内外流共同作用下立管流固耦合振动数值模拟

发布时间：2018-01-01 21:02

本文关键词：内外流共同作用下立管流固耦合振动数值模拟　出处：《西南石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：以圆柱绕流为代表的钝体涡激振动问题一直以来都是学术界研究的热点,在工程实践中应用广泛。由涡激振动导致的海洋立管疲劳失效,使得海洋立管成为海洋油气勘探开发中最易损坏的部件。本文在商业化CAE软件Ansys的多物理场耦合平台Workbench下,采用CFX作为流场解算器,选用LES湍流模型,并与Ansys动力响应模块实现大长径比立管模型的三维实体双向流固耦合数值模拟。并结合模态分析,突破性地对内外流共同作用下大长径比立管模型进行涡激振动特性分析。本文的主要内容包括：本文的第一章回顾了国内外海洋立管涡激振动的研究现状；第二章简要地介绍了涡激振动的机理和耦合模拟所涉及到的数值方法；本文的第三章通过数值模拟结果与实验结果的对比,验证了耦合数值模拟方法的可靠性；第四章对大长径比立管模型进行了模态分析,并对外流作用下立管涡激振动特性进行了耦合模拟和分析；第五章对内外流共同作用下立管涡激振动特性进行了模拟和分析；本文的最后一章对全文进行了总结。通过对立管模型进行三维耦合模拟分析,发现立管的振动特性主要受绕流的升力影响,随着外流雷诺数的增高,升力变化频率接近结构固有频率,结构发生共振,振幅陡然提升；随着升力变化频率的进一步升高,流体力激发了立管阶数更高而振幅较小的振动。当立管内部有流体介质流动时,流动的介质对立管涡激振动产生了显著的影响,激发了更高阶的振动形态。
[Abstract]:The problem of vortex-induced vibration of blunt body, represented by the flow around a cylinder, has always been a hot topic in academic circles, and has been widely used in engineering practice. The fatigue failure of marine riser caused by vortex-induced vibration has been widely used. The marine riser has become the most vulnerable component in offshore oil and gas exploration and development. This paper is based on the multi-physical field coupling platform Workbench of commercial CAE software Ansys. Using CFX as flow field solver, LES turbulence model and Ansys dynamic response module are used to realize three-dimensional solid two-way fluid-solid coupling numerical simulation of riser model with large aspect ratio, and combined with modal analysis. The vortex-induced vibration characteristics of the riser model with large aspect ratio under the interaction of internal and external currents are analyzed in a groundbreaking way. The main contents of this paper are as follows: In the first chapter of this paper, the research status of vortex-induced vibration in marine risers is reviewed. In the second chapter, the mechanism of vortex-induced vibration and the numerical methods involved in coupled simulation are briefly introduced. In the third chapter, the reliability of the coupled numerical simulation method is verified by comparing the numerical simulation results with the experimental results. In chapter 4th, the modal analysis of the riser model with large aspect ratio is carried out, and the coupled simulation and analysis of the vortex-induced vibration characteristics of the riser under the action of external flow are carried out. In Chapter 5th, the vortex-induced vibration characteristics of riser subjected to internal outflow are simulated and analyzed. The last chapter of this paper summarizes the full text. It is found that the vibration characteristics of the riser are mainly affected by the lift around the flow through the three-dimensional coupling analysis of the opposing tube model. With the increase of Reynolds number of the outflow, the lift variation frequency is close to the natural frequency of the structure. The structure resonates and the amplitude rises steeply. With the further increase of lift frequency, the flow force excites the riser vibration with higher order and smaller amplitude, when there is fluid flow in the riser. The flow medium exerts a significant influence on the vortex-induced vibration of the tube and excites a higher order vibration form.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P756.2

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