The Research On Application Of Combined Energy Dissipation Of Contraction Pier And Drop Sill Stilling Basin In Small Spillway Project

Energy dissipation design is one of the important tasks in the design of hydraulic structures.Good energy dissipation facilities can reduce the flow energy of the water in the stilling basin,on the one hand,prevent the tailrace downstream of the reservoir from being scoured,and on the other hand,it can also improve the stability of the hydraulic structure.And safety.In smallscale water conservancy projects and reservoir reinforcement projects,the length and depth of the stilling basin are often difficult to reach the design value in actual implementation due to topographical reasons.During operation,the stilling basin and tailrace canal are washed out,which makes the dam safe.The flood discharge is threatened.It can be seen that studying the spillway of small projects is of great significance for improving the safe and stable operation of the spillway.In this paper,numerical simulation method is used to study the hydraulic characteristics of the combination of contraction pier and drop sill stilling basin in small spillway project.Taking the spillway of a dangerous reservoir as the prototype,the combined models of 12 groups of shrinkage piers with different sizes and stilling basin with the same size are designed.The structured grid of 12 groups of models is divided by ICEM software.The standard turbulence model of FLUENT software and the VOF method of traceable free water surface are used to carry out the three-dimensional numerical simulation calculation under the same flow rate,The hydraulic characteristics such as flow pattern,water surface profile,velocity field,pressure field and energy dissipation are studied.The conclusions are as follows(1)After adding wide tail piers,the flow pattern and water surface line in the stilling pool change from binary flow to ternary flow.The water stream squeezes inward horizontally through the shrinking pier,and shoots upward and forward vertically;(2)The pressure distribution of the shrinking pier and the bottom of the stilling pool is zigzag,and the distribution of the secondary pressure is basically the same in each group.The larger the value of the beam narrow length and the width of the beam,the greater the pressure value at the middle of the bottom of the stilling pool and the tail sill.;(3)The change of beam narrowness and length has a great influence on the longitudinal velocity distribution,and the change of beam narrowness and width has a great influence on the lateral velocity distribution;(4)With the addition of shrinking piers in the slumping stilling pool,the energy dissipation rate will increase compared with the case where no shrinking piers are added to the slumping stilling pool.The research results of this paper can provide references for the energy dissipation problems of general small spillway projects,and have strong research significance and value.