燃料相关组件棒流致振动可视化实验研究

Visualization of flow-induced vibration of fuel-related assembling rod

悬臂梁在反应堆系统当中是常见结构,悬臂组件棒在冷却剂轴向外流冲刷下会发生湍流激振现象,有害的振动将威胁到相关结构的完整性,而目前对大长径比组件棒在极小环隙下的流致振动特性缺乏有效的测量手段。为了解决对大长径比组件棒在极小环隙下的流致振动特性的测量问题,本文提出了可视化测量方法,使用了高速相机对悬臂梁轴向外流流致振动特性进行研究。通过外部施加单点激励单点拾振的方式,得到了相关组件棒的干模态参数,同时使用2台相机同步拍摄获得了组件棒的二维运动轨迹;实验结果表明:棒的自由端振动相较于固定端更剧烈;低流速时,棒的振幅随着流速增大而增大,振幅在0.2 mm以下,而高流速时,棒存在接触壁面的情况,使得棒振幅减小。

The cantilever is a common structure in the reactor system. A turbulent excitation phenomenon occurs in the cantilever assembly rod during the axial outflow of the coolant in the washing-out phase, and this harmful vibration threatens the integrity of the associated structure. As yet, there is no effective means for measuring the flow-induced vibration characteristics of component rods with large length-to-diameter ratios and a very small annulus. To solve this problem, in this paper, we propose a visual measurement method that makes use of a high speed camera to study the vibration characteristics of the axial outflow of the cantilever beam. We obtained the dry mode parameters of the relevant component rods by applying external single-point excitation single-point pick-up. At the same time, we obtained the two-dimensional motion trajectory of the component rods by shooting two cameras simultaneously. The test results show that the vibration at the free end of the rods is more intense than at the fixed end. At low flow rates, the amplitude of the rod increases with increasing flow rate, and the amplitude is below 0.2 mm. At high flow rates, however, the rods come in contact with the wall surface at times, which decreases their amplitude.