Inception Line of Air Entrainment for Converging Stepped Spillways
Publication: Journal of Hydraulic Engineering
Volume 151, Issue 1
Abstract
In the traditional stepped spillways with uniform width, the inception points of air entrainment along the spillway transverse direction generally remain at a similar distance from the spillway entrance, and can therefore be treated as a 2D problem. In the converging stepped spillways, the converging sidewall causes a nonuniform flow distribution along the spillway transverse direction, and a disturbed flow region is generated near the converging sidewall with significantly higher flow depth and discharge and lower air concentration. Their inception points are no longer a 2D problem and were investigated by physical experiments in this study. It was found that the line of the inception points curves downstream in the disturbed flow region and ended at the standing wave with limited air entrainment, while it formed the approximately straight line in the undisturbed flow region away from the converging sidewall. Therefore, the inception line of air entrainment in the converging stepped spillways can be described by the straight and curved lines and two intersections. The effects of the inlet flow discharge and the sidewall convergence angle were tested and analyzed. The expressions for the straight and curved lines and the two intersections are established, which can help to identify the inception line of air entrainment for the converging stepped spillways and make reasonable predictions.
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Data Availability Statement
All data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
This study was supported by the National Natural Science Foundation of China (Grant Nos. 51809079 and 52279063), Natural Science Foundation of Jiangsu Province (Grant No. BK20231462), Jiangsu Innovation Support Programme for International Science and Technology Cooperation (Grant No. BZ2023047), and Joint Funds of the Zhejiang Provincial Natural Science Foundation of China (Grant No. LZJWY23E090002).
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Published In
Journal of Hydraulic Engineering
Volume 151 • Issue 1 • January 2025
Copyright
© 2024 American Society of Civil Engineers.
History
Received: May 26, 2023
Accepted: Jul 17, 2024
Published online: Sep 28, 2024
Published in print: Jan 1, 2025
Discussion open until: Feb 28, 2025
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