Characteristics of Skimming Flow over Stepped Spillways
Publication: Journal of Hydraulic Engineering
Volume 125, Issue 4
Abstract
This paper presents the results of a laboratory study on the characteristics of fully developed skimming flow in a large model of a stepped spillway for two slopes, for a range of discharges with yc/h in the range of 0.7–4.4. Fully developed aerated flow on a stepped spillway can be divided into lower and upper regions, similar to those for self-aerated flow in steep chutes. The air concentration distributions in these two regions agree with the equations developed by Straub and Anderson for flow in steep chutes. It was found that the depth at which the air concentration is equal to 90% can be considered as the depth of aerated flow on stepped spillways. In the lower region, the velocity profiles were described by the Karman-Prandtl equation for rough turbulent flow when an equivalent bed roughness was used. A correlation was developed for the skin friction coefficient to predict the Reynolds shear stress at the virtual bed of the stepped spillway. It was found that the relative energy loss in the stepped spillway is in the range of 48–63%. It was also found that the mean air concentration on a stepped spillway is larger than that in a corresponding chute.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
ASCE Task Committee on Air Entrainment in Open Channels. (1961). “Aerated flow in open channels.”J. Hydr. Engrg., ASCE, 87(3), 73–82.
2.
Bayat, H. O. ( 1991). “Stepped spillway model investigations.” Proc., 17th ICOLD Congress, Vienna, Austria, III, 66, 1803–1817.
3.
Bindo, M., Gautier, J., and Lacroix, F. ( 1993). “The stepped spillway of M'Bali Dam.” J. Int. Water Power and Dam Construction, 45(1), 35–36.
4.
Chamani, M. R., and Rajaratnam, N. (1994). “Jet flow on stepped spillways.”J. Hydr. Engrg., ASCE, 120(2), 254–259.
5.
Chamani, M. R. ( 1997). “Skimming flow in a large model of a stepped spillway.” PhD thesis, University of Alberta, Canada.
6.
Chanson, H. ( 1994a). Hydraulic design of stepped cascades, channels, weirs and spillways . Elsevier Science, Amsterdam.
7.
Chanson, H. (1994b). “Hydraulics of skimming flows over stepped channels and spillways.”J. Hydr. Res., 32(3), 445–460.
8.
Christodoulou, G. C. (1993). “Energy dissipation on stepped spillways.”J. Hydr. Engrg., ASCE, 119(5), 644–649.
9.
Diez-Cascon, J., Blanco, J. L., Revilla, J., and Garcia, R. ( 1991). “Studies on the hydraulic behavior of stepped spillways.” J. Int. Water Power and Dam Construction, 43(9), 22–26.
10.
Essery, I. T. S., and Horner, M. W. ( 1978). “The hydraulic design of stepped spillways.” Rep. 33, CIRIA, U.K.
11.
Lamb, O. P., and Killen, J. M. ( 1950). “An electrical method for measuring air concentration in flowing air-water mixtures.” Tech. Paper 2, Series B, St. Anthony Falls Hydraulics Laboratory, University of Minnesota, Minneapolis, Minn.
12.
Logie, C. V. ( 1985). “Economic considerations in selection of a roller compacted concrete dam.” Proc., Symp. Sponsored by the Colorado Section and Construction Division of ASCE, Denver, 111–122, USA.
13.
Parker, J. W. ( 1992). “Economic factors in roller compacted concrete dam construction.” Proc., Roller Compacted Concrete III, 227–241.
14.
Rajaratnam, N. (1990). “Skimming flow in stepped spillways.”J. Hydr. Engrg., ASCE, 116(4), 587–591.
15.
Sikora, G. J. ( 1997). “An experimental study of the flow regimes in pool and weir fishways.” MSc thesis, University of Alberta, Canada.
16.
Sorensen, R. M. (1985). “Stepped spillway hydraulic model investigation.”J. Hydr. Engrg., ASCE, 111(12), 1461–1472.
17.
Straub, L. G., and Anderson, A. G. ( 1958). “Experiments on self-aerated flow in open channels.” Proc., ASCE, 87(7), 1890-1–1890-35.
18.
Tozzi, M. J. ( 1994). “Residual energy in stepped spillways.” J. Int. Water Power and Dam Construction, 46, 32–34.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 125 • Issue 4 • April 1999
Pages: 361 - 368
History
Received: Nov 11, 1997
Published online: Apr 1, 1999
Published in print: Apr 1999
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.