深水测试管柱流固耦合动力模型及应用研究

发布时间：2018-05-23 21:07

本文选题：深水管柱 + 流固耦合　；参考：《西南石油大学》2015年硕士论文

【摘要】：深水油气测试中,由于控制系统的操作或油气流体的压力脉动,导致流体运动状态发生改变,诱发管柱系统的变形和振动,此类管柱振动又反作用于流体,从而加剧管柱系统振动效应。这种流体流动、压力波动和管柱振动的相互作用的方式被称为流固耦合。受内外激励的影响,深水测试管柱在流固耦合作用下容易发生振动,其振动形式主要体现在三方面：第一,突然关井时,井口处油气流速瞬间变为零,使测试管柱产生环向应变,引起流体压力脉动和管柱应力波动,诱发管柱振动；第二,外界荷载频率与测试管柱系统频率相等,测试管柱系统发生共振现象；第三,管柱内流体流速超过临界流速,诱发管柱在平面方向发生振动,从而导致管柱的振颤失稳；这三种由流体和管柱相互作用诱发的管柱振动,都会从不同程度上影响管柱工作性能,更甚者会造成管柱结构的破坏。因此,在管柱设计过程中应考虑管柱与流体的相互作用,从而尽量避免由流固耦合诱发的管柱失效。本文首先以Timoshenko梁理论为基础,建立了测试管柱系统在海洋环境下的静力模型,运用有限差分法结合深水测试管边界条件计算管柱在海洋环境下的横向变形。然后结合深水管柱变形特点,采用以直管代替曲管方式,分别从流固耦合时域分析和频域分析出发,建立不同的流固耦合分析模型,计算得出深水管柱系统在考虑流固耦合作用下的应力波动曲线和自由振动频率。最后通过VISUAL BASIC和FORTRAN联合编程技术,研制一款适用于管柱流固耦合动力学分析的应用软件,从而实现其在工程中的运用。本文在对深水管柱流固耦合分析过程中,采用建立不同的计算模型分别进行分析。时域分析方面,从结构自身的本构关系和弹性力学入手,建立考虑管柱泊松耦合、连接耦合的14方程力学模型,再采用以直代曲方式简化了弯段管柱力学边界,运用特征线法计算了测试管柱动力响应曲线。频域分析方面,建立了测试管柱横向和轴向的动力方程,通过数学物理方程推导出管柱流固耦合振动传递矩阵,最后采用试值法计算管柱自由振动频率。本文研究结果对分析管柱与流体的耦合振动特性,预测其振动响应,选择抑制或减小系统振动的措施,保障测试管柱系统的正常运行具有重要的理论意义和实际意义。
[Abstract]:In deep water oil and gas testing, the operation of the control system or the pressure pulsation of the oil and gas fluid lead to the change of the fluid motion state, which induces the deformation and vibration of the string system, and this kind of string vibration reacts on the fluid. Thus, the vibration effect of the string system is aggravated. The interaction of fluid flow, pressure fluctuation and string vibration is called fluid-solid coupling. Under the influence of internal and external excitation, deep water test string is easy to vibrate under fluid-solid coupling. The vibration forms are mainly reflected in three aspects: first, when the well shuts suddenly, the velocity of oil and gas at the well head turns to zero instantly. Causes the test string to produce the circumferential strain, causes the fluid pressure pulsation and the string stress fluctuation, induces the string vibration; second, the external load frequency is equal to the test string system frequency, the test string system produces the resonance phenomenon; third, The velocity of fluid in the string exceeds the critical velocity, which induces the vibration of the string in the plane direction, which leads to the vibration instability of the string; these three kinds of vibration induced by the interaction between fluid and string, It will affect the working performance of the string to some extent, and even cause the damage of the string structure. Therefore, the interaction between the string and the fluid should be considered in the design of the string so as to avoid the failure of the string induced by the fluid-solid coupling as far as possible. In this paper, based on Timoshenko beam theory, the static model of test string system in marine environment is established, and the transverse deformation of pipe string in ocean environment is calculated by using finite difference method combined with the boundary condition of deep water test pipe. Then according to the deformation characteristics of deep water pipe string, different fluid-solid coupling analysis models are established based on time-domain and frequency-domain analysis of fluid-solid coupling, respectively, using straight pipe instead of curved tube. The stress fluctuation curve and free vibration frequency of deep water pipe string system considering fluid-solid coupling are obtained. Finally, an application software for the analysis of fluid-solid coupling dynamics of pipe columns is developed by using the combined programming technology of VISUAL BASIC and FORTRAN, and the application of the software in engineering is realized. In this paper, different calculation models are used to analyze the fluid-solid coupling of deep water pipe string. In time domain analysis, starting with the constitutive relation and elastic mechanics of the structure itself, a mechanical model of 14 equations considering the Poisson coupling and coupling of the pipe string is established, and then the mechanical boundary of the curved pipe string is simplified by means of direct curvature. The characteristic line method is used to calculate the dynamic response curve of the test string. In terms of frequency domain analysis, the dynamic equations of lateral and axial direction of the test string are established, the fluid-solid coupling vibration transfer matrix of the string is derived by mathematical and physical equations, and the free vibration frequency of the string is calculated by the method of trial value. The results of this paper have important theoretical and practical significance for analyzing the coupled vibration characteristics of string and fluid, predicting its vibration response, selecting measures to suppress or reduce the vibration of the system, and ensuring the normal operation of the test string system.
【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】：TE953

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