scholarly journals Water hammer protective performance of a spherical air vessel caused by a pump trip

2019 ◽  
Vol 19 (6) ◽  
pp. 1862-1869 ◽  
Author(s):  
Lin Shi ◽  
Jian Zhang ◽  
Xiaodong Yu ◽  
Sheng Chen
Keyword(s):  
Water Supply ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Supply System ◽  
Long Distance ◽  
Effective Measure ◽  
Gas Volume ◽  
Protective Performance ◽  
Force Characteristics ◽  
Control Water

Abstract The use of air vessels is an effective measure to control water hammer in a long-distance water supply system. The traditional shape of such vessels is cylindrical. In this paper, an innovative spherical air vessel is proposed to improve the force characteristics of the tank. A mathematical model of the spherical air vessel was established using the method of characteristics. A comparison was performed of water-hammer protection performance between the spherical air vessel and the cylindrical air vessel based on a practical water supply project. Furthermore, a sensitivity analysis on the parameters of the spherical air vessel was performed. The results showed that the spherical air vessels had better protective performance compared with the cylindrical air vessels. Under the same protection requirements, the spherical air vessel can reduce the total volume and surface area by more than 10%. In addition, for a fixed volume of the spherical air vessel, the protective effect improves with the increase of the initial gas volume. Increasing the connecting pipe diameter of the air vessel is beneficial for low-pressure protection, whereas it is adverse to high-pressure protection; in contrast, altering the installation elevation has little effect on water-hammer protection.

scholarly journals Research on the water hammer protection of the air vessel caused by underground pipe burst in long distance water supply system

2018 ◽  
Vol 246 ◽  
pp. 01066 ◽  
Author(s):  
Xingtao Wang ◽  
Jian Zhang ◽  
Xiaodong Yu ◽  
Lin Shi
Keyword(s):  
Water Supply ◽  
Check Valve ◽  
Water Hammer ◽  
Supply System ◽  
Water Supply System ◽  
Safe Operation ◽  
Long Distance ◽  
Underground Pipe ◽  
Pipe Burst ◽  
The Mathematical Model

The conventional air vessel installation is usually installed behind the check valve at the upstream end of the pipeline to effectively control the water hammer pressure due to pump trip. However, the water hammer pressure caused by underground pipe burst has been neglected. The water hammer protection of air vessel due to pipe burst in long distance water supply system was discussed in this paper. According to analysis of the process of the pipe burst, the mathematical model of underground pipe burst and air vessel were established. A new air vessel installation that was installed in the middle of the pipeline was proposed. The new air vessel installation was simulated by method of characteristics. Then it was compared with the conventional air vessel when the pump trip and the pipe burst occur respectively. The results show that both the conventional air vessel and the new air vessel can effectively protect the water hammer duo to the pump trip. Moreover, when pipe burst occurs, the conventional air vessel cannot achieve the safe operation of the long distance water supply system. However, under the same air vessel type parameters, the new air vessel installation can effectively protect the water hammer pressure.

Effect of multi-valve closure on superposed pressure in a tree-type long distance gravitational water supply system

2019 ◽  
Vol 68 (6) ◽  
pp. 420-430
Author(s):  
Xingtao Wang ◽  
Jian Zhang ◽  
Xiaodong Yu ◽  
Sheng Chen ◽  
Wenlong Zhao ◽  
...  
Keyword(s):  
Water Supply ◽  
Pressure Rise ◽  
Water Hammer ◽  
Supply System ◽  
Water Supply System ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Long Distance ◽  
Maximum Water ◽  
Tree Type

Abstract Valves are installed at the end of each branch pipeline in a tree-type long distance gravitational water supply system to regulate flow. However, the sequential closing of all valves may cause a tremendous superposed pressure rise, even larger than the pressure rise under simultaneous valve closure. In this paper, the effects of sequential valve closure on the superposed maximum water hammer pressure rise in a pipeline were investigated. By using the wave superposition principle, a sequential valve closure formula leading to maximum water hammer was proposed and verified using numerical simulation based on a practical project. In addition, the superposed maximum pressure rises in the pipeline were compared under single, simultaneous and sequential valve closure, respectively. The results show that the sequential valve closure formula agrees well with the numerical results and the pressure rise in the pipeline under the sequential closing was the largest. Moreover, compared with the superposed maximum pressure rises at the main pipeline, the effect of sequential valve closure on superposed maximum pressure rise at the branch pipeline is more sensitive.

scholarly journals Investigation on Water Hammer Control of Centrifugal Pumps in Water Supply Pipeline Systems

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 108 ◽  
Author(s):  
Wuyi Wan ◽  
Boran Zhang ◽  
Xiaoyi Chen
Keyword(s):  
Water Supply ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Moment Of Inertia ◽  
Evaluation Methodology ◽  
Centrifugal Pumps ◽  
Positive Effects ◽  
Pipeline Systems ◽  
The Moment ◽  
Water Supply Pipeline

Water hammer control in water supply pipeline systems is significant for protecting pipelines from damage. The goal of this research is to investigate the effects of pumps moment of inertia design on pipeline water hammer control. Based on the method of characteristics (MOC), a numerical model is established and plenty of simulations are conducted. Through numerical analysis, it is found that increasing the pumps moment of inertia has positive effects both on water hammer control as well as preventing pumps rapid runaway speed. Considering the extra cost of space, starting energy, and materials, an evaluation methodology of efficiency on the increasing moment of inertia is proposed. It can be regarded as a reference for engineers to design the moment of inertia of pumps in water supply pipeline systems. Combined with the optimized operations of the valve behind the pumps, the pipeline systems can be better protected from accident events.

scholarly journals Parameters affecting water hammer in metal pipelines

2018 ◽  
Vol 44 ◽  
pp. 00183
Author(s):  
Kamil Urbanowicz ◽  
Mateusz Firkowski
Keyword(s):  
Numerical Modelling ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Supply System ◽  
Hydraulic Systems ◽  
Wave Pressure ◽  
Hydraulic Machinery ◽  
Metal Pipes ◽  
The Individual ◽  
Pressure Changes

The water hammer related to rapid wave pressure changes in hydraulic systems have been subjected to intensive research for more than a hundred years. Nevertheless, a large number of new papers appear each year. Current literature indicates model differences resulting from the used material of the pipe. In the hydraulic machinery, elastic (metal) pipes are usually used, while water transport in water supply system is currently realized with pipes whose deformation of the walls is viscoelastic. In this paper, the individual and group impact of all parameters influencing the results of numerical modelling of the water hammer occurring in the pipes will be analysed. The method of characteristics will be used to solve partial differential equations describing the flow.

Polyline Closure Law Design and Realization in Long-Distance Water-Supply Project

2010 ◽  
Author(s):  
Jian Zhang ◽  
Xiaodong Yu ◽  
Jianfeng An ◽  
Arash Hazrati
Keyword(s):  
Water Supply ◽  
Theoretical Basis ◽  
Temporal Distribution ◽  
Break Point ◽  
Water Hammer ◽  
Long Distance ◽  
Closure Time ◽  
Water Conveyance ◽  
Flow Inertia ◽  
Application Scope

Long-distance water-supply project is an effective way to solve the uneven spatial and temporal distribution of water resources, but the safety of water conveyance system is threatened seriously by water-hammer. Based on the research of the characteristic of water-hammer with pipe friction considered, the formula of indirect water-hammer is deduced and the application scope of the formula is also discussed, which is the theoretical basis for the design of polyline closure law. To the defects that valve closure time is long and response of accident is slow in the long-distance water-supply project, polyline closure law is designed with consideration of valve overflowing property, which greatly reduces the closure time and water-hammer. At the same time, the flow inertia is large in long-distance water-supply project and break point of polyline closure law is hard to fix. In order to improve the reliability of the mechanical operating system, locking device is installed, which make the polyline closure law carry out successfully and provide a new idea for water hammer protection in long-distance water-supply project.

Ways to get water: rainwater utilization or long-distance water supply? A holistic assessment

1997 ◽  
Vol 36 (8-9) ◽  
pp. 313-318 ◽  
Author(s):  
Thilo Herrmann ◽  
Karin Hasse
Keyword(s):  
Water Supply ◽  
Market Price ◽  
Cost Effective ◽  
Supply System ◽  
Long Distance ◽  
Retention Capacity ◽  
Drinking Water Supply System ◽  
Holistic Assessment ◽  
Stormwater Retention

On the basis of a case study the costs of an existing long-distance drinking water supply system are compared to the potentiel costs of decentralized rainwater collection und usage systems. The costs of stormwater retention are included in the calculations in so far as rainwater utilization systems provide a retention capacity for stormwater in the cisterns. The results show, that in dependence of the market price of the rainwater usage systems, the decentral way to provide usage water to the households can be more cost effective compared to a central long-distance supply system.

scholarly journals A Case Study on Risk Assessment of Long Distance Water Supply System

2014 ◽  
Vol 70 ◽  
pp. 1762-1771 ◽  
Author(s):  
J. Zhang ◽  
J. Gao ◽  
M. Diao ◽  
W. Wu ◽  
T. Wang ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Water Supply ◽  
Supply System ◽  
Water Supply System ◽  
Long Distance
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