CLC number: TV131.2
On-line Access: 2024-08-27
Received: 2023-10-17
Revision Accepted: 2024-05-08
Crosschecked: 2017-02-07
Cited: 0
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Wu-yi Wan, Chen-yu Li, Yun-qi Yu. Investigation on critical equilibrium of trapped air pocket in water supply pipeline system[J]. Journal of Zhejiang University Science A, 2017, 18(3): 167-178.
@article{title="Investigation on critical equilibrium of trapped air pocket in water supply pipeline system",
author="Wu-yi Wan, Chen-yu Li, Yun-qi Yu",
journal="Journal of Zhejiang University Science A",
volume="18",
number="3",
pages="167-178",
year="2017",
publisher="Zhejiang University Press & Springer",
doi="10.1631/jzus.A1600325"
}
%0 Journal Article
%T Investigation on critical equilibrium of trapped air pocket in water supply pipeline system
%A Wu-yi Wan
%A Chen-yu Li
%A Yun-qi Yu
%J Journal of Zhejiang University SCIENCE A
%V 18
%N 3
%P 167-178
%@ 1673-565X
%D 2017
%I Zhejiang University Press & Springer
%DOI 10.1631/jzus.A1600325
TY - JOUR
T1 - Investigation on critical equilibrium of trapped air pocket in water supply pipeline system
A1 - Wu-yi Wan
A1 - Chen-yu Li
A1 - Yun-qi Yu
J0 - Journal of Zhejiang University Science A
VL - 18
IS - 3
SP - 167
EP - 178
%@ 1673-565X
Y1 - 2017
PB - Zhejiang University Press & Springer
ER -
DOI - 10.1631/jzus.A1600325
Abstract: A trapped air pocket can cause a partial air lock in the top of a hump pipe zone. It increases the resistance and decreases the hydraulic cross section, as well as the capacity of the water supply pipeline. A hydraulic model experiment is conducted to observe the deflection and movement of the trapped air pocket in the hump pipe zone. For various pipe flow velocities and air volumes, the head losses and the equilibrium slope angles are measured. The extra head losses are also obtained by reference to the original flow without the trapped air pocket. Accordingly, the equivalent sphere model is proposed to simplify the drag coefficients and estimate the critical slope angles. To predict the possibility and reduce the risk of a hump air lock, an empirical criterion is established using dimensional analysis and experimental fitting. Results show that the extra head losses increase with the increase of the flow velocity and air volume. Meanwhile, the central angle changes significantly with the flow velocity but only slightly with the air volume. An air lock in a hump zone can be prevented and removed by increasing the pipe flow velocity or decreasing the maximum slope of the pipe.
Influence of an air lock in the top of a hump pipe zone on a capacity of the water supply pipeline is discussed in the manuscript. The trapped air pocket can obstruct water flow due to increase in pressure losses. Although this problem is quite well recognized in the literature, it is still important from a practical point of view. The authors analyzed the influence of water flow rate in the pipe and the volume of an air pocket on both the friction and the critical equilibrium of the trapped air. The experiments were conducted for various pipe flow velocities and air volumes, to observe the deflection and movement of the trapped air pocket and to measure head losses. To describe the drag coefficients and estimate the critical slope angles Authors proposed a simplified model of trapped air pocket, called the Equivalent Sphere Model (ESM). Thus the calculations in the article relate to the assumed shape of the air pocket.
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