Investigation of Explosion Phenomena Induced by Bubble Collapse in Cryogenic fluids

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14675
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Japan Aerospace EXploration Agency
• Principal Investigator: SAKAMOTO Yuki 国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 助教 (50845774)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: キャビテーション / 気泡崩壊 / レーザー / 水素 / 液体水素

Outline of Final Research Achievements

An explosion may occur under certain conditions even at cryogenic temperatures when the liquid hydrogen supplying pipe is disconnected instantly. In this situation, hydrogen is released into the atmosphere, the cryogenic flange surface is exposed and liquefied air is generated. The applicant assume the explosion is caused by the local high-temperature bubbles in liquefied air which compressed adiabatically and attempted to clarify the phenomenon experimentally. In this experiment, helium gas is injected into liquid nitrogen and simultaneously generates a pressure wave by laser-induced cavitation. The result shows a possibillity that a helium gas bubble located in liquid nitrogen can be compressed to the ignition temperature of the hydrogen-oxygen mixture.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

水素社会実現には大規模水素サプライチェーン構築が必須であり，密度の面で有利である液体水素による運搬・貯蔵に対するニーズがますます高まっている．本研究では，特定の条件下で液体水素が大気に漏洩した際の着火・爆発する現象のメカニズム解明に取り組んだ．これまでの実験結果では，爆発現象の再現には至っていないものの，液体窒素とヘリウムガスを用いた試験から，圧力波により極低温流体中の気泡内部温度が着火温度程度まで上昇する収縮が得られる可能性が示されており，本研究は液体水素のさらなる安全利用に資する．