The proper orthogonal decomposition (POD) has been applied on a full-scale horizontal-axis wind turbine (HAWT) to shed light on the wake characteristics behind the wind turbine. In reality, the blade tip experiences high deflections even at the rated conditions which definitely alter the wake flow field, and in the case of a wind farm, may complicate the inlet conditions of the downstream wind turbine. The turbine under consideration is the full-scale model of the NREL 5MW onshore wind turbine which is accompanied by several simulation complexities including turbulence, mesh motion and fluid-structure interaction (FSI). Results indicated an almost similar modal behaviour for the rigid and flexible turbines at the wake region. In addition, more flow structures in terms of local vortices and fluctuating velocity fields take place at the far wake region. The flow structures due to the wake shed from the tower tend to move towards the center and merge with that of the nacelle leading to an integral vortical structure 2.5D away from the rotor. Also, it is concluded that the exclusion of the tower leads to missing a major part of the wake structures, especially at far-wake positions.

翻译：采用本征正交分解（POD）方法对全尺寸水平轴风力机（HAWT）的尾流特性进行了分析。实际上，即使在额定工况下，叶尖也会产生显著变形，这必然改变尾流流场，并在风电场场景下可能使下游风力机的入口条件复杂化。研究对象为NREL 5MW陆上风力机的全尺寸模型，该模型涉及湍流、网格运动及流固耦合（FSI）等复杂仿真因素。结果表明，在尾流区域，刚性叶片与柔性叶片风力机呈现几乎相似的模态特性。此外，近尾流区域存在更多由局部涡旋和脉动速度场构成的流动结构。由塔筒脱落形成的尾流结构倾向于向中心移动，并与机舱尾流结构融合，在距转子2.5D处形成整体涡旋结构。研究还发现，忽略塔筒将导致丢失尾流结构的主要部分，尤其在远尾流区域。