Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes
Publication: Journal of Hydraulic Engineering
Volume 144, Issue 9
Abstract
The effects of step edge and cavity shapes on skimming flow properties were investigated in a large-size 45° stepped chute model configured with uniform triangular steps, partially blocked cavities, and chamfers. The focus of this experimental study was the air–water flow regime and the energy dissipation performances. Visually, the partial cavity blockage and chamfers were respectively associated with an increase and a decrease in flow stability, while causing no substantial change in the general flow regimes. Comparisons of characteristic air–water properties indicated better aeration performance for the sharp edges than for the chamfers. A substantial reduction in friction factor was observed with the chamfers, while partial cavity blockages appeared to slightly improve flow resistance. A strongly negative correlation between total air entrainment and flow resistance was identified, which was more observable for the sharp edges. A comparative study revealed that sparsely spaced sharp edges at slopes between 30 and 45° might be optimal in terms of aeration and energy dissipation performances.
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Acknowledgments
The authors acknowledge the technical assistance of Jason Van Der Gevel and Stewart Matthews (School of Civil Engineering, University of Queensland). The financial support of the Australian Research Council (Grant No. DP120100481) is acknowledged.
References
Amador, A. 2005. “Comportamiento hidráulico de los aliviaderos escalonados en presas de hormigón compactado.” [In Spanish.] Ph.D. thesis, Dep. de Ingeniería Hidráulica, Marítima y Ambiental, Technical Univ. of Catalonia (UPC).
Boes, R. M., and W. H. Hager. 2003. “Hydraulic design of stepped spillways.” J. Hydraul. Eng. 129 (9): 661–670. https://doi.org/10.1061/(ASCE)0733-9429(2003)129:9(661).
Brattberg, T., H. Chanson, and L. Toombes. 1998. “Experimental investigations of free-surface aeration in the developing flow of two-dimensional water jets.” J. Fluids Eng. 120 (4): 738–744. https://doi.org/10.1115/1.2820731.
Carosi, G., and H. Chanson. 2006. Air-water time and length scales in skimming flow on a stepped spillway. Application to the spray characterisation. Brisbane, Australia: Division of Civil Engineering.
Chamani, M. R., and N. Rajaratnam. 1999. “Characteristics of skimming flow over stepped spillways.” J. Hydraul. Eng. 125 (4): 361–368. https://doi.org/10.1061/(ASCE)0733-9429(1999)125:4(361).
Chanson, H. 1993. “Stepped spillway flows and air entrainment.” Can. J. Civ. Eng. 20 (3): 422–435. https://doi.org/10.1139/l93-057.
Chanson, H. 1994. “Hydraulics of skimming flows over stepped channels and spillways.” J. Hydraul. Res. 32 (3): 445–460. https://doi.org/10.1080/00221689409498745.
Chanson, H. 2001a. The hydraulics of stepped chutes and spillways, 418. Lisse, Netherlands: Balkema.
Chanson, H. 2001b. “Hydraulic design of stepped spillways and downstream energy dissipators.” Dam Eng. 11 (4): 205–242.
Chanson, H. 2004. “Drag reduction in skimming flow on stepped spillways by aeration.” J. Hydraul. Res. 42 (3): 316–322. https://doi.org/10.1080/00221686.2004.9728397.
Chanson, H., and L. Toombes. 2002a. “Air-water flows down stepped chutes: Turbulence and flow structure observations.” Int. J. Multiphase Flow 28 (11): 1737–1761. https://doi.org/10.1016/s0301-9322(02)00089-7.
Chanson, H., and L. Toombes. 2002b. “Energy dissipation and air entrainment in stepped storm waterway. Experimental study.” J. Irrig. Drain. Eng. 128 (5): 305–315. https://doi.org/10.1061/(asce)0733-9437(2002)128:5(305).
Chanson, H., and L. Toombes. 2002c. “Experimental investigations of air entrainment in transition and skimming flows down a stepped chute.” Can. J. Civ. Eng. 29 (1): 145–156. https://doi.org/10.1139/l01-084.
Chanson, H., and L. Toombes. 2004. “Hydraulics of stepped chutes: The transition flow.” J. Hydraul. Res. 42 (1): 43–54. https://doi.org/10.1080/00221686.2004.9641182.
Chanson, H., Y. Yasuda, and I. Ohtsu. 2002. “Flow resistance in skimming flows and its modelling.” Can. J. Civ. Eng. 29 (6): 809–819. https://doi.org/10.1139/l02-083.
Chow, V. T. 1959. Open channel hydraulics, 680. New York: McGraw-Hill.
Djenidi, L., F. Anselmet, and R. A. Antonia. 1999. “The turbulent boundary layer over transverse square cavities.” J. Fluid Mech. 395: 271–294. https://doi.org/10.1017/S0022112099005911.
Felder, S. 2013. “Air-water flow properties on stepped spillways for embankment dams: Aeration, energy dissipation and turbulence on uniform, non-uniform and pooled stepped chutes.” Ph.D. thesis, School of Civil Engineering, Univ. of Queensland.
Felder, S., and H. Chanson. 2009. “Energy dissipation, flow resistance and gas-liquid interfacial area in skimming flows on moderate-slope stepped spillways.” Environ. Fluid Mech. 9 (4): 427–441. https://doi.org/10.1007/s10652-009-9130-y.
Felder, S., and H. Chanson. 2013. “Aeration, flow instabilities, and residual energy on pooled stepped spillways of embankment dams.” J. Irrig. Drain. Eng. 139 (10): 880–887. https://doi.org/10.1061/(ASCE)IR.1943-4774.0000627.
Felder, S., and H. Chanson. 2014. “Effects of step pool porosity upon flow aeration and energy dissipation on pooled stepped spillways.” J. Hydraul. Eng. 140 (4): 04014002. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000858.
Frizell, K. W., F. M. Renna, and J. Matos. 2013. “Cavitation potential of flow on stepped spillways.” J. Hydraul. Eng. 139 (6): 630–636. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000715.
Gonzalez, C. A. 2005. “An experimental study of free-surface aeration on embankment stepped chutes.” Ph.D. thesis, Dept. of Civil Engineering.
Gonzalez, C. A., and H. Chanson. 2004. “Interactions between cavity flow and main stream skimming flows: An experimental study.” Can. J. Civ. Eng. 31 (1): 33–44. https://doi.org/10.1139/l03-066.
Gonzalez, C. A., and H. Chanson. 2006. “Flow characteristics of skimming flows in stepped channels. Discussion.” J. Hydraul. Eng. 132 (4): 432–433. https://doi.org/10.1061/(ASCE)0733-9429(2006)132:4(432).
Gonzalez, C. A., and H. Chanson. 2007. “Hydraulic design of stepped spillways and down-stream energy dissipators for embankment dams.” Dam Eng. 17 (4): 1–18.
Gonzalez, C. A., and H. Chanson. 2008. “Turbulence and cavity recirculation in air-water skimming flows on a stepped spillway.” J. Hydraul. Res. 46 (1): 65–72. https://doi.org/10.1080/00221686.2008.9521843.
Leonardi, S., P. Orlandi, and R. A. Antonia. 2007. “Properties of d- and k-type roughness in a turbulent channel flow.” Phys. Fluids 19 (12): 125101. https://doi.org/10.1063/1.2821908.
Matos, J. 1999. “Emulsionamento de ar e dissipação de energia do escoamento em descarregadores em degraus” [Air entrainment and energy dissipation in flow over stepped spillways]. [In Portuguese.] Ph.D. thesis, IST.
Matos, J. 2000. “Hydraulic design of stepped spillways over RCC dams.” In Proc., Int. Workshop on Hydraulics of Stepped Spillways, edited by H. E. Minor, and W. H. Hager, 187–194. Rotterdam, Netherlands: Balkema Publisher.
Meireles, I. 2011. “Hydraulics of stepped chutes: Experimental-numerical-theoretical study.” Ph.D. thesis, Departamento de Engenharia Civil, Universidade de Aveiro.
Meireles, I., F. Renna, J. Matos, and F. A. Bombardelli. 2012. “Skimming, nonaerated flow on stepped spillways over roller compacted concrete dams.” J. Hydraul. Eng. 138 (10): 870–877. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000591.
Ohtsu, I., Y. Yasuda, and M. Takahashi. 2004. “Flow characteristics of skimming flows in stepped channels.” J. Hydraul. Eng. 130 (9): 860–869. https://doi.org/10.1061/(ASCE)0733-9429(2004)130:9(860).
Perry, A. E., W. H. Schofield, and P. N. Joubert. 1969. “Rough wall turbulent boundary layers.” J. Fluid Mech. 37 (2): 383–413. https://doi.org/10.1017/S0022112069000619.
Rajaratnam, N. 1990. “Skimming flow in stepped spillways.” J. Hydraul. Eng. 116 (4): 587–591. https://doi.org/10.1061/(asce)0733-9429(1990)116:4(587).
Stephenson, D. 1988. “Stepped energy dissipators.” In Proc., Int. Symp. on Hydraulics for High Dams. Beijing: IAHR.
Takahashi, M., Y. Yasuda, and I. Ohtsu. 2008. “Flow patterns and energy dissipation over various stepped chutes. Discussion.” J. Irrig. Drain. Eng. 134 (1): 114–116. https://doi.org/10.1061/(ASCE)0733-9437(2008)134:1(114).
Toombes, L. 2002. “Experimental study of air-water flow properties on low-gradient stepped cascades.” Ph.D. thesis, Dept. of Civil Engineering, Univ. of Queensland.
Toombes, L., and H. Chanson. 2008. “Flow patterns in nappe flow regime down low gradient stepped chutes.” J. Hydraul. Res. 46 (1): 4–14. https://doi.org/10.1080/00221686.2008.9521838.
Wuthrich, D., and H. Chanson. 2014. “Hydraulics, air entrainment and energy dissipation on gabion stepped weir.” J. Hydraul. Eng. 140 (9): 04014046. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000919.
Zhang, G., and H. Chanson. 2016a. “Gabion stepped spillway: Interactions between free-surface, cavity, and seepage flows.” J. Hydraul. Eng. 142 (5): 06016002. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001120.
Zhang, G., and H. Chanson. 2016b. “Hydraulics of the developing flow region of stepped spillways. I: Physical modeling and boundary layer development.” J. Hydraul. Eng. 142 (7): 8. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001138.
Information & Authors
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Published In
Journal of Hydraulic Engineering
Volume 144 • Issue 9 • September 2018
Copyright
©2018 American Society of Civil Engineers.
History
Received: Jun 30, 2017
Accepted: Mar 26, 2018
Published online: Jun 28, 2018
Published in print: Sep 1, 2018
Discussion open until: Nov 28, 2018
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