含沙量对坡面流水动力学特性的影响研究

Effects of Sediment Load on Hydrodynamic Characteristics of Overland Flow

摘要:

基于系列室内水槽冲刷试验，定量研究了在9°坡度、不同流量条件下含沙量对坡面流水动力学参数的影响。结果表明：随含沙量增加，水流雷诺数Re减小，水流紊动强度减弱。弗劳德数、水流流速及流速修正系数α随含沙量增加先呈减小趋势，当含沙量S>300kg/m3时，各值均突然增大，并随含沙量的进一步增加趋于稳定，表明此时水流型态发生变化，α均值为0.554。含沙水流和清水水流能量损失比较标准不同，得到的结论也不相同。当S<300kg/m3时，以相同Re或相同单宽流量作为比较标准，含沙水流阻力系数均大于清水对应值；当S>300kg/m3时，以相同的Re作为比较标准，则含沙水流阻力系数小于清水对应值，以相同的单宽流量作为比较标准，则含沙水流阻力系数大于清水对应值。

Abstract:

The potential effects of sediment load (S) on hydrodynamic parameters of overland flow were investigated in a smooth plexi-glass flume under a wider range of sediment load and slope gradient of 9°. The results showed that Reynolds number (Re) decreased as sediment load increased, implying a decrease in flow turbulence. Froude number, mean flow velocity and correction factor to flow velocity (α) first all decreased with sediment load increasing and then the values all suddenly increased and gradually become stable as sediment load further increased when S>300kg/m3. The mean α was 0.554. For the difference between standard of energy dissipation in sediment-laden and clear-water overland flow, the conclusions were also different. When S<300kg/m3, the friction coefficient of sediment-laden flow was larger than that of clear water flow either with the same Reynolds number or unit flow rate as standard. While, when S>300kg/m3, the friction coefficient of sediment-laden flow was smaller than that of clear water flow with the same Reynolds number and larger with the same unit flow rate.