AERODYNAMIC ACTIVE CONTROL FOR SUPPRESSING FLUTTER OF SUPER-LONG SUSPENSION BRIDGE

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The object of the research project is how to suppress aerodunamic instability of super-long suspension bridge, which will be constructed in 21st century. The problem to be solved is to suppress flutter of super-long suspension bridge or to increase the flutter-on-set wind velocity by a certain technical method. A few methods are already proposed. Most of them are the methods to improve the dynamic performances by changing structural performances. On the other hand, the present method is based on the idea to control aerodynamic forces inducing flutter of girder of super-long suspension bridge. Since the predominant aerodynamic forces are generated by the separation flow from the leading edge of the girder, in the present research, the separation flow from leading edge is controlled by setting the rotor at the leading edge of shallow rectangular cylinder, which is the typical cross section of the bridge girder.The experiments are conducted by using the wind tunnel. The aerodynamic responses and unsteady aerodynamic surface pressures are measured. According to the experimental results, the flutter-on-set wind velocity is raised up to 3 times of without rotor. The boundary layr is shrank by rotaing the cylinder and the surface pressure fluctuation is suppressed.The results show the usefulness to improve the aerodynamic performances of the super-long suspension bridge.