Real-time simultaneous measurement of pressure and gaseous species inside cavitation bubbles by using plasma

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K20969
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
• Research Institution: Tohoku University
• Principal Investigator: Sato Takehiko 東北大学, 流体科学研究所, 教授 (10302225)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 気泡 / 圧力 / 放電 / 分光 / 水素 / 酸素 / 窒素 / OHラジカル

Outline of Final Research Achievements

In this study, we developed the method and successfully measured the internal bubble pressure and identified gas species experimentally, which are important factors governing physical phenomena such as shock waves, chemical reactions, and luminescence generated at the bubble collapse in single cavitation bubbles. The pressure inside a single cavitation bubble was found to be 0.39×10^5 [Pa] at the maximum bubble diameter by developing a new pressure measurement method using the discharge phenomenon. A method was also developed to identify the gas species contained in the bubble by generating plasma inside the bubble and spectroscopy of the luminescence, and we clarified that the gas contained nitrogen and oxygen molecules in addition to OH radicals, hydrogen, and oxygen atoms originating from water vapor.

Free Research Field

プラズマ流体工学

Academic Significance and Societal Importance of the Research Achievements

本研究は、単一キャビテーション気泡の物理化学現象を理解する上で重要な気泡内圧力や含まれているガス種を明らかにした。これにより、飽和蒸気圧を仮定した理論・数値解析をさらに発展させ、未解明であったキャビテーション現象をより深く理解することが可能になるなど学術的意義のある成果となった。また、産業分野においても計測困難なキャビテーション現象を計測する手法を提供するとともに、より精緻な予測による産業機械の設計などへの展開が期待できることから、社会的意義が高い成果となった。