Numerical Simulation And Experimental Study On The Process Of Filling And Emptying Water In Pressurized Water Pipeline

With the continuous progress of society and the rapid development of economy,water shortage and water environment deterioration have become the constraints of social development in many areas.In order to meet the urban water demand and solve the problem of uneven distribution of water resources,people have established a long-distance water transmission project between the water source and the city.For the water resources transmission and distribution system,the gas content in the water body is a potential threat to the system operation.In the process of water filling and emptying before and after the first operation of the system and maintenance of the system,too fast velocity of water filling and emptying will cause complex water gas two-phase transient flow in the pipeline,and violent fluctuation of pressure and flow will cause damage to the pipeline,which is an important operation safety problem caused by gas in the water delivery system.In this paper,a three-dimensional geometric model of the water filling and emptying of the right angle elbow is established based on the actual background of the water filling and emptying of the pressure pipeline in the water conveyance system.Based on the VOF method,the standard k-? turbulence model is used to simulate the water gas two-phase flow in the process of filling and emptying of the pressurized water delivery pipeline under multiple working conditions by using FLUENT software.The change of water phase volume fraction,water gas two-phase flow pattern and hydraulic parameters in the process of filling and emptying are obtained,and the mathematical model of water phase volume fraction change in the process of filling and emptying of the pressurized pipeline is established The results are compared and analyzed to study the influence of the filling and emptying velocity on the water gas two-phase flow pattern and the change of hydraulic parameters.At last,the physical model test device of pipeline water filling and discharging is built,and the test scheme of water filling and emptying under the same boundary conditions as the numerical simulation is designed,which is convenient for the subsequent verification of the reliability of the numerical model calculation results.The research results are helpful to better understand the distribution and flow state of water and gas in the process of filling and emptying water in the right angle elbow,and have certain reference significance for making a relatively safe and efficient scheme of filling and emptying water velocity in the pressure pipeline.