以海底悬跨段输液管道为研究对象,考虑管内流体流动及管道轴向力和压强的作用,对其进行受力分析,导出管道振动微分方程。由于内流流速项的影响,使得导出的管道振动微分方程不能用振型分解法直接求解,故本文将解表示为具有正弦和余弦的对称和反对称的各个空间振型的总和,从而求出悬跨段管道固有频率。为防止管道发生横向涡激振动,用约化速度作为控制条件,求解出管道允许悬空长度。结果表明,管道允许悬空长度随着内流流速、轴向压力和管内压强的增加而减小,随着轴向拉力的加大而增大。

A differential equation is derived to describe the motion of a free span submarine pipeline,with the flow of the fluid inside the pipeline,the axial force and pressure on it taken into consideration.The resolution of this equation is expressed as a summation of symmetrical and anti-symmetrical spatial vibrational modes in the form of sinusoidal functions,from which the natural frequencies of the pipeline can be obtained.Preventing of VIV can be achieved by using reduced velocity as a control,leading to the emergence of an allowable span length,which decreases with the increase of internal flow velocity,compression and pressure,and increase with the increase of tension.