Vertical-Axis Wind Turbine Blade Vibration Modeling for Improved Reliability

要实现到2030年风能占美国能源的20%的目标，就需要一个多样化的风能收集器。各种风格和越来越大的风力涡轮机将需要安装在各种环境中，包括海上。大型涡轮机的维护和维修成本很高，而且需要大量的停机时间，因此对廉价风能的开发构成了挑战。目前，水平轴风力涡轮机（HAWTs）是最受欢迎的类型，其次是垂直轴风力涡轮机（VAWTs）。阻碍vawt发展的一件事是它们有振动和疲劳问题的名声。这种声誉是在现代叶片材料发展之前建立起来的。但是vawt有一些重要的优势。这些包括独立的风向，减少塔的尺寸，更低的质量中心，和更低的发电机放置。此外，HAWT的大小可能受到重力的限制。此外，当放置在风力发电厂阵列中时，VAWT的效率也会提高。因此，vawt可能更适合一些应用，包括大型海上设施，因此重新引起人们的兴趣。迄今为止，vawt的建模深度远不及hawt。这些情况都需要更好的VAWT模型，包括VAWT叶片振动。本工作的目的是建立VAWT叶片振动模型，并利用该模型了解VAWT叶片参数对振动的作用，为今后设计可靠的VAWT提供依据。本工作将建立h转子VAWT叶片的振动模型。h型转子叶片的简单几何形状使工作重点放在VAWT功能的复杂力学上。该模型将包括非线性梁理论和非线性气动力的半经验模型。对模型的初步了解表明，存在参数激励和直接激励以及非线性，所有这些都可以相互作用，产生各种共振和不稳定性。降阶建模和渐近分析将导致共振和不稳定性的识别。关键情况将进行更深入的数值模拟。研究结果将有助于了解VAWT叶片的共振机制和不稳定性，以及参数的作用，从而提出提高可靠性、降低维护成本和减少停机时间的设计建议。

Meeting the goal of 20 percent US energy by wind by 2030 will require a diverse fleet of wind energy harvesters. Wind turbines of various styles and of increasing size will need to be installed in a variety of environments including off shore. Maintenance and repair of very large turbines can be costly and involve significant down time, thereby challenging the development of affordable wind energy. Currently, horizontal-axis wind turbines (HAWTs) are the most popular type, with vertical-axis wind turbines (VAWTs) being the next most common. One thing that has hindered the development of VAWTs is their reputation for having vibration and fatigue problems. This reputation was established well before the development of modern blade materials. But VAWTs have some important advantages. These include independence of wind direction, reduced tower size, lower center of mass, and lower generator placement. Furthermore, HAWT size may be limited by gravity. Also, VAWT efficiency improves when placed in wind-farm arrays. Thus, VAWTs may turn out to be better for some applications, including large off-shore installations, and are therefore getting renewed interest. To date, VAWTs have been modeled in much less depth than HAWTs. These circumstances all converge to the need for better models for VAWTs, including VAWT blade vibration. The purpose of this work is to develop a model for VAWT blade vibration, and to use the model to understand the role of VAWT blade parameters on vibration, to enable the design of reliable VAWTs in the future. In this work, vibration models of H-rotor VAWT blades will be formulated. The simple geometry of H-rotor blades allows the work to focus on the complexity of the mechanics of VAWT function. The model will include nonlinear beam theory and a semi-empirical model of the nonlinear aerodynamic forces. Preliminary insight into the model suggests the existence of parametric and direct excitation, and nonlinearity, all of which together can interact to produce a variety of resonances and instabilities. Reduced-order modeling and asymptotic analysis will lead to identification of resonances and instabilities. Critical cases will be simulated numerically in more depth. The result will be an understanding of the mechanisms of resonances and instabilities of VAWT blades, as well as the role of parameters, leading to design recommendations for increased reliability, reduced maintenance costs, and less down time.