Effect of gap on the vortex-induced vibration suppression of a circular cylinder using two rotating rods

摘要

The vortex-induced vibration suppression of a circular cylinder by means of two counter-rotating rods located at 120° with gap ratio ranging from 0.03 to 1.00 is numerically investigated in the present work. It is observed that the rotating rods at an appropriate gap range (0.07D-0.10D) can lead to a reattachment of the flow on the leeward side of the main cylinder, resulting in a well-organised and narrower wake. Therefore, the vibration is well suppressed in this gap range. However, the vibration amplitude is slightly higher and the flow is not well controlled at too small gap. The effect of the rotating rods becomes weaker when the gap is beyond G = 0.12D. At G = 1.00D, the boundary layer of the main cylinder is almost unaffected by the rotating rods. Therefore, the flow control is not achieved at too large gap due to less injected momentum.