Orifice Spillway Aerator: Hydraulic Design
This article has a reply.
VIEW THE REPLYThis article has a reply.
VIEW THE REPLYPublication: Journal of Hydraulic Engineering
Volume 138, Issue 6
Abstract
Orifice spillways are in vogue for the dams in the hilly regions where the spillway has to serve the dual function of flood disposal and flushing of sediment through the reservoir. Deep-seated orifice spillways are subjected to cavitation damage as the cavitation index drops below the critical cavitation index of 0.2 because of negative pressures on the profile and high flow velocities. Aerators are provided for mitigating cavitation damage. Design guidelines for aerator of orifice spillways are scanty and not reported much in the literature so far; thus, there still remains gray area in the field of spillway aerator design. The present study investigates the performance of an offset aerator with and without a ramp for deep-seated orifice spillway on a physical and numerical model. Performance of the aerator for varying discharges, heads, and gate openings is studied for varying cavity subpressures. Results with respect to jet length, cavity subpressure and air entrainment coefficients are presented in the form of nondimensional plots. From this study, the nondimensional jet length is in the range of 2 to 35 and increases as the cavity subpressure, approaches atmospheric pressure. It is also found that the air entrainment increases with increase in Froude number, ramp height and cavity pressure. From the present study results, equations for jet length and air entrainment coefficient are developed and are presented for the orifice spillway aerator.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The first author is grateful to Dr. I. D. Gupta, Director, CWPRS for the consent to publish this paper and constant encouragement during the course of study.
References
Bhosekar, V. V. (2011). “Physical and numerical model studies for aerators on orifice spillways.” Ph.D. thesis, Indian Institute of Technology Bombay, Mumbai, India.
Bhosekar, V. V., Jothiprakash, V., and Deolalikar, P. B. (2008). “Hydraulics of aerator for orifice spillway.” ISH J. Hydraul. Eng., 14(1), 28–40.
Bhosekar, V. V., Jothiprakash, V., and Deolalikar, P. B. (2009). “Hydraulic design of aerators.” Dam Eng., 20(2), 117–148.
Cederstrom, M., Hammer, L., Johansson, N., and Yang, J. (2000). “Modelling of spillway discharge capscity with computational fluid dynamics (CFD).” Proc. 20th Int. Congress, ICOLD, Beijing.
Chanson, H. (1997). Air bubble entrainment in free surface turbulent shear flow, Academic Press, London.
Deolalikar, P. B., Bhosekar, V. V., and Pethe, P. C. (2009). Research in to factors influencing the design of breast wall spillways, CWPRS Technical Memorandum, Central Water and Power Research Station (CWPRS), Pune, India.
Ervine, A., Falvey, H. T., and Khan, A. (1995). “Turbulent flow structure and air uptake at aerators.” Int. J. Hydropower Dams, 2(5), 87–96.
Falvey, H. T. (1990). “Cavitation in chutes and spillways.” Engineering Monograph No. 42, United States Bureau of Reclamation (USBR), Washington, DC.
Gambit 2.3.16 [Computer software]. FLUENT, Lebanon, NH.
Gessler, D. (2005). “CFD modeling of spillway performance.” EWRI 2005: Impact of global climate change, Proc., 2005 World Water and Environmental Research Congress, Walton, R., ed., ASCE, Reston, VA.
Higgs, J. A. (1997). “Folsom dam spillway vortices computational fluid dynamics model studies.” Memorandum Report, Water Resources Research Laboratory, Water Resources Services, Denver Technical Center, Bureau of Reclamation, US Dept. of Interiors, Denver, CO.
Ho, D. K. H., Boyes, K. M., and Donohoo, S. M. (2001). “Investigation of spillway behavior under increased maximum flood by computational fluid dynamics technique.” 14th Australian Fluid Mechanics Conf., Adelaide Univ., Adelaide, Australia, 577–580.
Kokpinar, M. A., and Gogus, M. (2002). “High speed jet flows over spillway aerators.” Can. J. Civ. Eng.CJCEB8, 29(6), 885–898.
Oskolkov, A. G., and Semenkov, V. M. (1979). “Experience in developing methods for preventing cavitation in excess flow release structures.” Power Tech. Eng., 13(8), 754–761.
Ozturk, M., Mehmet, Cihan Aydin, and Seckin, Aydin (2008). “Damage limitation- A new spillway aerator.” Int. Water Power Dam Constr., 60(5), 36–40.
Peterka, A. J. (1953). “The effect of entrained air on cavitation pitting.” Joint meeting paper, IAHR/ASCE, Reston, VA.
Pfister, M., and Hager, W. H. (2010a). “Chute aerator I: Air transport characteristics.” J. Hydraul. Eng.JHEND8, 136(6), 352–359.
Pfister, M., and Hager, W. H. (2010b). “Chute aerator I: Hydraulic design.” J. Hydraul. Eng.JHEND8, 136(6), 360–367.
Pinto, N. L. (1984). “Model evaluation of aerators in shooting flow.” Scale effects in modelling hydraulic structures, Kobus, H., ed. Technische Akademie, Esslingen, Germany, 4.2, 1–6.
Rutschmann, P., and Hager, W. H. (1990). “Air entrainment by spillway aerators.” J. Hydraul. Eng.JHEND8, 116(6), 765–782.
Schmocker, L., Pfister, M., and Hager, W. H., Minor, H.-E. (2008). “Aeration characteristics of ski jump jets.” J. Hydraul. Eng.JHEND8, 134(1), 90–97.
Shuangke, S., Chen, Jie, Lin, Zhiping, and Guo, Jaun (2001). “Hydraulic research on deep level outlets of the three gorges project.” 29th IAHR Congress Proc., Vol. 1, The International Association for Hydro-Environment Engineering and Research (IAHR), Madrid, Spain.
Teklemariam, E., Korbaylo, B. W., Groeneveld, J. L., and Fuchs, D. M. (2002). “Computational fluid dynamics: Diverse applications in hydropower project’s design and analysis.” Proc., 55th Annual Canadian Water Resources Association Conf., Canadian Water Resources Association, Ottawa, ON.
Volkart, P., and Rutschmann, P. (1984). “Air entrainment devices.” Hydrologic and Glaziologic, No. 72, ETH, Zurich, Switzerland.
Volkart, P., and Rutschmann, P. (1986). “Aerators on spillway chutes: Fundamentals and application.” Proc., Specialty Conf. on Advancements in Aerodynamics, Fluid Mechanics and Hydraulics, ASCE, Reston, VA, 162–177.
Yang, J., and Johannson, N. (1998). “Determination of spillway discharge capacity-CFD modeling and experimental verification.” Proc., 3rd Int. Conf. on Advances in Hydro science and Engineering, Brandenburg University of Technology, Cottbus, Germany.
Zhou, C., and Zhu, S., and Yong, H. (2005). “Model study on aerators of three gorges project’s deep outlets.” Proc. Int. Symp. of IAHR, The International Association for Hydro-Environment Engineering and Research (IAHR), Madrid, Spain, 674–680.
Information & Authors
Information
Published In
Copyright
© 2012. American Society of Civil Engineers.
History
Received: May 14, 2011
Accepted: Dec 6, 2011
Published online: Dec 9, 2011
Published in print: Jun 1, 2012
Published ahead of production: Jun 15, 2012
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.