淹没植物条件下的明渠流速比尺研究.docVIP

 n 淹没植物条件下的明渠流速比尺研究# 闫静1,2,3，唐洪武1,2,3，田志军2，何晔2** （1. 水文水资源与水利工程国家重点实验室，南京 210098； 5 10 2. 河海大学水电学院，南京 210098； 3. 水资源高效利用与工程安全国家工程研究中心，南京 210098） 摘要：流速尺度是得到流速分布普适形式的必要参数。植物的存在改变了明渠流速分布，植 物条件下的明渠流速比尺也不同于无植物明渠。本文总结了前人采用的流速比尺，给出了各 种比尺的计算方法和物理意义，并采用圆柱铝棒模拟刚性植物进行水槽实验，利用激光流速 仪 LDV 对含淹没植物明渠流场进行了测量，对不同流速比尺进行了计算和比较。分析表明， 各种实验条件下，分别由最大雷诺应力和雷诺应力线性回归延长至床面换算的速度比尺比较 接近，由均匀流公式计算的速度比尺最大，各种速度比尺具有不同的适用条件。 关键词：水力学及河流动力学；淹没植物；明渠；流速比尺；LDV 中图分类号：TV 91 15 Velocity Scale of open channel flows with vegetation Yan Jing1,2,3, Tang Hongwu1,2,3, Tian Zhijun2, He Ye2 (1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, NanJing 210098; 20 25 30 2. college of Water Conservancy and Hydropower, Hohai University, NanJing 210098; 3. National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, NanJing 210098) Abstract: Velocity Scale is an important parameter in describing the universal velocity distribution. The existence of vegetation changes the velocity profile of open channel flows and the velocity scale of the vegetated flows is different with that of non-vegetated ones. In this paper, the velocity scales adopted by different investigators are summarized. Based on the flume experiments with aluminum cylinders simulating rigid submerged vegetation and the laser Doppler velocimetry, the velocity scales are calculated and comparison are made among them . The analysis shows that for each flow condition, the velocity scale determined by maximum Reynolds stress and that calculated by the Linear regression of Reynolds stress are closed to each other and the one computed by uniform flow are the maximum one, and the application scope for each scale is also introduced. Keywords: Hydraulics and River Dynamics; submerged vegetation; open channel folw; Velocity Scale; LDV 35 0 引言 流速分布规律是明渠水流的基本特性，也是明渠水流结构研究的重要内容。天然的河道， 总是自然或人工的分布着植物，植物的存在改变了流速的分布。有研究表明，对于流经非淹 没植物的水流，其纵向流速沿水深垂线分布近似为一常数（近床面除外）[1] 。对于流经淹 40 没植物的水流，纵向流速 U 沿水深分布存在两区和三区划