水下输液管道动力特性研究

Study on Dynamic Characteristics of a Subsea Pipe Conveying Flowing Fluid

该文研究水下横向输液管道的动力特性 ,假定管道系统承受外界均匀流的作用 ,同时考虑管内流体流动的影响 ,建立了水下输液管道侧向振动的微分方程。采用 Hermite插值函数和Galerkin法离散得到其有限元标准形式。研究管内流动为恒定流时输液管道长度、内部流体流动速度对管道动力特性的影响及管内流动含有谐波挠动的情况下输液管道固有频率的变化。结果表明 ,在管内恒定流动的情况下 ,输液的自振频率随管道长度及管内流速的增加而降低 ,同时管内流动的谐波挠动对管道的自振频率也有影响。

This paper focuses on the dynamic characteristics of a subsea pipe conveying flowing fluid. The lateral motion equation of the pipe subjected to external steady current and internal flow is developed. The equation is more general than that derived by earlier researchers as it includes an acceleration term which was always neglected. By using Hermite interpolation function, Galerkin method is adopted to discretize the motion equation. Focus is on the dynamic characteristics of the pipe. The relations between the pipe span, the steady inner flow velocity, inner flow with harmonic turbulence and the natural frequency are investigated to avoid 'lock-in' phenomenon with vortex-shedding frequency. The results indicate that the natural frequency decreases as the pipe span and the inner flow velocity increase. At the same time, the harmonic turbulence of the inner flow speed can effect on the natural frequency of the pipe.