垂直轴风力机自适应柔性叶片流动控制机理研究

Suppressing or mitigating dynamic stall caused by drastic and periodic change of attack angle is one of the most critical but challenging factors for VAWTs which could help to reduce the aerodynamic load fluctuation and improve aerodynamic efficiency. Moreover, it is the key point to produces adequate advantages of VAWTs, such as large-scale of structure easily. VAWT works in frequent change natural wind conditions and large scale unit is affected by multi-scale factors. In addition, air flow becomes more unstable under the interactive influences of shedding vortex, tip vortex, wake vortex and some other complex fluid dynamic effects. In terms of the reasons mentioned above, flexible aerodynamic films attaching on blade surface are applied. Fluid and solid response interaction are used to achieve self-adaptive flow control and suppress overall stall. Sturdies will mainly focus on the themes listed as below: ① dynamic interactions mechanism between the vertex structure and flow around airfoil induced by the flexible film self-adaptive deformation; ② optimization of the characteristic factors of the film, such as material selection, arrangement, shapes; ③ the mechanism of action of flexible films to increase the efficiency and load stability of VAWTs. On the basis of the above investigation, some meaningful results, that can be provided to contribute the method of blade design which could introduce high efficiency, reduced load and high stability to VAWTs. These will be the foundation of promoting VAWTs airfoil/blade design and its large scale development. It is considered to have promising future for blade design and unit upgrade.

抑制或减缓攻角周期性大幅变化导致的动态失速, 是解决垂直轴风力机载荷波动大、气动效率低，从而发挥其固有最易大型化结构优势的关键与重要挑战。考虑复杂自然风况频繁变化及大型化多尺度因素，针对大分离流动下脱落涡、叶尖涡、尾迹涡等相互干涉而形成的非稳定流动，提出在叶片表面布置柔性气动弹片，实现流态变化与结构响应的双向信息传递，以达到叶片自适应控制流动从而抑制失速的目的整体效果。为此开展如下研究：①柔性气动弹片自适应变形诱导涡结构与叶片绕流流场动态干涉机理；②柔性气动弹片材料特性、布置方式、几何形状与参数等特征因素优化；③柔性气动弹片提高垂直轴风力机效率及载荷稳定性的作用机理。最终形成高效、低载、稳定的垂直轴风力机新型叶片设计理论与实现方法，为推动垂直轴风力机翼型/叶片设计理论及其大型化提供新的基础支撑，研究成果对新机组叶片设计及现役机组升级改造均具有广阔的应用前景。

目前我国正处在从风电制造大国到强国又一次跨越的关键时期。垂直轴风力机本质上的结构特点使其具有诸多优越性。如， ①受风多向性，无需复杂的偏航装置，系统复杂性低，结构简单，叶片易加工，运动部件少，适应风速范围大、环境多样； ②地面安装，重心低系统稳定，便于安装和维修，成本低； ③ 受力恒定性，寿命长、易于大型化； ④环保与生态优势。.然而，垂直轴风力机因其特有的运动形式导致其运行过程中存在大幅度的流动分离，致使其风能利用率损失较大。抑制或减缓攻角周期性大幅变化导致的动态失速,是解决垂直轴风力机载荷波动大、气动效率低，从而发挥其固有最易大型化结构优势的关键与重要挑战。.项目组考虑了复杂自然风况频繁变化及大型化多尺度因素，针对大分离流动下脱落涡、叶尖涡、尾迹涡等相互干涉而形成的非稳定流动，提出在叶片表面布置柔性气动弹片，实现流态变化与结构响应的双向信息传递，以达到叶片自适应控制流动从而抑制失速的目的整体效果。为此开展如下研究：①柔性气动弹片自适应变形诱导涡结构与叶片绕流流场动态干涉机理；②柔性气动弹片材料特性、布置方式、几何形状与参数等特征因素优化；③柔性气动弹片提高垂直轴风力机效率及载荷稳定性的作用机理。.本项目通过对垂直轴风力机复杂流场的获取与控制，表明气动弹片改善流动分离与涡脱落的显著效果及作用特点。项目组最终形成了一套高效、低载、稳定的垂直轴风力机新型叶片设计理论与实现方法，为推动垂直轴风力机翼型/叶片设计理论及其大型化提供新的基础支撑，研究成果对新机组叶片设计及现役机组升级改造均具有广阔的应用前景。.