Finite Crest Length Weir Nappe Oscillation
Publication: Journal of Hydraulic Engineering
Volume 144, Issue 6
Abstract
Low-head discharge over weirs and crest gates can produce a nappe instability in curvilinear weir nappe flow, referred to as nappe oscillation or vibration, that is characterized by horizontal waves (sinusoidal wave pattern in the longitudinal cross section) and significant low-frequency sound pressure waves. This topic has previously received minimal documentation in the literature. The current study documents weir-flow nappe oscillation research conducted using a prototype-scale quarter-round linear short-crested weir ( tall with a 152-mm radius) with confined and unconfined nappe conditions. The objective of this research was to develop a better understanding of the mechanisms behind nappe oscillation, evaluate oscillation frequencies (three different potential sources), and investigate potential mitigation techniques. Crest roughness modifications were evaluated as potential nappe vibration mitigation alternatives. The results suggest that the source of nappe oscillation is located at or near the weir crest downstream edge. Some modifications effectively suppressed nappe oscillation, whereas other factors functioned as oscillation amplifiers.
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Acknowledgments
Funding for this study was provided by the State of Utah and the Utah Water Research Laboratory (Utah State University).
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 144 • Issue 6 • June 2018
Copyright
©2018 American Society of Civil Engineers.
History
Received: Nov 7, 2016
Accepted: Nov 20, 2017
Published online: Mar 19, 2018
Published in print: Jun 1, 2018
Discussion open until: Aug 19, 2018
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