偏航工况下叶片翼型动态特性研究

STUDY ON DYNAMIC CHARACTERISTICS OF BLADE AIRFOIL UNDER YAW CONDITION

首先通过理论分析,研究风力机偏航运行时叶片各翼型的攻角变化规律,建立翼型俯仰运动模型;然后基于大涡模拟(LES)方法,研究偏航工况下叶片翼型的动态气动特性。结果表明:风轮在偏航工况下运行时,叶片各截面翼型攻角变化呈近似的正余弦规律;叶片不同展向位置翼型均发生不同程度的流动分离,出现动态失速现象,越靠近叶根,由偏航引起的动态迟滞效应越明显;翼型俯仰过程中,吸力面前缘分离泡的动态变化过程,导致吸力面前缘压力出现小范围的剧烈振荡,增大流动的不稳定性。

Though theoretical analysis,the variation rules of attack Angle of each blade airfoil during yaw operation were studied,and the airfoil pitch movement model was established.Then,the dynamic aerodynamic characteristics of the blade airfoil under yaw conditions were studied based on the LES method.The results showed that the attack angle of each blade section was changeable with approximate sine or cosine regularity when the wind turbines are running under yaw conditions.Different degrees of flow separation occurred with different spanwise positions of the blades,appeared dynamic stall phenomenon,and closer to the blade root,the dynamic hysteresis effect was becoming more obvious.The dynamic change of the separation bubbles of suction-side front edge leads to the pressure of which have vicious oscillation in small areas,which increases the instability of the flow.