Effect of pitch angle on power performance and aerodynamics of a vertical axis wind turbine
Effect of pitch angle on power performance and aerodynamics of a vertical axis wind turbine
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DOI：
10.1016/j.apenergy.2017.03.128
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发表时间：
2017-07
期刊：
影响因子：
11.2
通讯作者：
A. Rezaeiha;I. Kalkman;B. Blocken
中科院分区：
文献类型：
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作者：
A. Rezaeiha;I. Kalkman;B. Blocken
由于人们对海上和城市环境中的风能收集越来越感兴趣，垂直轴风力涡轮机（VAWT）最近重新受到关注。它们的全方位能力使它们成为一个非常有趣的选择，用于建筑环境中经常遇到的风向变化，而它们的可扩展性和低安装成本使它们非常适合海上风电场。然而，它们需要进一步的性能优化以与水平轴风力涡轮机（HAWT）竞争，因为它们目前具有较低的功率系数（CP）。这可以归因于VAWT周围的流动的复杂性以及它们所收到的研究量明显较少。桨距角是提高VAWT性能的一个潜在参数。本研究采用计算流体动力学（CFD）计算，研究了涡轮机上的载荷和力矩变化，以及作为桨距角函数的攻角、脱落涡量和边界层事件（前缘和后缘分离、层流到湍流转捩）。采用非定常雷诺平均纳维尔-斯托克斯（URANS）计算研究了-7 °至+3°的俯仰角，同时采用4方程转捩SST模型模拟湍流。结果表明，在叶尖速比为4时，桨距角为−2°时，CP可增加6.6%。此外，还发现桨距角的变化会使涡轮机的逆风部分和顺风部分之间的瞬时负载和力矩发生变化。在不同的俯仰角旋转过程中的瞬时力矩的变化表明，动态俯仰可能是一个非常有前途的方法，为进一步的性能优化。
Due to growing interest in wind energy harvesting offshore as well as in the urban environment, vertical axis wind turbines (VAWTs) have recently received renewed interest. Their omni-directional capability makes them a very interesting option for use with the frequently varying wind directions typically encountered in the built environment while their scalability and low installation costs make them highly suitable for offshore wind farms. However, they require further performance optimization to become competitive with horizontal axis wind turbines (HAWTs) as they currently have a lower power coefficient (CP). This can be attributed both to the complexity of the flow around VAWTs and the significantly smaller amount of research they have received. The pitch angle is a potential parameter to enhance the performance of VAWTs. The current study investigates the variations in loads and moments on the turbine as well as the experienced angle of attack, shed vorticity and boundary layer events (leading edge and trailing edge separation, laminar-to-turbulent transition) as a function of pitch angle using Computational Fluid Dynamics (CFD) calculations. Pitch angles of −7° to +3° are investigated using Unsteady Reynolds-Averaged Navier-Stokes (URANS) calculations while turbulence is modeled with the 4-equation transition SST model. The results show that a 6.6% increase in CPcan be achieved using a pitch angle of −2° at a tip speed ratio of 4. Additionally, it is found that a change in pitch angle shifts instantaneous loads and moments between upwind and downwind halves of the turbine. The shift in instantaneous moment during the revolution for various pitch angles suggests that dynamic pitching might be a very promising approach for further performance optimization.