Estimation of Directional Wave Spectrum of Encounter Waves on Board, by an Array of Two Wave-height Meters
| Project/Area Number |
62460069
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
応用物理学一般(含航海学)
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| Research Institution | Tokyo University of Mercantile Marine |
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Principal Investigator |
YASUDA Akio Tokyo University of Mercantile Marine, 商船学部, 教授 (00023250)
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| Co-Investigator(Kenkyū-buntansha) |
KUWASHIMA Susumu Tokyo University of Mercantile Marine, 商船学部, 教授 (30016943)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Wave-height Meter / Shipborne-type Wave-height Meter / Directional Wave Spectrum / 波向スペクトル / マイクロ波式波高計 / 波向ベクトル |
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| Research Abstract |
The authors tried to develop a simple method to estimate directional wave spectra from a steaming ship, in the present research project.
At first in 1987, they designed an array comprised of two wave height meters and tested it in a wave tank. Then they acquired the encounter wave height records off Nojima-zaki by the array whose sensors were installed at the both sides of the bow of a steaming ship. The encounter wave spectra and the frequency dependency of coherency and phase difference between the two wave records are deduced by a 2-channel FFT analyzer. They developed a program on a personal computer to estimate the real wave spectrum and directional wave spectrum using these data which were transmitted from the FFT analyzer.
In the conventional estimation at a fixed position, more than three sensors are necessary, allocated with star- or delta-shape. While they proved that estimation was possible from the two series of encounter wave records by the array with an additional information of a velocity vector of a steaming ship, in the method of the present research project.
In 1988, they improved the program for the real-time display of the directional wave spectrum. It has not been verified yet on board, however, because the sensors were swept away on the way to the real ocean experiment.
Thus they tried another method to estimate the wave direction. They measured the relative wave velocity by a microwave Doppler radar, used in their wave height meter, with rotating the radiation angle azimuthally. Some tests in a wave tank and real sea show the applicability of this method to the estimation of the directional wave spectrum, although there are some problems to be solved.
The experiment of real-time display by the wave meter array is almost prepared now and will be executed in near future.
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Report
(3 results)
Research Products
(18 results)
