Aeroelasticity and unsteady aerodynamics at low reynolds numbers

气动弹性学研究的是柔性结构与其周围流体的相互作用。结构物周围的流动会在其上产生力，如果结构物是柔性的，它会变形，随后改变流动，等等，直到达到某种类型的平衡状态。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，其他许多问题仍然存在。例如，机翼的持续振荡有时会在没有任何明显的外部原因的情况下发生。这非常类似于一阵风穿过窗户时威尼斯百叶窗的飘动运动。飞行的昆虫和鸟类也由于其灵活的翅膀而经历流体弹性相互作用。然而，与大多数人类设计相反，这些相互作用通常对动物的飞行能力产生积极影响。本研究旨在通过简单但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，这是非常适合无人驾驶航空器（UAV）和更大的和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.