正态漏斗附近水沙数值模拟

Numerical Simulation of Water and Sediment near the Normal Funnel

针对水库淤积问题,设计了一种正态漏斗排沙装置,在水槽中开展水流试验。对正态漏斗附近水流-泥沙进行欧拉两相流模拟,用水流试验数据对数值模型进行验证,进而分析了不同边界条件下流速、涡量和相浓度场。结果表明,漏斗内部流速梯度较大,泥沙相浓度等值线呈V型不对称分布,漏斗前缘、左后侧和右后侧出现大涡量区。与锥形漏斗对比,正态漏斗近壁面流速大,水流阻力小,3种边界条件下平均涡量减小25.8%~27.2%,出口泥沙相浓度增大15.2%~16.5%,具有降低能量耗散、显著提高排沙效率的作用。

The sediment-carrying capacity is reduced due to the rise of water level and the reduction of velocity,which leads to sedimenta⁃tion in the reservoir,especially in front of the dam.Therefore,the storage capacity,flood control ability,and power generation are reduced,which affects reservoir functions and economic efficiency owing to reservoir sedimentation.The main measures to solve the problem of reser⁃voir sedimentation include dredging in reservoir,reducing inflow sediment realized by soil protection and vegetation,as well as reservoir op⁃eration management such as“storing clear water and discharging muddy flow”,and sediment discharging by heterogeneous flow,etc.In this paper,a normal funnel device with the smooth surface that has arbitrary order derivative is designed for discharging sediment in reservoir.The Euler two-phase flow near the normal funnel is numerically simulated with the Realizable k-εturbulence model on rectangle and O-type grids.Numerical model is tested by data on experiment flow that carried out in flume.The flow velocities,vorticities and sediment phase con⁃centrations are analyzed under different boundary conditions.Research shows that velocity gradient is large in normal funnel,and phase con⁃centration contours display the V-shaped asymmetrical distribution.Three large vorticity areas appear in the front edge,the left and right rear sides of the normal funnel.The large flow velocities and small resistance appear near the wall of the normal funnel.The average sediment concentrations at the output of the normal funnel are 0.462,0.521 and 0.558 under three boundary conditions.The average vorticity is re⁃duced by 25.8%~27.2%,the efficiency of discharging sediment remarkably increases with 15.2%~16.5%in contrast to the cone funnel.It demonstrates that the normal funnel is more favorable than the cone to smoothing flow,reducing energy dissipation,enhancing the capacity of sediment transport and discharging sediment outwards reservoir.