Vertical-Axis Wind Turbine Blade Vibration Modeling for Improved Reliability

要实现到2030年美国风能占20%的目标，将需要一支多样化的风能收割机船队。各种类型和不断增大的风力涡轮机将需要安装在包括离岸在内的各种环境中。超大型涡轮机的维护和维修可能成本高昂，并涉及大量停机时间，因此对负担得起的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存在振动和疲劳问题的名声。这一声誉早在现代叶片材料开发之前就建立起来了。但VAWT也有一些重要的优势。这些因素包括独立于风向、减小塔身尺寸、降低质心和降低发电机位置。此外，HAWT的大小可能受到重力的限制。此外，VAWT的效率在放置在风电场阵列中时也会提高。因此，VAWT可能被证明更适合某些应用，包括大型离岸设施，因此重新引起了人们的兴趣。到目前为止，VAWTs的建模深度比HAWTs小得多。所有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变速行波管叶片振动模型，并利用该模型来了解变速行波管叶片参数对振动的影响，为今后设计可靠的变速行波管提供依据。在这项工作中，将建立H-转子VAWT叶片的振动模型。H-转子叶片的简单几何形状使工作可以集中在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。对模型的初步洞察表明，参数和直接激发以及非线性的存在，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。危急情况将进行更深入的数值模拟。其结果将是了解VAWT叶片的共振和不稳定机制以及参数的作用，从而为提高可靠性、降低维护成本和减少停机时间提供设计建议。

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.