Air Voids at Downshaft‐tunnel Bends
Publication: Journal of Hydraulic Engineering
Volume 109, Issue 2
Abstract
In closed conduit water flows containing a small amount of free air, an air void can form at a bend which connects a vertical shaft to a horizontal tunnel. A sudden reduction in the water flow rate can cause this void to vent back up the shaft. Tests were conducted on eight perspex pipe bends whose center‐line radius varied from 0.5 times–1.5 times the pipe diam, and over a range of pipe diameters from 2.8 in.–7.5 in. (0.072 m–0.190 m). The air volumetric flow rate was up to 2% of the water volumetric flow rate. A combined theoretical and analytical approach yielded equations which can be used to predict void formation and venting at a downshaft‐tunnel bend. Extrapolation of the results shows that these voids will not occur in large diameter bends with moderate air flows.
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References
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 109 • Issue 2 • February 1983
Pages: 189 - 198
Copyright
Copyright © 1983 ASCE.
History
Published online: Feb 1, 1983
Published in print: Feb 1983
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