风力机翼型失速胞动态及非稳定演化机理研究

The flow stage near stall angle is key to aerodynamic performance of airfoils with the increase of angle of attack. Aerodynamic parameters of airfoils are unstable and have more values than one at a specific angle of attack, with the evolution of stall cell, which is unsafe to wind turbine blades under operation. A research routine is put forward to solve the above problems. That is developing a theory to estimate the unsteady aerodynamic loads by creating a new method that describes dynamic performance of airfoils. The information of boundary layer transition and flow separation will be measured by PIV, hot-wire anemometer, and dynamic pressure acquiring equipment with high sample frequency. The experimental data are used to analyze the instability of flow and to reveal the production and evolution of stall cell on airfoils. Moreover, the disturbances that cause the flow field change from one status to another will be distinguished; and then, methods to control the unstable flow will be worked out. Based on the method that describes dynamic performance of airfoils, the theory to calculate unsteady aerodynamic performance of wind turbine blades is developed. The investigation is aimed to reveal the correlation between unstable separation at large angle of attack and boundary layer transition and dynamic stall, firstly. Secondly, the candidates expect to disclose the mechanism that how the flow nearby the stall of airfoils become unstable and what makes the flow status change from one to another. Lastly, the study is hope to reveal the effect of flow separation and instability of airfoils at large angle of attack on the safety of blades. These results will contribute to improve the basic theories of fluid dynamics against the challenges in the future of wind power technologies and to develop the integrated design system of wind turbine blades.

失速附近的流动状态是翼型气动特性随攻角变化的关键阶段。伴随着失速胞的演化，翼型气动参数出现多值性及非稳定性，对风电叶片的安全运行造成极大影响。针对该问题，提出通过建立表征翼型动态气动性能的新方法从而发展叶片非定常气动载荷评估理论的研究思路。拟利用PIV、热线风速仪及高频动态压力采集设备测量翼型边界层转捩及流动分离信息，结合数值方法及非稳定分析理论，研究翼型失速胞的产生及动态演化机理，探索失速附近非稳定分离的诱导因素及控制方法，建立翼型动态特性的表征方法，进而改进叶片非定常气动评估理论。预期澄清边界层转捩、动态失速等流动现象与大攻角非稳定分离的相关性；揭示风力机专用翼型失速附近流动稳定性及平衡状态转换的机理；揭示翼型大攻角流动分离及非稳定特性对叶片安全特性的影响机理。研究结果将为解决未来风力发电技术挑战中的流体力学关键基础问题以及建立大型风电叶片一体化设计体系，提供新思路、方法与技术积累。

针对失速附近翼型流动状态的非定性及其导致的叶片气动载荷问题，本项目提出通过建立表征翼型动态气动性能的方法从而发展叶片非定常气动载荷评估理论的研究思路。研究翼型失速胞的产生及动态演化机理，探索失速附近非稳定分离的诱导因素及控制方法，建立翼型动态特性的表征方法，进而改进叶片非定常气动评估理论。已针对多种相对厚度的翼型进行了实验研究、数值模拟及初步理论分析，获得了翼型的动态特性并建立了叶片动态模拟方法。流动控制、叶片设计及载荷分析等部分研究成果，已经进行成果转化，进行批量应用。