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
Arch, A. (2008). “Luftein- und Austragsprozesse bei Anlagen mit Peltonturbinen im Gegendruckbetrieb [Air entrainment and detrainment processes at hydropower plants with Pelton turbines using back-pressure operation].” Dissertation, TU Graz, Graz, Austria (in German).
Arch, A., and Mayr, D. (2006). “De-aeration of air–water flows in the tailwater channels of Pelton turbines.” Int. J. Hydropower Dams, 13(2), 106–110.
Boes, R. M., and Hager, W. H. (1998). “Fiber-optical experimentation in two-phase cascade flow.” Proc., Int. RCC Dams Seminar, K. Hansen, ed.
De Cesare, G., Bieri, M., Terrier, S., Candolfi, S., Wickenhäuser, M., and Micoulet, G. (2014). “Optimization of a shared tailrace channel of two pumped-storage plants by physical and numerical modeling.” Advances in hydroinformatics, P. Gourbesville, ed., Springer, Berlin, 291–305.
Erlach, J. M. (2012). “New Pelton concept: Up to six nozzles horizontal.” 17th Int. Seminar Hydropower Plants: Pumped Storage in the Context of Renewable Energy Supply, C. Bauer and E. Doujak, eds., Institute for Energy Systems and Thermodynamics, Vienna, Austria, 453–462.
Ervine, D. A., and Elsawy, E. M. (1975). “The effect of a falling nappe on river aeration.” Proc., 16th IAHR Congress, Vol. 3, IAHR, Delft, Netherlands, 390–397.
Giesecke, G., and Mosonyi, E. (2009). Wasserkraftanlagen: Planung, Bau und Betrieb [Hydropower plants: Design, construction and operation], Springer, Berlin (in German).
Kjølle, A. (2001). “Hydropower in Norway: Mechanical equipment.”, Norwegian Univ. of Science and Technology, Trondheim, Norway.
Kobus, H. (1984). “Local air entrainment and detrainment.” Proc., Symp. on Scale Effects in Modelling Hydraulic Structures, H. Kobus, ed., Vol. 4.10, Technische Akademie, Esslingen, Germany, 1–10.
Mosonyi, E. (1991). High-head power plants, Akadémiai Kiadó, Budapest, Hungary.
Osterwalder, J. (1966). “Tailwater depression of multi-jet impulse turbines.” Water Power, 18(9), 358–362.
Terrier, S., Bieri, M., De Cesare, G., and Schleiss, A. J. (2014). “Surge wave propagation in a common tailrace channel for two large pumped-storage plants.” J. Hydraul. Eng., 218–225.
Volkart, P. (1980). “The mechanism of air-bubble entrainment in self-aerated flow.” Int. J. Multiphase Flow, 6(5), 411–423.
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Information
Published In
Journal of Hydraulic Engineering
Volume 141 • Issue 7 • July 2015
Copyright
© 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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