A STUDY OF THE MECHANISM OF VORTEX BREAKDOWN

涡流击穿机理的研究

• 批准号: 03650153
• 负责人: KIKUCHI Masanori
• 金额: $ 1.34万
• 依托单位: MIYAZAKI,University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650153/
• 关键词: vortex breakdown; flow visualization; Laser-Doppler Velocimeter; linear instability theory; acoustic streaming; レーザードップウー流速計; レ-ザ-ドップラ-流速計

The features of the vortex breakdown are that there are three types of breakdown, and it has a stagnation point on the vortex axis and the prominent frequencies of oscillating velocities. We presented an analytical model to explain these all features consistently under the idea that the small velocity disturbances of any wave length lying within a certain region would be amplified and unsteady velocity would produce acoustic streaming. We analyzed the stability and the velocity fields, and compared the calculated streak lines with the observed flow pattern for the three types of vortex breakdown.The three types of vortex breakdown were observed in water flows through a straight pipe by a visualization technique : bubble, spiral and double-helix types. Laser-Doppler velocimeter measurements upstream and in the wakes of breakdown of bubble type are described. Spectra of the fluctuating velocities, as well as timeaveraged swirl and axial velocity profile both inside and outside the recirc … More ulation zone, have been obtained. Spectral analysis of the data indicates that the prominent frequencies of oscillating velocities are constant in the steady recirculation.We made a spinning wave generator(SWG), which is a device to produce, at a specified frequency, a sinusoidal wave disturbance spinning in the circumferential direction, in order to confirm the idea that the azimuthal wave number of the disturbance would determine the type of breakdown. SWG is composed of four pistons, which operate in the cylinders attached to the test pipe wall, and creates four kinds of spinning sinusoidal wave disturbances : four azimuthal wave numbers m = 0, +1, -1, 2. The four kinds of sinusoidal waves with azimuthal wave number were imposed to the swirl flow and the transition process of the breakdown type and location was investigated. It was shown that the m = 0, +1, and 2 sinusoidal wave disturbances produce the bubble, spiral type breakdown, and two-tailed bubble or flattened bubble respectively. Less

涡流击穿的特点是有三种类型的击穿，并且在涡流轴上有驻点和振荡速度的突出频率，我们提出了一个分析模型来一致地解释这些特征，即小值的思想。特定区域内任何波长的速度扰动都会被放大，不稳定的速度会产生声流。我们分析了稳定性和速度场，并将计算的条纹线与观测到的三种类型的流型进行了比较。涡流破裂。描述了通过可视化技术在流经直管的水流中观察到的三种类型的涡流破裂：气泡型、螺旋型和双螺旋型的上游和气泡破裂后的激光多普勒测速仪测量。获得了脉动速度的频谱，以及再循环区域内外的时间平均涡流和轴向速度剖面。数据的频谱分析表明，主要频率是。在稳定再循环中振荡速度是恒定的。我们制作了旋转波发生器（SWG），它是一种在指定频率下产生沿圆周方向旋转的正弦波扰动的装置，以证实方位角旋转的想法扰动的波数将决定击穿的类型 SWG 由四个活塞组成，它们在连接到测试管壁的气缸中运行，并产生四种旋转正弦波扰动：四种。方位波数m=0、+1、-1、2。对旋流流施加四种方位波数正弦波，研究了击穿类型和位置的转变过程。 =0、+1、2正弦波扰动分别产生气泡、螺旋型破裂、双尾气泡或扁平气泡。

项目成果

菊地 正憲: "縦渦崩壊のアクティブコントロール" 日本機械学会 松山地方講演会 講演論文集. 925-2. 37-39 (1992)

Masanori Kikuchi：“纵向涡塌的主动控制”日本机械工程师学会松山地区会议记录925-2（1992）。

菊地 正憲: "LDVによる渦崩壊流れ場の計測" 日本機械学会宮崎地方講演会講演論文集. 418ー2. 61-64 (1991)

Masanori Kikuchi：“使用 LDV 测量涡流击穿流场”日本机械工程师学会宫崎地区会议记录 418-2（1991 年）。

菊地 正憲: "LDVによる渦崩壊流れ場の計測" 宮崎大学工学部研究報告. 38. (1992)

Masanori Kikuchi：“使用LDV测量涡流击穿流场”宫崎大学工学部的研究报告38。（1992年）