Self-aeration development and fully cross-sectional air diffusion in high-speed open channel flows
Self-aeration development and fully cross-sectional air diffusion in high-speed open channel flows
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DOI：
10.1080/00221686.2021.2004250
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发表时间：
2022-01
影响因子：
2.3
通讯作者：
Wang-ru Wei;Wei-lin Xu;Jun Deng;Yakun Guo
中科院分区：
文献类型：
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作者：
Wang-ru Wei;Wei-lin Xu;Jun Deng;Yakun Guo
由于自由表面夹带空气，明渠流中会发生自曝气。自曝气的发展和空气浓度的完全横截面分布尚未完全了解。在本研究中，使用自由表面空气夹带的简化机制建立了逐渐变化区域中平均横截面空气浓度的解析解。针对受通道底部影响的全截面空气浓度分布，提出了无壁面约束的扩散区域模型，并根据平均截面空气浓度将两种情况分类。实测数据与计算结果吻合较好，提高了近壁空气浓度分布的计算精度。结果表明，渠道坡度决定了引气量，而水流流量决定了自曝气演化距离。平均横截面空气浓度和底壁对空气扩散的影响的解决方案促进了空气-水流在水利工程实践中的应用。
Self-aeration in open channel flows occurs owing to free surface air entrainment. Self-aeration development and fully cross-sectional distribution of air concentration are not thoroughly understood. In the present study, an analytical solution for the averaged cross-sectional air concentration in the gradually varying region is established using a simplified mechanism of free surface air entrainment. For a fully cross-sectional distribution of air concentration affected by the channel bottom, a model of a diffusion region without wall restraint is proposed, and two situations are classified based on averaged cross-sectional air concentration. Good agreement between measured data and calculations is obtained, and the computational accuracy of the air concentration distribution near the wall is improved. The results reveal that the channel slope determines the air entrainment quantity, while water flow discharge determines the self-aeration evolution distance. The solutions for the averaged cross-sectional air concentration and the effect of the bottom wall on air diffusion promote air–water flow applications in hydraulic engineering practices.