明渠交汇口分离区三维几何特性的大涡模拟研究  

Investigation of three-dimensional geometry of separation zone at open-channel junctions by large eddy simulation

作　　者：胥宗强 魏炳乾[1] 薛博升 魏书琦 杨泓 刘小华[1] Xu Zongqiang;Wei Bingqian;Xue Bosheng;Wei Shuqi;Yang Hong;Liu Xiaohua(State Key Lab of Eco-hydraulics in Northwest Arid Region of China,Xi’an University of Technology,710048,Xi’an,China;State Key Lab of Hydraulics and Mountain River Engineer,Sichuan University,610065,Chengdu,China;Urban and Rural Construction Institute,Hebei Agricultural University,071001,Baoding,China)

机构地区：[1]西安理工大学省部共建西北旱区生态水利工程国家重点实验室,西安710048 [2]四川大学水力学与山区河流开发保护国家重点实验室,成都610065 [3]河北农业大学城乡建设学院,保定071001

出　　处：《应用力学学报》2021年第1期409-417,共9页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(51479163);陕西水利科技计划资助项目(2014skj-14)。

摘　　要：为更准确地把握交汇角对分离区三维几何特性的影响,建立了不同角度的交汇水槽模型并进行数值模拟。采用大涡模拟(LES)方法求解交汇区的湍流流场,并基于平衡层模型的Werner壁面函数法处理近壁区流场。模拟所得垂向流速分布及分离区尺寸等结果与实测资料吻合程度较高。以90°交汇水槽为例较详尽地分析了分离区的三维几何特性,并从流场结构角度对其形成机理进行了剖析。随后聚焦于不同交汇角度下分离区的三维几何特性,给出了交汇角对不同水深层面分离区各几何参数的影响。研究结果显示:交汇口的分离区三维几何特性与流场结构有较强的关联性,分离区宽度沿水深的分布规律是分离区内外的流向涡及与之伴随的象限事件作用的结果。随着交汇角的增大,各水深层面的分离区长度基本呈增大趋势;当交汇角达到105°时,各水深层面分离区长度达到最大值,其原因是受干流顶冲作用,支流的实际入流角将小于交汇角,当交汇角为90°时,支流入汇对分离区长度的影响达到最大;随着交汇角的增大,各水深层面的分离区宽度总体呈增大趋势,显示出与90°交汇水槽相似的分布特性;随着交汇角的增大,各水深层面的分离区对称系数逐渐减小,这是分离区附近水平绕流涡的三维取向和分离区的长度变化共同作用的结果。In order to more accurately grasp the influence of intersection angle on the three-dimensional geometric characteristics of the separation zone, the model of intersection flume with different angles is established and the numerical simulation is carried out. In this study, the turbulent flow field in the intersection region is solved using the Large Eddy Simulation method, and the near-wall flow field is treated by the wall function method based on the Equilibrium Layer model. The results agree well with the measured data. With 90°intersection tank as an example, the three-dimensional geometric characteristics of the separation zone was analyzed in detail, whose formulation mechanism is also analyzed from a view of the flow field structure. Then according to the three dimensional geometric characteristics of the separation zone at different intersection angles, the effects of the intersection angle on the geometrical parameters of the separation zone at different depth levels are investigated. The results show that there is a strong correlation between the three-dimensional geometry of the separation zone and the structure of the flow field. With the increase of intersection angle, the length of the separation zone along the depth of water level shows basically a trend of increase. There is an exception that the length of the separation zone in each depth level reaches maximum value when the intersection angle is 150°. The reason for this is that the angle of branch inflow is slightly smaller than the actual intersection angle α. As a result, when the intersection angle is slightly greater than 90°,the influence of tributary toward the length of separation zone is greatest. With the increase of the intersection angle α, the width of the separation zone at each depth levels generally increases, which shows a similar distribution characteristic with the 90°intersection. With the increase of the intersection angle, the symmetry coefficient of the separation zone at each depth levels gradually decreases;this is

关 键 词：交汇口 大涡模拟 分离区 流体结构 几何参数 

分 类 号：TV14[水利工程—水力学及河流动力学]