Chute Aerators: Steep Deflectors and Cavity Subpressure
Publication: Journal of Hydraulic Engineering
Volume 137, Issue 10
Abstract
Chute aerators are applied to high-velocity spillways to entrain air into the flow so that cavitation damage is avoided. Air entrainment occurs locally at the aerator, whereas further downstream the flow is deaerated. This process is relevant because it defines the influence range of an aerator. A preliminary study investigated the effect of the aerator geometry and of the approach flow conditions on the streamwise bottom and average air concentration characteristics. Two aspects were excluded, namely, the effect of (1) steep deflectors, which operate more efficiently regarding air entrainment yet with simultaneously poor flow features; and (2) cavity subpressure effect on the streamwise air concentration field. A cavity subpressure reduces, in particular, the streamwise bottom air concentrations or it provokes aerator choking so that the cavitation protection is not ensured. Physical model tests indicate that optimum aerator performance results at deflector angles around 10°, i.e., a slope of relative to the chute bottom with acceptable shock wave formation, spray generation, and jet height.
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Acknowledgments
Professor Dr. Willi H. Hager, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, supported the writer with valuable advice. Professor Dr. Arturo Marcano, Electrificacion del Caroni C.A. (EDELCA), Venezuela, kindly provided information related to the Guri Dam aerator damage. Thanks also to Mr. Alexander Schmid who conducted measurements related to cavity subpressure.
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 137 • Issue 10 • October 2011
Pages: 1208 - 1215
Copyright
© 2011 American Society of Civil Engineers.
History
Received: May 5, 2010
Accepted: Apr 8, 2011
Published online: Sep 15, 2011
Published in print: Oct 1, 2011
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