Study On Model Test And Numerical Simulation For River Closure Of Jiacha Hydropower Station

River closure is the key control project of water conservancy and hydropower construction.The development of appropriate river closure programs is of great significance to shorten the construction period,reduce the project cost,ensure the safety of construction and improve the quality of the project.Therefore,it is necessary to master the river water flow changes before river closure.In this paper,the model test and the numerical simulation are used to study the river closure project of Jiacha hydropower station.This paper discusses the scale determination,the model layout,the fabrication of the cross-section panel,the test process design and so on in the model test,and uses a one to fifty ratio scale of the physical model.Based on single closure dike,wide embankment and two embankments closure program,the hydraulic model test of the river closure is studied in 12 working conditions with the effects of the river closure program,the residual rock ridge and river closure flow.In addition,this paper completes the test data collation and the results analysis.In the numerical simulation,the three-dimensional model of river closure project of Jiacha hydropower station based on actual terrain was established by using CATIA software,which is introduced into the FLOW-3D software.A three-dimensional numerical simulation of river closure based on FLOW-3D is established with the Navier-Stokes equation as the governing equation,the RNG model in the turbulence two equations,and the real three-step VOF method used to track the free surface.The hydraulic parameters such as river flow,water level and flow velocity are obtained for some experimental conditions by using this calculation model.By comparing the numerical simulation results with the model test results,the effects of river closure program,residual rock ridge and river closure flow on the hydraulic parameters of river closure process are mainly studied.Finally,a comprehensive analysis is carried out to provide a proper suggestion for the design of river closure program,which is to use single closure dike closure program,to remove the residual rock ridge as cleanly as possible,and according to the actual hydrological conditions,to select the river closure time when the river flow is as small as possible.