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基于改进的严重段塞流瞬态数学模型和平面刚架理论,建立严重段塞流海洋立管耦合振动数学模型,对数学模型进行求解,研究了严重段塞流引起的海洋立管振动响应。数值模拟过程中,采用欧拉法计算严重段塞流流动参数,利用Galerkin法对立管结构动力学方程进行有限元离散,Newmark-β法求解离散方程。为了提高计算效率和精度,采用了变时间步长逐步积分方案。将数值模拟结果与实验数据进行对比,验证了数学模型和数值方法的准确性。对严重段塞流引起的立管系统位移响应、内力和支承力变化进行了深入分析。结果表明:立管系统的振动响应、内力变化规律与严重段塞流的周期性特征密切相关;弹性基础可以极大降低管道结构的振动幅度及内力,尤其是下倾管的弯曲内力;上升管的高频振动幅度较大,轴力和弯曲内力变化也较大。严重段塞流引起海洋立管振动响应的分析对海洋立管设计及其支承防护具有重要的指导意义。
Based on the improved transient slug flow transient mathematical model and plane rigid frame theory, a mathematical model of severe slugging-coupled vertical riser coupling vibration is established and the mathematical model is solved. The vibration response of the marine riser caused by severe slugging flow is studied. In the process of numerical simulation, the Euler method was used to calculate the flow parameters of severe slugging flow. The dynamic equations of the riser were discretized by Galerkin method and the discrete equation was solved by Newmark-β method. In order to improve the computational efficiency and accuracy, a step-by-step integration scheme with variable time step is adopted. The numerical simulation results are compared with the experimental data to verify the accuracy of the mathematical model and numerical methods. The displacement response, internal force and supporting force caused by severe slugging flow were analyzed in depth. The results show that the variation of vibration response and internal force of riser system is closely related to the periodicity of severe slugging flow. The elastic foundation can greatly reduce the vibration amplitude and internal force of pipe structure, especially the bending internal force of down pipe. The high-frequency vibration amplitude larger, axial force and bending force changes also larger. The analysis of the vibration response of marine riser caused by severe slugging flow is of great guiding significance to the design of marine riser and its support and protection.