Energy Dissipation and Air Entrainment in Stepped Storm Waterway: Experimental Study
Publication: Journal of Irrigation and Drainage Engineering
Volume 128, Issue 5
Abstract
For the last three decades, research focused on steep stepped chutes. Few studies considered flat-slope stepped geometries such as stepped storm waterways or culverts. In this study, experiments were conducted in a large, flat stepped chute (θ=3.4°) based upon a Froude similitude. Three basic flow regimes were observed: nappe flow without hydraulic jump, transition flow, and skimming flow. Detailed air–water flow measurements were conducted. The results allow a complete characterization of the air concentration and bubble count rate distributions, as well as an accurate estimate of the rate of energy dissipation. The flow resistance, expressed in terms of a modified friction slope, was found to be about 2.5 times greater than in smooth-chute flow. A comparison between smooth- and stepped-invert flows shows that greater aeration and larger residence times take place in the latter geometry. The result confirms the air–water mass transfer potential of stepped cascades, even for flat slopes (θ<5°).
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Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 128 • Issue 5 • October 2002
Pages: 305 - 315
Copyright
Copyright © 2002 American Society of Civil Engineers.
History
Received: Jun 28, 2001
Accepted: Jan 2, 2002
Published online: Sep 13, 2002
Published in print: Oct 2002
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