摘要
为满足通行的需求悬浮隧道管体宜设计成大尺度的多车道宽幅截面,洋流是施工及运营阶段所面临的主要环境荷载。洋流作用下宽幅截面的绕流特性,以及缩尺试验或数值模拟时的尺寸效应值得重点关注。以椭圆形、圆端形、八边形3种按双向八车道设计的宽幅截面为对象,并以圆形截面为对照,用CFD软件fluent建立了非定常流下的二维数值模型。研究了不同形状及不同缩尺比的宽幅截面在均匀流下的复杂绕流特性,建立了各类截面升力系数幅值、阻力系数均值和力矩系数幅值与流速的关系图,获取了不同缩尺比下三分力系数的时程曲线,并在此基础上给出了稳定周期内的涡量云图。结果表明:当流速增大时,宽幅截面三分力系数变化不大,圆形截面阻力系数、升力系数则明显减小;3种宽幅截面中,八边形升力系数、阻力系数和力矩系数均最大,脱涡频率最小,椭圆形则与之相反;各类宽幅截面不同缩尺比之间的三分力系数存在不同程度的差异,需考虑尺寸效应带来的影响;尾涡脱落对结构所受三分力有一定影响,阻力系数与涡量云图中尾涡强度、分离点有关。
To meet the traffic demand,the tube of the submerged floating tunnel(SFT)should be designed as a large-scale multi-lane wide section.And the current is the main environmental load faced during the construction and service stages.The flow characteristics of the wide section under the action of ocean currents,as well as the scale effect in scale test or numerical simulation,deserve special attention.The two-dimensional numerical models under unsteady flow are established by using CFD software fluent,by taking the elliptical,round-end and octagonal wide sections designed according to two-way eight lanes as the objects,and taking the circular section as the contrast.The complex flow characteristics of wide sections with different shapes and different scale ratios under uniform flow are studied.The relationship between lift coefficient amplitude,drag coefficient mean-value,moment coefficient amplitude and flow velocity for various sections is established.The time history curves of the three component coefficient under different scale ratios are obtained.On this basis,the vorticity cloud chart in a stable period is given.The results show that the three component coefficients of wide section change little in the increasing course of the flow velocity,while the drag and lift coefficients of circular section decrease significantly.For the three wide sections,the octagonal section has the largest lift coefficient,drag coefficient and moment coefficient,but the smallest vortex shedding frequency,while the elliptical section is just the opposite.The three component coefficients for various wide sections and scale ratios have differences in different degrees,so the influence of scale effect should be considered.The wake shedding has a certain influence on the three component forces,and the drag coefficient is related to the wake strength and separation point in the vorticity cloud chart.
作者
陈志威
刘宏专
易壮鹏
CHEN Zhiwei;LIU Hongzhuan;YI Zhuangpeng(School of Civil Engineering,Changsha University of Science&Technology,410114 Changsha,China)
出处
《应用力学学报》
北大核心
2025年第1期223-235,共13页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金资助项目(No.52278139,52278141)
湖南省自然科学基金资助项目(No.2022JJ30612)
湖南省教育厅科学研究资助项目(No.19A004)
长沙市科技计划资助项目(No.kq2202204)。
