驳船横荡运动下海洋立管的动力响应

海洋浮式生产系统下立管的受力情况复杂,国内的研究大多集中于两端固支或简支的情况。本文则以水面驳船的横荡运动作为立管上端的动力边界条件,将Matteo Luca Facchinetti的尾流振子模型与考虑外流涡激振动作用下海洋立管运动微分方程相结合,得到管道与流体的耦合振动方程,用Hermit插值函数将方程进行有限元离散,并用Newmark时程分析法及迭代法求解,得到管道各点的位移时程曲线。结果表明:立管的振动频率主要由上端驳船的运动频率所确定,随着驳船运动频率的增加,立管中点的位移幅值先增加后减小;在有动边界存在的条件下,改变外流流速对立管中点的位移幅值影响不大。

DYNAMIC RESPONSE OF SUBMARINE RISER CONNECTED TO A VESSLE WITH LATERAL MOTION

Forces acting on the riser connected to a floating system are complex.Domestic researches mostly focus on a state which satisfies the fixed or pinned boundary condition.In this paper the boundary condition is determined by the lateral motion of the vessel.Combining Matteo Luca Facchinetti's wake oscillator model with the differential equation derived for the dynamic response of the finite element approximation to derive the matrix equations of equilibrium.The newmark method combined with simple iteration was used to solve the system of equations and obtain the displacements.The results indicate that the oscillatory frequency of the riser is mainly determined by the frequency of the vessel.With the increase of the lateral motion frequency,the displacement of the middle of the riser will first increase and then decrease.Under moving boundary conditions,the external current speeds have little effect on the middle point displacement of the riser.