AN INVESTIGATION ON VORTEX INDUCED VIBRATION AND WAKE INDUCED GALLOPING IN TANDEM CYLINDERS SYSTEM

The flow-induced vibration (FIV) of multi cylinders is a problem involving the safety of fluid engineering and energy harvesting. Due to the effect of wake galloping and vortex induced vibration (VIV), the mechanism of two tandem cylinders is more complex than that of a single cylinder. In this study, the vibration modes of two tandem cylinders with different spans (L/D = 1.5 - 4.0) are investigated at subcritical Reynolds number and high mass damping ratio through wind tunnel tests. In the experiment, the cylinders are free to vibrate in the transverse and in-flow direction. The characteristics of the vibration amplitude and vibration frequency response are discussed with the vibration mode. The results show that the vibration mode is related to the reduced pitches between the cylinders. The vibration of the two tandem cylinder system is combines results of vortex induced vibration and wake induced galloping (WIG). When the span is lower than 2.0, the galloping effect is more obvious than that of larger spans cylinders at the experiment mass damping parameters. The two cylinders turn to vibrate separately as the span grows larger.