张紧器系统对顶张式立管固有频率的影响研究

Influence analysis of tensioner system on natural frequency of top tensioned riser

采用Euler-Bernoulli梁模型建立立管的水平运动控制方程,并应用Galerkin方法化简求得立管的固有频率。考虑平台的升沉运动,对比了推导的张紧器详细模型和工程常用的简化模型下立管的固有频率。最后基于推导的详细模型,研究了张紧器结构参数对立管固有频率的影响。结果表明:立管固有频率受浮体升沉运动的影响,浮体升沉运动会改变立管的共振特性,引起立管共振点的迁移和转变;采用不同张紧器模型,立管固有频率存在差异,且该差异随着固有频率阶次的增大而增大;立管固有频率受张紧器结构参数的影响,在实际工程中应合理选择张紧器的参数大小,以避免发生参激共振和涡激共振。

The lateral vibration equation of top tensioned riser was derived based on the Euler-Bernoulli beam model,and the natural frequency of the riser was studied by the Galerkin method.Considering the heave motion of platform,the natural frequency of riser calculated by the detailed tensioner model proposed in this paper was compared with that calculated by the conventional simplified model used in the engineering.At last,the impact of the tensioner structure parameters on the natural frequency of riser was studied based on the proposed model.The results show that the natural frequency of riser is influenced by the heave motion of platform.The resonance characteristics of riser may change with the heave motion of platform.The natural frequency of riser differs with different tensioner models,and the difference increases with increase of the natural frequency order.The natural frequency of riser is impacted by the tensioner structure parameters,and the tensioner parameters should be chosen reasonably to avoid parametric resonance and vortex-induced vibration of riser.