| Project/Area Number |
11450274
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Nippon Bunri University (2000)
Kyoto University (1999) |
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Principal Investigator |
HATTA Natsao Nippon Bunri Univ. Professor, 工学部, 教授 (30026041)
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| Co-Investigator(Kenkyū-buntansha) |
KOYANAKA Hideki Nippon Bunri Univ. Assoeiate Professor, 工学部, 助教授 (40248620)
FUJIMOTO Hitoshi Kyoto University Professor Instructor, エネルギー科学研究科, 助手 (40229050)
ISHII Ryuji Kyoto University Professor, エネルギー科学研究科, 教授 (20026339)
宅田 裕彦 京都大学, 大学院・エネルギー科学研究科, 助教授 (20135528)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥3,600,000 (Direct Cost: ¥3,600,000)
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| Keywords | Hot wetallic surface / Leidenfrost point / Wething Pheaomenon / Solid / liguid Interface / Vapor filw / Boiling / Weber number / Black Zone / ウェーバー数 / 数値解析 / 自由表面 / レイノルズ数 / スプレー冷却 / 熱伝達 / 固液接触 |
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| Research Abstract |
The collision dynamics of a water droplet impinging on solid surfaces above the Leidenfrost temperature have been investigated, during the period of fiscal 1999 to 2000, from an experimental and theoretical point of view. Emphasis has been placed upon understanding the recoiling, and rebounding/breaking-up processes of a water droplet after collision with surfaces. The behavior of a water droplet colliding with hot surface has been confirmed to strongly depend on the Weber number (=We). For a small We number, the droplet impinging on the hot surface spreads in the shape of a flattened disk and reaches a maximum diameter. Thereafter, the swelling process in the central region and center part of the liquid drop continues to elongate upwards. Finally, the liquid drop rebounds as a bowling-pin shaped mass from the surface. For a larger We number, the droplet has been found to break up into some parts. Also, it has been found that there is the first critical Weber number We_<cril> whether o
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f not the droplet is disintegrated into some parts. Furthermore, the droplet disintegration mechanism has been examined experimentally. The droplet disintegration occurs in the We number range above We_<cri1> in the spreading/recoiling process. With increasing the Weber number, the deformation scale of the droplet is enlarged and the sectional area of the ring structure in the peripheral region tends to be small and ununiform. Hence We_<cri1> the difference in the rotational velocity of the ring structure occurs locally in the circumferential direction. The droplet disintegration process has been found to be divided into two types according to the We number. For the case of low We number, but above We_<cri1> the droplet breaks up into some parts in the recoiling process. But. above the 2-nd Weber number We_<cri2> the droplet disintegration occurs in the spreading process and disintegrated drops move far away outorwards.
A series of results obtained in the present in the present investigation were reported in the international journals as a lot of papers. Again, A report of the research performed by Grant-In-Aid for scientific research was written to report the results obtained to The Ministry of Education. Therefore, one can refer to this report for inspecting the results. Less
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