Influence of Plunge Pool Geometry on High-Velocity Jet Impact Pressures and Pressure Propagation inside Fissured Rock Media
Publication: Journal of Hydraulic Engineering
Volume 135, Issue 10
Abstract
The geometrical development of unlined plunge pools downstream large dams depends on both local geology and type of plunging jet and its diffusion pattern. Experimental investigations in plunge pools with different lateral confinements are presented. They show that the pool geometry influences plunging jet diffusion, air entrainment in the pool, and, as a consequence, impact pressures at the water-rock interface and inside the fissured rock mass. Results include impact pressures definition for variable pool depths, jet velocities, and pool geometries, depending explicitly on the lateral confinement of the jet. The main pool flow features are described focusing on their contribution to energy dissipation. Should the lateral confinement limit the development of macroturbulent rollers around the plunging jet (instead of the pool depth), the mean pressures at impact are considerably reduced, as well as RMS pressures in transitional and deep pools. For shallow pools, RMS pressures increase as a result of enhanced jet development.
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Acknowledgments
The first writer acknowledges the Fundação para a Ciência e a Tecnologia (FCT, Portugal) for the fellowship (Grant No. UNSPECIFIEDBPD/21847/2005). The research project was performed at the LCH-EPFL and cofunded by the FCT (Grant No. UNSPECIFIEDBD/6894/2001) and the Swiss Federal Office of Energy. The suggestions made by professors Virgilio Fiorotto (University of Trieste, Italy) and Jorge Matos (IST Lisbon, Portugal) throughout the development of this work are deeply appreciated.
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Published In
Journal of Hydraulic Engineering
Volume 135 • Issue 10 • October 2009
Pages: 783 - 792
Copyright
© 2009 ASCE.
History
Received: Oct 16, 2007
Accepted: Apr 8, 2009
Published online: Sep 15, 2009
Published in print: Oct 2009
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