Research and Development on Shapes of Non-Vibrational Thermocouple in the Pipe System of Industrial Plants

通过水洞和风洞的自由振动试验和数值模拟，研究了圆柱体和矩形圆柱体的流致振动。钝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厂房中。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形结构很容易因流动而产生振荡。我们进行了多个实验和数值研究，其中圆柱体两端弹性支撑，圆柱体悬臂。通过实验和数值模拟得到的主要结论如下：(1)与长径比为5和10的圆柱体相比，长径比为5和10的圆柱体在折合速度Vr为1.0时到4.0时的响应特性呈现单一激励区，而长宽比为…的圆柱体的响应特性为单激励区14和21的更多比率。研究发现，锥度比为2.5%~10%的圆柱有两个激发区，而锥度比小于1%的圆柱有一个激励区。因此，锥度比影响第二激发区的幅度。考虑到被测圆柱体振动特性的结果，锥形圆柱体的参考直径由距顶端1/3的直径定义。具有任何锥度比的圆柱体在VR&lt；1.0时没有振荡。当质量阻尼参数Cn小于2.5时，任意锥度比圆柱体的振幅被抑制，这是抑制二维圆柱体顺行振动的准则。(3)日本机械工程师学会出版的《管道中圆柱体结构流致振动评估指南》，JSME S012-1998标准证实，包括有限跨度悬臂形圆柱体的情况。较少

Flow-induced oscillation of circular and rectangular cylinders were studied by free-oscillation tests in a water tunnel and a wind tunnel and also by numerical simulations. Flow-induced oscillation 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. We carried out multiple experimental and numerical studies where cylinders were elastically supported at both ends and where the cylinder was cantilevered. The main conclusions to obtained from these experiments and numerical simulations are as follows.(1)The response characteristics of cylinders with aspect ratios of 5 and 10 show single excitation region in the range of reduced velocity Vr from 1.0 to 4.0, in contrast to the cylinders with aspect … More ratios of 14 and 21. Most notably, the aspect ratio affects the depth of valley between the first and second excitation regions and the amplitudes of the second excitation regions.(2)It was found that cylinders with taper ratios of 2.5% to 10% had two excitation regions, while cylinders with taper ratios less than 1% had one excitation region. The taper ratio, therefore, affects the amplitude of the second excitation region. The reference diameter of the tapered cylinder was defined by the diameter at 1/3 length from tip in consideration of the results of oscillation characteristics of tested cylinders. The cylinder with any taper ratio did not oscillated at Vr<1.0. The amplitude of the cylinder with any taper ratio was suppressed at less mass-damping parameter Cn than 2.5, which is the suppression criteria for in-line oscillation of 2-dimensional cylinder.(3)The 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 is certified to include the case of a cantilever-shaped cylinder with a finite span length. Less