内孤立波与Spar型浮式风机平台耦合作用研究

Numerical Study on the Fluid-Structure Interaction of Internal Solitary Waves and a Spar-Type FOWT

针对内孤立波与系泊浮式平台的耦合作用问题,本文以单立柱Spar型浮式风机平台为研究对象,研究了平台在内孤立波作用下的耦合运动特性。利用重叠网格技术及自编耦合动力程序,以计算流体动力学求解Navier-Stokes流体控制方程,建立了Spar型浮式风机平台与内孤立波(Internal solitary waves,ISWs)流固耦合作用数值模型。通过系列数值模拟,研究了Spar型浮式风机平台在内孤立波作用下的水平动态载荷和纵荡、横荡规律。研究表明,内孤立波对Spar平台会产生较显著的水平作用力,并产生大幅的水平位移;在水深一定时,同一流体分层比下,随着内孤立波振幅提高,纵荡运动幅值增大;当振幅一定时,随着流体分层比的增大,纵荡幅值减小;通过调整系泊系统,发现非线性系泊系统下平台纵荡幅值要大于线性系泊系统下的情况,即线性系泊系统会低估纵荡运动幅值。

A Spar-type floating offshore wind turbine(FOWT) was taken as the example to investigate its motion performance in action of Internal solitary waves(ISWs) considering the fluid-structure interaction effects.A numerical model of fluid-structure interaction between Spar floating fan platform and internal solitary waves was established by solving Navier Stokes fluid governing equations by computational fluid dynamics using overlapping grid technology and self-programmed coupled dynamic program.Through a series of numerical simulation,the horizontal dynamic load and the rules of pitch and transverse swing of Spar type floating fan platform under the action of internal solitary wave are studied.The research results show that the internal solitary wave will produce sudden horizontal load on the Spar platform and produce a large surge motion;when the water depth is constant and the same fluid stratification ratio,with the amplitude of the internal solitary wave increasing,the amplitude of the surge motion increases;when the amplitude is constant,with the increase of the fluid stratification ratio,the amplitude of the surge motion decreases;by adjusting the stiffness of the mooring system,it is found that the amplitude of the surge motion of the platform under nonlinear stiffness is greater than the case of linear stiffness,that is,the linear stiffness system will underestimate the amplitude of swaying motion.