深海立管顺流与横流耦合涡激振动中的内流效应分析  

Internal flow effect in IL-CF coupled VIV of deep-sea risers

作　　者：赵桂欣 孟帅[1] 车驰东[1] 赵创业 张文龙 ZHAO Guixin;MENG Shuai;CHE Chidong;ZHAO Chuangye;ZHANG Wenlong(State Key Lab of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Jiangnan Shipbuilding Group Co.,Ltd.,Shanghai 201913,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]江南造船(集团)有限责任公司,上海201913

出　　处：《振动与冲击》2023年第19期7-13,共7页Journal of Vibration and Shock

基　　金：国家自然科学基金面上项目(51879161)。

摘　　要：深海立管因长径比大幅增加导致柔性增强、内流效应凸显,其在顺流和横流耦合涡激振动中的内流效应尚未得到很好理解。采用半经验时域涡激振动水动力模型,建立深海立管在均匀洋流下的横向和纵向耦合振动方程,并利用有限元法求解,探究不同内流速度、内流密度和洋流下立管在顺流和横流耦合涡激振动中的内流效应。研究发现,当洋流速度和内流密度一定时:①内流效应可使系统固有频率降低,因此随着内流速度增加,顺流和横流涡激主导频率可能脱离激励区,主导模态转移到高阶,同时主导频率发生阶跃增加;②立管横向位移均方根最大值是增加还是减少取决于横向涡激主导频率是接近还是远离涡脱频率;③当横流向涡激振动主导模态不变时,由于内流效应可以降低系统刚度,顺流向的静态位移随着内流速度的增加而逐步增加,当横流向主导模态转移至高阶时,顺流向的拖曳力系数会发生突然减少导致静态位移呈现阶跃性下降;④内流效应对顺流向振动有着不可忽略的影响。立管顺流向振动响应是内流效应、拖曳力(受横流向涡激响应影响)和顺流向涡激流体力联合作用的结果。Due to great increase in aspect ratio,the flexibility of deep-sea risers is enhanced and their internal flow effect(IFE)is prominent.However,IFE in in line(IL)-cross flow(CF)coupled vortex induced vibration(VIV)of deep-sea riser has not been well understood.Here,using a semi-empirical time-domain VIV hydrodynamic model,the lateral-longitudinal coupled vibration equations of a deep-sea riser under uniform ocean currents were established,and solved using finite element method to explore the IFE of riser in IL-CF coupled VIV under different internal flow velocities,internal flow densities and ocean currents.The study showed that when ocean current velocity and internal current density are constant,①IFE can reduce natural frequencies of the system,with increase in internal flow velocity,dominant frequencies of IL and CF vortex excitations may detach from excitation zone,and dominant modes transfer to higher orders while dominant frequencies increase jumply;②whether the maximum RMS value of riser lateral displacement increases or decreases depends on whether the dominant frequency of CF vortex excitation is close to or far from vortex shedding frequency;③when the dominant mode of riser CF VIV remains unchanged,system stiffness can be reduced due to IFE,and IL static displacement gradually increases with increase in internal flow velocity;when CF dominant mode transfers to a higher order,the IL drag coefficient can suddenly decrease to cause jump decrease in static displacement;④IFE has an undeniable impact on riser IL vibration,riser IL vibration response is the results of combined action of IFE,drag force affected by CF VIV,and IL vortex turbulence force.

关 键 词：内流效应(IFE) 横流向(CF) 涡激振动(VIV) 主导模态转移 顺流向静态位移 顺流向振动响应 

分 类 号：TE835[石油与天然气工程—油气储运工程]