Aeroelasticity and unsteady aerodynamics at low reynolds numbers

气动弹性学科研究的是柔性结构与其周围流体的相互作用。结构周围的气流会对结构产生作用力。如果这种结构是柔性的，它就会变形并随后改变流动，以此类推，直到达到某种平衡状态。一个典型的例子是飞机机翼进入大气湍流区域时的振动。这些气动弹性运动的许多方面是众所周知的。然而，其他许多项目仍然存在问题。例如，机翼的持续振荡可能发生，有时没有任何明显的外部原因。这非常类似于当一阵风吹过窗户时百叶窗的抖动动作。飞行的昆虫和鸟类由于其灵活的翅膀也经历了流体-弹性相互作用。然而，与大多数人类的设计相反，这些相互作用通常对动物的飞行能力有积极的影响。本研究旨在通过简单但具有代表性的模型来理解这些流体-弹性相互作用现象。它侧重于低空速飞行制度，这非常适合无人驾驶飞行器（UAV）和更大且非常灵活的高空长航时（HALE）飞机。

The discipline of aeroelasticity is concerned with the interaction of a flexible structure and its surrounding fluid. The flow around a structure will induce forces on it. If this structure is flexible, it will deform and subsequently modify the flow, and so on until some type of equilibrium state is achieved. A typical example is the vibrations of an aircraft wing as it enters a region of atmospheric turbulence. Many aspects of these aeroelastic motions are well known. Many others are, however, still problematic. For instance, sustained oscillations of a wing can occur, sometimes without any apparent external cause. This is very similar to the fluttering motion of venitian blinds when a gust of wind occurs through a window. Flying insects and birds are also experiencing fluid-elastic interactions due to their flexible wings. However and contrary to most human designs, these interactions often have a positive impact on the ability of the animal to fly. This research aims at understanding these fluid-elastic interactions phenomena via simple but representative models. It focuses on low airspeed flight regimes, which are well suited to unmanned air vehicles (UAV) and larger and very flexible high altitude long endurance (HALE) aircraft.