Feedback Mechanism of Combinated Vibration Phenomenon of Fluid-Structure and Its Control

本文旨在研究流固耦合振动现象的反馈机理及其控制。采用了具有基本结构构型的不同深度比的矩形棱柱。通过自由振动和受迫振动试验，研究了直角棱镜的旋转振动响应特性。流激振动的抑制是由一个T形板和一个分离板连接到上游和下游的矩形棱柱。主要结果可归纳如下。(1)棱柱体侧面除尾缘外的脉动压力是由棱柱体前缘周期性脱落的前缘涡冲击产生的。(2)本文研究了B/H=3的棱柱体在前缘涡和尾涡相互作用下的流致振动。T型板抑制了前缘冲击涡的产生，分流板抑制了前缘冲击涡的产生， 关于我们 尾流涡流的产生。(3)带分束板的棱镜的脉动力矩与普通棱镜的脉动力矩基本相同。而T形板棱柱体的脉动力矩比平面棱柱体的脉动力矩大幅度减小。因此，人们认识到，流动诱导的棱柱体的振动强烈地依赖于冲击前缘涡，而不是尾涡。(4)在受迫振动频率Sv<1.0范围内，平面棱镜和带隔板棱镜的脉动力矩做功为正值，流激振动发散。另一方面，具有T形板的棱镜的功在Sv=0至0.06的范围内几乎变为零值。并且振动收敛，因为功在Sv=0.23的范围内是负的。(5)本文通过对带有前缘冲击涡的平面矩形柱体的自由振动试验，发现存在三种流激振动，即：低速扭振、涡激和高速扭振。(6)在棱镜下游加装分离板后，抑制了涡的激发。上游附加T形板后，低速、高速扭转颤振和涡激均得到抑制。因此，当用T形板抑制撞击前缘涡流时，最有效地抑制了棱柱体的流致振动。少

The objective of this study to investigate the feedback mechanism of combined vibration phenomenon of fluid-structure and its control. The rectangular prism with various ratio of depth having a fundamental structure configuration is adopted. The response characteristics of rotary oscillation of the rectangular prism are investigated on the free and forced vibration test. The suppression of the flow-induced vibrations is established by a T-shape plate and a splitter plate attached to the upstream and downstream of rectangular prism. The main results can be summarized as follows.(1) The fluctuating pressure on side surface of the prism except near the trailing edge is generated by impinging leading-edge vortex shed periodically from the leading edge of the prism.(2) Flow-induced vibrations of a prism with B/H=3 is induced by impinging leading-edge vortex and wake vortices. The T-shape plate suppresses the generation of impinging leading-edge vortex and the splitter plate suppresses the g … More eneration of the wake vortices.(3) The fluctuating moment of the prism with splitter plate is almost same to the plain prism. However, the fluctuating moment of the prism with T-shape plate greatly decreases in comparison with the plain prism. Therefore, it is recognized that flow-induced vibrations of the prism are strongly dependent on the impinging leading-edge vortices rather than the wake vortices.(4) The work done by fluctuating moment of the plain prism and the prism with splitter plate becomes a positive within forced oscillation frequency Sv<1.0 and flow-induced vibration diverges. On the other hand, the work of the prism with T-shape plate becomes almost zero value in the range of Sv=0 to 0.06. And the vibration converges because the work is negative in the range to Sv=0.23.(5) From the free-vibration test for the plain rectangular prism with impinging leading-edge vortices, it is found that there exists three types of flow-induced vibration, I.e., low-speed torsion flutter, vortex excitation and high-speed torsion flutter.(6) The vortex excitation is suppressed when the splitter plate is attached at the downstream of a prism. The low-speed and the high-speed torsion flutter and the vortex excitation are suppressed when the T-shape plate is attached at the upstream side. Therefore, suppression of the flow-induced vibrations of the prism is done with the most effectiveness when the impinging leading-edge vortices are suppressed with the T-shape plate. Less