有植被明渠纵向流速垂向分布特性的PIV试验分析

Experimental analysis of vertical profiles of stream-wise velocities in flows through vegetation with PIV

有植被河道水流的流速分布是确定植被河道阻力和过流能力的基础。在室内矩形断面水槽中模拟了有树桩存在的河流环境,采用粒子图像速度仪(PIV)测量了同一流量情况下,非淹没及淹没刚性植被稳恒流纵向流速垂向分布。试验结果表明矩形断面非淹没刚性植被水流时空平均纵向流速垂向分布符合'J'形分布,淹没刚性植被水流时空平均纵向流速垂向分布符合'S'形分布,植被中不同位置垂线的时均纵向流速分布不同。笔者给出的流速资料可作为植被水流数值模拟对比的参考。

The distribution of velocity of flow in open vegetated channel is the most basic knowledge required by hydraulic engineers for determining flow resistance and conveyance capacity. Vegetated river flow with stump beds was simulated in a laboratory flume. The Particle Image Velocimetry（PIV）was used to measure the mean stream-wise velocity profiles of steady flow through emersed and submerged vegetation at same discharge respectively. It is found that the vertical profile of stream-wise velocities based on time and spatial averaging in flows through emersed vegetation follow the J-shaped distributions, and the one through submerged vegetation obey the S-shaped distributions. The vertical distribution of mean stream-wise velocities is different at different position within vegetation. The experimental results can be used to identify the turbulent models and numerical methods.