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，以及大型和小型涡轮机的气动驱动振动。建议的研究项目是对垂直轴风力机的空气动力学进行研究。这里的重点是中、高稠度水轮机，在这些水轮机中，可以使用较高的凝固度来降低涡轮机转速，降低噪音，并更好地避免共振振动。然而，较高的凝固度会导致涡轮机和叶片周围的流动非常复杂，包括：叶片攻角大、动态失速和大量流动分离、叶片-尾流相互作用以及涡轮机周围风的非均匀分流。这些流动产生的非定常气动载荷具有既能提供涡轮机动力又能激发振动的部件。我的团队是世界上仅有的两个研究振动激励和涡轮机功率的团队之一，尽管涡轮机振动一直是VAWTs广泛使用的主要障碍。该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更低振动、更高效率的涡轮机。 该研究计划将使用两种方法：风洞测试和计算流体力学模拟，这两种方法都面临着重大的研究挑战。风洞测试将在3.5千瓦的大型涡轮机上进行，因为较小模型的性能高度依赖于它们的大小。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的基础上，并将受益于我们之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性质的复杂性，大规模的数值模拟必须使用大量的计算资源。 拟议的研究计划将首次深入调查一系列相互关联的基本涡轮机参数，包括叶片展宽比、涡轮机展宽比和涡轮机坚固性，以及它们复杂且往往相互竞争的空气动力影响。对涡轮机空气动力学的物理理解将被用来利用这些发现(例如，通过不对称叶片和第一次应用小翼)来提高动力效率和减少振动负荷，这最终将有助于实现用于可再生能源发电的VAWT。

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.