Hydraulics of Circular Drop Manholes
Publication: Journal of Irrigation and Drainage Engineering
Volume 137, Issue 2
Abstract
Circular drop manholes are widely employed in steep urban drainage systems. Drop manholes may lead to poor hydraulic conditions if their energy dissipation is inadequate. The dominant hydraulic features of drop manholes depend on the flow regimes, characterized in terms of the dimensionless impact parameter. Depending on the latter parameter, the energy dissipation can vary within large limits, affecting thereby the downstream flow features. Also, the water pool depth inside the manhole and the air entrainment have been studied in terms of both the hydraulic and geometric parameters. Moreover, the conditions for which a drop manhole generates flow choking at its inlet or outlet have been investigated. Empirical equations for practical manhole design are provided. The importance of suitable manhole aeration is highlighted.
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Acknowledgments
The writers would like to thank Engr. Tiziana Calcagni for having performed selected experimental tests.
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Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 137 • Issue 2 • February 2011
Pages: 102 - 111
Copyright
© 2011 ASCE.
History
Received: Sep 23, 2009
Accepted: Jul 13, 2010
Published online: Jul 16, 2010
Published in print: Feb 2011
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