An Experimental Study on Suppression of Wind-induced Vibration of a Rectangular Cylinder by Pusating Jets from the Leading Edges

Abstract

Effectiveness of pulsating jet flows from inside of cylinder for suppression of wind-induced vibration is investigated by a series of specially arranged wind tunnel experiments. The jet flows are generated through thin slits along the two leading edges of a rectangular cylinder of d/b=2. The jet flows can be pulsated by two computer-controlled AC servomotor wind tunnels. Measured time histories of the cylinder displacements are immediately feed backed to the pulsating jets. The pulsating jets at the two leading edges always have the opposite phases. From the experiments, it is observed that the pulsating jet which has the same phase with the cylinder displacement is quite effective to suppress the vibration, whereas pulsating jets of different phases have less effect or even activate the vibration. The present experimental results suggest that the effective pulsating jet is perturbing the separated flow just when separation bubbles are being formed or start to grow. Interestingly, these experimental observations coincide to the preceding CFD results.