张紧器结构非线性对深海顶张式立管系统参激稳定性的影响分析  

Effects of tensioner structural nonlinearity on parametric excitation stability ofdeepwater top-tensioned riser system

作　　者：丁明 孟帅[1] 丁英 DING Ming;MENG Shuai;DING Ying(State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;School of Electrical Engineering,Xinjiang University,Urumqi 830046,China)

机构地区：[1]上海交通大学海洋工程国家重点实验室,上海200240 [2]新疆大学电气工程学院,乌鲁木齐830046

出　　处：《振动与冲击》2023年第15期277-284,共8页Journal of Vibration and Shock

基　　金：国家自然科学基金面上项目(51879161)。

摘　　要：顶张式立管在作业时,浮式平台垂荡运动导致立管轴向张力随时间变化,可能引发立管在水平方向发生参激失稳。随着海洋开发进入深海区,海洋环境愈加恶劣,立管因长径比大幅增加而柔性增强。为确保系统作业安全,必须寻找新的(以前被忽略或简化)关键影响因素以实现对立管动态响应准确预测和系统稳定性科学预判。在参激稳定性预报中,直接作用式张紧器最常采用的是线性弹簧模型和工程简化模型。考虑液压缸装置的气体压强和容积、摩擦力、液压损失等因素,建立了直接作用式张紧器非线性模型。采用张紧器线性弹簧模型、工程简化模型和非线性模型,基于富洛开理论预报1 000 m顶张式立管系统的参激稳定性。研究表明,张紧器结构非线性影响立管张紧力和固有频率计算,进而可能导致系统参激稳定误判。采用3种张紧器模型预报参激不稳定区的差别主要发生在低频区,利用非线性模型预报的参激不稳定区最大。随着蓄能器高压气体初始体积的增加和低压氮气瓶初始压强的提高,张紧器结构非线性效应会进一步加强。研究成果可用于修正现用的参激分析软件以更适用于深海区。During operation of top tensioned riser,heave motion of floating platform causes axial tension of riser to vary with time,it may lead to parametric excitation instability of riser in horizontal direction.As ocean development enters deep sea,marine environment becomes increasingly harsh,and riser becomes more flexible due to great increase in its aspect ratio.To ensure the safety of system operations,it is necessary to find new key affecting factors which are previously ignored or simplified,and realize accurate prediction of riser dynamic response and scientific prediction of system stability.In parametric excitation stability prediction,linear spring model and engineering simplified model are most commonly used for direct acting tensioners.Here,considering factors of gas pressure and volume,friction,and hydraulic loss of hydraulic cylinder device,a nonlinear model of direct acting tensioner was established.Using tensioner’s linear spring model,engineering simplified model and nonlinear model,the parametric excitation stability of a 1000 m top tensioned riser system was predicted based on Fuluki theory.The study showed that the nonlinearity of tensioner structure affects calculating riser tension and natural frequencies to further possibly cause misjudgment of system parametric excitation stability;differences to predict parametric excitation instability regions using 3 tensioner models mainly occur in low frequency region,and the parametric excitation instability region predicted with the nonlinear model is the largest;with increase in initial volume of high-pressure gas in energy accumulator and initial pressure of low-pressure nitrogen cylinder,the nonlinear effect of tensioner structure can be further strengthened;the study results can be used to modify the current parametric excitation analysis software so that it can be more suitable for deep sea area.

关 键 词：深海立管 参激振动 张紧器非线性 不稳定区 

分 类 号：P751[交通运输工程—港口、海岸及近海工程]