某抽水蓄能电站拦沙库泄洪排沙系统的水力特性研究

摘要

Based on the similarity theory,a scale model which focused on the flood and sediment discharge tunnel of the lower reservoir of pumped storage power station was established and verified by river resistance.The water flow regime,water surface profile,velocity,energy dissipation and erosion of the downstream revetment were observed under different hydraulic conditions in an experiment.The experimental research results show that the flow pattern in the inlet of the flood and sediment discharge tunnel is smooth,the discharge capacity and the flow regime of tunnel section meet the design requirements.But there still remain some problems about the excessive water level in the tunnel,the insufficiency of channel water depth,the incapacity of sediment concentration in export diffusion section.Based on the modified ideas of the adjustment of longitudinal slope,coordination of each section of water transport capacity and inhibition of water jump strength,the optimal modification test was conducted.After a number of comparison tests,the optimal modification scheme was finally determined and the coordination between the culvert section and the open channel section was solved.Because the modification scheme can control the water depth within the tunnel more reasonably,the phenomenon of water jump in the open channel is eliminated and the flow pattern in the cavity is improved.At the same time,the addition of diffusion section of the sediment transport tank also effectively improve the ability of the sediment concentration of small flow and meet the different flow conditions under the discharge safety requirements.Research results have certain reference value for similar engineering design and safe operation.%以某抽水蓄能电站下水库泄洪排沙洞为研究对象,利用相似理论建立了比尺模型,该模型通过了河道阻力试验验证.试验中,观测了不同水力条件下的洞内水流流态、水面线、流速、消能状况以及下游护岸冲刷情况.试验观测结果表明,泄洪排沙洞进口流态平顺、泄流能力及隧洞段流态均满足设计要求,但陡坡扩散段以下的急流涵洞段出现水跃闷洞、明渠深度不足、出口扩散段不能集中拉沙等问题.基于调整纵坡、协调各段输水能力、抑制水跃强度的修改思路,进行了优化修改试验.经多次比对试验,最终确定了优化修改方案,解决了涵洞段与明渠段水流衔接的协调性.修改方案较合理地控制了洞内水深,消除了明流洞水跃壅塞现象,改善了洞内流态;同时,增设扩散段输沙槽,有效提高了小流量集中拉沙的能力,满足了不同水流条件下的泄流安全要求.该研究成果对类似工程设计与安全运行具有一定的参考价值.