Self-Suction-and-Jet Control in Flow Regime and Unsteady Force for a Single Box Girder

Self-suction-and-jet flow control is a passive flow control method involving self-organized suction at the leading edge and a wake jet at the trailing edge of a structure. In this study, it was used in a 1:125 physical model of the Great Belt East Bridge to decrease dynamic wind loads and modify the flow structure around the main girder. Experiments were performed in a wind tunnel at a wind speed of 12 m/s, yielding a Reynolds number of 2.8 × 10⁴ for the height of the main girder model. The surface pressure (and therefore, the aerodynamic force) fluctuated less in the controlled models than in the uncontrolled model. The velocimetry data indicated that self-suction-and-jet flow control effectively changed the vortex shedding process in the wake of the model. The interactions between the self-organized jet flows and shear flows caused the trailing edge vortex shedding to transform from asymmetric to symmetric, eliminating the vortex shedding completely. Linear stability analysis of the mean wake flow structures indicated that self-suction-and-jet flow control pushed the unstable flow region farther downstream.