Numerical Simulation Research On Water Hammer Prevention Measure In Water Transimission

With the development of the economy of different countries, the continual increasing water consumption of resident, and water body contaminated, more and more cities are in order to solve the sharp contradiction between supply and demand of water resources, long distance and large-scale water delivery cascade pumping stations must be built. In order to prevent the water-supply systems from causing water hammer accidents because many kinds of reasons when transient phenomenon taken place in pipe, when we design, it is necessary to make water hammer analysis, predict and simulate the occurrence of water hammer accidents and diffuse law at power failure to the pumps. Besides considering the routine pressing water hammer, it must be considered that some position in pipeline may take place the circumstances of gas-liquid two-phase hydraulic transient such as gas release, producing hole in flow and liquid column separation. It is of the key that predicting and control studying of gas-liquid two-phase hydraulic transient in pipeline systems for optimizing engineering design, reducing the fabrication cost of the projects, guaranteeing the project safe operation, they have important theory meaning and practical value.The dissertation consists of the following five chapters:Chapter one presents the purpose and significance of the dissertation, and summarizes the historical and current situation,the development trend of water hammer,presents the main research context.Chapter two describes the conception of water hammer,the basic differential equation of water hammer,the theory of water hammer numerical explain.Chapter three expounds the computational principle of pump boundary condition,assistant boundary condition and the element of systems, when accidental pump-stopping happened.Chapter four sets up the mathematics models calculated in two-phase hydraulic transient and the boundary condition of combined air vent valve protection, by taking Guangdong Dongxiang Water Supply Project as an example, according to the numerical simulation and analyses in water hammer characteristic of pump system on not adding the combined air vent valve and operating mode with combined air vent valve, and calculates the influence on hydraulic transient process of the change in numbers. Setting positions and release of combined air vent valve, research detailedly on function of water hammer protection with combined air vent valve in water-supply system of long distances, it has elicited valuable conclusions and suggestions on engineering design and movement.Chapter five summaries the whole research works on the basis of above research, and puts forward the thinking and imagination that will be studied further in the future.