The presented investigation is motivated by the need to uncover connections between underlying rotor fluid–structure interactions and vortex dynamics to fatigue performance and characterization of flexible rotor blades, their hub, and their supporting superstructure. Towards this effort, temporal stability characteristics of tip vortices shed from flexible rotor blades are investigated numerically. An aeroelastic free-vortex wake method is employed to simulate the helical tip vortices and the associated velocity field. A linear eigenvalue stability analysis is employed to quantify stability trends (growth rate v. perturbation wavenumber) and growth-rate temporal evolution of tip vortices. Simulations of a canonical rotor with rigid blades and its generation of tip vortices are first conducted to validate the stability analysis employed herein. Next, a stationary wind turbine is emulated using the National Renewable Energy Laboratory (NREL) 5-MW reference wind turbine base design to investigate the impact rotor aeroelasticity has on tip-vortex stability evolution in time. Blade flexibility is shown to reduce the sensitivity of tip vortex destabilization to low wavenumber perturbations, also blade-pitch reduces growth-rate magnitude and alters the growth-rate peak dependence on perturbation wavenumber, all of which have in the past not been reported in the rotorcraft literature. The presented investigation aims to develop insight into the tip vortex kinematics and stability of the NREL 5-MW reference wind turbine. However, the frameworks presented herein can be applied to generalized rotor designs to work towards identifying the impact tip-vortex kinematics and stability have on fatigue loading and adverse blade–vortex interaction effects, such as excessive noise emission and rotor vibrations.

本研究的动机是需要揭示潜在的转子流体－结构相互作用以及涡流动力学与疲劳性能之间的联系，并对挠性转子叶片，其轮毂及其支撑上层结构进行表征。为此，从数值上研究了从挠性转子叶片脱落的尖端涡流的时间稳定性特征。采用气动弹性自由涡旋唤醒方法来模拟螺旋尖端涡旋和相关的速度场。线性特征值稳定性分析用于量化稳定性趋势（增长率与扰动波数）和尖端涡旋的增长率随时间的变化。首先进行具有刚性叶片的规范转子的仿真及其尖端涡的生成，以验证本文采用的稳定性分析。接下来，使用美国国家可再生能源实验室（NREL）5兆瓦参考风力发电机基础设计对固定风力发电机进行仿真，以研究转子的空气弹性对尖端涡旋稳定性的影响。叶片的柔韧性已显示出可降低尖端涡旋失稳对低波数扰动的敏感性，并且叶片桨距降低了增长率幅度，并改变了增长率峰值对扰动波数的依赖性，而在过去，这些均未见报道。旋翼飞机文献。提出的调查旨在深入了解NREL 5兆瓦参考风力涡轮机的尖端涡旋运动学和稳定性。然而，