2018 Fiscal Year Final Research Report
Characteristics of nonaerated skimming flows in stepped channels
| Project/Area Number |
16K06518
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Hydraulic engineering
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| Research Institution | Nihon University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 階段状水路 / エネルギー減勢構造物 / skimming flow / 減勢工 / 落差工 / nonaerated skimming flow |
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| Outline of Final Research Achievements |
Stepped channels are effective for dissipating the energy of supercritical flow that occurs at steep channels. For a large discharge and/or small dam height, the nonaerated region occupies a large portion of the skimming flow in stepped spillways. For hydraulic design of stepped channels, it is important to know the depth and the velocity in nonaerated skimming flows in order to estimate the specific energy. However, most experimental studies for stepped channels have focused on aerated skimming flows, and characteristics of nonaerated skimming flows have not yet been clarified. This study shows reasonable equations for estimating the boundary layer development and the water surface profile along the channels for nonaerated skimming flows. The energy head along the channel is obtained, indicating that the energy dissipation for the stepped channel becomes larger than that for the smooth channel.
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| Free Research Field |
水工水理学
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| Academic Significance and Societal Importance of the Research Achievements |
近年の多発する集中豪雨による超過洪水がダムやembankment damの階段状洪水吐を流下する場合，あるいは階段状の落差工で大流量の越流が生じた場合，階段状水路上の流れが全てnonaerated skimming flowの流況となり，この場合の水理特性の解明が階段状水路の水工設計のために必要である．本研究成果によって，nonaerated skimming flowの水深，断面平均流速，比エネルギーの大きさを定量的に求めることが可能となった．その結果，階段状水路によるエネルギー減勢は平坦な傾斜水路に比べて大きいことが明確にされた．
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