剪切来流下钝体绕流与涡激振动效应模拟与分析

发布时间：2018-07-05 01:57

本文选题：四步CBS稳定化有限元 + 任意拉格朗日-欧拉(ALE)　；参考：《上海交通大学》2014年博士论文

【摘要】：自然界中流体流动多以剪切来流的形式存在,而非均匀来流的形式出现。剪切来流作用下的钝体结构(群)绕流与流致振动问题在自然界中广泛存在,如高层建筑结构、拉索结构、桥梁结构、海洋结构物等钝体结构。本文以土木工程和海洋工程的相关问题为背景,发展新型稳定化有限元计算方法,研究剪切来流作用下钝体结构(群)绕流和流致振动的科学基础问题,分析剪切来流作用下钝体结构(群)互扰效应和尾流特性,单钝体结构的流致振动和多钝体结构的流固耦合互扰效应,主要研究工作和创新点如下:1.提出了四步半隐式特征线分裂算子(Four-step Semi-implicit CharacteristicBased Split;4-SICBS)稳定化有限元新型格式,为钝体绕流研究提供了新的计算手段。该方法可求解层流范围内的不可压缩黏性流体问题,同传统显式特征线分裂算子(CBS)有限元格式相比,允许更大的计算时间步和获得更好的计算稳定性。2.发展了求解涡激振动问题的流体稳定化有限元新型格式:4-SICBS-ALE,为求解钝体结构(群)涡激振动问题提供有效的计算手段。将上述4-SICBS稳定化有限元格式推广到任意拉格朗日-欧拉(ALE)描述下,并结合一种引入光滑技术的动网格方法,发展了适用于剪切来流作用下钝体结构(群)流致振动问题的高效分区耦合算法。该算法可有效解决刚体大位移运动而导致网格失效的问题,为研究剪切来流作用下钝体结构(群)涡激振动问题提供了更高效更稳定的计算方法。3.以输电线、拉索结构与海洋管道结构物等为应用背景,研究了剪切来流作用下静止顺排双圆柱系统的钝体结构群绕流问题,揭示了来流剪切率、双圆柱间距比和雷诺数对静止结构群绕流特性与气动参数的影响,揭示钝体结构物周围的流动互扰机理。研究发现:在剪切来流作用下,双圆柱体结构之间的互扰效应十分复杂,其气动特性与尾流模态较均匀来流工况产生显著变化。4.以多边形高层建筑结构物、户外广告支撑结构体系与海洋结构物等为应用背景,研究了均匀来流时强迫转动下三角柱钝体结构的绕流问题。深入分析了三角柱钝体结构在不同来流攻角与雷诺数时,转动幅度与转动频率对绕流的影响,揭示了该系统下锁定区间范围、气动参数与尾流特性,阐明了强迫转动条件下三角柱钝体结构绕流机理。研究发现:在不同的来流攻角下,该系统的雷诺数效应显著。5.以拉索结构、海洋立管、海底输油管道等为应用背景,研究了剪切来流作用下单圆柱体钝体结构的单/双自由度流致振动问题。采用本文所发展的4-SICBS-ALE算法,研究了在Re=150时,关键参数(来流剪切率、折减速度与频率比)对单圆柱体钝体结构的振动响应特征与尾流泄涡模式的影响,揭示了该系统的动力响应、运动轨迹、尾流泄涡模式和气动力参数特性,阐明了流体-固体耦合作用的涡动力机理。6.以拉索群、输电线群与海洋立管群等为应用背景,研究了剪切来流作用下顺排布置双圆柱体结构的双自由度涡激振动问题。研究了在Re=160时,关键参数(来流剪切率、间距比与折减速度)对双圆柱体结构体系的振动响应特性与尾流模态的影响,揭示了该系统的动力响应、轨迹特征和尾流特性,阐明了多钝体流固耦合互扰机理。本文发展的新型稳定化有限元算法,可准确高效稳定地求解剪切来流作用下钝体结构(群)绕流和涡激振动问题;针对工程应用背景,提炼出的关键性问题所获得的研究成果,可为土木工程和海洋工程领域工程设计计算提供理论依据和设计参考,具有重要的应用价值,对认识该问题的力学机理具有重要的学术意义。
[Abstract]:Fluid flow in nature exists mostly in the form of shear flow and non uniform flow. The problem of blunt body structure (Group) around flow and flow induced vibration under shear flow is widely existed in nature, such as high-rise building structure, cable structure, bridge structure, ocean structure and other blunt body structures. This paper is based on civil engineering and ocean. A new stable finite element method is developed to study the scientific basic problems of the flow induced and flow induced vibration of the blunt body structure (Group) under shear flow. The interaction and wake characteristics of the blunt body structure (Group), the flow induced vibration of the single blunt body structure and the fluid solid coupling of the multi blunt body structure are analyzed. The main research work and innovation are as follows: 1. a new four step semi implicit characteristic line splitting operator (Four-step Semi-implicit CharacteristicBased Split; 4-SICBS) is proposed to stabilize the flow around the blunt body. This method can solve the incompressible viscous fluid problem in the laminar flow. Compared with the traditional explicit characteristic line splitting operator (CBS) finite element scheme, the new finite element method for solving the problem of vortex excited vibration is developed by allowing a larger calculation time step and obtaining a better computational stability.2.. 4-SICBS-ALE, which provides an effective calculation method for solving the problem of vortex induced vibration of the blunt body structure (Group). The ICBS stabilization finite element method is extended to the arbitrary Lagrange Euler (ALE) description, and a high efficient zoning coupling algorithm is developed to solve the vibration problem of the blunt body structure (Group) flow under the action of the shear flow, which can effectively solve the grid failure caused by the large displacement of the rigid body. In order to study the problem of vortex induced vibration of a bluff body structure (Group) under shear flow, a more efficient and stable method for calculating the vortex induced vibration of the blunt body structure (Group),.3. is used to study the flow around the blunt body structure group in the static row double cylindrical system under the action of shear flow. The influence of the ratio of the spacing of two cylinders and the Reynolds number on the flow behavior and aerodynamic parameters of the static structure group is revealed, and the interaction mechanism of flow around the structure of the blunt body is revealed. It is found that the interaction effect of the double cylinder structure is very complex under the action of the shear flow, and the aerodynamic characteristics and the wake mode have a significant change of.4 in the uniform flow condition. The flow around a triangular column blunt body structure under the forced rotation of a uniform flow is studied with a polygon tall building structure, an outdoor advertising support structure and a marine structure. The influence of the rotational amplitude and the rotational frequency on the flow around the triangle column blunt body structure at different attack angles and Reynolds numbers is deeply analyzed. The locking interval range, aerodynamic parameters and wake characteristics under the system are revealed, and the mechanism of flow around the blunt body of a triangular column under forced rotation is clarified. It is found that the Reynolds number effect of the system is significantly.5. under the different current angle of attack, with the application background of the cable structure, the marine riser and the bottom oil pipeline, and the shear flow is studied. Using the 4-SICBS-ALE algorithm developed in this paper, the effects of the key parameters (the shear rate of the flow, the reduction rate and the frequency ratio) on the vibration response characteristics of the single cylinder blunt body structure and the wake vortex mode are investigated by using the developed 4-SICBS-ALE algorithm, and the dynamic response of the system is revealed. The motion trajectory, the tail flow vortex mode and the aerodynamic parameter characteristics illustrate the vortex dynamic mechanism of the fluid solid coupling action.6., which is applied to the cable group, the transmission line group and the marine riser group, and studies the double degree of freedom vortex excited vibration of the double cylinder arrangement under the action of the shear flow. The key parameters are studied at the time of Re=160. The dynamic response, trajectory characteristics and wake characteristics of the system are revealed by the influence of the number of flow shear rate, spacing ratio and reduction velocity on the vibration response characteristics and wake modes of the system. The new stabilization finite element method developed in this paper can be accurately and efficiently solved. The research results obtained from the key problems of the engineering application background can provide theoretical basis and design reference for the engineering design and calculation in the field of civil engineering and marine engineering. The research results obtained from the key problems of the engineering application background can be provided for the engineering design and calculation in the field of Civil Engineering and marine engineering. It has important application value and the mechanical mechanism to understand the problem. There is an important academic significance.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU311.3

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