Suppression of vortex-induced vibration of a box girder using active suction-jet slit

An active suction-jet flow control method was employed to suppress vortex-induced vibrations (VIVs) of a singlebox girder based on a wind tunnel test. The flow structure around a fixed model was measured by time-resolved particle image velocimetry (PIV), and the stability of the flow field was evaluated in the controlled and uncontrolled cases according to the solution of the Orr-Sommerfeld equation. The PIV results show that the maximum value and distribution region of the turbulence kinetic energy were alleviated. The linear stability analysis indicates that the unsteady flow of the controlled cases was pushed downstream. The vibration response and flow structures of vertical and torsional vortex-induced vibrations (V- and T-VIVs) were then investigated. The results show that the amplitudes of V-VIVs and T-VIVs were greatly suppressed by the active suction-jet slit, and the momentum coefficient at 0.0301 had the most-effective control. Moreover, time-resolved PIV was utilized to investigate the flow structures of the baseline and optimal control cases. The results indicate that the vortex dissipation behind the optimal control case was accelerated, and the topological structure in the wake changed. The vortex contours show that the jet flow strongly interacted with the separated layer and alleviated the interaction of shear flow from the upper and lower surfaces, thereby weakening the unsteady aerodynamic force acting on the test model and mitigating the VIVs. Furthermore, a test of the flutter performance indicated that the critical velocity of flutter in the optimal case improved slightly.