基于流固耦合偏航下风力机尾迹湍流特征的研究

偏航状态下风力机叶片与流场之间相互作用会导致风力机近尾迹流场的湍流特征变化,采用双向流固耦合对不同偏航工况下水平轴风力机近尾迹流场进行数值模拟研究,获得不同偏航角下尾迹湍流特征演化规律。结果表明：随着偏航角的增大,正偏航侧会出现“速度亏损圆环”,且此圆环的范围呈扩大趋势;偏航角的增大对叶根处速度亏损影响最大,对叶尖处速度亏损影响最小,与正偏航侧相比,负偏航侧的速度亏损值减为约1/2;随着偏航角的增大,正负偏航侧的湍流强度变化呈不对称性,正偏航侧对湍流耗散的影响程度较负偏航侧大;涡流黏度越来越小,且在偏航10°涡流黏度相对于偏航5°减小约1/2,沿着轴向叶尖涡的管状环涡结构变得不稳定,出现明显耗散,且在偏航15°之后涡结构的耗散破裂程度越来越剧烈,进而对风力机气动噪声产生较大影响。

RESEARCH ON TURBULENCE CHARACTERISTICS OF WIND TURBINE WAKE UNDER YAW CONDITION BASED ON FLUID-STRUCTURE COUPLING

The near wake flow field of the horizontal axis wind turbine under different yaw conditions was studied by numerical simulation method with two-way of fluid-solid coupling due to the interaction between the wind turbine blades and the flow field will lead to the change of the turbulence characteristics of the wind turbine near the wake in the yaw state. And the evolution law of the wake turbulence characteristics under different yaw angles was obtained. The results showed that speed loss ring was presented on the positive yaw side with the increasing of yaw angle and the range of this ring expanded continually. Meanwhile, the velocity loss at the blade root was affected significantly by yaw angle increasing, on the contrary, the velocity loss at the blade tip was few impacts. Compared with the positive yaw side, the velocity loss at the negative yaw side was reduced to a half. The variation of turbulence intensity on the positive and negative yaw side displayed an asymmetric variation when yaw angle was increased, while the influence of the turbulence dissipation positive on the positive yaw side was obvious than that of negative yaw side. The eddy viscosity became smaller gradually and the eddy viscosity at the position of 10° yaw angle was decreased half of that at the yaw angle was 5° position. The tubular circular vortex structure along the axial tip vortex became unstable and dissipated obviously, and the degree of dissipation breakdown of the vortex structure was more intensive after 15° yaw angle which resulted in a great impact on the aerodynamic noise of the wind turbine.