摘要
考虑到实际水利工程与河道流体运行过程中广泛存在双圆柱绕流及桥墩冲刷问题,由此造成水工结构稳定性减弱和疲劳破坏等问题。采用LES方法详尽开展了三维弯道内Re=3 900等直径并列双圆柱绕流的数值模拟研究及流动机理分析。首先,给出了不可压缩流体运动的N-S方程,并介绍了LES方法中常用的Smagorinsky-Lilly的亚格子尺度模型。第二步,针对三维流场模拟的计算网格进行了网格无关性验证和讨论;第三步,以不同双圆柱中心间距比L/D、不同切向高度z和弯道内不同摆放角度α为设计指标,重点开展了三维直道和弯道内Re=3900的并列双圆柱绕流流场数值预测研究。数值结果表明,随着L/D的增大,直道和弯道内圆柱尾缘部分均由旋涡掺混形成单一宽尾流逐渐发展为分离式尾流,不同摆放角度情形下的并列双圆柱流场也展现出相似的特征。在L/D和圆柱摆放角度变化的情形下,相同切向高度z截面上的流场特征分布基本一致。区别于直道情形,不同摆放角度下的升阻力时间曲线差异显著且幅值增大,同时随着L/D和摆放角度的增大,弯道内流场展现出流速内高外低且二次流显著等流动特点,从而在弯道内侧聚集强涡束结构,在出口通道处出现零碎涡结构的分布区域增大等现象,说明圆柱摆放角度、弯道的高曲率和离心效应会引起流场特征的显著变化。综上所述,本文开展的弯道并列圆柱绕流研究能够为水利工程中广泛存在的双圆柱绕流及桥墩冲刷等物理问题提供数据参考。
Flow around twin cylinders and bridge pier scouring are widespread problems in practical hydraulic engineering and river fluid dynamics,often leading to reduced structural stability and fatigue damage.In this paper,a numerical simulation and flow mechanism analysis of the flow around juxtaposed twin cylinders(Re=3900)with equal diameter in a three-dimensional curved channel is carried out using the LES method.First,the N-S equations for incompressible fluid motion are given,and the sublattice scale model of Smagorinsky-Lilly,which is commonly used in the LES method,is introduced.Second,the grid-independence is verified and discussed for the computational grid of 3D flow field simulation.Third,numerical predictions of the flow field around the juxtaposed twin cylinders(Re=3900)in both straight and curved channels are conducted,with design parameters including different center-to-center spacing ratios L/D,different tangential heights z,and different placing anglesαin the curved channel The numerical results show that,with the increase of L/D,the cylindrical trailing edge in both straight and curved channels gradually develops from a single wide wake with vortex mixing to a separated wake,and the juxtaposed double-cylindrical flow field with different placing angles also shows similar characteristics.The distributions of the flow field characteristics at the same tangential height z section are basically the same for different L/D and cylinder placement angles.Different from the case of straight channel,the drag time curves of different placement angles are significantly different and the amplitude increases.Meanwhile,with the increase of L/D and placement angle,the flow field in the curved channel shows the flow characteristics of high velocity inside and low velocity outside,and the secondary flow is significant.This leads to the gathering of strong vortex structures in the inside of the curved channel,and the increase of the distribution area of fragmented vortex structures in the exit channel.These phenomena indicate that the placement angle of the cylindrical columns,high curvature of curved channel and centrifugal effect can cause significant changes in the flow field characteristics.In summary,the study of parallel cylindrical flow in curved channel carried out in this paper can provide data reference for the physical problems such as double cylindrical flow and bridge abutment scour which are widely encountered in water conservancy projects.
作者
张莹
王芳
ZHANG Ying;WANG Fang(School of Civil Engineering,North Minzu University,Yinchuan 750021,Ningxia,China)
出处
《中国农村水利水电》
北大核心
2026年第3期120-133,共14页
China Rural Water and Hydropower
基金
宁夏自然科学基金项目(2023AAC03299)
国家自然科学基金项目(12462023)
宁夏高等学校科学研究项目(NYG2024068)。
关键词
弯道
并列双圆柱
数值模拟
绕流
涡结构
curved channel
juxtaposed twin cylinders
numerical simulation
flow around cylinders
Vortex structure
