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.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
Funding for this study was provided by the State of Utah and the Utah Water Research Laboratory (Utah State University).
References
Adobe Audition version 5.0 [Computer software]. Adobe Systems, Inc., San Jose, CA.
Binnie, A. M. (1972). “The stability of a falling sheet of water.” Proc. R. Soc. London Ser. A Math. Phys., 326(1565), 149–163.
Casperson, L. W. (1993). “Fluttering fountains.” J. Sound Vib., 162(2), 251–262.
Chanson, H. (1996). “Some hydraulic aspects during overflow above inflatable flexible membrane dam.”, Univ. of Queensland, St Lucia, QLD, Australia.
Helmholtz, H. V. (1868). “Über discontinuierliche Flüssigkeits-Bewegungen [On the discontinuous movements of fluids].” Monatsberichte der Königlichen Preussische Akademie der Wissenschaften zu Berlin [Monthly Reports of the Royal Prussian Academy of Philosophy in Berlin], Vol. 23, Royal Prussian Academy of Philosophy, Berlin, 215–228 (in German).
Kyotoh, H. (2002). “Incipient oscillations of a sheet of falling water and the instability mechanisms.” J. Hydrosci. Hydraul. Eng., 20(1), 77–93.
Metropolitan Water, Sewage and Drainage Board. (1980). “Investigation into spillway discharge noise at Avon Dam.” ANCOLD Bull., 57, 31–36.
Naudascher, E. (1974). “Flow-induced structural vibrations.” Symp. of the Int. Union of Theoretical and Applied Mechanics and the Int. Association of Hydraulic Research, Springer, Berlin, 167–182.
Naudascher, E., and Rockwell, D. (1994). Flow-induced vibrations: An engineering guide, Dover Publishing, Inc., Mineola, NY, 142–146.
Sato, Y., Miura, S., Morii, S., and Ohkubo, S. (2007). “Behavior of a falling water sheet.” J. Environ. Eng., 2(2), 394–406.
Schmid, P. J., and Henningson, D. S. (2002). “On the stability of a falling liquid curtain.” J. Fluid Mech., 463, 163–171.
Schwartz, H. I. (1966). “Edgetones and nappe oscillation.” J. Acoust. Soc. Am., 39(3), 579–582.
USBR (U.S. Bureau of Reclamation). (1964). Experiences of the bureau of reclamation with flow-induced vibrations, Denver.
Information & Authors
Information
Published In
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
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.