Aerodynamic Instabilities of Thin-walled Structures for Driving Novel Energy Harvesters - Numerical Simulation Method, Physical Effects and Analytical Model

气动弹性现象，如颤振是主要相关的轻型工程结构，如飞机机翼和桥梁的设计。这些线状结构具有大致保持其形状的横截面，并且它们被设计成不会颤振。相比之下，能量收集的新概念是基于从经历弯曲的气动弹性不稳定薄壁结构中提取能量。这些被设计成具有低颤振起始风速，并且它们表现出大的横截面变形。影响这些元件动态响应的重要因素是大气湍流和几何非线性。在实际应用中，感兴趣的参数是起始风速、可提取能量和结构需求。为了详细研究这种和许多其他类似结构的基本流体-结构相互作用机制，量化影响行为的重要参数并促进系统的优化，需要分析模型。在这里，涡粒子法（VPM）的基础上的数值模拟方法应开发，耦合几何非线性结构动力学有限元公式与VPM的边界元法的一个新的扩展，从而占固体界面几何形状的大变形。此外，还应应用大气湍流建模的最新发展，以便能够说明自然风的阵风。该方法将被开发和实施的一种通用的方式，允许应用到其他问题，如轻型屋顶结构。这里，新的电磁能量采集器的概念将被用作参考对象。原型模型将在风洞中进行测试，以验证模拟方法。在试验过程中将详细测量结构的动力响应。然后，将使用数值模型来量化关于收割机的效率和结构需求的相关方面。最后，一个新的分析模型的量化的薄壁结构上的自诱导流体动力的发展，这扩展了Scanlan导数的概念。该模型将允许简化的分析稳定性分析，并促进对影响系统行为的参数的研究。

Aeroelastic phenomena such as flutter are of major relevance for the design of light engineering structures such as aircraft wings and bridges. These line-like structures have cross sections that approximately retain their shape and they are designed not to flutter. In contrast, novel concepts of energy harvesting are based on extracting energy from aeroelastically unstable thin-walled structures that undergo bending. These are designed to have a low flutter onset wind speed and they exhibit large cross sectional deformations. Important factors influencing the dynamic response of these elements are atmospheric turbulence and geometric nonlinearities. Parameters of interest in the context of practical applications are onset wind speed, extractable energy and structural demand. In order to study the underlying fluid-structure interaction mechanisms of such and many other similar structures in detail, to quantify the important parameters influencing the behaviour and to facilitate an optimisation of the system, analysis models are required. Here, a numerical simulation method on the basis of Vortex Particle Methods (VPM) shall be developed, which couples a geometrically nonlinear structural dynamics Finite Element formulation with a new extension of the Boundary Element Method of the VPM, thus accounting for large deformations of the solid interface geometry. Further, recent developments for modelling atmospheric turbulence shall be applied, in order to be able to account for the gustiness of the natural wind. The method will be developed and implemented in a generalised manner that allows the application to other problems such as light roof structures. Here, the concept of a new electromagnetic energy harvester shall be used as a reference object. Prototype models will be tested in the wind tunnel in order to validate the simulation methods. The dynamic response of the structure will be measured in detail during the tests. The numerical model will then be used to quantify relevant aspects with regard to efficiency of and structural demand on the harvester. Finally, a new analytical model for the quantification of the self-induced fluid dynamic forces on thin-walled structures shall be developed, which extends the concept of Scanlan Derivatives. This model would allow simplified analytical stability analyses and facilitate studies of parameters influencing the system behaviour.