Jet Impinging in Plunging Dropshafts of Medium Height
Publication: Journal of Hydraulic Engineering
Volume 148, Issue 12
Abstract
A physical model study was conducted on jet impingement in a plunging dropshaft with different drop heights of 3.38 and 1.88 m. Experimental observations show that an upward splash, annular flow, and downward bounced jet could be formed when the approaching jet hits the opposite shaft wall. The impinging pressure on the shaft wall was mainly dominated by the incoming flow velocity, and the mean pressure on the shaft wall can be reasonably well-predicted when considering the bounced flow. The pulsation of the impinging pressure on the shaft wall was significant, with the maximum pressure being approximately 1.4–3.8 times the mean value. The impinging pressure at the shaft bottom was primarily determined by the velocity at which the falling jet reached the pool. The mean value can be well estimated using the annular flow and bounced jet assumption. The pulsation intensity increased with an increase in drop height or flow rate, which could be alleviated by a plunging pool with a larger depth. However, for flows in dropshafts under study, the impinging pressure and the hydrostatic pressure of the cushion layer were within the same order of magnitude; thus, the increase of the pool depth leads to a reduction of the energy-dissipation rate.
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Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
The authors gratefully appreciate the financial support from the Natural Science Foundation of Zhejiang Province (No. LQ22E090002), the Key Research and Development Program of Zhejiang Province (No. 2020C03082), and the Belt and Road Special Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (No. 2021492011). The authors would also like to thank anonymous reviewers for their careful work and thoughtful suggestions that have helped improve this paper substantially.
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 148 • Issue 12 • December 2022
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Jul 28, 2021
Accepted: Jul 26, 2022
Published online: Oct 12, 2022
Published in print: Dec 1, 2022
Discussion open until: Mar 12, 2023
ASCE Technical Topics:
- Continuum mechanics
- Dynamic pressure
- Dynamics (solid mechanics)
- Energy dissipation
- Engineering fundamentals
- Engineering mechanics
- Flow (fluid dynamics)
- Fluid dynamics
- Fluid mechanics
- Fluid velocity
- Geotechnical engineering
- Hydrologic engineering
- Hydrostatic pressure
- Models (by type)
- Physical models
- Pressure (type)
- Shafts
- Solid mechanics
- Structural engineering
- Structural members
- Structural systems
- Thermodynamics
- Tunnels
- Walls
- Water and water resources
- Wave velocity
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