Aerodynamics of vertical axis wind turbines

风力涡轮机利用的两个主要工程限制是功率性能，特别是对于较小的涡轮机，以及对于大型和小型涡轮机两者的空气动力学驱动的振动。建议的研究计划是垂直轴风力涡轮机（VAWTs）的空气动力学的调查。这里的重点是中等和高稠度涡轮机，其中较高的稠度可用于降低涡轮机转速，降低噪音并更好地避免共振。然而，较高的凝固度导致通过涡轮机和叶片周围的非常复杂的流动，包括：高叶片攻角、具有大量流动分离的动态失速、叶片-尾流相互作用以及涡轮机周围的风的不均匀转向。来自这些流的非定常空气动力学载荷具有既提供涡轮机功率又激发振动的分量。尽管涡轮机振动一直是VAWT广泛使用的主要障碍，但我的小组是世界上仅有的两个检查振动激励以及涡轮机功率的小组之一。这项研究计划的目标是增加对这些涡轮机周围流动的了解，并利用这些流动来生产低振动，高效率的涡轮机。 该研究计划将使用两种方法：风洞测试和计算流体动力学模拟，这两种方法都面临着重大的研究挑战。风洞试验将使用3.5 kW大型涡轮机进行，因为小型模型的性能高度依赖于其尺寸。这项研究将建立在我的团队在涡轮机测试方面的成熟经验基础上，并将受益于我们以前开发的大型研究涡轮机和相关测量系统。由于旋转几何形状和流动的性质，大规模的数值模拟必须使用大量的计算资源。 拟议的研究计划将是第一个彻底研究一系列相互关联的基本涡轮机参数的项目，这些参数包括叶片展弦比、涡轮机展弦比和涡轮机实度，以及它们复杂且经常相互竞争的空气动力学效应。对涡轮机空气动力学的更好物理理解将用于利用这些发现（例如，通过不对称叶片和首次应用小翼），以提高功率效率并减少振动负载，这将最终有助于VAWT用于可再生能源发电的实施。

Two of the main engineering limits on wind turbine utilization are power performance, particularly for smaller turbines, and aerodynamically driven vibration for both large and small turbines. The proposed research program is an investigation of the aerodynamics of vertical axis wind turbines (VAWTs). Emphasis here is on medium- and high-solidity turbines where higher solidities can be used to lower turbine rotational speeds, reducing noise and allowing better avoidance of resonance vibration. Higher solidities, however, lead to very complex flows through the turbine and around the blades, including: high blade angles of attack, dynamic stall with massive flow separation, blade-wake interactions and non-uniform diversion of the wind around the turbine. The unsteady aerodynamic loads from these flows have components that both provide turbine power and excite vibrations. My group is one of only two in the world examining vibration excitation as well as turbine power even though turbine vibration has been the main impediment to the extensive use of VAWTs. The objectives of this research program are to increase understanding of the flows around these turbines, and exploit those flows to produce lower vibration, higher efficiency turbines.  The research program will use two approaches: wind tunnel testing and computational fluid dynamics simulations, both of which face significant research challenges. Wind tunnel testing will be done with a large 3.5 kW turbine as the behaviour of smaller models is highly dependent on their size. This research will build on my group's proven experience with turbine testing, and will benefit from our previous development of a large research turbine and associated measurement systems. Extensive computational resources must be used for the large-scale numerical simulations, which are complicated by the rotating geometry and the nature of the flows.  The proposed research program will be the first to thoroughly investigate a range of inter-related fundamental turbine parameters, including blade aspect ratio, turbine aspect ratio and turbine solidity, and their complex and often competing aerodynamic effects. The improved physical understanding of the turbine aerodynamics will be used to exploit these findings (e.g. through asymmetric blades and the first-time application of winglets) to increase power efficiency and reduce vibration loading, which will ultimately help the implementation of VAWTs for renewable energy generation.