H型垂直轴风力机实时高效攻角调节方法研究

Study on the Real time and Efficient Adjustment Law for H-Type Vertical Axis Wind Turbine

叶片攻角是影响垂直轴风轮气动特性最重要的因素之一。针对一种1 kW H型对称翼垂直轴风力机,以获取最大风能利用率为目的,得到了叶片在上风区和下风区应保持的理论最佳攻角分别为10.7°和-10.7°。鉴于现有风轮运行一周过程中,叶片攻角呈类正弦规律变化,未能保持在理论最佳值附近;同时由于风轮上风区和下风区的诱导速度分布规律不同,故提出采用分风区的方法研究实时高效攻角调节规律。首先利用双致动盘多流管理论计算出上风区叶片攻角的变化情况,建立叶片安装角与攻角的关系,通过调节安装角使叶片攻角在上风区保持在理论最佳值附近。考虑到下风区流场分布复杂,采用数值模拟方法确定下风区各个方位诱导速度的大小和方向。在此基础上,提出风轮下风区局部叶尖速比的概念,建立下风区叶片攻角的精确计算公式,并获得下风区叶片理论最佳攻角的调节策略。最后利用双致动盘多流管理论对提出的上风区和下风区叶片攻角的调节规律进行了验证。计算结果显示:在额定风速下,与原始风轮相比,调节攻角后H型垂直轴风轮的风能利用率提高了11.03%。

Angle of attack of blade is one of the most important factors that affect the aerodynamic characteristic of a vertical axis wind rotor. For a kind of 1 kW H-type vertical axis wind turbine with symmetric airfoil, the theoretical optimum angles of attack 10.7°and-10.7°of upwind area and downwind areas of wind rotor are determined for the purpose of obtaining the maximum utilization rate of wind power of the wind wheel. For the existing wind rotor, the change law of blade angle of attack is similar to the sine curve, not in the vicinity of an optimum value, and so the blade angle of attack needs to be adjusted real-time. First, the change of blade attack angle in the upper wind area is calculated based on the multi flow management theory of double actuated disk. And the relationship between blade installation angle and angle of attack is established. By adjusting the installation angle, the blade angle of attack is maintained at a reasonable value in the upwind area. Considering the complex flow field in the downwind area, the sizes and directions of induction velocity various orientation are obtained by using numerical simulation method. Based on it, the concept of local tip speed ratio in downwind area is presented, the calculation formula of blade angle of attack is established in the downwind area, and the adjustment law of blade angle of attack is also obtained. Finally, based on the Multi flow management theory of double actuated disk, the calculation results show that the utilization rate of wind power of the wind rotor can be increased by 11.03% by the real-time adjustment law of blade angle of attack proposed in this paper compared with the original wind turbine.