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

本研究的目的是探讨流固耦合振动现象的反馈机理及其控制。采用具有基本结构构型的不同深度比的矩形棱镜。在自由振动和强迫振动试验中，研究了矩形棱镜旋转振动的响应特性。流致振动的抑制是由一个T形板和一个附加在矩形棱镜上下游的分流板来实现的。主要研究结果如下：(1)棱镜前缘涡的冲击产生了棱镜侧面除后缘外的脉动压力。(2)前缘涡和尾流涡的撞击诱导了B/H=3棱镜的流致振动。T形板抑制了撞击前缘涡的产生，分离板抑制了g…分流棱镜的脉动力矩与普通棱镜的脉动力矩基本相同。但是，与普通棱镜相比，T形板棱镜的脉动力矩大大减小。因此，我们认识到棱镜的流致振动强烈地依赖于撞击的前缘涡旋，而不是尾迹涡。(4)在强迫振动频率Sv&lt；1.0范围内，平面棱镜和带有分流板的棱镜的脉动力矩所做的功变为正功，流致振动发散。另一方面，在Sv=0到0.06的范围内，T形板棱镜的功几乎为零。在Sv=0.23的负功范围内，振动收敛。(5)对前缘有撞击的矩形棱镜进行自由振动试验，发现存在低速扭转颤振、涡激振动和高速扭转颤振三种类型的流致振动。(6)在棱镜下游安装分离板后，涡激振动被抑制。当T形板安装在上游侧时，低速和高速扭转颤振和涡激被抑制。因此，当T形板抑制撞击前缘涡流时，对棱镜流致振动的抑制是最有效的。较少

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