MECHANISM OF VIBRATION SUPPRESSION EFFECT FOR CONNECTED CANTILEVERED STRUCTURE OSCILLATING IN-LINE DIRECTION IN CROSS FLOW

横流直列振动连体悬臂结构的振动抑制机理

基本信息

批准号：
12450094
负责人：
KANEKO Shigehiko
金额：
$ 9.6万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

This study is related to self-excited in-line vibration of a thermo-well in liquid sodium cross flow experienced in Fast Breeder Reactor Monju. Although quite a large number of research on the in-line oscillation of a cantilevered cylinder have been conducted in Japan after the failure of the thermo-well, clear cut explanation of the cause of the vibration has not yet been done. Especially, the explanation on the reason why only single particular thermo-well was broken is not yet given and is still under investigation. From the viewpoint of academic interest, this is an exciting topic.Therefore, we decided, to conduct precise measurement of fluid dynamic forces acting on the vibrating cylinder by using water tunnel at CRIERI Abiko Research Center under small forcing amplitude external excitations. In a series of experiments, we changed forcing amplitudes, oncoming flow velocities and excitation frequencies to check the effect of the dependency on the amplitude of the cylinder and reduced velocity.As a result, we found the fact that fluid force is composed of the component proportional to acceleration, velocity and displacement of the vibrating circular cylinder. We also found that excitation parameter which determines the instability is strongly dependent on the cylinder amplitude. In addition, added mass coefficient varies depending on reduced velocity and the stability criteria of reduced damping is slightly affected by the mass ratio. Finally, we collected unsteady fluid dynamic data as a database for further studies.

这项研究与快速育种反应堆Monju中经历的液体钠交叉流中的热孔自我旋转有关。尽管在热孔失败后，日本已经进行了大量有关悬臂缸的在线振荡的研究，但尚未完成对振动原因的清晰解释。特别是，关于仅给出只有单个特定热孔被打破的单个特定热孔的原因的解释尚未给出并且仍在研究中。从学术兴趣的角度来看，这是一个令人兴奋的话题。因此，我们决定通过在小强迫外部激励下使用Crieri Abiko Research Center的水隧道来精确测量作用于振动缸上的流体动力学。在一系列实验中，我们更改了强迫幅度，迎面速度的流速和激发频率，以检查依赖性对圆柱体振幅的影响并降低速度。结果，我们发现流体力是由组成部分组成的事实与振动圆柱体的加速度，速度和位移成比例。我们还发现，确定不稳定性的激发参数很大程度上取决于气缸振幅。此外，添加的质量系数因速度降低而变化，减少阻尼的稳定性标准受质量比略有影响。最后，我们收集了不稳定的流体动态数据作为进一步研究的数据库。