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MECHANISM CREATING IMPULSIVE-FORCE DUE TO VORTEX CAVITATION BUBBLE WTTH HIGH EROSIVE POWER

由于涡流空化气泡具有高侵蚀力而产生冲力的机制

基本信息

批准号：
07650226
负责人：
SATO Keiichi
金额：
$ 1.34万
依托单位：
KANAZAWA INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650226/
关键词：
CAVITATION EROSION VORTEX BUBBLE DYNMICS HIGH SPEED LIQUID FLOW IMPULSIVE FORCE 気泡崩壊

项目摘要

In the present research, a circular and a triangular cylinder were used as a cavitating body. Two kinds of circular cylinders were chosen to investigate the three-dimensional characteristics of bubble behaviors toward the freestream direction as well as the wall-direction. A triangular cylinder was used for high-speed flow experiments and cavitation erosion-impulsive pressure tests.A simultaneous measurement system for instantaneous appearance at bubble collapse and impulsive pressure, as well as instantaneous appearance at bubble collapse and an erosion pit, was made up, especially for the purpose of an anlysis of a cavitation bubble pattern with high impulsive force and was used for the above-mentioned test bodies. As the result, the process of bubble collapse is approximately divided into three patterns, A) three-dimensional radial collapsing motion at a slight distance from the solid wall boundary, B) axial collapsing motion toward the solid wall boundary with an impinging rapid movement.C) two-dimensional radial collapsing motion keeping the orginal slender shape.The collapsing patterns like this was also examined from the relation with the erosion effects. For the type-B pattern, especially, the vortex cavitation bubble shows a typical singular behavior near the solid wall compared with the inside of flow and the vortex cavitation bubble pattern with an axis perpendicular to the solid wall has a special strong impulsive force. The measurement method using an impulsive pressure sensor for cavitation attack is proposed together with a simultaneous measurement method of the erosion pits and the bubble collapsing behaviors.In order to solve the mechanism of impulsive force generation from a vortex cavitation bubble, the simultaneous measurement method of high-speed-video observation with the impulsive force and/or the erosion pits are developed so that the results are experimentally discussed. As a result, the valuable data are shown quantitatively.

本文采用圆形圆柱体和三角形圆柱体作为空化体。选取了两种不同的圆柱体，研究了气泡在自由流方向和壁面方向的三维行为特征。采用三角形圆柱体进行高速流动实验和空化冲蚀-冲击压力试验，研制了气泡崩塌和冲击压力瞬时出现、气泡崩塌瞬时出现和冲蚀坑瞬时出现的同时测量系统，用于分析高冲量空化气泡的形态，并用于上述试验体。结果表明，气泡的崩塌过程大致可分为三种模式：A)距离固壁边界较近的三维径向崩塌运动，B)向固壁边界的轴向崩塌运动，并伴随着撞击的快速运动，C)保持原始细长形状的二维径向崩塌运动，并从冲蚀效果的关系上对这种崩塌模式进行了考察。尤其对于B型涡空泡型，与流内相比，涡空化气泡在固壁附近表现出典型的奇异行为，轴线垂直于固壁的涡空化气泡具有特殊的强冲击力。提出了利用脉冲式压力传感器进行空化冲击的测量方法，并提出了同时测量冲蚀坑和气泡崩塌行为的方法。为了解决涡流空化气泡产生冲击力的机理，发展了高速视频观测脉冲力和/或冲蚀坑的同时测量方法，并对测量结果进行了实验讨论。因此，有价值的数据被定量地显示出来。