具有组合式叶片的导流型垂直轴风力机气动性能的数值研究

Numerical Investigation on Aerodynamic Performance for Guiding VAWT with Combined Blades

在分析传统垂直轴风力机低效率原因的基础上阐述导流型垂直轴风力机的结构优势,并提出一种带组合式叶片的导流型垂直轴风力机,同时数值研究该垂直轴风力机的气动特性。这种垂直轴风力机由导风轮与风轮构成,其中导流叶片分别由进口径向段、出口导流段,以及与两者相切的中间圆弧段等三段组合而成,风叶是由进口圆弧段及与之相切的出口直线段组合而成。导流叶片不仅可以有效地降低因来流对风叶吸力面的直接冲击而造成的阻力转矩,而且还有助于增强来流对风叶压力面的有效冲击。这两方面均有助于使该种风力机风轮的旋转转矩得到显著增加。研究结果表明:这种带有组合式叶片导流型垂直轴风力机,具有工作范围宽、最佳尖速比大、风能利用率高等特点,其气动性能在数值上已明显超过常规垂直轴风力机的一般水平。在此基础上,将机翼型叶片引入导流型垂直轴风力机中,并数值论证了即使在这种变攻角、剧烈分离的垂直轴风力机的内部流场中,机翼型叶片对整个风力机性能的提高也能起到一定的作用。这种带有组合式叶片的导流型垂直轴风力机不仅具有较好的气动性能,而且具有简单的二维外形结构便于加工,具有推广使用的潜力。

On the basis of the analysis of the cause for low efficiency of the traditional vertical axis wind turbine（VAWT）,the structure advantage of a new type of VAWT—Guiding VAWT is introduced.On that basis,a new blade shape called as combined blade for Guiding VAWT is proposed and numerical investigation is completed on its aerodynamic performance by computational fluid dynamics（CFD） technique.The guiding VAWT includes two components：Guiding impeller and rotating impeller,both are combined blade in shape.The guiding blade is composed of three sections,namely,radial section at inlet,linear section at outlet and the arc section tangent to the above two sections.The rotor blade consists of two sections： Arc section at inlet and linear section tangent to the arc section at outlet.The guiding impeller can not only prevent the rotating impeller from direct impact by the coming flow on its suction section of the blade so as to decrease the drag torque,but also improve the effective impact by the coming flow on the pressure section of the blade,both of which contributes to the enhancement of the driving torque of the wind turbine.Results indicate that the new type of guiding VAWT with combined blade has a wider operating range,higher aerodynamic efficiency than the traditional VAWTs.Moreover,the aerofoil blade is introduced into this new type of VAWT and the validation is numerically obtained that even though the flow inside the VAWT is a large separated flow with variable attack angles,the aerodynamic advantages of the aerofoil shape blade can still be shown,to some extent,which helps to enhance the aerodynamic efficiency of the VAWT.Furthermore,this new type of VAWT has an essentially planar structure,which is convenient for manufacture and has the potential of popularization.