【作者】 曹亮；

【导师】 张立翔；

【作者基本信息】 昆明理工大学 ， 工程力学， 2004， 硕士

【摘要】 在管道有压流动的过程中，由于控制系统的操作，导致流体运动状态发生突变，诱发出水力暂态过程，严重时产生称作水锤的极端水力现象。对于大多数弱约束的工业管道来说，水锤将会诱发管道的自激振动，而管道的振动又会引起新的水力暂态过程，从而构成流体流动、压力波动及管道振动等多种运动形式的耦合。这种耦合作用称为流体结构相互作用，简称流固耦合。 众所周知，管道系统在众多的工业领域中都具有十分广泛的应用，发挥着极其重要的作用。而流固耦合将会引起系统振荡，降低系统运行的可靠性，恶化工作环境，影响仪器仪表的精度，严重时甚至使管道爆裂。因此，研究输流管道系统中的流固耦合现象对于了解系统的力学特性、稳定系统运行、提高运行可靠度等方面具有重要的实用及学术价值，在航空航天、石油化工、水利电力、城市供排水等众多的工业领域中具有重要的意义。 本文对输流管道系统的流固耦合现象进行了分析研究，并对直管系统及弯管系统进行了模态分析。具体工作包括以下几个方面： 1．总结推导了输流管道轴向及横向振动的线性微分方程。可以看出，讨论时假设系统的轴向运动和横向运动是分离的，流固耦合作用是通过流体与结构之间的边界接触来实现的。 2．基于输流管道轴向及横向振动的微分方程，考虑流体与管道之间的泊松耦合，详细推导出了输流直管的轴向及横向振动的传递矩阵；同时采用中线不可伸长理论的离散模型，将弯管离散为一组首尾相连，成一定角度的短直管单元，通过力的平衡方程和连续性方程，建立了弯管平面内振动的传递矩阵。 3．对于实际的管道中常见边界条件的计算处理方法进行了讨论，建立了一套采用传递矩阵法对管道进行模态频率、模态振型以及频域响应计算的方法。对输流直管、输流弯管进行了模态分析，并与相关文献及ANSYS有限元分析软件的计算结果进行了比较，验证了所建传递矩阵的正确性，并讨论了流固耦合作用对系统特性的影响。结果表明，流固耦合作用对系统模态频率的影响较大，对系统模态振型的影响较小。更多还原

【Abstract】 Very often when mechanical operation applied to piped flowing fluid, a state transform will occur as a result inducing a hydraulic transient, or even waterhammer when situation is severe. As most industrial piping systems are weakly restricted, waterhammer will bring self-excited vibration of the piping system, which further engenders new hydraulic transients, therefore to produce a sophisticated coupling of different influences caused by fluid flow, pressure wave and pipe vibration. We name it fluid structure interaction, or simply FSI.Piping system has already seen a wide use in many fields of industry, and has acted an important role. However, FSI deteriorates the performance of the system, worsens the reliability of operation, affects on the precision of the instruments, and even blows out the pipe. Thus the research on this phenomenon is very important to understand the systems mechanical characteristics so that some effective methodologies can be adapted to avoid those bad effects, which could also be important in the industrial fields of aeronautics and space, petroleum chemistry, electric power, civil drainage, and so on.In this thesis we studied FSI in liquid-filled pipe and analyzed the straight and L-shaped pipes. The research work involves several aspects as follows:1. summarize and develop the linear differential equations of axial and transverse vibrations of piping systems filled with liquid. Herein we show that the axial and transverse movements are separable, and the effect of FSI is achieved by the interaction of the fluid and the structure of the piping.2.based on the axial and transverse vibration differential equations, considering Poisson coupling, the transfer matrixes of the axial and transverse movements are developed. According to the inextensible axes discrete model, L-shaped pipe is viewed as a series of end to end short straight pipe elements jointed together, therefore to establish the force balance equations and continuity equations, and the transfer matrix of L-shaped pipe in-plane vibration.3.After a detailed discussion on some practical numerical methods on the problem of boundary conditions, an effective way using transfer matrix to calculatethe modal frequency, modal vibration mode shape, and response in frequency domain is established. The numerical results are compared with these from concerned literature and from ANSYS, which proves the validity of our method. A further discussion on the influence of FSI on the system characteristics is followed. Our results show that FSI affects the system modal frequencies seriously, but mode shapes slightly.更多还原