刚性双层植物河道水流垂向流速分布试验研究

Experimental Study on Vertical Distribution of Flow Velocity in Vegetated Channel

天然河道中植物高低不等,为了研究在淹没条件下含刚性双层植物河道的水流流速垂向分布规律,试验在矩形平底水槽中,采用PVC圆柱棒对刚性植物进行模拟,用三维多普勒超声测速仪(ADV)对流速进行测量,分析在两种不同高度植物存在的情况下流速的变化规律。试验结果表明:(1)高棒之后区域的流速分布曲线存在4个拐点,分布曲线分为5个部分,各部分水流特性各不相同。(2)短棒之后的区域的流速分布曲线存在3个拐点,分布曲线分为4个部分。这两个区域的流速分布曲线的形状在短棒之上、高棒之下的部分有所不同,其他部分大体相似。(3)短棒之下的水流速度大小不尽相同,但在高棒之上的水流流速分布逐渐收敛于一条对数曲线上,高棒之上的水流流速分布符合无植物水流水面附近的流速分布情况。

In the experimental study on vertical distribution of flow velocity in double layer vegetated channel, PVC cylindrical rods are simulated as a rigid vegetation. Three-dimensional ultrasonic Doppler speedometer ADV is used to measure velocities in different locations of the rectangular flume. The results show that： （1） the velocity profile behind tall rods exists four inflection points that divide the velocity profile curve into five parts. And the flow characteristics of each part are not identical. （2） the velocity profile behind short rods existes three inflection points that divide the velocity profile curve into four parts. The shapes of velocity profile between the height of tall rods and short rods are different and other parts are generally similar.（3） the velocities under the height of short rods are different, but velocity profile at all locations above the tall rods can appear to converge onto a single logarithmic profile with a slip velocity, which is consistent with the velocity distribution near the water surface of the non-vegetated layer.