Abstract
This article covers the application of the windward-suction-leeward-blowing concept in the reduction of flow-induced vibration of an elastically-mounted square-section cylinder in the active open-loop control framework. Certain slots with equal length are devised on the front and rear surfaces of the cylinder to perform flow suction and flow blowing. These slots have the same actuation velocity. To study the effectiveness of the present flow control approach, fluid-structure interaction simulations for both the lock-in (85 < Reynolds Number < 95) and galloping (Reynolds Number > 170) regions are conducted based on a finite volume code. According to the plots of maximum cylinder cross-flow displacement, planar orbital trajectories and snapshots of vorticity contours, the success of this control approach in complete suppression of vortex shedding and thus the flow-induced oscillations in both mentioned regions is shown. Also, increasing the actuation velocity and slot length improves the performance of windward-suction-leeward-blowing in flow control and vibration attenuation. The minimum actuation velocity required for attenuation of cylinder oscillations in the galloping zone is higher than that of the lock-in region. Moreover, with increasing actuation velocity and slot length, the shear layer is stretched, suppressing the vortex-shedding and changing the mode of wake structure from 2S (for lock-in region) and 2S+2P (for galloping zone) to a vortex-free symmetric wake. Also, the proposed control approach alters the orbital pattern diagrams of the cylinder that are in the form of figure-8-shaped plots and transfers them to a bounded region commensurate to the small transverse and in-line displacements of the cylinder.
Published Version
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