Study On Water Hammer Of Long-pressure Water Diversion System Of Hydropower Station And Structural Action Characteristics

Long pressure diversion pipeline accounts for a large proportion in the construction process of hydropower stations,and it is prone to water hammer,which constitutes a great hidden danger to the safe operation of hydropower stations.In order to study the flow pattern change of water flow with different pipe lengths under the action of water hammer and the stress distribution of pipe wall structure,this paper takes the 1#～6#(length558.65m～335.06m)diversion pipeline on the left bank of Wudongde Hydropower Station as the research object,and combines the two-dimensional water hammer calculation software and the three-dimensional simulation platform to carry out the following numerical simulation analysis:1.According to the actual parameters of the water diversion pipeline of hydropower station,the modeling and water hammer simulation are carried out in two-dimensional water hammer calculation software to obtain the flow velocity and pressure values of each node and each part of the 1#～6#water diversion pipeline.Through the analysis,the pressure value of the penstock section is larger than that of other parts,and the maximum and minimum flow velocity at the entrance is obtained by calculation.A velocity curve is fitted for the three-dimensional simulation_tv=3.73-0.005t(0?t?1 0).2.Three-dimensional modeling software is used to establish the three-dimensional model of 1#～6#water diversion pipeline,which is imported into three-dimensional simulation platform for flow analysis.The boundary conditions are calculated by two-dimensional water hammer calculation software,and the velocity curve is obtained through analysis.(1)In the gradient section of the pipeline,the average velocity of the 1#～6#diversion pipeline increases and the average pressure decreases along the flow direction;For the section of 1#～6#diversion pipeline at the same position,the average velocity increases and the average pressure decreases with the decrease of pipeline length.(2)In the pipeline pressure steel pipe section,the pressure steel pipe section consists of three sections,namely 13.5m diameter section,gradual change from 13.5m to 11.5m diameter section and 11.5m diameter section.Among them,along the flow direction,the average flow velocity and average pressure of13.5m pipe section show a decreasing trend;the average flow velocity gradually increases and the average pressure gradually decreases from 13.5 m to11.5m;The average velocity and pressure of 11.5 m pipe section also showed a decreasing trend along the flow direction.For the section at the same position,with the decrease of pipe length,the average flow velocity and average pressure of 13.5m pipe diameter section show an increasing trend.The average velocity decreases with the decrease of tube length from 13.5m to 11.5m,and the average pressure increases with the decrease of tube length.The average velocity and pressure of 11.5m pipe section also showed an increasing trend.(3)In the vertical section of the pipeline,the variation trend of the average flow velocity and the average pressure along the flow direction of the 1#～6#diversion pipelines are basically the same,showing a decreasing trend in general.On the section at the same position,the average velocity and average pressure also show a decreasing trend with the decrease of the total length of the pipeline.The results show that the longer the pipeline length is,the greater the water pressure under the action of water hammer is,and the greater the danger to the wall structure is.Therefore,this paper focuses on the fluid-solid coupling simulation of 1#diversion pipeline.3.Through the fluid-solid coupling simulation of 558.65m long 1#diversion pipeline,it is found that the total deformation of the shaft section is the largest,which is 0.0028078m,and the deformation value of the gradual section and the variable section of the pressure steel pipe is also large.