海上浮式风机平台弱非线性耦合动力响应分析

Analysis on weak nonlinear coupled dynamic response of floating offshore wind turbine platform

为了准确有效地预报海上浮式风力机载荷与运动响应,本文针对系泊平台系统提出一种弱非线性间接时域方法。风力机平台遭遇的入射波作用力和静水恢复力直接在瞬时湿表面上积分计算获得;散射力采用线性势流理论处理;平台系泊力由悬链线方程计算得到。以OC3-Hywind spar风力机平台为对象进行了计算与分析,与线性方法相比,弱非线性方法得到的幅值响应算子(response amplitude operator,RAO)更大,且能够反映波浪力和恢复力与平台响应的相互影响。由于考虑了瞬时湿表面的影响,弱非线性方法计算结果更为合理,可以更好地反映大波高海况的波浪力特征,因而更加适合高海况下的平台运动性能分析。

To accurately and effectively predict the load and motion responses of a floating offshore wind turbine,a weak nonlinear indirect time-domain method is proposed for the mooring platform system. This method obtains a nonlinear Froude-Krylov force and nonlinear restoring force on an instantaneous wetted surface. Scattering forces are obtained by linear potential flow theory,and mooring force is calculated by the Catenary equation. The computation model is the OC3-Hywind spar platform. Compared with linear method,the RAO obtained by weak nonlinear method is larger. In addition,the method can also reflect the interaction between wave force,resilience,and platform response. Considering an instantaneous wetted surface makes the weak nonlinear method more reasonable. This method can better reflect the characteristics of the wave forces under a sea condition with large wave amplitude;therefore,it is more suitable for platform motion performance analysis under a high sea state.