Numerical study on suppression of vortex-induced vibration of circular cylinder by helical wires

Abstract

The mechanism of suppression for the vortex-induced vibration (VIV) of circular cylinder by the helical wires is investigated using LES turbulence model. Numerical models for the free-vibrating circular cylinders with and without the helical wires are proposed and validated by the experiments. Simulations are carried out for a large mass ratio of 248 and a small damping ratio of 0.00257 with the Reynolds numbers ranging from 16000 to 24500 and the reduced velocities ranging from 4.5 to 6.8. It is noticed that the helical wires of diameters ratio d/D ​= ​0.1 effectively suppress the amplitude of VIV by nearly 80% and avoid the “lock in”. The steady and unsteady aerodynamic forces of circular cylinders with and without the helical wires as well as the flow patterns are also examined to clarify the mechanism of VIV suppression. It is found that the fluctuating lift forces and their spanwise correlation for the wired cylinder are significantly reduced comparing with those for the bare cylinder, due to the enhancement of three-dimensional disturbance to the wake caused by helical wires. The aerodynamic damping for the oscillated bare cylinder is negative, while that for the wired cylinder is positive with a vibration amplitude A/D ​= ​0.1 ​at the resonance velocity of bare cylinder.