Cavitation inception and metastable state in liquid due to backscattering of HIFU from a bubble interface

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04270
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Fluid engineering
• Research Institution: Osaka Prefecture University
• Principal Investigator: Takahira Hiroyuki 大阪府立大学, 工学(系)研究科(研究院), 教授 (80206870)
• Co-Investigator(Kenkyū-buntansha): 小笠原 紀行 大阪府立大学, 工学(系)研究科(研究院), 助教 (00552184) ; 藤川 重雄 北海道大学, 工学研究院, 名誉教授 (70111937)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 混相流 / キャビテーション初生 / 気泡 / 相変化 / 準安定状態 / 集束超音波 / 後方散乱

Outline of Final Research Achievements

The cavitation inception and the following bubble cloud formation due to the backscattering of HIFU from bubble interfaces are investigated experimentally and numerically. A laser-induced bubble in the vicinity of the geometrical focus of HIFU is utilized as a primary cavitation. Optical observation with a high-speed video camera and pressure measurement with a fiber optic prove hydrophone (FOPH) are conducted simultaneously in the present experiments. Also, the minimum negative pressure distribution around the bubble cloud is calculated with the ghost fluid method to investigate the forming process of the bubble cloud in the experiments. The results show that the bubble cloud grows accompanied with the formation of multiple layers composed of tiny bubbles, and becomes a cone-shape. The pressure measurement reveals that the cavitation inception pressure is about -26 MPa when 2.0 mg/L＜DO＜3.5 mg/L at about 296 K.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

集束超音波によるキャビテーションの初生圧力ならびに気泡クラウドの形成機構を解明することにより，液体の準安定状態に関する理解が深まり，相変化や相分離の物理学の発展に寄与するとともに，流体機器内のキャビテーションの初生予測に有用な知見を与える．さらに，超音波治療法の一つである高密度焦点式超音波法において，治療の効率化を図るためにキャビテーション気泡クラウドの崩壊を有効利用する方法が考えられているが,
本研究成果は，キャビテーション気泡クラウドの制御に関する有用な知見を与える．