Abstract
Vortex drop structure is used to convey water through underground conduits in urban sewers and drainage systems. During the plunge, a large volume of air is entrained into the water and then is released from the drop shaft downstream. Basically, volume of entrained air is comparatively hard to measure. In this research, a physical model was constructed to understand the mechanism of air circulation through vortex structure. In fact, experiments were tested to investigate effects of variables on the air circulation. Through the experiments, results of dimensional analysis results indicated that the approach flow Froude number (), drop total height to shaft diameter ratio (), and sump depth to shaft diameter ratio () had significant influences on the relative air discharge (). To express the role of each independent variable on relative air discharge () in terms of regression analysis, response surface methodology, based on central composite face-entered design (RSM-CCFD) was examined. Hence, a regression-based-equation in form of quadratic polynomial was proposed to estimate variable. Additionally, experimental design was to investigate simultaneous effects of , , and on the . Results of experimental study indicated that variable had upward trends with an increase in variable and ratio. Analysis of variance for the proposed regression model demonstrated that simultaneous effect of and on variable remained statistically significant, whereas other interaction effects of variables were insignificant. Ultimately, the optimum location for installation of air vent pipe ranged from to in a way that air vent pipe had the most satisfying level of air outlet flow performance.
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Data Availability Statement
Some or all data, models, or codes that support the findings of this study are available from the corresponding author upon reasonable request.
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© 2021 American Society of Civil Engineers.
History
Received: Mar 9, 2020
Accepted: Oct 23, 2020
Published online: Feb 22, 2021
Published in print: May 1, 2021
Discussion open until: Jul 22, 2021
ASCE Technical Topics:
- Analysis (by type)
- Drainage
- Drainage systems
- Engineering fundamentals
- Entrainment
- Fluid dynamics
- Fluid mechanics
- Geotechnical engineering
- Hydraulic engineering
- Hydrologic engineering
- Infrastructure
- Irrigation engineering
- Lifeline systems
- Regression analysis
- Sewers
- Shafts
- Statistical analysis (by type)
- Structural engineering
- Structures (by type)
- Tunnels
- Underground structures
- Urban and regional development
- Urban areas
- Vortices
- Water and water resources
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