低雷诺数下双方柱绕流的数值模拟-动力工程及工程热物理专业论文.docxVIP

Classified Index: TB126 U.D.C: 530 Dissertation for the Master Degree of Engineering THE NUMERICAL SIMULATION OF THE FLOW PAST TWO SQUARE CYLINDERS AT LOW REYNOLDS NUMBERS Candidate: Fu Na Supervisor: Prof. Chaoying Zhou Academic Degree Applied for: Master of Engineering Specialty: Power Engineering and Engineering Thermophysics Affiliation: Shenzhen Graduate School Date of Defence: December, 2007 Degree-Conferring-Institution: Harbin Institute of Technology 哈尔滨工业大学工学硕士学位论文 哈尔滨工业大学工学硕士学位论文 I I 摘要 在流体机械工程领域中，双柱绕流是一个很重要的流体现象。比如说， 海洋平台、海底电缆、烟囱、热交换管等。双柱的摆放多为串列放置或并排 放置。对于流体流过串列或并排放置的圆柱的流场前人曾做过很多的研究。 方柱作为另一种常见的结构体，人们对多方柱流场的研究要相对少些。 本文利用流体力学软件程序 FLUENT 对方柱的外流场进行了数值模拟 研究。首先应用 FLUENT 的前置处理软件 GAMBIT 建立计算模型并对流场 进行网格划分，然后导入 FLUENT 中进行数值计算。FLUENT 求解器采用 有限体积法对流体力学控制方程离散的 Navier-Stokes 方程进行离散，用 SIMPLE 方法求解。 本文对绕双方柱的二维不可压缩流动进行了数值计算。详细的研究了两 方柱不同间距对方柱间相互作用和尾流特征的影响。计算均在雷诺数 Re =300 的条件下进行，此时的流场是层流且为二维。针对方柱的并列和串 列两种排列方式和多种间距情况，分别分析了两柱体升力和阻力的特征及流 场的涡脱落情况。其中，串列方柱研究 L/D=2.0，3.0，4.0，5.0 四种情况(L 为两方柱中心间的距离，D 为方柱的边长)。并列方柱研究 H/D=0.8，2.0， 4.0 三种情况(H 为两方柱壁面距离，D 为方柱的边长)。 计算结果表明：对该绕流问题，涡的脱落频率、涡的强度和下游方柱涡的 演化等流动特征在很大程度上取决于 L 和 H 的大小。 关键词 双方柱；数值模拟；雷诺数 II II Abstract Fluid structure interaction between two cylinders is an important phenomenon in engineering flows. For example, it occurs in flows that involve offshore structures, transmission cables with twin conductors, twin chimney stacks and heat exchanger tubes. The arrangement of the cylinders with respect to the freestream flow direction can be broadly classified as tandem (or in-line), transverse (or side-by-side) or staggered. Significant research has gone into the understanding of flows past cylinders in transverse or in-line arrangement. However, our understanding on the fluid structure interaction in a system with multiple structures is far from enough. In this study, flow over a circular cylinder is numerically studied using the CFD （Computational Fluid Dynamics）software FLUENT. Gambit, the pre-processor of FLUENT, is used to generate th