水科学进展2017，Vol.28Issue(4)：579-587,9.DOI:10.14042/j.cnki.32.1309.2017.04.012
明渠紊流中涡结构的运动规律
Experimental study on the movement of vorticesin turbulent open-channel flows
摘要
Abstract
Vortices convecting with the local flow play an important role in mass transfer in a turbulent open-channel flow.To capture the movements of vortices throughout their life spans, two time-resolved particle image velocimetry systems are placed side by side in the streamwise direction to achieve a wider field of view.This experimental setup is used to measure the two-dimensional velocity fields in the streamwise-wall-normal plane of uniform open-channel flows with friction Reynolds number ranging from 490 to 870.By tracking the spanwise vortices in the measured velocity fields, their lifetime, displacements, convection velocities, maximum strengths, and rates of change in strength are obtained.The vortices are found to lift away from the wall while convecting with the local flow in the streamwise direction.For the case of the lowest Reynolds number, the maximum lifetime and vertical displacement are approximately 10 eddy turnover times and 0.4 water depth, respectively.As the Reynolds number increases, the maximum strength of the vortices increases at a smaller speed than the rate of change in strength, causing a shortening of their lifetime.Because the dimensionless convection velocities remain unchanged in magnitude, the vortex displacements shorten accordingly.The investigation reveals the lifetime to be the critical parameter for characterizing the movement of vortices and yields a preliminary estimate of the trend of variation in the movement of vortices under different flow conditions.关键词
明渠紊流/涡结构/生存时间/运动规律/粒子图像测速Key words
open-channel flow/vortex/lifetime/movement/particle image velocimetry分类
建筑与水利引用本文复制引用
陈启刚,钟强..明渠紊流中涡结构的运动规律[J].水科学进展,2017,28(4):579-587,9.基金项目
中央高校基本科研业务费专项资金资助项目(2016JBM033) （2016JBM033）
国家自然科学基金资助项目(51609002)The study is financially supported by the Fundamental Research Funds for the Central Universities (No.2016JBM033) and the National Natural Science Foundation of China (No.51609002). （51609002）
