小型飞行器空气动力学

AERODYNAMICS OF SMALL VEHICLES

对小型飞行器设计中涉及的空气动力学问题进行了综述。描述了雷诺数和展弦比对固定翼飞行器的设计以及飞行性能的影响。在低雷诺数飞行范围。翼型上边界层的特性对飞行器的设计尤为关键。本文讨论了大量有关层流边界层(包括层流分离泡影响)的实验,作为例子,列举了几个此飞行雷诺数范围的小型低空无人驾驶飞行器(UAVs)。此外,对扑动翼推进的理论模型进行了简述;其范围涵盖了早期的准定常附着流模型,以及后来计及非定常尾涡、流动分离以及气动弹性等效应的模型。文中还介绍了那些与理论互补并最终导致扑翼机设计成功的实验。

In this review we describe the aerodynamic problems that must be addressed in order to design a successful small aerial vehicle. The effects of Reynolds number and aspect ratio (AR) on the design and performance of fixed-wing vehicles are described. The boundary-layer behavior on airfoils is especially important in the design of vehicles in this flight regime. The results of a number of experimental boundary-layer studies, including the influence of laminar separation bubbles, are discussed. Several examples of small unmanned aerial vehicles (UAVs) in this regime are described. Also, a brief survey of analytical models for oscillating and flapping-wing propulsion is presented. These range from the earliest examples where quasi-steady, attached flow is assumed, to those that account for the unsteady shed vortex wake as well as flow separation and aeroelastic behavior of a flapping wing. Experiments that complemented the analysis and led to the design of a successful ornithopter are also described.