The application of biomimetic principles to enhance wind-turbine and micro aerial vehicle performance in gusty environments

风力涡轮机和微型飞行器（MAV）设计的进步目前受到各自叶片和机翼上的非定常、阵风诱导结构载荷的限制。通过研究动物在不稳定环境中如何游泳和飞行，可以实现对阵风性能的改进。这种仿生研究利用了数百万年的进化优化。一个优雅的例子是海鸥翅膀的高效拍动、形状和灵活性，所有这些都是动物在大风环境中生存的基础。本文提出了一项关于阵风场对分离的、旋涡结构形成的影响的研究。旋涡结构被描述为叶片或机翼周围由强非定常和粘性效应主导的区域。这种非定常的分离流动通常由相干涡结构主导，这对叶片和机翼的瞬时载荷有极大的影响。本次考试将使用一系列数值和实验技术进行，包括比例自适应模拟（SAS）、粒子图像测速（PIV）和三维粒子跟踪测速（3D-PTV）。以最简单的纵向阵风为例，它可以沿叶片/机翼的跨度产生快速但不均匀的入射角变化，从而产生具有强三维性的分离区域。在过去，关于向心和科里奥利贡献的旋转对这些分离区域内的横向流动的影响也有很大的推测。因此，目前的研究计划希望通过研究日益复杂的三个方面，即纵横比的影响，旋转的影响，最后是展向灵活性的影响，来揭示这些涡旋流的潜在物理特性。预计一旦问题的这些基本方面得到正确理解，未来的风力涡轮机和MAV叶片/机翼的形状、结构和材料就可以进行改进。

Advancements in wind-turbine as well as Micro Aerial Vehicle (MAV) design are currently limited by the unsteady, gust-induced structural loadings incurred on their respective blades and wings. By studying how animals swim and fly in unsteady environments, improvements to gust performance can be achieved. Such biomimetic research takes advantage of millions of years of evolutionary optimization. One elegant example is found in the efficient flapping kinematics, shape and flexibility of seagull wings, all of which are fundamental to the animal's survival in gusty environments. An investigation into the influence of gust fields on the formation of separated, vortical structures - described as regions around the blade or wing dominated by strong unsteady and viscous effects - is proposed here. Such unsteady, separated flows are often dominated by coherent vortex structures, which are known to affect instantaneous blade and wing loadings tremendously. This examination will be undertaken using an array of numerical and experimental techniques including Scale-Adaptive Simulations (SAS), Particle Image Velocimetry (PIV) and Three-Dimensional Particle Tracking Velocimetry (3D-PTV). The simplest case of a longitudinal gust can generate a rapid yet non-uniform change in incidence along the span of a blade/wing, thus generating separated regions with strong three-dimensionality. In the past there has also been great speculation as to the influence of rotation - both centripetal and Coriolis contributions - on the spanwise flows within these separated regions. Therefore the current research program looks to uncover the underlying physics of these vortical flows by examining three aspects of increasing complexity, i.e. the influence of aspect ratio, the influence of rotation and finally, the influence of spanwise flexibility. It is expected that once these fundamental aspects of the problem are properly understood, advancements to future wind-turbine and MAV blade/wing shapes, structures and materials can be undertaken.