Real-time simultaneous measurement of pressure and gaseous species inside cavitation bubbles by using plasma
| Project/Area Number |
20K20969
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
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| Research Institution | Tohoku University |
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Principal Investigator |
Sato Takehiko 東北大学, 流体科学研究所, 教授 (10302225)
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| Project Period (FY) |
2020-07-30 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000)
Fiscal Year 2021: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2020: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
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| Keywords | 気泡 / 圧力 / 放電 / 分光 / 水素 / 酸素 / 窒素 / OHラジカル / パッシェンの法則 / 平行平板電極 / レーザー誘起気泡 / 広範囲圧力計測 |
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| Outline of Research at the Start |
プラズマの発生は，ガスの圧力pと電極間距離dの積pdと放電開始電圧Vを関係づける「パッシェン曲線」に従う．任意の電極間距離を有する平行平板電極を水中に設置し，一方の電極に任意の電圧を印加し，電極間にレーザー誘起気泡を発生させる．気泡は膨張し電極に接し，電極間の空間を気泡で満たす．気泡内の圧力は膨張と共に減少し，それに伴い放電開始電圧が低下すると，電極間で放電が発生し放電開始電圧が求まり，気泡内圧力が求まる．さらに，放電時の発光分析により気泡内のガス種を特定することで，圧力・ガス種を同時に計測する。
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| 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.
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| 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。
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Report
(4 results)
Research Products
(15 results)
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[Presentation] Propagation processes of underwater streamers2022
Author(s)
Takehiko Sato, Hidemasa Fujita, Seiji Kanazawa, Kiyonobu Ohtani, Atsuki Komiya, Toshiro Kaneko
Organizer
National Conference on Recent Developments and Evolving Trends In Plasma Science and Technology & Pre-Conference Workshop on Modelling and Simulation of Industrial Plasmas
Related Report
Int'l Joint Research / Invited
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[Presentation] Formation and Measurement of Plasma Fine Bubbles2021
Author(s)
Takehiko Sato, Satoshi Uehara, Ryo Kumagai, Takashi Miyahara, Masanobu Oizumi, Tatsuyuki Nakatani, Shiroh Ochiai, Takamichi Miyazaki, Hidemasa Fujita, Seiji Kanazawa, Kiyonobu Ohtani, Atsuki Komiya, Toshiro Kaneko, Tomoki Nakajima, Marc Tinguely, Mohamed Farhat
Organizer
12th Asia-Pacific International Symposium on the Basics and Applications of Plasma Technology (APSPT-12)
Related Report
Int'l Joint Research / Invited
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