Analysis of Wake Induced Dynamic Stall on Wind Turbine Blades

研究由上游涡轮机尾迹或大气边界层波动引起的非定常流入条件下风力机叶片的动态失速现象。在项目的第一阶段，对风力机尾迹进行了分析，重点分析了叶尖和轮毂的涡流。根据大涡模拟对尾迹进行了预测。主动控制被用来激励湍流尾迹中的不稳定模式，以最小化风电场装置中涡轮叶片上的动态载荷。风力机叶片上非定常载荷的一个主要来源是流动分离，这种情况经常发生在上游安装的涡轮机或大气湍流产生的尾迹引起的非定常流入条件下。也就是说，需要详细的风力机叶片动态失速数据，以便将动态失速模型扩展到摄动进气条件和旋转布局。这项建议的目的是提高对典型风力涡轮机应用的动态失速现象的理解和建模。此外，还分析了动态失速对尾迹湍流的影响。这一知识将使更准确地预测结构负荷和风力涡轮机的功率输出。采用基于贴体和非结构混合结构笛卡尔网格的大涡模拟方法研究涡轮叶片的动态失速，从而准确地捕捉到包括边界层增长、分离、向湍流过渡和流动再附着在内的流动特征。动态模式分解将被用来分析失速时和尾流动力学中发生的各个模式。这些模拟补充了达姆施塔特大学和达姆施塔特大学进行的测量。Oldenburg通过自适应弯度减少动态失速影响，也适用于扫掠条件。此外，还将对柏林理工大学的风力涡轮机模型进行模拟。

Dynamic stall phenomena on wind turbine blades generated by unsteady inflow conditions from upstream turbine wakes or atmospheric boundary layer fluctuations will be investigated. In the first project phase, wind turbine wakes were analyzed with the focus on the tip and hub vortices. The wake was predicted based on large-eddy simulations. Active control has been applied to excite unstable modes in the turbulent wake to minimize dynamic loads on turbine blades in wind farm installations. A major source of unsteady loads on wind turbine blades is flow separation which frequently happens under unsteady inflow conditions caused by wakes generated by upstream installed turbines or atmospheric turbulence. That is, detailed data of dynamic stall on wind turbine blades are necessary to extend dynamic stall models to perturbed inflow conditions and rotating configurations. The objective of this proposal is to improve the understanding and modeling of dynamic stall phenomena for typical wind turbine applications. In addition, the influence of dynamic stall on the wake turbulence will be analyzed. This knowledge will enable more accurate predictions of structural loads and the power output of a wind turbine. The dynamic stall on the turbine blade will be investigated by large-eddy simulations based on hybrid structured body-fitted and unstructured Cartesian meshes, such that the flow features including boundary layer growth, separation, transition to turbulence and flow reattachment can be captured accurately. Dynamic mode decomposition will be used to analyze the individual modes occurring at stall and in the wake dynamics. These simulations complement the measurements conducted by the TU Darmstadt and Univ. Oldenburg to reduce dynamic stall effects by an adaptive camber also for sweep conditions. Furthermore, simulations for the wind turbine model from the TU Berlin will be performed.