基于一种迭代算法的圆柱结构涡激振动数值研究

发布时间：2018-06-10 02:13

本文选题：涡激振动 + 迭代算法　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：涡激振动在工程结构中较为常见,如海底输油管跨的涡致振动等,是设备疲劳破坏的诱因之一,使得对这类圆柱结构涡激振动的研究具有工程意义。采用数值模拟手段研究圆柱涡激振动由于其经济合理的特点越来越多地受到研究者重视。本文针对圆柱的涡激振动的求解问题,为了揭示涡激振动规律,利用FLUENT求解器对N-S方程进行求解,提出一种迭代算法,其特点是利用自定义函数提取圆柱运动参数,对圆柱运动方程进行迭代求解,研究了单自由度、二自由度圆柱在均匀来流下的涡激响应,讨论了不同湍流模型的影响,并利用Euler梁模型计算了工程结构的振动响应。研究结果表明,本文采用的算法成功捕捉了涡激振动的频率锁定、拍振等特征现象,可以对圆柱结构涡激振动做出合理计算,并得到以下结论:阻尼比、质量比对涡激振动响应有显著影响,随着阻尼比的逐渐增加,涡激振幅、升阻力系数时程曲线将由多频率拍振,最终演变为单一频率主导的振动,且涡激振幅逐渐减小;低质量比圆柱产生的振幅更大,较高质量比能产生更大的升力系数,且升力相对横向位移的相位“突跳”对应更大的来流速度;SST k-ω模型和Realizable k-ε模型均可捕捉涡激振动特征现象,SST k-ω能有效捕捉2P泻涡模式,但计算的振幅曲线的上支振幅偏小,流体力系数的峰值及相位突跳现象较文献值对应的来流速度更小;Realizable k-ε模型不能重现2P泻涡模式,得出的振幅曲线上支振幅偏大,但相位差的突跳现象比实验结果较文献值对应更大的来流速度;长径比对涡激振幅有显著影响,在相同来流下,大长径比结构产生的涡激振幅更大,工程应用中应避免设计过大长径比的单跨结构以免激发大振幅的振动。鉴于大阻尼、质量对涡激振幅的有很好的抑制作用,可在符合设计要求的前提下增加石油化工设备的阻尼和质量以降低设备的涡激振幅。本文对圆柱结构涡激振动的数值计算和结构涡激振动的抑制具有重要的理论和工程意义。
[Abstract]:Vortex-induced vibration is common in engineering structures, such as the vortex-induced vibration of submarine oil pipeline span, which is one of the inducements of equipment fatigue failure, which makes the study of vortex-induced vibration of this kind of cylindrical structure of engineering significance. More and more researchers pay more and more attention to the study of vortex induced vibration of a cylinder by numerical simulation because of its economical and reasonable characteristics. In this paper, in order to reveal the law of vortex-induced vibration, an iterative algorithm is proposed to solve the N-S equation by using fluent solver to solve the problem of vortex-induced vibration of a cylinder. The characteristic of this algorithm is to extract the motion parameters of the cylinder by using self-defined functions. The vortex-induced response of a cylinder with single degree of freedom and two degrees of freedom under uniform flow is studied. The effects of different turbulence models are discussed. The Euler beam model is used to calculate the vibration response of engineering structures. The results show that the proposed algorithm can successfully capture the characteristic phenomena such as frequency locking and beat vibration, and can be used to calculate the vortex-induced vibration of cylindrical structures. The following conclusions are obtained: damping ratio, etc. The mass ratio has a significant effect on the response of vortex-induced vibration. With the increase of damping ratio, the vortex-induced amplitude and the resistance coefficient curve will change from multi-frequency beat to single frequency-dominated vibration, and the vortex-induced amplitude will gradually decrease. The lower mass produces a larger amplitude than the cylinder, and the higher mass produces a larger lift coefficient than the cylinder. The phase "sudden jump" of lift relative to transverse displacement corresponds to a larger inflow velocity and SST k- 蠅 model and realizable k- 蔚 model can capture the characteristic phenomena of vortex-induced vibration. SST k- 蠅 can effectively capture the 2P vortex model, but the amplitude of the upper branch of the calculated amplitude curve is smaller than that of the calculated amplitude curve. The peak value of flow force coefficient and the phenomenon of phase jump are smaller than the corresponding value of the literature. The realizable k- 蔚 model can not reproduce the 2P vortex model, and the amplitude of the upper branch of the amplitude curve is larger. But the phenomenon of sudden jump of phase difference is larger than the experimental results, and the ratio of length to diameter has a significant effect on the amplitude of vortex-induced flow, and under the same flow, the amplitude of vortex-induced flow is larger than that of the structure. In engineering application, it is necessary to avoid the design of single span structure with too large aspect ratio to excite the vibration of large amplitude. In view of the large damping, mass has a good inhibition on the amplitude of vortex excitation, which can increase the damping and mass of petrochemical equipment to reduce the amplitude of vortex-induced vibration under the premise of meeting the design requirements. This paper is of great theoretical and engineering significance for the numerical calculation of vortex-induced vibration of cylindrical structures and the suppression of vortex-induced vibration.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE973.1

【参考文献】