不同来流条件下急弯段环流结构演化过程研究  

STUDY ON THE EVOLUTION PROCESS OF SECONDARY FLOWS IN A SHARPLY CURVED BEND UNDER DIFFERENT INFLOW CONDITIONS

作　　者：胡呈维 余明辉[3] 渠庚[1,2] HU Cheng-wei;YU Ming-hui;QU Geng(River Research Department,Yangtze River Scientific Research Institute,Wuhan 430010,China;Key Laboratory of River and Lake Regulation and Flood Control in the Middle and Lower Reaches of the Changjiang River of Ministry of Water Resources,Yangtze River Scientific Research Institute,Wuhan 430010,China;State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China)

机构地区：[1]长江科学院河流研究所,武汉430010 [2]长江科学院水利部长江中下游河湖治理与防洪重点实验室,武汉430010 [3]武汉大学水资源与水电工程科学国家重点实验室,武汉430072

出　　处：《工程力学》2025年第1期259-272,共14页Engineering Mechanics

基　　金：国家自然科学基金项目(52009008,42006156,U2240224);武汉市知识创新专项基础研究项目(2023020201010112)。

摘　　要：弯道环流是弯道水流运动的典型特征之一,一直以来都是众多学者关注的重点。弯道环流主要分为两类:第一类由水流经过弯道时受到的径向压差力差而引起,流速较大;第二类主要由紊流各向异性引起,尽管流速很小,但其与弯道岸坡冲刷过程密切相关。然而当前成果较少关注第二类弯道环流发展演化过程。因此,该文采用弯道水槽试验与数值模拟方法得到的高精度三维流速数据,研究弯道环流结构的变化规律及其动力特性,特别是第二类弯道环流的发展变化。研究结果表明:对于高雷诺数的急弯水流,由于紊动各向异性特征明显,弯道水流常会出现多个环流;对于纵向流速,当水流流经弯顶断面后,纵向流速沿垂向的分布已经明显偏离对数流速分布;当水流经过弯顶断面后,纵向流速沿着垂线存在着显著的均匀化趋势;当弗劳德数较大时,大尺寸涡体在不断分解中,使得原来的各向异性影响越来越小,凹岸附近的小尺寸环流趋近于各向同性状态,造成凹岸小环流逐渐微弱并最后消失;急弯段中环流与纵向水流互馈作用十分显著,弯道环流将对断面内的动量进行重分配,携带某些高速流体到断面内的其他区域,因此,在出现弯道环流的区域其纵向流速也一般比较小。Secondary flow is one of the typical characteristics of flow movement in curved bends,which are divided into two categories.The first type is caused by the difference of radial differential pressure acting on the fluid when flowing through the elbow.The second is mainly caused by turbulent anisotropy.Although the velocity of this type is relatively small,it is closely related to the bank erosion process.However,the research in recent years has paid less attention to the evolution process of the second type of secondary flow.Therefore,this study uses high-precision three-dimensional velocity data to investigate the secondary flow structure and its dynamic characteristics,especially the evolution process of the second type of secondary flow.The results show that:for sharp bend flow with high Reynolds number,multiple circulation often occurs in bend flow due to obvious turbulence anisotropy;for longitudinal velocity,when water flows through the apex of the bend,the distribution of longitudinal velocity along the vertical direction significantly deviates from the logarithmic velocity distribution;when water flows through the apex of the bend,there is an obvious trend of uniformity along the vertical line of longitudinal flow velocity;when the Froud number is large,the large-scale vortices continue to decompose,reducing the influence of the original anisotropy;the small-scale vortices near the concave bank tend to be isotropic,causing the small vortices to gradually weaken and eventually disappear;the interaction between secondary flow and longitudinal flow is significant in sharp bends;and the secondary flow redistributes momentum within the section and carries some high-speed fluid to other regions of the section.Therefore,in the area where the secondary flow occurs,the longitudinal flow velocity is generally smaller.

关 键 词：弯曲型河流 急弯河段 弯道环流 水槽试验 数值模拟 

分 类 号：TV147[水利工程—水力学及河流动力学]