Bottom Outlet for Sewers
Publication: Journal of Irrigation and Drainage Engineering
Volume 123, Issue 4
Abstract
The bottom opening is a standard structure in storm sewers, provided the approach flow is supercritical. Based on extended experimentation and by using the governing flow equations, the hydraulic characteristics of bottom openings were derived. These include the approach reach, the end depth ratio, the average discharge coefficient, the tailwater depth, and the hydraulic loss across the outlet. Further, velocity distributions in the outlet zone are discussed. The results of this study reveal that the approach Froude number has a significant effect on the flow mechanism. General expressions are derived for the lower and upper nappes of the flow across the bottom opening, and a hydraulic design procedure is described. A generalized streamwise coordinate is also introduced that allows description of supercritical sewer flow. It is demonstrated that the excess discharge to the treatment station under design discharge is within the requirements of European standards.
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Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 123 • Issue 4 • July 1997
Pages: 246 - 252
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Jul 1, 1997
Published in print: Jul 1997
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