking of vorticity concentrations. The brief actuation pulses lead to remarkably strong changes in the circulation about the entire airfoil that is manifested by manipulation of the surface vorticity layer. It is shown that a burst of a few actuation pulses during the oscillation cycle can lead to a remarkable increase in lift over most of the cycle including at angles of attack that are below stall by trapped vorticity over the entire oscillation cycle.