水库底坡对异重流运动特性影响分析

Plunging Flow Transport Speciality Influence by the Reservoir Bottom Slopes

在前人所作工作的基础上,运用剖面二维水流泥沙数学模型,分析水库底坡对异重流运动特性的影响。为此拟定8种计算方案,具体的分析底坡对异重流潜入点佛汝德数、潜入点水深、异重流厚度、明流运行时间和异重流到达坝前的时间的影响。结果表明,水库底坡J越大,潜入点佛汝德数FrP越大;水库底坡J越大,潜入点水深越小,异重流厚度越小;水库底坡J越大,明流运行时间越小,异重流传播到达坝前的时间也越小;这些都表明水库底坡越大,异重流就越容易潜入,反之亦然。此外,还对异重流的形成条件进行分析,结果表明,异重流的形成需要一定的流量和含沙量,当进口单宽流量很小但含沙量很大,或是进口单宽流量很大而含沙量很小是都不能形成异重流。

Based on the work of predecessors, a lateral 2-D sediment numerical model is used to analyze the plunging inflow as the changes of the reservoir bottom slopes. This paper develops eight computing programs , analyzes the Frp and the depth of plunge point, the density flow thickness, the open jet running time and the creeping time of plunging flow. The results show that, the Fre of plunge point, the plunge depths and the creeping time of plunging inflow depend on reservoir bottom slopes -- the bigger the slope, the bigger Frp of plunge point while the water depth, density flow thickness and the time are smaller. These show that the reservoir foothill is bigger, the density current is easier to submerge, and vice versa. In addition, this paper makes an analysis of the density current formation condition. The results show that the density current formation needs certain current capacity and the silt content. When the import list wide current capacity is very small but the silt content is very big, or import list wide current capacity is very big but the silt content is the smallest cannot form the density current.