Air-Transport Processes in Tailrace Channels
Publication: Journal of Hydraulic Engineering
Volume 141, Issue 7
Abstract
Air-entrainment and detrainment processes in tailrace channels downstream of Pelton turbines were investigated in a physical laboratory model of the new hydropower plant Veytaux 2, Switzerland. These processes are mainly influenced by the emergent jet velocity of the Pelton turbine and the resulting air entrainment to the water cushion due to high-speed jet impact. The air demand in the turbine housing, and the air concentration and velocity distributions in the tailrace channel are analyzed. The project-specific results are generalized by additional investigations involving a simplified model geometry. A comparison with previous model and prototype data is presented. The results indicate that the deaeration length relative to the tailwater flow depth depends mainly on the jet Froude number made up by the emergent jet velocity relative to the tailwater propagation velocity, plus the water discharge, the tailwater cross-sectional area, and the presence or absence of a flow straightener at the tailrace-channel entrance.
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Acknowledgments
The authors kindly thank the Forces Motrices Hongrin-Léman, represented by Gaël Micoulet, for excellent collaboration, and Christian Schneider for having conducted the measurements on the basic model during his Master’s thesis.
References
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© 2015 American Society of Civil Engineers.
History
Received: Feb 12, 2014
Accepted: Jan 19, 2015
Published online: Mar 19, 2015
Published in print: Jul 1, 2015
Discussion open until: Aug 19, 2015
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