1996 Fiscal Year Final Research Report Summary
Fundamental Understanding of Cavitation Phenomenon
| Project/Area Number |
06402054
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
船舶工学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KATO Hiroharu Univ. Tokyo, Naval Arch. & Ocean Eng., Prof., 大学院・工学系研究科, 教授 (00010695)
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| Co-Investigator(Kenkyū-buntansha) |
MAEDA Masatugu Univ. Tokyo, Naval Arch. & Ocean Eng., Assistant, 大学院・工学系研究科, 助手 (60219277)
KOMURA Takashi Univ. Tokyo, Naval Arch. & Ocean Eng., Assistant, 大学院・工学系研究科, 助手 (10010894)
YAMAGUCHI Hajime Univ. Tokyo, Naval Arch. & Ocean Eng., Assoc. Prof., 大学院・工学系研究科, 助教授 (20166622)
MIYATA Hideaki Univ. Tokyo, Naval Arch. & Ocean Eng., Prof., 大学院・工学系研究科, 教授 (70111474)
FUJINO Masataka Univ. Tokyo, Naval Arch. & Ocean Eng., Prof., 大学院・工学系研究科, 教授 (10010787)
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| Project Period (FY) |
1994 – 1996
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| Keywords | cavitation / viscous effect / temperature / vaporization / heat and mass transfer / cloud / re-entrant jet / burst |
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| Research Abstract |
This research has been made to understand cavitation phenomenon more deeply, focusing on (a) relation between cavitation and viscous flow, and (b) thermodynamic effect and internal flow of cavity.
Observation and detailed measurement of flow field were made on developed sheet cavitation of a 2D foil section. Following conclusions were obtained :
1. The sheet cavity was classified into two types whether the separated boundary layr around the cavity bursted or not. Accordingly, the cavity model for numerical analysis should be different.
2. It was confirmed that generation of cloud cavitation was caused by re-entrant jet, which flowed upstream on the foil surface. Therefore, the generation of cloud cavitation could be prevented by a small obstacle such as fence or ditch on the foil surface.
A small cavitation tunnel for high-temperature water (up to 140 deg.) was newly constructed and tested. The results were summarized as follows :
1. The maximum temperature depression was about 1.4 degree in a developed sheet cavity at 140 degrees and 14 m/s of main flow. The depression was increased when the upstream boundary layr became thicker by manipuration.
2. The prediction using Z-factor which was proposed by Kato (1984), agreed with experimental result.
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