Research On Water Hammer Protective Measures In Water Supply Project By Pumping Yellow River Of Weinan City

Water supply project by pumping yellow river of Weinan city includes pumping system,pressure-gravity water conveyance system and water works,etc.This project is characterized by large water delivery flow and long pipeline.Water hammer is a key factor that endangers the safe operation of long-distance water conveyance project.It is of great significance to ensure the safe operation of this water conveyance system by determine safe,reliable,economical and reasonable water hammer protective measures.This paper focuses on water hammer protection in Beiwan pumping system and Dangwei pressure-gravity water conveyance system.Beiwan pumping system sets 6 Type 50011b-40 submerged pumps,with 4.04 m3/s design flow rate and 11.504 km conveyance pipeline.The design flow rate of Dangwei pressure-gravity water conveyance system is 3.25 m3/s,and its pressure pipeline is 29.32 km long.According to characteristics of this water conveyance project,method of characteristics(MOC)is used in water hammer calculation,and the following research results are obtained:(1)Beiwan pumping system uses slow closing check valves,water hammer type air valves and terminal flow and pressure regulating valve as protective measures,by which can effectively protect water hammer of the pumping station.The longer time the end valve is closed,the less the pump outlet pressure increases,while the cavity volume of the pipeline is greater.It is recommended that the uniform closing time of the end valve should not be less than 200 s.(2)Two-stage closed butterfly end valve water hammer protection measure is adopted in Dangwei pressure-gravity water conveyance system.The closing procedure of two-stage butterfly end valve was optimized by univariate search technique.It can be seen that when the total closing time is greater than 150 s,there is no negative pressure along the pipeline,and with the extension of total valve closing time,the maximum pipeline pressure head gradually decreases.When the total valve closing time is more than 350s,the maximum pressure head of the pipeline decreases more slowly.It is recommended that total closing time of the two-stage butterfly end valve is not less than 350s.