宽窄相间河道上游流速特性分析

Characteristics of Flow Rate in the Upstream of Wide and Narrow Alternated Channels

山区河道受地质和河床演变的影响,平面形态呈宽窄相间的形态特征。采用水槽模型试验,建立不同比例的宽窄相间河道模型,对上游断面进行流速测量,对比均匀流分析其流速变化规律,并反算其摩阻流速。结果表明:宽窄相间河道上游较远处流速分布基本符合对数流速分布规律,接近收缩段处不符合对数流速分布规律;宽窄相间河道横向流速分布符合指数分布规律,其横向流速分布参数与摩阻流速呈规律性变化,与宽窄比及距收缩段的距离有关。研究成果可为宽窄相间河道工程整治提供理论参考。

Affected by geology and flu vialprocess, rivers in mountain area are featured with alternated wide and narrow channels. In this research, river model with wide and narrow alternated channels with varying width ratios was established through flume model test. The flow velocity in the upstream section was measured, and the rule of velocity variation was analyzed in comparison with uniform flow, hence obtaining the frictional velocity. Results re-veal that velocity distribution in the upstream far from the wide and narrow alternated channel is in line with loga-rithmic distribution in general, but does not follow logarithmic distribution near the contraction segment; whereas in the wide and narrow alternated channel, the transverse flow velocity distribution conforms with exponential distribu-tion. Moreover, the coefficient of transverse velocity distribution and the frictional velocity change regularly, and are related with the ratio of width and the distance from contraction segment.