Flow Induced Vibrations in Engineering Systems and the Control of Flow Induced Vibrations. Active Control of Vortex Shedding from Circular Cylinder by Cross-Flow Cylinder Oscillations.

Abstract

The present paper describes the active method for controlling vortex shedding from a circular cylinder in uniform flow. The cylinder motion in the cross-flow direction is controlled by the reference velocity signal in the wake with some phase lag, with the aim of reducing vortex shedding from the circular cylinder. The effectiveness of this method is studied by wind-tunnel experiments with flow measurement and visualization. All the results indicate that the reference velocity in the wake is weakened by active control at the optimum phase lag and is strengthened at the reverse phase lag. A similar reduction and enhancement in the velocity fluctuations in the wake with this control at these phase lags is observed in the flow measurement in the cross section of the wake, and is also cofirmed in the whole flow-field visualization study by the smoke-wire method with a laser-sheet technique. These results suggest the possibility of reduction of vortex shedding from a circular cylinder and modification of the wake by the present active control method.