Aerodynamic mechanisms of flutter control for a π -shaped section with a central stabilizer and a spoiler

Abstract

The π-shaped section, as a typical blunt section, exhibits significant airflow separation around its section, making it susceptible to wind-induced vibrations. To investigate the flutter mechanism and control measures of a π-shaped section, the Ebtehaj cable-stayed bridge is taken as a case study. Wind tunnel tests and numerical simulations are combined to examine the effects of an upper central stabilizer and a spoiler. The differences in the flutter control performance are clarified through analyses of the spatiotemporal evolution of vortices and the characteristics of zonal aerodynamic work. The results show that an upper central stabilizer with a height of two-thirds of rib height can completely eliminate divergent vibration, while, within the tested parameter range, 60° is identified as the optimal aerodynamic angle for the spoiler. The upper central stabilizer suppresses flutter by modifying the vortex distribution over the upper surface, interrupting the vortex correlation between the upstream and downstream regions of the stabilizer and enhancing vortex interactions in the wake region. However, the spoiler primarily regulates the flow by suppressing vortex generation on the upper surface and altering the vortex distribution on the lower surface. From an energy perspective, the central stabilizer enhances the negative aerodynamic work at the leading edge while altering the aerodynamic work characteristics at the trailing edge. The spoiler, on the other hand, significantly strengthens the negative aerodynamic work at the leading edge and changes the aerodynamic work in the mid-leading-edge region from negative to positive.