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

本课题的研究对象是将于世纪建成的超长悬索桥的气动失稳控制。如何抑制超长悬索桥的颤振或采用一定的技术措施提高颤振风速是需要解决的问题。已经提出了一些方法。其中大部分是通过改变结构性能来改善结构的动态性能。另一方面，本方法是基于控制气动力诱导的特大悬索桥主梁颤振的思想。针对主梁前缘分离流产生的主要气动力，本文将旋翼设置在主梁典型截面的扁矩形柱前缘，利用风洞试验进行了控制主梁前缘分离流的研究。测量了气动响应和非定常气动表面压力。实验结果表明，该装置的颤振风速比无转子时提高了3倍以上。通过旋转圆柱体来减小边界层，抑制表面压力脉动，对改善超长悬索桥的气动性能是有效的。

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.