Numerical Simulation of Aerodynamic Characteristics of Two Rectangular Cylinders in Side-by-side Arrangement

We present numerical results of flows around two rectangular cylinders in side-by-side arrangement by three-dimensional computations. The two rectangular cylinders are arranged with various distances between the cylinders. The three-dimensional flow structures around two rectangular cylinders denote significant features depending on the distance between the cylinders. In our computations, the Reynolds number Re is set as 10,000, and both the aspect ratio of section of two rectangular cylinders and the distance between the cylinders are considered as parameters to calculate the flow around two rectangular cylinders. The obtained numerical results are also compared with experimental data.     

管间距对串联双圆柱表面压力分布特性的影响研究

对气液两相流中串联双圆柱表面压力分布特性进行了系统的实验研究 ,着重讨论了管间距的影响。实验双圆柱的间距比分别为 2 .0 ,3.0 ,4.0 ;截面含气率的范围为0～ 0 .3;来流雷诺数的范围为 3× 1 0 4 ～ 8× 1 0 4 。     

壁面对串列双圆柱尾迹影响的实验研究

为研究壁面对近壁等直径串列双圆柱尾迹特性的影响,用PIV和压力传感器测量尾迹湍流的涡结构及频谱.实验在循环水槽内进行,基于圆柱直径D的雷诺数为1696,壁面边界层厚度为6.6D.影响尾迹流场结构的两个重要的特征参数是T/D和G/D(T为两圆柱中心间的距离,G为圆柱下表面与壁面间的距离),文中主要考察G/D的影响.实验中...     

等边布置三圆柱绕流的数值分析

用有限元方法对于等边三角形布置的三个相同直径的二维圆柱绕流问题进行了数值模拟，分别求得了在不同间距比下的流场分布和各圆柱的升、阻力系数以及斯托哈罗数。计算结果表明，小间距比情形下三圆柱之间的干扰是严重的，流动并不对称于中心轴线，而是偏向下游的某个圆柱。数值计算结果与有关文献和实验进行了对比，结果令人满意。     

侧柱与串列双柱绕流之间的干扰

本文给出了关于串列双柱与创柱间流动干扰的实验研究结果。当三个圆柱排成等边三角形并靠得很近时，由于三圆柱间强烈的缝隙流动，大大地改变了绕流其中的串列双圆柱的流态。特别，当三圆柱中心距等于二倍圆柱直径时，在串列双柱的前、后柱之间形成了强烈的偏斜的缝隙流，出现了独特的压力分布以及要比单柱高出三倍以上的旋涡脱落频率。     

Numerical Study of the Effect of Periodic Velocity Excitation on Aerodynamic Characteristics of an Oscillating Circular Cylinder

A finite element method based on ALE formulation has been adopted in order to examine the effect of periodic velocity excitation on the aerodynamic characteristics of an oscillating circular cylinder. Periodic excitation, which was placed on the cylinder surface, stimulated the separated shear layers around the cylinder, and numerical results showed that some excitation can reduce negative damping, which is caused by unsteady lift force, and thereby stabilize the aerodynamics of the cylinder. Furthermore, the change of lift phase caused by periodic excitation seems to be important in stabilizing the aerodynamics of the cylinder. The simulation also confirmed that periodic excitation can suppress the vortex-induced vibration of the cylinder.     

分块法研究圆柱绕流升阻力

使用新的分块耦合方法，分别对单圆柱和串列双圆柱绕流进行了数值模拟．对于单圆柱绕流，低Re下计算所得到的定常涡尺寸与实验非常接近．对于串列双圆柱绕流，研究分析了改变双圆柱中心间距对上下游圆柱的升阻力系数和脉动频率所产生的影响，计算结果与实验非常吻合，为进一步研究涡致振动提供了依据．     

串列双圆柱绕流下游圆柱两自由度涡致振动研究

数值研究了串列双圆柱绕流下游圆柱两自由度涡致振动问题，研究发现：(1) 双自由度的圆柱振幅峰值及出现振峰的频率比都比单自由度的大；(2) 尾流圆柱中的升力远大于均匀来流的，而阻力却相反；(3) 下游圆柱的位移响应对于频率比的变化没有均匀来流中的"敏感"；(4) 尾流中，在频率比1.16和0.87之间，出现了明显的"拍"现象，即圆柱的振幅响应包含不同的频率，而在均匀来流中，并无明显的"拍"现象. 采用ALE方法，计算网格采用H-O非交错网格系统，结合分块耦合方法. N-S方程的对流项和扩散项分别采用三阶迎风紧致格式和四阶中心紧致格式离散. 圆柱振动采用弹簧柱体阻尼器模型，柱体的振动方程采用龙格-库塔法求解. 通过模拟柱体和流体之间的非线性耦合作用，成功地捕捉到了"拍"和"相位开关"等现象.     

并行多步法及其在两铰圆拱动力响应中的应用

本文在基于个人计算机的transputer并行处理子母板系统上提出了一种结构动力分析中适合于并行处理的对时间域积分的多步法——并行多步法。并用此方法对两铰弹性圆拱在矩形荷载作用下的动力响应进行分析。算例表明,对于四处理器系统算法加速比可达3.05,效率为76.25％。对圆拱的分析表明,当中心角之半θ_0较小时,矩形荷载作用完后圆拱在偏离原静止状态的位置附近自由振动。这主要是由于几何非线性所致。     

Three-dimensional computation for flow-induced vibrations of an upstream circular cylinder in two tandem circular cylinders

It is well known from a lot of experimental data that fluid forces acting on two tandem circular cylinders are quite different from those acting on a single circular cylinder. Therefore, we first present numerical results for fluid forces acting on two tandem circular cylinders, which are mounted at various spacings in a smooth flow, and second we present numerical results for flow-induced vibrations of the upstream circular cylinder in the tandem arrangement. The two circular cylinders are arranged at close spacing in a flow field. The upstream circular cylinder is elastically placed by damper-spring systems and moves in both the in-line and cross-flow directions. In such models, each circular cylinder is assumed as a rigid body. On the other hand, we do not introduce a turbulent model such as the Large Eddy Simulation (LES) or Reynolds Averaged Navier-Stokes (RANS) models into the numerical scheme to compute the fluid flow. Our numerical procedure to capture the flow-induced vibration phenomena of the upstream circular cylinder is treated as a fluid-structure interaction problem in which the ideas of weak coupling is taken into consideration.     

钢筋混凝土斜交刚构连续梁桥的实验与数值分析

本文利用三维光弹性法和ANSYS软件分析了铁路斜交刚构连续梁桥在一期、二期自重载荷和两种不同工作载荷下的梁体应力分布，数值研究中分别针对实验模型和建筑实物建立计算模型，并将计算结果与实验结果进行了比较，结果表明，桥梁的应力分布呈明显的不对称特征，有其自身的独到之处。     

纵横加肋圆柱壳的应力分析

建立了一种纵横加肋圆柱壳有限元分析的正确的力学模型,通过大量数值计算,论证了纵骨尺寸,纵骨间距对壳体应力状态的影响,提出了一种等效各向同性壳的近似解析公式,为开展纵横加肋圆柱壳的结构设计打下了良好的基础。     

Modified Galerkin Method for Unsteady Two-Dimensional Viscous Fluid Flow Analysis

The Modified Galerkin Method (MGM) has been proposed as one of the most efficient methods for two-dimensional convection-diffusion equations. In the MGM, the non-symmetric matrices, which are derived from the convection term in the Galerkin formulation, are not used, and an artificial diffusion is introduced through an error analysis approach to improve its discretization accuracy in both time and space directions. In this study, the MGM is applied for two-dimensional viscous fluid flow analysis, and the driven cavity flow problems are solved up to Reynolds number of 10,000 using the vorticity-stream function formulation and non-uniform meshes. The results show the effectiveness of MGM.     

圆形截面约束阻尼梁整体有限元建模与振动分析

为克服约束阻尼结构在工程应用中存在的由三维有限元建模造成的单元数目巨大的问题,本文提出了圆形实心截面梁附加约束阻尼层横向振动的整体有限元建模方法,并基于此模型,研究了材料的物理属性和几何因子对这类结构的固有频率的影响。通过与三维有限元解法相比较,证明了该方法的可行性与正确性,并给出了该方法的适用范围。     

沥青路面弹塑性动力响应分析

采用弹塑性理论,建立了沥青路面弹塑性动力响应分析的三维有限元模型,利用有限元法分析了沥青路面的弹性和弹塑性动力响应、以及弹塑性状态下层间接触对沥青路面力学性能的影响．结果表明：在相同条件下,沥青路面为弹塑性状态时得到的弯沉和最大主应变均比弹性状态时大;卸载后,弹塑性状态时存在残余变形,说明沥青路面的弹塑性动力学响应分析得到的结果和路面实际情况较符合;沥青路面在弹塑性状态下,层间完全光滑时其弯沉是完全连续时的6 倍,上面层最大竖向应变是层间连续时的3.7 倍,下面层处最大竖向应变是层间连续时的2.3 倍;卸载后,层间完全光滑时,面层A 点与B 点均存在残余应变;随着层间摩擦系数的增大,路面弯沉值减少,说明在弹塑性状态下,层间接触状态对沥青路面的动力响应有较大影响．     

独塔斜拉桥的环境振动试验与分析

桥梁环境振动试验具有简单方便和花费少等优点.本文以吉林市临江门大桥为工程背景,通过动力试验,研究了该桥在天然脉动荷载作用下的固有特性.采用结构分析软件ANSYS建立全桥的空间模型,计算该桥的固有特性.有限元计算结果与动力试验结果比较吻合.结果表明,环境振动响应足以识别出该桥所感兴趣的模态,可作为该桥的有限元模型修正、损伤检测、使用状态评估和健康监测的基础.     

杭州市文晖路立交桥主桥的空间分析

现代桥梁跨径不断增大，宽度也在不断加宽，受力条件愈来愈复杂，其表现的空间效应越来越明显，单纯的由平面分析很难反应桥梁的实际受力情况。运用实体退化单元对杭州市文晖路立交桥主桥(斜拉桥)进行了其三维空间分析，特别分析了主梁纵、横向的正应力和索塔竖向正应力。分析结果表明该桥的空间效应比较明显，在恒载作用下桥梁的受力比较合理。     

一种新的金属压缩试验方法的有限元分析

对一种新的金属压缩试验方法进行了有限元数值分析，论证了这种方法的可行性和有性，并且对不同尺寸的试件进行了有限元计算．