Three-dimensional Numerical Simulation Of Scour Downstream Of Juting Hydropower Station

The flow velocity of the discharge structure is large,and the turbulence of the water flow is violent.The downstream of the river bed is susceptible to local scouring caused by the turbulence,and even the structure of the hydraulic structure is damaged.The problem of erosion and erosion has always been of great concern.Taking the hydropower station as an example,the method of combining physical model test and numerical simulation was used to study the problem of discharge erosion.A three-dimensional numerical model was established by Flow-3D,and the characteristics of the three-dimensional flow field and morphology of the scouring pit downstream of the sluice were analyzed.The process and the influence of different factors on local scouring,discussed the shape and depth of the scouring pit under the condition of one flood in 5 years and one flood in 200 years,which can provide reference for related engineering design.The research has drawn the following main conclusions :(1)In the course of the simulation results,the dimensionless flow intensity values ??of the bed surface of each working condition gradually decrease with time,and the river bed area that exceeds the critical starting shear stress also gradually decreases with time.(2)In this paper,the local scouring of the downstream of the discharge structure can be roughly divided into three stages.The erosion of the river bed caused by the discharge in the first stage is more intense;The scope of the scouring pit still keeps expanding downstream;the third stage is the scouring balancing stage,and the depth and scope of the scouring pit reach equilibrium with the passage of time.(3)Within 30% of the initial time of scouring,the crater depth of each working condition can reach 80% of the equilibrium depth.The shape distribution of the crater is steep uphill and downhill.The depth and range increase and increase with the increase of flow.Downstream movement(4)Under the condition of bed sand median diameter of 7.5mm and inlet flow rate of150L/s,the maximum punching depth is 9.58 m and the punching pit length is 72.5m.The relative error from the measured value is the smallest,3.23% and 4.47%;The bed sand median diameter is 10 mm,the relative error under the inlet flow rate of 150L/s is relatively small,4.74% and 4.7%;the median particle diameter is 10 mm,the relative error under the inlet flow rate of 100L/s is relatively large,is 10.16% and 9.15%.From the relative error,wecan see that the effect of changing the flow rate on the maximum erosion pit depth in this paper is greater than the effect of changing the particle size of the sediment.