拟焦沙模拟低含沙量异重流运动初步分析

低含沙量异重流带来大量细颗粒浑水,由于颗粒沉速极小,在山区、高原地区的引调水、水环境、水处理等方面带来难以估量的困难,引起了社会和设计部门重视。以金沙江支流牛栏江上德泽水库回水变动区上下游河段为原型,利用概化水槽试验研究拟焦沙模拟低含沙量异重流形成与运动,探究低含沙浑水异重流运行时头部流速及含沙量沿程变化特征。结果表明:头部流速及含沙量沿程逐渐减小;相同流量不同含沙量所形成的中层、底层异重流头部流速,含沙量越大,同一位置头部流速越大;相同流量和含沙量所形成的表层、中层、底层异重流头部流速,表层异重流头部流速最大,底层异重流次之,中层异重流最小。

Preliminary analysis on movement of density current with low sediment content simulated by pseudo-chark

Density currents with low sediment concentration are muddy and consist of a large number of fine granular particles. The extremely small settling velocity of the granules leads to adverse water environment, and immense difficulties in water diversion and water treatment in mountainous and plateau areas. This is a cause of concern for society in general, and design departments in particular. In this work, we have used the upper and lower reaches of the Niulan River, a tributary of the Jinsha River, as prototypes, and studied the formation and movement of currents with low sediment concentration and density using a generalized flume test. In addition, we have explored the variations in the characteristics of the head velocity and sediment concentration along the flow path. The results reveal a gradual decrease of the head velocity and sediment concentration along the flow path. For the same amount of discharge, the head velocity of the middle and bottom layers of the current increases with an increase in the sediment concentration. The top layer exhibits a higher head velocity compared to the middle and bottom layers for the same amount of discharge and sediment concentration. The middle layer exhibits the smallest velocity head, while the velocity head of the bottom layer has an intermediate value. These results can serve as a guide for test simulations of physical models of reservoirs.