考虑纵摇工况的漂浮式海上风机尾流特性数值研究

Numerical Analysis of Wake Characteristics for Floating Offshore Wind Turbine Under Pitch Motion

海上风-浪-流的存在使得海上风力机平台会产生六个自由度方向的运动。为研究纵摇运动对海上风力机尾流特性的影响,基于OpenFOAM平台,采用RANS方法的k-ε模型和重叠网格技术,考虑风剪切来流和简化的漂浮式平台六自由度运动条件,对纵摇状态下的风力机尾流进行数值研究。研究结果表明,纵摇工况下的风力机尾流恢复速度更快,且尾流恢复速度会随着纵摇运动的频率和幅值增加而增加。当纵摇运动的振幅较小时,近场尾流的风速恢复会受到一定的影响,而对远场尾流影响不大;当振幅较大时,纵摇运动会加速全部尾流区域的风速恢复,并出现更为明显的扩散现象。研究结果对揭示漂浮式海上风电机组纵摇运动下尾流产生和扩散的机理有一定的意义,为完善漂浮式海上风电场尾流损失模型提供了一定的物理基础。

Floating offshore wind turbine platform experiences the motions of six degrees-of-freedom due to the existence of offshore wind-wave-stream.In order to study the effect of the wake characteristics of offshore wind turbines under pitch motion,this research concentrated the investigation of the wind turbine wake under pitch motion by using RANS method of k-εmodel and overset grid technique based on OpenFOAM,simulating the wind shear flow conditions and simplifying the floating platform six-degrees-of-freedom movement.The results revealed that the wake recovery speed of wind turbine under pitch condition was faster,and the wake recovery speed increased with the increase of pitch motion frequency and amplitude.The wind speed recovery of the near-field wake was affected to some extend when the amplitude was small,while the far-field wake was not affected.When the amplitude was larger,the pitch motion accelerated the wind speed recovery in all wake areas,and more obvious diffusion occurred.These results revealed the mechanism of wake generation and diffusion under the pitch motion of floating offshore wind turbine,and provided a certain physical basis for improving the wake deficit model of floating offshore wind farms.