Performance increase and improvement of the fatigue strength of vertical axis water turbines through active blade adjustment

Darrieus涡轮机是升力驱动的垂直轴交叉流风力和水轮机（VAWT）。涡轮的最佳工作范围是在2和5之间的叶尖速比（切向叶片与流速之间的比率）。它们可以成为利用风能、河流、海洋或潮汐能等可再生能源发电的有趣解决方案。与基于水平轴的系统相比，它们还提供了更高的区域开发效率。它们的功能与水流方向无关；它们可以很容易地被设想为一个模块化系统，这在经济上是有前途的。然而，涡轮内的流动是非常复杂的。到目前为止，还没有令人满意的分析模型，它的空气动力学行为，这将允许一个简单的设计可媲美水平轴涡轮（HAWT）。入射角、相对速度以及湍流特性随着转子的旋转角度而变化。这导致动态失速期间，每个革命的显著部分。通过主动俯仰迎角，由于抑制深度失速，可以显著提高效率和自启动能力。与HAWT不同的是，俯仰函数不仅取决于叶尖速比，还取决于旋转角度。这需要一个高度动态的控制系统，控制响应时间取决于转速。在一个涉及流体力学和电气驱动系统领域的跨学科项目中，将在两年内实现以下目标，并以实验为重点实施三个工作包：1。提高涡轮机的效率。减小载荷变化，提高抗疲劳性能更好地了解VAWT的流体力学，特别是关于动态失速的知识。基于实验的主动俯仰控制优化轨迹估计算法设计[j]。开发了一种新型的有限角度扭矩电机，具有薄而长的格式，允许在转子叶片中集成俯仰致动器。分散安装的执行机构应该允许更高的自由度，以提高涡轮效率。转矩电机能量消耗最小的高动态轨迹控制设计。

Darrieus turbines are lift driven vertical axis cross flow wind and water turbines (VAWT). The turbine’s best operation range is in a tip-speed-ratio between 2 and 5 (ratio between the tangential blade to flow speed). They can become an interesting solution for electrical power generation from renewable energy sources like wind, river, ocean or tidal energy. They also offer a significant higher efficiency in the area exploitation, compared to horizontal axis based systems. Their functionality is independent of the flow direction; they can easily be conceived as a modular system, which is economically promising. However, the flow in the turbine is very complex. Until now there exists no satisfying analytical model for its aerodynamical behavior, which would allow a simple design comparable to horizontal axis turbines (HAWT). The angle of incidence, the relative speed, and thus the turbulence properties change with the rotation angle of the rotor. This leads to dynamic stall during a noticeable part of each revolution. By actively pitching the angle of attack, the efficiency can be significantly raised, as well as the self-starting capability, due to the inhibition of deep stalling. In contrast to HAWT, the pitch function is not only depending on the tip-speed-ratio, but also on the rotation angle.This requires a highly dynamical control system, with control response times depending of the revolution speed. In an interdisciplinary project, involving the fields of fluid mechanics and electrical drive systems, the following objectives will be achieved in two years, implementing three work packages with experimental focus:1. Improving the turbine’s efficiency2. Improving the fatigue resistance by minimizing the load variations3. Getting a better knowledge of the fluid mechanics in VAWT, in particular concerning dynamic stall.4. Experimental-based design of an optimization algorithm to estimate the optimized trajectory for the active pitch control5. Development of a new class of Limited-Angle Torque Motor with a thin and long format allowing the integration of the pitch actuators in the rotor blades. The decentralized mounted actuators should allow a higher degree of freedom for the improvement of the turbine efficiency.6. Design of a high dynamic trajectory control with minimal energy cost for the torque motors.