Self-aeration development and fully cross-sectional air diffusion in high-speed open channel flows

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 th...

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Bibliographic Details
Published in:Journal of hydraulic research Vol. 60; no. 3; pp. 445 - 459
Main Authors: Wei, Wangru, Xu, Weilin, Deng, Jun, Guo, Yakun
Format: Journal Article
Language:English
Published: Madrid Taylor & Francis 04.05.2022
Taylor & Francis Ltd
Subjects:
Aeration
Air
air concentration distribution
Air entrainment
Channel flow
Computer applications
Cross-sections
Diffusion
Diffusion rate
Distribution
Entrainment
Exact solutions
Free surfaces
Hydraulic engineering
Open channel flow
Open channels
Radioactivity
self-aeration development
spillway
Water discharge
Water flow
ISSN:0022-1686, 1814-2079
Online Access:Get full text
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Summary: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.
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ISSN:0022-1686
1814-2079
DOI:10.1080/00221686.2021.2004250