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Open AccessArticle

Air Diffusion and Velocity Characteristics of Self-Aerated Developing Region in Flat Chute Flows

1
China Energy Dadu River Hydropower Development Co., Ltd., Chengdu 610065, China
2
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
*
Author to whom correspondence should be addressed.
Academic Editor: Maksim Pakhomov
Water 2021, 13(6), 840; https://doi.org/10.3390/w13060840
Received: 14 February 2021 / Revised: 9 March 2021 / Accepted: 10 March 2021 / Published: 19 March 2021
(This article belongs to the Special Issue Gas-Liquid Two-Phase Flow in the Pipe or Channel)
Self-aerated flows in flat chutes are encountered downstream of the bottom outlet, in spillways with a small slope and in storm waterways. In the present study, the development of self-aeration in flat chute flow is described and new experiments are performed in a long flat chute with a pressure outlet for different flow discharge rates. The distribution of air concentration, time mean velocity and velocity fluctuation in flow direction in the self-aerated developing region—where air bubbles do not diffuse next to the channel bottom—were measured and analyzed. The region of self-aeration from free surface was about 27.16% to 51.85% of the water depth in the present study. The analysis results revealed that the maximum distance of air bubble diffusion to the channel bottom increased with the development of self-aeration along the flow direction. This indicates that for flat chute flow, the process of air bubble diffusion from free surface to channel bottom was relatively long. Cross-section velocities increased along the flow direction in the self-aerated developing region, and this trend was much more remarkable in the area near water free surface. The velocity fluctuations in flow direction in cross-sections flattened and increased with the development of self-aerated flow. Higher velocity fluctuations in flow direction corresponded to the presence of much stronger turbulence, which enhanced air bubble diffusion from the water free surface to channel bottom along the flow direction. View Full-Text
Keywords: self-aeration; chute flow; air concentration; velocity; experimental study self-aeration; chute flow; air concentration; velocity; experimental study
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MDPI and ACS Style

Song, L.; Deng, J.; Wei, W. Air Diffusion and Velocity Characteristics of Self-Aerated Developing Region in Flat Chute Flows. Water 2021, 13, 840. https://doi.org/10.3390/w13060840

AMA Style

Song L, Deng J, Wei W. Air Diffusion and Velocity Characteristics of Self-Aerated Developing Region in Flat Chute Flows. Water. 2021; 13(6):840. https://doi.org/10.3390/w13060840

Chicago/Turabian Style

Song, Liaochao; Deng, Jun; Wei, Wangru. 2021. "Air Diffusion and Velocity Characteristics of Self-Aerated Developing Region in Flat Chute Flows" Water 13, no. 6: 840. https://doi.org/10.3390/w13060840

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