前缘旋转风力机的风能吸收机理研究

It is essential to conduct fundamental research on the effective absorption of wind energy production, in order to reduce China's dependence on the foreign suppliers of technology, lower the costs and promote the independent development of China's wind power industry. However, in the modern wind turbines, some aviation airfoils are still quite frequently used.The operating environment of the wind turbines has the features of low wind speed and sudden changes in wind speed and direction. Therefore, based on the physical mechanism of wind energy absorption, design of airfoils specifically suited for wind turbine blade application is important for improving the wind energy utilization coefficient of wind turbines. For conventional airfoils, the lift coefficient of the airfoil will increase with the increase of the angle of attack. When a specific angle of attack is reached, flow separation begins to occur and results in a rapid reduction of the lift coefficient of the airfoil. Even controlled by varying pitch or speed, some areas of the turbine blade still operate at large angles of attack, and thus the flow separation is difficult to avoid. This project proposes a new type of wind turbine blade which has a rotating cylinder at the leading edge. This kind of blade can not only use the Magnus effect for propulsion, but also simultaneously delay the onset of flow separation and stall to a higher angle of attack. As a result, both the lift coefficient and lift to drag ratio of this new turbine blade can be greatly increased. In-depth study on control mechanism and wind energy absorption mechanism of this kind of airfoil can significantly increase the wind power utilization coefficient.

开展风能吸收机理的基础性研究,对改变我国在风能利用技术上严重依赖进口的现状和降低成本，促进我国风能产业的自主发展有着重要的意义。目前,风力机叶片翼型大多是从传统的航空翼型演化而来的，而风力机叶片的运行环境具有风速低、风速风向多变等特点。因此,从物理本质上研究风能吸收机理,设计新型风力机专用翼型将有助于提高风能利用率。对于常规翼型，当攻角开始增大时，翼型上的升力系数会随攻角的增大而增大，但当攻角大到一定值时，就可能会出现流动分离现象，导致翼型升力系数迅速下降，即使采用变桨或变速调控，叶片上某些部位的攻角仍然可能很大，流动分离难以避免。本项目提出一种前缘带旋转圆柱的新型风力机叶片，研究其气体动力学的基本原理。此前缘旋转翼型能够在利用Magnus效应的同时有效推迟翼型失速攻角，大幅度地提高翼型的升力系数及升阻比，深入研究这种前缘旋转翼的流动控制机制与风能吸收机理，可以显著地提高风能利用率。

1.探究了一种在稳态求解器下分析翼型静力和静转矩的方法，进而研究平板、NACA0012 、NACA23012翼型空气动力稳定性。.2. 提出了一种专用于升力型垂直轴风力机的基于空气动力稳定性翼型正向设计方法。将翼型的基本参数与风轮的尺寸相关联，让翼型的参数随着风轮实度改变。.3.研究了一种前缘附加旋转圆柱的NACA0015、NACA6系和S809翼型气动性能。设计了具有最佳气动特性的前缘旋转翼型的结构参数。.4.分析了不同安装角度、翼型、叶片弦长、叶片数、风速对VAWT功率的影响。分别建立基于NACA0015翼型和NACA6系列翼型的前缘旋转VAWT模型，仿真分析増升减阻和边界层分离抑制效果。.5.设计制作了多套前缘旋转VAWT模型样机，针对不同参数分别进行风洞吹风试验，验证了前缘旋转风力机的气动性能及流动控制特性。.通过研究，获得主要结论如下：.1.平板的偏离度和波动度最大，代表对称翼型的NACA0012具有全程更稳定的cm和在TSR为2和5时比较稳定的cd，NACA23012代表的带弯度翼型在所有运作过程中具有更稳定的cl。.2. NACA0012-800mm、LJY-800mm、LJY-200mm 能正常运行。当载荷增加， NACA23012停转。LJY-800mm 比NACA0012-800mm 产生更低湍流值。LJY-200mm加速要比LJY-800mm慢，但能达到更高速度和获得更高功率系数。.3. NACA001X系列翼型未加前缘圆柱，当叶片安装角为5°，弦长140mm，叶片数3，NACA0015时VAWT能获得最优的气动性能。针对NACA0015，当控制前翼型弦长为1000mm时，前缘旋转圆柱间隙为3.2mm，圆心位于距前缘25%弦长处的翼型具有较好的气动性能，且该新型VAWT风能利用率能达到0.334。基于上述结构特征，换成NACA6系列翼型时，加旋转圆柱后效果最为显著的翼型是最低压力点距离前缘相对值为30%，设计升力系数为0.8，翼型的相对厚度为20%。.4. 通过烟线法发现，在风力机翼型S809前缘施加旋转圆柱能够有效抑制流动分离。但对于这类结构，精确测量升阻力及叶片表面压力分布是相当有难度的，因为旋转圆柱的不平衡总会存在。.5.通过吹风试验，验证了前缘旋转圆柱对风力机性能有一定的提升作用，垂直轴风力机功率输出有一定程度的提高，平均提升7.4%