Suppression characteristics of flow-induced vibration in a test cylinder with varying locations of a control cylinder

This study was designed to identify the suppression characteristics and mechanisms of flow-induced vibration occurring in a test cylinder installed on an elastic support by placing a control cylinder with a smaller diameter behind the test cylinder. To identify the effects of this installation, the diameter and location of the control cylinder were varied systematically to examine the characteristics of flowinduced vibration occurring in the test cylinder. Furthermore, the fluctuating streamwise velocity of the wake flow of the test cylinder was examined as it varied with the installation of the control cylinder. Subsequently, the peripheral flow of the test cylinder installed in front of the control cylinder was examined via a flow visualization test that used a water channel. Results obtained from the experiments are summarized as follows. i) Flow-induced vibrations in the test cylinder, which occur and are varied by the installation of the control cylinder behind the test cylinder, have four types that change according to the different diameters and locations of the control cylinder. ii) The domain of the positions of the control cylinder, which can suppress flow-induced vibration in the test cylinder, increases in proportion with the diameter of the control cylinder. iii) Flow-induced vibration that will be generated in the test cylinder is predicted by examining the distribution of the flow velocity of the wake flow and the intensity of the fluctuating streamwise velocity at the lower flow velocity level before it reaches a flow velocity that can create flow-induced vibration in the test cylinder.