Emptying of Large-Scale Pipeline by Pressurized Air
Publication: Journal of Hydraulic Engineering
Volume 138, Issue 12
Abstract
Emptying of an initially water-filled horizontal PVC pipeline driven by different upstream compressed air pressures and with different outflow restriction conditions, with motion of an air-water front through the pressurized pipeline, is investigated experimentally. Simple numerical modeling is used to interpret the results, especially the observed additional shortening of the moving full water column due to formation of a stratified water-air “tail.” Measured discharges, water-level changes, and pressure variations along the pipeline during emptying are compared using control volume (CV) model results. The CV model solutions for a nonstratified case are shown to be delayed as compared with the actual measured changes of flow rate, pressure, and water level. But by considering water-column mass loss due to the water-air tail and residual motion, the calibrated CV model yields solutions that are qualitatively in good agreement with the experimental results. A key interpretation is that the long air-cavity celerity is close to its critical value at the instant of minimum flow acceleration. The influences of driving pressure, inertia, and friction predominate, with the observed water hammer caused by the initiating downstream valve opening insignificantly influencing the water-air front propagation.
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Acknowledgments
The project Transient Vaporous and Gaseous Cavitation in Pipelines carried out at Deltares, Delft, the Netherlands, was funded through EC-HYDRALAB III Contract 022441 (R113) by the European Union. The authors would like to thank Richard Tuin, Martin Boele, and Theo Ammerlaan for their technical support during the experiments.
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Information & Authors
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Published In
Journal of Hydraulic Engineering
Volume 138 • Issue 12 • December 2012
Pages: 1090 - 1100
Copyright
© 2012 American Society of Civil Engineers.
History
Received: Jul 6, 2011
Accepted: May 11, 2012
Published online: May 15, 2012
Published in print: Dec 1, 2012
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