Study On Water Hammer Risk And Protective Measures Of High Lift And Multi-undulating Water Transfer System

As China’s urbanization construction continues to advance,a large number of longdistance water delivery systems have been built.As an important part of urban infrastructure,a large number of design researchers are particularly concerned about the safety and reliability of water delivery systems.There are a large number of highlift,multi-undulating water delivery systems in the western part of China.Due to the complicated pipeline structure,it is more prone to dangerous water hammer accidents.Because the pump-water hammer phenomenon is difficult to predict and its hydraulic transition process is complicated,it is extremely damaging to the water delivery system.Therefore,it is necessary to carry out numerical simulation calculation on the pump-stopping water hammer phenomenon of high-lift and multi-undulating water delivery system,so as to accurately assess the risk degree of water hammer and optimize the applicability of water hammer protection equipment,and accurately evaluate the protective effect of these protective equipment on water hammer.This paper is based on the basic theory and calculation method of elastic water hammer.The HAMMER water hammer analysis software is used to simulate the water hammer of the high lift and multi-floating water delivery system and the numerical simulation of the water hammer protection scheme.Firstly,it summarizes the domestic and foreign research results,explains the basic theory and calculation method of water hammer,and expounds the process of modeling and calculation of HAMMER water hammer analysis software;Secondly,using the "distance and bit value" calculation method in the extension engineering method,a water hammer risk assessment model for pipeline nodes is constructed,and by applying the model to typical engineering examples,quantitatively evaluate and compare the water hammer risk degree of each node of the pipeline under different working conditions or different water hammer protection schemes under the same working condition;Then,based on the water hammer risk assessment model of the pipeline node,the position and parameter settings of the commonly used water hammer protection equipment are optimized.Finally,using the reliability theory and the water hammer risk assessment model of the pipeline node,an evaluation model for the water hammer protection effect is constructed.And by applying the model to typical engineering examples,the water hammer protection effect of the pipeline nodes and the whole system under the same working conditions with different water hammer protection schemes is quantitatively evaluated and compared.Mainly got the following conclusions:(1)Based on the extension engineering method,a water hammer risk assessment model for pipeline nodes of high-lift and multi-floating water delivery systems is constructed.The model is verified by typical engineering,The model can accurately quantify the water hammer risk degree of each node of the pipeline under different working conditions or different water hammer protection schemes under the same working condition,and divide the water hammer risk status and grade of the pipeline node.Therefore,a method for evaluating the water hammer risk of high lift and multifloating water delivery systems is proposed.(2)Based on the water hammer risk assessment model of pipeline nodes,the position setting of air valve group,one-way pressure regulating tower and two-way pressure regulating tower is optimized,and a way to guide the position setting of water hammer protection equipment is proposed.(3)Based on the water hammer risk assessment model of the pipeline node,the effect of different parameter values of the slow-closed check valve and the one-way pressure regulating tower is evaluated.Accurately guide the comparison of parameter values of water hammer protection equipment from the perspective of reducing the risk of node water hammer.(4)When setting the initial water level and the water supply pipe diameter of the one-way pressure regulating tower,it is necessary to consider that there is sufficient water supply capacity and water supply speed,and it will not cause serious direct water hammer phenomenon or cause excessive water hammer pressure increase at the pump end.(5)Based on the reliability theory and the water hammer risk assessment model of the pipeline node,an evaluation model for the water hammer protection effect of the high lift and multi-floating water delivery system is constructed.It can accurately quantify the water hammer protection effect of the pipeline node and the whole system,and propose a method to evaluate the water hammer protection scheme of the high lift and multiundulating water delivery system.