Prototype and Laboratory Low-Level Outlet Air Demand Comparison for Small-to-Medium-Sized Embankment Dams
Publication: Journal of Irrigation and Drainage Engineering
Volume 140, Issue 6
Abstract
Low-level outlet works through dams are typically used to provide irrigation, reservoir sediment flushing, reservoir draw down, and/or minimum downstream flows to meet biological needs. To reduce the likelihood of negative pressure development downstream of the control gate, which may lead to cavitation noise, vibration, and damage, air vents are typically installed downstream of the gate. Undersized air vents may allow vapor pressure and cavitation to occur; oversized air vents have a negative economic impact. Air demand design criteria have been developed for vertical control gates (common to larger dams). The guidance for sizing air vents for an inclined slide gate, which are common for small-to-medium-sized embankment dam geometries, however, is limited. This study compares laboratory-scale and prototype-scale air-demand data. The influences of conduit slope, hydraulic jump presence, and air delivery system geometry on air demand were found to influence air demand. A method for estimating the required air vent diameter for a low-level outlet with an inclined slide gate at the inlet is presented.
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References
Campbell, F. B., and Guyton, B. (1953). “Air demand in gated outlet works.” Proc., 5th Int. Association for Hydraulic Research Congress, ASCE, Reston, VA, 529–533.
Falvey, H. T. (1980). “Air-water flow in hydraulic structures.” Engineering monograph 41, Water and Power Resources Service, U.S. Dept. of the Interior, Denver, CO.
Kalinske, A. A., and Robertson, J. W. (1943). “Closed conduit flow.” ASCE Trans., 108, 1435–1447.
Mortensen, J. D., Barfuss, S. L., and Tullis, B. P. (2012). “Effects of hydraulic jump location on air entrainment in closed conduits.” J. Hydraul. Res., 50(3), 298–303.
Mura, Y., Ijuin, S., and Nakagawa, H. (1959). “Air demand in conduits partly filled with flowing water.” Proc., 8th Congress IAHR, IAHR, Madrid Spain.
Sharma, H. R. (1976). “Air-entrainment in high head gated conduits.” J. Hydraul. Div., 102(11), 1629–1646.
Speerli, J. (1999). “Air entrainment of free-surface tunnel flow.” Proc., 28th IAHR Congress, IAHR, Madrid Spain.
Speerli, J., and Hager, W. (2000). “Air-water flow in bottom outlets.” Can. J. Civ. Eng., 27(3), 454–462.
Tullis, B. P., and Larchar, J. (2011). “Determining air demand for small- to medium-sized embankment dam low-level outlet works.” J. Irrig. Drain. Eng., 793–800.
Tullis, J. P. (1989). Hydraulic design of pipelines: Pumps, valves, cavitation, transients, Wiley, New York.
U.S. Army Corps of Engineers (USACE). (1964). “Hydraulic design criteria: Air demand-regulated outlet works.”, Washington, DC.
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© 2014 American Society of Civil Engineers.
History
Received: Sep 5, 2013
Accepted: Dec 16, 2013
Published online: Feb 24, 2014
Published in print: Jun 1, 2014
Discussion open until: Jul 24, 2014
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