Prediction and Guideline for Evaluation of Flow-Induced In-Line Oscillation of a Cylindrical Structure in the Bubbly Flow of the Pipe System.

管道系统气泡流中圆柱形结构流动引起的同轴振动的预测和评估指南。

• 批准号: 11555054
• 负责人: OKAJIMA Atsushi
• 金额: $ 8.83万
• 依托单位: Kanazawa University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555054/
• 关键词: Flow-induced vibration; In-Line Oscillation; Circular cylinder; Bubbly flow; Reduced mass damping parameter; Water tunnel; Aspect ratio; Taperd circular cylinder; 円柱; 数値シミュレーション; 気液ニ相流

This study are for providing important data to support and develop "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. Flow-induced in-line oscillation of a cantilevered circular cylinder model like a thermocouple that is actually used in industrial plants has been experimentally studied by free-oscillation tests in a water tunnel.Free- oscillation test for a cantilevered model like a thermocouple in a water (a single- phase flow): The response tip amplitudes of a circular cylinder were measured at varying reduced velocity from 1.0 to 4.0. A cantilevered cylinder was supported by plate spring mounted on the water tunnel wall. The aspect ratio of a cylinder was varied from 5 to 21 to investigate the effect of aspect ratio on the response amplitude. It is found that the cylinders with aspect ratio of 5 and 10 show one excitation region, but the cylinders with aspect ratio of 14 an … More d 21 showed two excitation regions. The aspect ratio, therefore, strongly affects the amplitude of the second excitation region. The influence of end-effect also was investigated using cylinders with an end plate attached on the free end. Because the cylinders with an end plate show two excitation regions even if the cylinder has an aspect ratio of 5, the flow around the free end of cantilevered cylinder makes the end-effect. The mechanism of vibration was investigated using a cylinder with a splitter plate in wake to prevent the alternate vortices. The amplitude is bigger than normal cylinder especially at the reduced velocity from 2.3 to 3.0 where the cylinder attached an end plate shows the second excitation region; that is to say, the alternate vortices suppress the amplitude in this range. The maximum amplitude of each excitation region decreases in proportion to the reduced dumping parameter and the amplitude of the first excitation is more sensitive to that parameter. The amplitudes are suppressed in each excitation region when the reduced dumping parameter is greater than 2.5 with each aspect ratio of 10 and 21.Free- oscillation test for a cantilevered model in two-phase flow: As the fundamental study on flow-induced in-line oscillation of a cantilevered circular cylinder model in two-phase flow, the variations of void fraction, bubble diameter and bubble velocity are measured using an electrical resistivity probe when two-phase flow goes through the region of sudden area expansion in the vertical pipe. In this study two different radial void distributions in the pipe are considered. One is called as sliding flow regime, which occurs when the bubble diameters are less than 5mm. The other is termed as coring flow regime, which takes place when the bubble diameters are greater than 5mm. And the response amplitudes of a circular cylinder have been measured by the free-oscillation tests in the two-phase flow in a water tunnel. Comparing the response amplitudes with the results in a water, we found that the flow-induced vibration are suppressed by the two phase flow. Less

本研究旨在为日本机械工程师学会标准JSME S012-1998《管道中圆柱体结构流致振动评价导则》的制定提供重要数据支持。在水洞中对实际应用的热电偶等悬臂式圆柱体模型的流致顺排振动进行了水洞自由振动试验研究。悬臂式模型如热电偶在水(单相流)中的自由振动试验：测量了折减速度从1.0到4.0的圆柱体的响应尖端振幅。悬臂圆柱体由安装在水洞壁上的板簧支撑。为了研究长径比对响应幅值的影响，将圆柱体的长宽比从5变化到21。结果表明，长宽比为5和10的圆柱体只有一个激发区，而长宽比为14的圆柱体只有一个激发区域…更多的d21显示两个激动区。因此，长宽比对第二激发区的幅度有很大影响。在自由端装有端板的圆柱体上，也研究了端面效应的影响。由于有端板的圆柱体在纵横比为5的情况下表现出两个激振区，所以悬臂圆柱体自由端周围的流动产生了端部效应。在尾迹带有分离板的圆柱体上研究了振动的机理，以防止交替的涡流。在减速为2.3~3.0时，圆柱体与端板相连的圆柱体出现第二激振区，即在此范围内交替涡系对振幅有抑制作用。各激励区域的最大幅值随倾倒参数的减小而减小，且第一激励的幅值对该参数更为敏感。当折算倾倒参数大于2.5时，各激振区的振幅均受到抑制，各激振区的长宽比分别为10和21。悬臂模型两相流自由振荡试验：作为悬臂圆柱模型两相流流致顺行振荡的基础研究，利用电阻率探头测量了两相流通过垂直管内突变区时空泡率、气泡直径和气泡速度的变化。在这项研究中，考虑了管内两种不同的径向空穴分布。一种称为滑移型流型，当气泡直径小于5 mm时发生。另一种称为取心流态，当气泡直径大于5 mm时发生。并通过水洞内两相流自由振动实验，测量了圆柱体的响应幅值。将响应幅值与水中的结果进行了比较，发现两相流对流致振动有抑制作用。较少

项目成果

A.OKAJIMA: "Flow-Induced In-Line Oscillation of a Circular Cylinder in a Water Tunnel"Proc. of ASME PVP-Vol.420-1, Flow-Induced Vibration-2001. No.01. 351-352 (2001)

A.OKAJIMA：“水隧道中圆柱体的流动引起的直线振动”Proc。

岡島厚: "円柱および矩形柱の流れ方向流力振動特性"日本機械学会論文集B編. 65巻・635号. 2196-2203 (1999)

Atsushi Okajima：“圆形和矩形柱的流动方向流体振动特性”日本机械工程师学会会刊，B 版，第 65 卷，第 635 期。2196-2203（1999 年）。

中村晶: "円柱構造物の流体励起振動"J.Institute of Nuclear Safety System. Vol.7. 201-215 (2000)

Akira Nakamura：“圆柱形结构的流体引起的振动”J.Institute of Nuclear Safety System Vol.7（2000）。

Okajima, A., Yasuda, T., Iwasaki, T.: "Flow Visualizations of In-Line Oscillation of a Cylinder with a Circular or Rectangular section"Proceeding of 6th Triennial Int'l Sympo. On FLUCOME. (CD-ROM), FL-048. 1-6 (2000)

Okajima, A.、Yasuda, T.、Iwasaki, T.：“具有圆形或矩形截面的圆柱体的直线振动的流动可视化”第六届三年一次国际研讨会论文集。

A.NAKAMURA: "Experiments on Flow-Induced In-Line Oscillation of a Circular Cylinder in a Water Tunnel(2nd Report, The Influence of the Aspect Ratio of a Cantileverd Circular Cylinder)"JSME International. Journal. 44・4B. 705-711 (2001)

A.NAKAMURA：“水隧道中圆柱体流动引起的直线振动实验（第二次报告，悬臂圆柱体纵横比的影响）”JSME 国际期刊 44・4B。 711（2001）