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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.

本研究是关于快速增殖反应堆文殊液态钠横流中温度计套管的自激在线振动。日本在热电偶套管失效后，对悬臂圆筒的在线振动进行了大量的研究，但至今尚未对振动的原因作出明确的解释。特别是，为什么只有一个特定的热电偶套管破裂的原因尚未给出解释，仍在调查中。从学术的角度来看，这是一个令人兴奋的课题。因此，我们决定利用CRIERI Abiko研究中心的水洞，在小强制振幅的外部激励下，对作用在振动圆柱上的流体动力进行精确测量。在一系列的实验中，通过改变激振振幅、来流速度和激振频率来考察激振振幅和折合速度对激振力的影响，发现流体力是由与振动圆柱的加速度、速度和位移成正比的分量组成的。我们还发现，决定不稳定性的激励参数强烈依赖于缸的振幅。此外，附加质量系数随折合速度的变化而变化，折合阻尼的稳定性准则受质量比的影响较小。最后，我们收集了非定常流体动力学数据作为进一步研究的数据库。