Skimming Flow in Stepped Spillways
Publication: Journal of Hydraulic Engineering
Volume 116, Issue 4
Abstract
Flow on stepped spillways can be divided into nappe and skimming flow regimes. This technical note presents an approximate method of predicting the characteristics of skimming flow on stepped spillways. Expressing the turbulent shear stress between the skimming stream and the recirculating fluid, trapped by the stream between the steps, in terms of a fluid friction coefficient and dynamic pressure (in terms of the mean velocity), a flow equation has been developed. Using the model studies of Sorensen on the new Monksville dam, this friction coefficient was found to be equal to about 0.18. An estimate has been made of the energy loss caused by the steps and it was found that this loss is significant. It was also found that the skimming flow sets in when the critical depth is greater than about 0.8 times the height of the steps.
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References
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Ervine, D. A., and Baird, J. I. (1982). “Rating Curves for Rivers with Overbank Flow,” Proc. Instn. of Civ. Engrs., Part 2, Institute of Civil Engineers, 465–472.
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Essery, I. T. S., and Horner, M. W. (1971). “The hydraulic design of stepped spillways.” Report 33, Constr. Industry Res. and Information Assoc., London, England.
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Rajaratnam, N., and Katopodis, C. (1984). “Hydraulics of Denil fishways.” Proc, ASCE, 110(9), 1219–1233.
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Rajaratnam, N., Katopodis, C., and Mainali, A. (1988). “Plunging and streaming flows in pool and weir fishways.” Proc., ASCE, 114(8), 939–944.
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Rajaratnam, N., van der Vinne, G., and Katopodis, C. (1986). “Hydraulics of Vertical Slot fishways.” Proc, ASCE, 112(10), 909–927.
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Sorensen, R. M. (1985). “Stepped spillway hydraulic model investigation.” Proc., ASCE, 111(12), 1461–1472.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 116 • Issue 4 • April 1990
Pages: 587 - 591
Copyright
Copyright © 1990 ASCE.
History
Published online: Apr 1, 1990
Published in print: Apr 1990
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