Tethered cube stabilization by means of leading-edge DBD plasma actuation

Abstract

An experimental investigation was carried out to assess the effectiveness of active flow control as a means for suppressing oscillations of a tethered cube. Two experimental configurations were considered: a static configuration involving surface pressure and particle image velocimetry (PIV) flow field measurements and a dynamic, tethered, configuration. Corner-mounted, dielectric barrier discharge plasma actuators were employed at the leading-edges and were pulsed at reduced frequencies of order one and at varying duty cycles. On the static configuration, actuation changed the direction of the side-forces and virtually eliminated yawing-moment excursions. Surface pressure and flow field measurements showed that control of separation bubbles on the surfaces, as well as control of the separated shear layer, were responsible for these effects. Phase-averaged PIV measurements elucidated the mechanism whereby actuation severs the leading-edge vortex that subsequently sheds downstream. For the tethered cube, actuation dramatically reduced the yawing motions, particularly when the momentum coefficient exceeded 0.3 %. Drag reduction, based on the deflection of the cube, was estimated to be approximately 12 %, consistent with the static data. Reduced frequency and duty cycle had a marked effect on control effectiveness.