Self-Aeration and Flow Resistance in High-Velocity Flows Down Spillways with Microrough Inverts
Publication: Journal of Hydraulic Engineering
Volume 149, Issue 6
Abstract
Free-surface aeration is a key characteristic of high-velocity flows on spillways. Despite their common use as conveyance structures, there is a research gap in the understanding of flows across spillways with small invert roughness. To address this gap, this study investigated flows down a moderate sloped spillway with four different microrough invert configurations, providing novel information on flow patterns, flow properties, and flow resistance. Visual observations identified distinctive differences between free-surface roughness and air entrainment, where the former increased with invert roughness and occurred consistently upstream of the intersection of the turbulent boundary layer with the free-surface. The evolution of velocities, air concentrations, and interface frequencies along the chutes was documented. All velocity distributions were well represented by a log law with wake function and uniform free-surface layer. A semianalytical model was able to predict air concentration and interface frequency distributions for all experiments with a characteristic length that was linked closely to the mean air concentration. Analysis of the flow resistance provided previously missing design data and suggested that researchers need to be cautious when reporting microrough invert conditions in order to avoid overestimating their flow resistance. A comparative analysis of the air–water flow properties for the three microroughness configurations showed that the air concentration distributions were well scaled with a Froude similitude, and that the number of free-surface perturbations and entrained bubbles was affected by scale effects.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
All data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The authors acknowledge the technical assistance of Rob Jenkins (WRL, UNSW Sydney). The authors thank Reilly Cox (WRL, UNSW Sydney) and Hanwen Cui (School of Engineering and Information Technology, UNSW Canberra) for discussions of data postprocessing.
References
Aivazyan, O. M. 1986. “Stabilized aeration on chutes.” Hydrotech. Constr. 20 (12): 713–722. https://doi.org/10.1007/BF01425070.
Anderson, A. G. 1965. “Influence of channel roughness on the aeration of high-velocity, open-channel flow.” In Proc., 11th IAHR Congress, 1–13. Madrid, Spain: IAHR - International Association for Hydro-Environment Engineering and Research.
Anwar, H. 1994. “Discussion of ‘Self-aerated flows on chutes and spillways’ by H. Chanson (February, 1993, vol. 119, no. 2).” J. Hydraul. Eng. 120 (6): 778–779. https://doi.org/10.1061/(ASCE)0733-9429(1994)120:6(778).
Auel, C., I. Albayrak, and R. M. Boes. 2014. “Turbulence characteristics in supercritical open channel flows: Effects of Froude number and aspect ratio.” J. Hydraul. Eng. 140 (4): 04014004. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000841.
Boes, R. 2000. “Two-phase flow and energy dissipation at large cascades.” [In German.] Ph.D. thesis, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich.
Boes, R. M., and W. H. Hager. 2003. “Hydraulic design of stepped spillways.” J. Hydraul. Eng. 129 (9): 671–679. https://doi.org/10.1061/(ASCE)0733-9429(2003)129:9(671).
Bung, D. 2009. “Zur selbstbeluefteten Gerinnestroemung auf Kaskaden mit gemaessigter Neigung.” Ph.D. thesis, Dept. of Civil Engineering, Bergische Universitaet Wuppertal.
Cain, P. 1978. “Measurements within self-aerated flow on a large spillway.” Ph.D. thesis, Dept. of Civil Engineering, Univ. of Canterbury.
Castro-Orgaz, O., and W. H. Hager. 2010. “Drawdown curve and turbulent boundary layer development for chute flow.” J. Hydraul. Res. 48 (5): 591–602. https://doi.org/10.1080/00221686.2010.507337.
Chanson, H. 1988. “Study of air entrainment and aeration devices on spillway model.” Ph.D. thesis. Dept. of Civil Engineering, Univ. of Canterbury.
Chanson, H. 1994. “Closure to ‘Self-Aerated Flows on Chutes and Spillways’ by H. Chanson (February, 1993, Vol. 119, No. 2).” J. Hydraul. Eng. 120 (6): 779–782. https://doi.org/10.1061/(ASCE)0733-9429(1994)120:6(779).
Chanson, H. 1996. Air bubble entrainment in free-surface turbulent shear flows. London: Academic.
Cheng, N.-S. 2017. “Simple modification of Manning-Strickler formula for large-scale roughness.” J. Hydraul. Eng. 143 (9): 04017031. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001345.
Coles, D. 1956. “The law of the wake in the turbulent boundary layer.” J. Fluid Mech. 1 (2): 191–226. https://doi.org/10.1017/S0022112056000135.
Falvey, H. T. 1980. Air-water flow in hydraulic structures (engineering monograph no. 41). Washington, DC: US Bureau of Reclamation (USBR).
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. 2015. “Phase-detection probe measurements in high-velocity free-surface flows including a discussion of key sampling parameters.” Exp. Therm. Fluid Sci. 61 (Feb): 66–78. https://doi.org/10.1016/j.expthermflusci.2014.10.009.
Felder, S., and H. Chanson. 2016. “Simple design criterion for residual energy on embankment dam stepped spillways.” J. Hydraul. Eng. 142 (4): 04015062. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001107.
Felder, S., and H. Chanson. 2017. “Scale effects in microscopic air-water flow properties in high-velocity free-surface flows.” Exp. Therm. Fluid Sci. 83 (May): 19–36. https://doi.org/10.1016/j.expthermflusci.2016.12.009.
Felder, S., B. Hohermuth, and R. M. Boes. 2019. “High-velocity air-water flows downstream of sluice gates including selection of optimum phase-detection probe.” Int. J. Multiphase Flow 116 (Jul): 203–220. https://doi.org/10.1016/j.ijmultiphaseflow.2019.04.015.
Felder, S., and N. Islam. 2017. “Hydraulic performance of an embankment weir with rough crest.” J. Hydraul. Eng. 143 (3): 04016086. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001255.
Gulliver, J. S., and A. J. Rindels. 1993. “Measurement of air-water oxygen transfer at hydraulic structures.” J. Hydraul. Eng. 119 (3): 327–349. https://doi.org/10.1061/(ASCE)0733-9429(1993)119:3(327).
Hohermuth, B., R. M. Boes, and S. Felder. 2021. “High-velocity air–water flow measurements in a prototype tunnel chute: Scaling of void fraction and interfacial velocity.” J. Hydraul. Eng. 147 (11): 04021044. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001936.
Hunt, S. L., and K. C. Kadavy. 2011. “Inception point relationship for flat-sloped stepped spillways.” J. Hydraul. Eng. 137 (2): 262–266. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000297.
Keller, R., and A. Rastogi. 1975. “Prediction of flow development on spillways.” J. Hydraul. Div. 101 (9): 1171–1184. https://doi.org/10.1061/JYCEAJ.0004414.
Killen, J. M. 1968. The surface characteristics of self aerated flow in steep channels. Minneapolis: Univ. of Minnesota.
Kim, D. G., and J. H. Park. 2005. “Analysis of flow structure over ogee-spillway in consideration of scale and roughness effects by using cfd model.” KSCE J. Civ. Eng. 9 (2): 161–169. https://doi.org/10.1007/BF02829067.
Kramer, M., S. Felder, B. Hohermuth, and D. Valero. 2021a. “Drag reduction in aerated chute flow: Role of bottom air concentration.” J. Hydraul. Eng. 147 (11): 04021041. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001925.
Kramer, M., B. Hohermuth, D. Valero, and S. Felder. 2020. “Best practices for velocity estimations in highly aerated flows with dual-tip phase-detection probes.” Int. J. Multiphase Flow 126 (May): 103228. https://doi.org/10.1016/j.ijmultiphaseflow.2020.103228.
Kramer, M., B. Hohermuth, D. Valero, and S. Felder. 2021b. “On velocity estimations in highly aerated flows with dual-tip phase-detection probes - closure.” Int. J. Multiphase Flow 134 (Jan): 103475. https://doi.org/10.1016/j.ijmultiphaseflow.2020.103475.
Kramer, M., D. Valero, H. Chanson, and D. B. Bung. 2019. “Towards reliable turbulence estimations with phase-detection probes: An adaptive window cross-correlation technique.” Exp. Fluids 60 (2): 6. https://doi.org/10.1007/s00348-018-2650-9.
Kundu, P. K., I. M. Cohen, and D. R. Dowling. 2016. Fluid mechanics. 6th ed. New York: Academic.
Lai, K. 1968. “A study of air entrainment in steep open channels.” In Proc., Third Australasian Conf. on Hydraulics and Fluid Mechanics, 41–44. Barton, Australia: The Institution of Engineers, Australia.
Marusic, I., B. J. McKeon, P. A. Monkewitz, H. M. Nagib, A. J. Smits, and K. R. Sreenivasan. 2010. “Wall-bounded flows at high Reynolds numbers: Recent advances and key issues.” Phys. Fluids (1994) 22 (6): 065103. https://doi.org/10.1063/1.3453711.
Meireles, I., F. Renna, J. Matos, and F. 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.
Nagib, H. M., and K. A. Chauhan. 2008. “Variations of von Kármán coefficient in canonical flows.” Phys. Fluids (1994) 20 (10): 101518. https://doi.org/10.1063/1.3006423.
Nikora, N., V. Nikora, and T. O’Donoghue. 2013. “Velocity profiles in vegetated open-channel flows: Combined effects of multiple mechanisms.” J. Hydraul. Eng. 139 (10): 1021–1032. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000779.
Nikuradse, J. 1933. Laws of flow in rough pipes. Washington, DC: National Advisory Commitee for Aeronautics.
Pagliara, S., I. Carnacina, and T. Roshni. 2011. “Inception point and air entrainment on flows under macroroughness condition.” J. Environ. Eng. 137 (7): 629–638. https://doi.org/10.1061/(ASCE)EE.1943-7870.0000369.
Pagliara, S., and P. Chiavaccini. 2006. “Energy dissipation on block ramps.” J. Hydraul. Eng. 132 (1): 41–48. https://doi.org/10.1061/(ASCE)0733-9429(2006)132:1(41).
Petrillo, A., and M. Ranieri. 1984. “The influence of self-aeration on resistance in smooth and rough steep channels.” Meccanica 19 (2): 116–126. https://doi.org/10.1007/BF01560459.
Pfister, M., and W. H. Hager. 2010. “Chute aerators. II: Hydraulic design.” J. Hydraul. Eng. ASCE 136 (6): 360–367. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000201.
Pfister, M., W. H. Hager, and H.-E. Minor. 2006. “Stepped chutes: Pre-aeration and spray reduction.” Int. J. Multiphase Flow 32 (2): 269–284. https://doi.org/10.1016/j.ijmultiphaseflow.2005.10.004.
Plott, J., P. Diplas, J. Kozarek, C. Dancey, C. Hill, and F. Sotiropoulos. 2013. “A generalized log law formulation for a wide range of boundary roughness typically encountered in natural streams.” J. Geophys. Res. Earth Surf. 118 (3): 1419–1431. https://doi.org/10.1002/jgrf.20104.
Rao, N., and H. Kobus. 1971. “Characteristics of self-aerated free-surface flows.” In Vol. 10 of Water and waste water/current research and practice. Berlin: E. Schmidt.
Scheres, B., H. Schüttrumpf, and S. Felder. 2020. “Flow resistance and energy dissipation in supercritical air-water flows down vegetated chutes.” Water Resour. Res. 56 (2): e2019WR026686. https://doi.org/10.1029/2019WR026686.
Severi, A. 2018. “Aeration performance and flow resistance in high-velocity flows over moderately sloped spillways with micro-rough bed.” Ph.D. thesis, School of Civil and Environmental Engineering, UNSW Sydney.
Stephenson, D. 1991. “Energy dissipation down stepped spillways.” Int. Water Power Dam Constr. 43 (9): 27–30. https://doi.org/10.1061/(ASCE)0733-9429(1993)119:5(644).
Straub, L. G., and A. G. Anderson. 1958. “Experiments on self-aerated flow in open channels.” J. Hydraul. Div. 84 (7): 1–35. https://doi.org/10.1061/JYCEAJ.0000261.
Toombes, L., and H. Chanson. 2007. “Surface waves and roughness in self-aerated supercritical flow.” Environ. Fluid Mech. 7 (3): 259–270. https://doi.org/10.1007/s10652-007-9022-y.
Valero, D., and D. B. Bung. 2016. “Development of the interfacial air layer in the non-aerated region of high-velocity spillway flows. Instabilities growth, entrapped air and influence on the self-aeration onset.” Int. J. Multiphase Flow 84 (Sep): 66–74. https://doi.org/10.1016/j.ijmultiphaseflow.2016.04.012.
Valero, D., and D. B. Bung. 2018. “Reformulating self-aeration in hydraulic structures: Turbulent growth of free surface perturbations leading to air entrainment.” Int. J. Multiphase Flow 100 (Mar): 127–142. https://doi.org/10.1016/j.ijmultiphaseflow.2017.12.011.
Valero, D., H. Chanson, and D. B. Bung. 2020. “Robust estimators for free surface turbulence characterization: A stepped spillway application.” Flow Meas. Instrum. 76 (Dec): 101809. https://doi.org/10.1016/j.flowmeasinst.2020.101809.
Wei, W., J. Deng, and F. Zhang. 2016. “Development of self-aeration process for supercritical chute flows.” Int. J. Multiphase Flow 79 (Mar): 172–180. https://doi.org/10.1016/j.ijmultiphaseflow.2015.11.003.
Wei, W., W. Xu, J. Deng, and Y. Guo. 2022. “Self-aeration development and fully cross-sectional air diffusion in high-speed open channel flows.” J. Hydraul. Res. 60 (3): 445–459. https://doi.org/10.1080/00221686.2021.2004250.
Wei, W., W. Xu, J. Deng, Z. Tian, and F. Zhang. 2019. “Bubble formation and scale dependence in free-surface air entrainment.” Sci. Rep. 9 (1): 1–8.
Wilhelms, S. C., and J. S. Gulliver. 2005. “Bubbles and waves description of self-aerated spillway flow.” J. Hydraul. Res. 43 (5): 522–531. https://doi.org/10.1080/00221680509500150.
Wood, I. R. 1983. “Uniform region of self-aerated flow.” J. Hydraul. Eng. 109 (3): 447–461. https://doi.org/10.1061/(ASCE)0733-9429(1983)109:3(447).
Wood, I. R. 1991. “Free surface air entrainment on spillways.” In Air entrainment in free-surface flows, IAHR monograph, edited by I. R. Wood. Rotterdam, Netherlands: A.A. Balkema.
Wood, I. R., P. Ackers, and J. Loveless. 1983. “General method for critical point on spillways.” J. Hydraul. Eng. 109 (2): 308–312. https://doi.org/10.1061/(ASCE)0733-9429(1983)109:2(308).
Xi, R. 1988. “Characteristics of self-aerated flow on steep chutes.” In Proc., Int. Symp. on Hydraulics for High Dams, 68–75. Beijing: Chinese Hydraulic Engineering Society.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 149 • Issue 6 • June 2023
Copyright
© 2023 American Society of Civil Engineers.
History
Received: Feb 1, 2022
Accepted: Nov 11, 2022
Published online: Mar 31, 2023
Published in print: Jun 1, 2023
Discussion open until: Aug 31, 2023
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.
Cited by
- Steven C. Wilhelms, John S. Gulliver, Resurrecting a Neglected Measurement Technique for Air–Water Flows, Journal of Hydraulic Engineering, 10.1061/JHEND8.HYENG-13904, 150, 5, (2024).
- Jin Liu, Fei Ma, Jianhua Wu, Effects of Stepped Chute Slope and Slit Location on a Jet from Abrupt Contraction Aerator, Journal of Hydraulic Engineering, 10.1061/JHEND8.HYENG-13690, 150, 2, (2024).