Experimental Investigation of the Emptying Process and Air Cavity Dynamic in Pipelines
Publication: Journal of Irrigation and Drainage Engineering
Volume 148, Issue 11
Abstract
The emptying process of initially stagnant full-pipe flows in sewer systems and water transmission lines was extensively studied in the literature. The following air intrusion and depressurization wavefronts can cause several issues such as the collapse of pipes, damage to joints, and valves. However, there is a lack of study on the emptying process when the flow has initial velocity. Thus, the present study focuses on the emptying process of a full-pipe flow with an initial flow rate, which decreases during the emptying process. For this purpose, two experiments without and with initial flow rates were performed in a reservoir-circular pipe system. In both experiments, an air cavity intrusion starts downstream of the pipe at the top of the free-surface flow and propagates upstream. It was found that when there is no initial flow rate, the pressure inside the cavity is atmospheric. However, when there is an initial flow rate, at the onset of the air intrusion, a subatmospheric pressure develops inside the air cavity. It was also found that the magnitude of this subatmospheric pressure decreases when the cavity further propagates upstream. In addition, when there is an initial flow rate, the cavity appears at a certain driving pressure.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. These data correspond to:
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Flow number upstream (), downstream (), and nondimensional celerity (), for and 1.8.
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Values of the measured parameters , , and , for and 1.8.
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Pressure in the sensors and water depth’s profile below the air cavity, when the sensors are located downstream of the pipe, for and 1.8.
Acknowledgments
The writers would like to express their gratitude to the Natural Sciences and Engineering Research Council of Canada (NSERC) for the financial support.
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Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 148 • Issue 11 • November 2022
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Jul 15, 2021
Accepted: Jul 2, 2022
Published online: Sep 8, 2022
Published in print: Nov 1, 2022
Discussion open until: Feb 8, 2023
ASCE Technical Topics:
- Air flow
- Cavitation
- Flow (fluid dynamics)
- Flow rates
- Fluid dynamics
- Fluid mechanics
- Hydrologic engineering
- Infrastructure
- Joints
- Pipe joints
- Pipeline systems
- Pipes
- Pressurized flow
- River engineering
- Rivers and streams
- Structural engineering
- Structural members
- Structural systems
- Transient flow
- Water and water resources
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