Orifice Spillway Aerator: Hydraulic Design
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VIEW THE REPLYPublication: Journal of Hydraulic Engineering
Volume 138, Issue 6
Abstract
Orifice spillways are in vogue for the dams in the hilly regions where the spillway has to serve the dual function of flood disposal and flushing of sediment through the reservoir. Deep-seated orifice spillways are subjected to cavitation damage as the cavitation index drops below the critical cavitation index of 0.2 because of negative pressures on the profile and high flow velocities. Aerators are provided for mitigating cavitation damage. Design guidelines for aerator of orifice spillways are scanty and not reported much in the literature so far; thus, there still remains gray area in the field of spillway aerator design. The present study investigates the performance of an offset aerator with and without a ramp for deep-seated orifice spillway on a physical and numerical model. Performance of the aerator for varying discharges, heads, and gate openings is studied for varying cavity subpressures. Results with respect to jet length, cavity subpressure and air entrainment coefficients are presented in the form of nondimensional plots. From this study, the nondimensional jet length is in the range of 2 to 35 and increases as the cavity subpressure, approaches atmospheric pressure. It is also found that the air entrainment increases with increase in Froude number, ramp height and cavity pressure. From the present study results, equations for jet length and air entrainment coefficient are developed and are presented for the orifice spillway aerator.
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Acknowledgments
The first author is grateful to Dr. I. D. Gupta, Director, CWPRS for the consent to publish this paper and constant encouragement during the course of study.
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Information
Published In
Journal of Hydraulic Engineering
Volume 138 • Issue 6 • June 2012
Pages: 563 - 572
Copyright
© 2012. American Society of Civil Engineers.
History
Received: May 14, 2011
Accepted: Dec 6, 2011
Published online: Dec 9, 2011
Published in print: Jun 1, 2012
Published ahead of production: Jun 15, 2012
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