Influence of Surface Tension on Air-Water Flows
Publication: Journal of Hydraulic Engineering
Volume 139, Issue 1
Abstract
Stricter environmental regulations have led to new wastewater treatment plants and a centralization of existing wastewater treatment plants. Therefore, pressurized wastewater mains have become an indispensable link between the collection systems and the treatment plants. In urban areas in particular, these pipelines include many inverted siphons to cross other infrastructure, like railways, motorways, other pipelines, and buildings. Accumulation of air in downward sloping sections of these wastewater mains reduces the transport capacity significantly. A dominant air transport mechanism is the air-entraining hydraulic jump at the tail of an accumulated air pocket. The novelty of this paper is a systematic investigation of the influence of surface tension on the air discharge in downward sloping pipe sections. Experiments have been performed with clean water, surfactant-added water, and wastewater. The experiments with surfactant-added water confirm that the air discharge increases significantly at lower surface tension. However, the lower surface tension of wastewater does not enhance the air transport in comparison with the air transport in clean water.
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Acknowledgments
This study was undertaken as part of the CAPWAT project on capacity losses in pressurized wastewater mains. The authors wish to thank the participants of the CAPWAT project: water boards Delfland, Hollands Noorderkwartier, Brabantse Delta, Reest en Wieden, Rivierenland, Zuiderzeeland, Fryslân and Hollandse Delta, water companies Aquafin and Waternet, consultants Royal Haskoning, Grontmij Engineering Consultancy, Gemeentewerken Rotterdam, pump manufacturer ITT Water & Wastewater BV, Foundation Stowa, and the Dutch Ministry of Economic Affairs. The authors also wish to acknowledge the employees at the treatment plant for their flexible cooperation and interest in the project.
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 139 • Issue 1 • January 2013
Pages: 44 - 50
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Aug 4, 2011
Accepted: May 24, 2012
Published online: May 29, 2012
Published in print: Jan 1, 2013
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