2023 Fiscal Year Final Research Report
Cryogenic microjet/transpiration cooling for reentry heat shield
| Project/Area Number |
21K18779
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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 24:Aerospace engineering, marine and maritime engineering, and related fields
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| Research Institution | Nagoya University |
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Principal Investigator |
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| Project Period (FY) |
2021-07-09 – 2024-03-31
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| Keywords | 極低温流体 / 気液二相流 / 再突入 / 宇宙輸送 |
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| Outline of Final Research Achievements |
In this study, regarding thermal protection during re-entry, which is a major issue for reusable space transportation systems, we propose fluid cooling using cryogenic liquids such as liquid hydrogen carried as propellants, instead of conventional heat-resistant materials. We adopt microchannels with a large internal wetted surface area, which are expected to have high cooling efficiency. However, due to the small channels, surface tension may dominate, and vapor film growth may reduce cooling efficiency. Therefore, we devised a method of impinging liquid jets onto the heated surface to promote the removal of vapor films. Through fundamental experiments, we found conditions for vapor film removal based on the Weber number. Based on this, we additively fabricated a metal test module and conducted a cooling experiment using liquid nitrogen. Compared to quasi porous structure, we confirmed that the proposed microjets halved the cooling time under large We number conditions.
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| Free Research Field |
航空宇宙工学
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| Academic Significance and Societal Importance of the Research Achievements |
従来の多孔質材に対する提案するマイクロジェット方式の優位性の実証を通し，未だ実現されていない宇宙輸送機の「完全」再使用への貢献の可能性を示すことができた．また，ロケットエンジン等の過酷な熱流束に曝される機器の熱防護にも応用できる．例えばタービン翼の冷却等に採用することにより，発電効率の向上，脱炭素への貢献も期待される．
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