毕业论文移动版

摘要世界能源日益短缺，对于那些有着辽阔海域的国家而言，获取海上能源已经成为防止能源短缺的重要途径。现阶段世界海洋大国不断研制出新型的海洋装备开发海上能源，立管作为海工装备中的重要设备发挥着不可替代的作用，而开采环境不同，就会有不一样的质量比，会对立管涡激振动产生不一样的影响。本文的主要研究工作是研究不同质量比对刚性圆柱体涡激振动运动响应的影响。本文利用ANSYS-CFX软件进行数值模拟，主要研究方法以及计算分析得到的结论如下：81902

首先，本文为了通过约化速度比较出雷诺数对圆柱涡激振动的影响，先在静水中通过模态模块计算出定质量比下的固有频率，再改变雷诺数进行数值模拟计算。分析计算得到的数据，绘制出不同雷诺数下圆柱体的轨迹、升力以及拖曳力曲线，综合比较不同约化速度下的无量纲振幅，得到“锁定区间”大约在雷诺数为[2500,3800]，为研究质量比对涡激振动的响应奠定基础。

接着，根据改变雷诺数而得到的“锁定区间”，确定研究质量比时的流速。在中低质量比范围内选择几组合适的质量比值，分析不同质量比下的涡激振动响应，绘制出不同质量比下圆柱体的轨迹、升力以及拖曳力以及无量纲振幅曲线，分析归纳发现质量比的改变对升力、拖曳力以及泻涡频率无影响，质量比上升振幅都下降；研究超低质量比时，升力、拖曳力以及泻涡频率相对于中低质量比无变化，而振幅下降了一些。

最后，对全文进行总结。本文数值计算分析得到的结果将会为工程师更新立管装备供理论依据。

毕业论文关键词：圆柱体；涡激振动；ANSYS-CFX；质量比；雷诺数

Abstract  Nowadays, resources have become a big problem, for those countries with vast sea areas, it’s important for them to obtain offshore energy, which benefits for them to prevent resources problems。Recently, many countries with vast sea areas have constructed new ocean engineering to collect energy, those cylinders have played important roles in ocean engineering, while exploiting different resources will lead to different mass ratios,which making up to different VIV。 This article mainly studies the effects of the mass ratio on VIV of a rigid circular cylinder, which will provide theories for engineers using power produced by VIV of cylinder。 Researchers used ANSYS-CFX to produce models, the main methods and result of the article as follow:

  Firstly, the essay use reduced velocity to calculate the effects on VIV of cylinders on different Reynolds numbers。 At first, it’s important to calculate the natural frequency by calculating models, then changing Reynolds numbers and trying numerical simulation calculation。 Using the results calculated by computers, drawing up pictures about trajectory, lift and drag on different Reynolds numbers。 Comparing non dimensional amplitude, “Lock ” section range from 2500 to 3800。 This step will be beneficial to study VIV on different mass ratio。

Meanwhile, the velocity used in studying mass ratio has been decided according to the “Lock” section deciding by Reynolds numbers。 Studying VIV on different mass ratio, the value of mass ratio is chose around low-middle mass ratio section。Of course, it’s essential to draw up pictures about trajectory, lift and drag on different mass ratio。 The results show that the lift, drag and trajectory are same as low-middle mass ratio, while amplitude are lower than low-middle mass ratio。 

Last, the summarize of the essay will provide the researchers with enough evidence when they want to renew cylinders。 

Keywords: rigid circular cylinder; VIV; ANSYS-CFX; mass ratio; Reynolds numbers