Abstract
It has been shown [1] that the axisymmetric wake is dominated by three types of instability mechanism: an axisymmetric “pumping” of the recirculation bubble at very low frequencies, antisymmetric fluctuations induced by a helical vortex structure that forms just downstream of the rear stagnation point and several higher-frequency, axisymmetric instability modes of the separated shear layer. The environmental requirement for drag reduction has placed a greater emphasis on base-pressure recovery of bluff bodies. The active control of separating flow around bluff bodies has tended to focus on 2D bodies [2, 3] demonstrating that large drag reductions are possible, usually by controlled blowing, at frequencies close to the von Karman shedding frequency. However, in terms of control, 3D bluff bodies have received considerably less attention even though this configuration appears in many practical problems. Even then, active control has tended to focus on the delay of separation [4]. In the present work, we show that the base pressure of a blunt trailing edge may be increased by a high-frequency jet from a zero-net-mass-flux (ZNMF) device.
Published Version
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