Numerical study on wake galloping of tandem circular cylinders considering the effects of mass and spacing ratios

The mass and spacing ratios of parallel circular cylinder structures change over a wide range in engineering applications. In this study, the effects of mass ratio, spacing ratio and helical wires on the wake galloping of tandem circular cylinders are investigated by LES turbulence model at the subcritical Reynolds number regime. The upstream cylinder is fixed and the downstream one is free to respond in the transverse direction. The characteristics of wake galloping of tandem circular cylinders are systematically studied for the cases of mass ratios m∗ ​= ​1.8, 200 and spacing ratios x0/D ​= ​4, 8 and 12. A critical velocity of wake galloping is derived as a function of mass ratio and lift coefficient slope using a wake-stiffness-based model. The suppression of wake galloping by the 4-start helical wires is examined and the maximum amplitude of vibration is found to decrease by 63% because of the positive added damping generated by helical wires. •For the wake-induced vibration of tandem circular cylinders, the resonant and galloping regimes are combined with low mass ratio m∗ ​= ​1.8 and small spacing ratios x0/D ​= ​4, but separated with high mass ratio m∗ ​= ​200 for x0/D ​= ​4 to 12.•An analytical model for predicting the critical velocity of wake galloping is derived as a function of mass ratio m∗ and lift coefficient slope α using a wake-stiffness-based model. The critical velocity of wake galloping increases with m∗ and decreases with α .•The 4-start helical wires with a pitch ratio of ​8 and a diameter ratio of ​0.1 are used to suppress the wake galloping of tandem circular cylinder successfully. The positive added damping is generated by helical wires, which is the main reason of wake galloping suppression.