基于熵产理论的垂直轴风力机顺风向安装距离的研究

Research on the Along-wind Installation Distance of Vertical Axis Wind Turbine Based on Entropy Production Theory

针对顺风向垂直轴风力机(Vertical axis wind turbine,VAWT)安装距离问题,采用熵产理论,对VAWT进行模拟,分析了风轮表面的压力、风速和涡场分布。在尾迹区域施加控制面和控制线,研究了熵产分布情况,进一步计算出能量损失系数。结果表明:迎风面的上下缘速度大小不同,造成叶片上下缘出现正负压力;背风面因捕风效果使叶片上缘负压明显,涡量主要分布在叶片前后缘处;不同相位角下,VAWT叶片尾迹区相同距离下的熵产强度分布相似;在相同相位角下,随着尾迹区距离的增加,熵产强度逐渐降低;尾迹区面能量损失系数与线能量损失系数随距离变化基本一致,线能量损失系数结果值较高。在5倍风轮直径尾迹之后,面上能量系数降低到0.01以下。能量损失系数揭示出风能恢复情况,因此在VAWT尾部5倍旋转直径距离处可以获得有效风能。研究可为优化VAWT顺风向安装距离提供理论依据。

Aiming at the problem of installation distance of along-wind vertical axis wind turbine(VAWT),the entropy production theory is used to simulate VAWT,and the pressure,wind speed and vortex field distribution on the surface of the wind turbine are analyzed.The control surface and control line are applied to the wake region,the entropy production distribution is studied,and the energy loss coefficient is further calculated.The results show that:The different in velocity between the upper and lower edges of the windward side causes positive and negative pressure on the upper and lower edges of the blade;the leeward side causes significant negative pressure on the upper edge of the blade due to the wind-catching effect,and the vorticity is mainly distributed at the front and rear edges of the blade.Under different phase angles,the distribution of entropy production intensity in the wake region of VAWT blades is similar at the same distance;under the same phase angle,the entropy production intensity decreases gradually with the increase of the distance in the wake region.The surface energy loss coefficient in the wake region is basically consistent with the linear energy loss coefficient with distance,and the result value of the linear energy loss coefficient is higher.The surface energy coefficient is reduced to less than 0.01 after the wake of 5 times the wind turbine diameter.The energy loss coefficient reveals the wind energy recovery,so the effective wind energy can be obtained at the distance of 5 times the rotation diameter of the tail of the VAWT.The study can provide a theoretical basis for optimizing the installation distance of VAWT downwind.