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

钝体的流激振动常见于核电站、石油/化工厂和海洋平台等工业装置中。通常，在管道系统中插入热电偶和传感器探头。如果工作流体是液体，这种质量比极小的悬臂状结构很容易受到流动的影响而产生振荡。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”的热电偶损坏主要是由水流引起的振动引起的。如果系统阻尼较小时，弹性支承圆柱体的涡流脱落会导致圆柱体在横向（横流）和顺流（直线）方向上振荡。通过水洞和风洞自由振荡试验和数值模拟，研究了圆柱流致直线振荡问题。在一个水洞和一个风洞中，我们进行了多个实验…更多的研究是圆柱体两端弹性支承和圆柱体悬臂。在较宽的测试范围内改变结构阻尼参数，以评估当圆柱体两端支承并悬臂时抑制在线振荡响应的临界值。对圆柱的响应幅值进行了测量和计算，以评估小于1.0的减质阻尼参数的值。在自由振荡试验中，圆柱体模型采用弹簧安装，在水洞和风洞中作为二维刚性圆柱体进行振荡。两种类型的激励现象出现在大约一半的共振流速度。具有对称涡街的第一激励区直线振荡时，响应幅值对质量阻尼参数的减小敏感，交替涡周期性脱落，与第二激励区圆柱的振动锁定。在后一区域的直线振荡中观察到一种迟滞现象。对有限长宽高比为10的悬臂圆柱体的流体弹性特性进行了测试，发现这些特性与二维圆柱体的流体弹性特性有很大的不同，只有一个宽的速度激励区。水洞和风洞试验结果与数值模拟预测结果吻合较好。这项研究的结果为日本机械工程师学会最近出版的《管道中圆柱形结构流致振动评估指南》标准JSME S012-1998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