聚焦波下漂浮式风机气动特性数值分析

Numerical Analysis of Aerodynamic Characteristics of Floating Offshore Wind Turbine in Focused Waves

该文基于计算流体力学方法,对极端海况聚焦波作用下的漂浮式风机运动响应与气动特性进行研究。首先,依托开源软件OpenFOAM与自研求解器FOWT-UALM-SJTU,实现了面向双参数PM波浪谱聚焦波的数值模拟,并与试验结果进行比较验证,吻合良好。随后,在两种不同聚焦幅值工况下,以OC3 Spar型漂浮式风机平台及NREL 5 WM风机作为研究对象,开展气动-水动-系泊一体化仿真计算,对聚焦波作用下的漂浮式风机运动响应和气动性能进行分析。结果表明:聚焦波将引起风机在纵摇运动与垂荡运动时产生剧烈响应,风机叶片展向的气动攻角在聚焦时刻显著降低,风机气动功率与气动推力难以在短时间内恢复;同时,聚焦波将导致尾流中心和边界出现波动,极端波浪条件将扩大风机尾流速度亏损范围,对下游风机产生不利影响。

In this paper,the hydrodynamic motion response and aerodynamic characteristics of floating offshore wind turbine(FOWT)under extreme sea conditions are analyzed based on computational fluid dynamic method.Firstly,a method for generating focused wave by two parameters PM spectrum method has been developed in our own code FOWT-UALM-SJTU which is based on opensource software OpenFOAM.The results of numerical simulation have a good agreement with experiment.Following this,the OC3 Spar floating platform with NREL 5 MW wind turbine is simulated in two focused wave conditions by integrated coupling calculation of aero-hydrodynamics and mooring.The analysis focuses on the hydrodynamic motion response and aerodynamic performance.The results indicate that the focused wave induces significant responses in the pitch and heave motions,leading to a significant reduction in the aerodynamic attack angle of the turbine blades spanwise at focusing moment.Besides,the aerodynamic power and thrust of the turbine are challenging to recover within a short duration.Additionally,the focusing effect causes fluctuations in the wake center and boundary and enlarges the velocity deficit region in the wake zone under extreme wave conditions,which is not beneficial for downstream wind turbines.