垂直轴风力机动态特性及气动性能

垂直轴风力机流场属典型的非定常大分离流动,因其气动性能复杂,采用工程气动模型会有较大误差.为了研究垂直轴风力机动态失速与翼型附着涡的形成与发展,针对4种不同厚度的NACA对称翼型系列,基于Fluent软件的滑移网格技术,并选用S-A湍流模型和基于压力的Simple算法对H型垂直轴风轮流场进行瞬态CFD计算,得到了风轮旋转中动态失速相位角范围,较好地解释了小叶尖速比下翼型多处于动态失速区的流动机理.同时,提出了升阻系数计算方法,计算得到了该4种翼型系列的叶片扭转力矩、风力机功率和风能利用系数随叶尖速比变化规律.研究结果表明,风力机运行中翼型的动态与静态特性存在较大差别,翼型厚度对风力机扭转力矩、功率和风能利用率具有较大影响.故在进行垂直轴风力机设计时应综合考虑垂直轴风力机的翼型厚度等几何参数与旋转等动态参数对其气动特性的影响.

Dynamic characteristics and aerodynamic performance of vertical axis wind turbine

The flow field of a vertical axis wind turbine(VAWT)is a typical unsteady large separation flow, which exhibits strong dynamic characteristics. Because of the complexity of aerodynamic perfor-mance for VAWT,it will result in more errors when common engineering algorithms is used to estimate VAWT′s performance. Firstly, the transient flow fields of four NACA symmetric airfoil series on H-type VAWT with different thickness were calculated based on the sliding mesh technique. And the relationship between airfoil dynamic stall and bound vortex generation and development were studied in detail. The range of phase angle when rotor dynamic stall occurs has been obtained and simultaneously the flow mechanism in the airfoil dynamic stall zone was explained preferably at the small tip speed ratio conditions. At the same time, the results also show that airfoil dynamic and static characteristics are very different for a running VAWT, thus the lift-drag coefficient calculation method has been proposed. Secondly, it was also been calculated that the changing trends of four airfoils blade torsion moment, wind electrical power and wind energy utilization coefficient change with the tip speed ratio. The results show that the thickness of airfoil for the blade torsion moment, wind electrical power and wind energy utilization coefficient has great influence. Therefore, the influence of geometry parameters on aerodynamic characteristics should be consided, such as airfoil thickness and rotary dynamic parameter for the design and development of H-type VAWT.