1991 Fiscal Year Final Research Report Summary
Numerical Analysis of Hydrodynamic Performance of Finite Span Hydrofoil
| Project/Area Number |
02302054
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
船舶抵抗・運動性能・計画
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KATO Hiroharu The University of Tokyo Professor, 工学部, 教授 (00010695)
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| Co-Investigator(Kenkyū-buntansha) |
NAKATAKE Kuniharu Kyushu University Professor, 工学部, 教授 (70037761)
MORI Kazuhiro Hiroshima University Professor, 工学部, 教授 (90011171)
NAKATO Michio Hiroshima University Professor, 工学部, 教授 (20034324)
YAMAGUCHI Hajime The University of Tokyo Assistant Professor, 工学部, 助教授 (20166622)
KAJITANI Hisashi The University of Tokyo Professor, 工学部, 教授 (80010693)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Finite Span Foil / Finite Difference Method / Lifting Body Theory / Cavitation / Free Surface / Tip Vortex / CFD |
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| Research Abstract |
Made were the numerical and experimental investigations on the hydrodynamic performance and flow situations of a finite span hydrofoil. The following results were obtained :
The lift and drag forces and the pressure distribution obtained by the lifting body theory agreed well with those of the experiments unless the large boundary layer separation occurred on the hydrofoil surface.
This theory, however, could not argue the details of the flow situations such as boundary layer and its relation to the tip vortex.
Two kinds of finite difference calculations were made with a low Reynolds number of 1, 000. Some kinds of calculation conditions were selected such as with free surface and with cavitation. The results were compared and discussed in detail with the experimental ones. As a result the future works of the CFD research were clarified on the hydrodynamic study of finite span hydrofoils.
The calculation of a hydrofoil under a free surface showed the wave-making due to the foil and the lift force decrease due to the free surface.
It was shown that the tip vortex had two cores caused by the two boundary layers on the foil upper and lower surfaces, respectively. The rolling-up to the tip vortex and the tip vortex separation were also calculated.
The calculated cavitation on the foil surface had similar appearance to that of the experiments although the quantitative agreement could not be obtained because of the large difference in the Reynolds numbers.
The measurements showed that the tip vortex had a very small radius of 1% the maximum chord length and a high rotation speed of over 0.6 times the uniform flow velocity. A solution adaptive grid, multi-grid system or some modeling of the tip vortex might be required in addition to the turbulence model, in order to calculate a high Reynolds number flow and argue the tip vortex in detail.
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