Study On The Influence Of Pump Outlet Valve Regulation Characteristics On Water Hammer In Long-distance Water Transmission

Long-distance water transportation projects have the characteristics of long line distance,many branch points,large terrain fluctuations,and complex pipeline layout.This will lead to complex and uncertain operating conditions in long-distance pressurized water pipelines.In case of sudden shutdown of valves or pumps,Local flow rates and flow rates will change dramatically,and the separation and hedging of water columns will occur,leading to the generation of water hammers and damage to valves,pumps,pipelines and other equipment.Valve regulation is one of the effective measures for water hammer control,which can effectively reduce the impact of water hammer.In order to ensure the safe operation of long-distance water transmission projects and explore the control of water hammers in long-distance water transmission projects,this paper studies the following about the adjustment characteristics of pump outlet valves,the impact of valve regulation on the water hammers,and the optimization of valve regulation methods:Based on the theory of computational fluid mechanics,a valve regulation characteristic measurement model is established,and the changes in pressure,speed and streamline in the region are calculated by analyzing valves with different nominal diameters and models at different openings.We have an in-depth understanding of the overflow flow state in the process of valve regulation.By analyzing the valve flow coefficient and resistance coefficient,the valve regulation characteristic data are obtained.Through experiments,the reliability of the measurement model is verified,and detailed valve regulation parameters are provided for the optimization of valve regulation.On the basis of verifying the reliability test of the measurement model,a single-pump single-valve and double-pump double-valve water transmission system is built,and a single-valve linear closure,two-stage closure(slow before fast,first fast,slow,discontinuous),three-stage shutdown mode,double valve linear closure,two-stage shutdown(slow first,fast and then slow down).The influence of the regulation characteristics of the pump outlet valve on the water hammer is studied.This paper deeply analyzes the propagation,superposition and interference process of water hammer waves,deepens the understanding of the transient underwater transition process,and provides a modeling basis and optimization strategy for valve regulation optimization.Establish a valve adjustment model based on water hammer control,build research variables,optimization goals and constraints of the adjustment model optimization,and propose a method to optimize the adjustment model with genetic algorithm theory.Taking the single-valve and double-valve systems of the reliability test system as examples,an optimal model is established and the sensitivity of the model is analyzed.According to the optimization strategy,the calculation results of the adjustment model are transmitted to the genetic algorithm,and the optimal valve adjustment method is obtained through genetic algorithm selection,crossover,variation Finally,the validity of the adjustment model and optimization method is verified by an engineering example,which has certain guiding significance for the reasonable adjustment of the pump outlet valve in the long-distance water transmission project.