Study on Flow-Induced In-Line Oscillation of a Structure in the Pipe System of Industrial Plants in the Region of High Reynolds Number

海崖体的流致振动发生在核电站、石油/化工厂和海上平台等工业装置中。通常，热电偶和传感器探头插入管道系统中。如果工作流体是液体，则这种具有极小质量比的波纹状结构可以容易地被流动引起振荡。例如，1995年日本核循环开发研究所的快中子增殖反应堆“文殊”中的热电偶损坏主要是由流向流动引起的振动引起的。本文通过水洞和风洞自由振动试验以及数值模拟，研究了弹性支承圆柱在横向（横流）和流向（顺向）两个方向上的流动诱导顺向振动。在水洞和风洞中，我们进行了多次实验， 关于我们 l研究了两端弹性支承的圆柱和悬臂圆柱的情况。在较宽的试验范围内改变结构阻尼参数，以评估当圆柱两端支撑和悬臂时，在线振动响应被抑制的临界值。已被测量和计算的响应振幅的圆柱的评价值的约化质量阻尼参数小于1.0。在自由振荡试验中，圆柱体模型被弹簧安装，以便在水洞和风洞中作为二维刚性圆柱体振荡。两种类型的激励现象出现在大约一半的共振流速。在第一激励区域的轴向振动过程中，响应幅值对质量阻尼参数的变化敏感，在第二激励区域中，交替涡周期性地脱落，并与圆柱的振动锁定在一起。观察到滞后现象出现在后一个区域的在线振荡。本文对一有限长宽高比为10的悬臂圆柱进行了流体弹性特性试验，发现其流体弹性特性与二维圆柱的流体弹性特性有很大的不同，只有一个较宽的速度激励区。水洞和风洞实验测量的结果与数值模拟预测的结果基本一致。本研究的结果为日本机械工程师学会最近出版的《管道中圆柱形结构的流致振动评价指南》JSME S 012 -1998标准提供了重要的支持数据。少

Flow-induced vibration of bluff bodies occurs in industrial plants such as nuclear power plants, petroleum/chemical plants and offshore platforms. Usually, a thermocouple and a sensor probe are inserted in the pipe system. If the working fluid is a liquid, such cantilever-shaped structures with extremely small mass ratios may be easily induced by the flow to oscillate. For example, the damage to a thermocouple in the fast breeder reactor "Monju" of the Japan Nuclear Cycle Development Institute in 1995 was caused mainly by a stream wise flow-induced vibration. Vortex shedding from an elastically supported cylinder can cause the cylinder to oscillate in the transverse (cross-flow) and strea mwise (in-line) directions if the damping of the system is small.Flow-induced in-line oscillation of a circular cylinder was studied by free-oscillation tests in a water tunnel and a wind tunnel and also by numerical simulations. In a water tunnel and a wind tunnel, we carried out multiple experimenta … More l studies where a circular cylinder was elastically supported at both ends and where the cylinder was cantilevered. The structure damping parameter was varied over a wide testing range to evaluate the critical value at which the in-line oscillation response is suppressed, when a cylinder is supported at both ends and cantilevered. Response amplitudes of a circular cylinder have been measured and computed for evaluating the values of the reduced mass-damping parameter of less than 1.0. In the free-oscillation tests, the cylinder models were spring-mounted so as to oscillate as a two-dimensional rigid cylinder in the water and wind tunnels. Two types of excitation phenomena appear at approximately half of the resonance flow velocity. The response amplitudes are sensitive to the reduced mass-damping parameter during the in-line oscillation of the first excitation region with a symmetric vortex street, and the alternate vortices are periodically shed, locking-in with the vibration of the cylinder in the second excitation region. A hysteresis phenomenon is observed to appear in the in-line oscillation of the latter region. A cantilevered circular cylinder with a finite length aspect ratio of 10 was tested for fluid-elastic characteristics of the cylinder, and these characteristics are found to be quite different from those of the two-dimensional cylinder, having only one wide velocity region of excitation. The results measured by experiments in the water tunnel and the wind tunnel, and predicted by numerical simulations are in fair agreement. The results of this study are providing important supporting data for the recent publication "Guideline for Evaluation of Flow-Induced Vibration of a Cylindrical Structure in a Pipe" by the Japan Society of Mechanical Engineers, Standard JSME S012-1998. Less