| In the northern plains of China,a large number of river gates(control gates)and storage and drainage gates have been built on the river channels.In addition to flooding and drainage,most of the porous sluices are often used with a few holes and small openings.This leads to insufficient diffusion of the mainstream after the gate,complicated water flow,secondary flooding,and erosion of the downstream river(channel),thus threatening the operational safety of the water conservancy project.In actual engineering,the energy dissipator usually requires a large amount of engineering and a relatively high cost.In view of this,this paper sets up a new type of auxiliary energy dissipator with small size and economical cost in the stilling pool behind the sluice.It consumes energy through counterattack and disperses the main stream into multiple streams,forming a forced water jump before the ridge,and finally achieving the purpose of reducing the length of the water jump and increasing the energy loss;At the same time,when the water flows through the water retaining dam,it rubs against its surface and creates a swirling vortex after the ridge,thereby eliminating excess energy and achieving the purpose of enhancing the energy dissipation effect.Through the combination of physical model test research and numerical simulation,the influence of the staggered retaining dam on the water flow characteristics of the porous sluice with a small opening of a few holes is preliminarily studied.The following is the main research content and results of this article.(1)The flow pattern of the porous sluice in the partial opening of the partial sluice and the damage to the downstream riverbed are analyzed.The non-standard water jump problem and its control measures in the underflow energy dissipation under the gate are discussed.(2)The design idea of staggered retaining sill is proposed.By consulting the literature and related books,the five design factors such as ridge height,ridge length,arrangement position,row spacing and net width are determined as the main design parameters of the staggered retaining dam.Based on the uniform design method,10 different forms of layout schemes were developed.(3)The RNG k-? three-dimensional turbulence model was established by CFD fluid mechanics software.Under the condition of partial opening of the porous sluice,three kinds of sluice models with different forms of staggered retaining dams were simulated by three-dimensional numerical simulation.,got the flow field distribution.According to the observation of the flow state,it is found that the energy dissipation effect of the scheme 3 is superior to other schemes.Then the layout of the scheme is improved.The three-dimensional numerical simulation results show that the improved scheme further enhances the energy dissipation effect.(4)Comparison with a 0.5x diversion wall and a 60° submerged delta wing.The 0.5x diversion wall,the 60° submerged delta wing and the staggered dam have less impact on flow than the initial solution without the auxiliary energy dissipator;in terms of flow rate,the surface flow rate increases by 4.55%,respectively.The decrease was 1.52%,the decrease was 25.76%,the bottom flow velocity was reduced by 1.72%,the increase was 3.45%,and the decrease was 20.69%.In terms of the length and width of the exit stream segment,the length increased by 3.51% and increased by 0.49%.The decrease was 16.04%,the width decreased by 13.19%,increased by 0.69%,and decreased by 6.67%.In terms of water depth,the water depth of a water jump increased by 11.83%,decreased by 3.79%,decreased by 1.97%,and the second water jump The water depth decreased by 77.67%,increased by 1.28%,and decreased by 9.90%.In terms of flow rate,it increased by 0.009%,decreased by 0.009%,and decreased by 0.502%.In general,the interlaced retaining scheme is superior to the other.Two options. |
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