采用三维水流模型,模拟了淹没式取水工程(单侧引水箱、蘑菇头)附近三维空间内的水流运动。计算发现,取水工程处表层水体中水平流速增量与取水吸水方向可相同,也可相反。结合模拟结果和明渠水流基本理论,探讨了取水口附近水流变化现象的形成机理。理论分析表明,黏性(垂向扩散)、动水压力作用是产生上述现象的决定因子,它们对表层水流变化的驱动方向相反,其综合作用效果随着取水工程之上水深h′的不同而不同。对于单侧引水箱,当h′较小时,黏性扩散作用占主导,取水层与表层水流流速增量方向一致;当h′较大时,动水压力作用占主导,取水层与表层水流流速增量方向相反。较之单侧引水箱,蘑菇头从水平各个方向均吸水,导致了在蘑菇头正上、正下方水域形成2个压力集中区。环绕着这2个区域边缘,靠近取水口的水层由于黏性扩散向中心运动,远离取水口的水层(底层、表层)被向外压出。
Abstract
A 3-D numerical model is used to simulate flows around submerged water intakes of mushroom-style and single-sided box-style. According to the simulations, the signs of horizontal velocity increment at the top-layer and intake-layer of the flows are observed to be the same or opposite under different conditions. On the basis of 3-D simulations and theory of open-channel flow, the mechanism of the above phenomena is studied. Theoretical analysis suggests that the operation of intakes disturbs the flow diffusion and dynamic water pressure, hence facilitating velocity variations of the top-layer flow in the opposite direction. Their combined effect is different when the water depth above the intake h′ varies. For the box-style intakes, when h′ is small, the viscous diffusion dominates the variation, and velocity increments of the same direction are produced at the intake-layer and the top-layer of the flows. When h′ is big, the pressure dominates the variation, and velocity variations of the opposite direction are produced at the intake-layer and the top-layer of the flows. Mushroom-style intakes absorb water from all horizontal directions, resulting in two areas of concentrated pressures above and below the intake. On the edge of these two areas, the water layers near the intake move towards the intake, and those at the bottom and the top are pushed away from the intake.
关键词
淹没式取水工程 /
三维数学模型 /
流速垂线分布规律变异
Key words
submerged water intake /
3-D numerical model /
variation of vertical distribution of velocity
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参考文献
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基金
国家自然科学基金项目(51109009,513390001)
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