扑翼柔性及其对气动特性的影响

以往对扑翼气动特性的研究基本上都是基于简单的匀速刚性模型，但是通过大量观察不同飞鸟的扑翼动作发现，该模型与鸟翼的实际扑动还有很大差别。鸟翼不但上扑段和下扑段所需时间不同，而且在扑动过程中，鸟翼的形状无论沿弦向或展向都存在着相当大的柔性变形。本文在原有匀速刚性模型的基础上，加入了扑动速率变化和形状变化的影响，得出新的变速柔性扑翼分析模型，使之更接近鸟翼柔性扑动的真实情况。通过对比计算发现，柔性变形对扑翼的升力与推力都有着显著影响，如果控制得当，柔性变形能大大改善扑翼的气动性能。

Flexibility of flapping wing and its effect on aerodynamic characteristic

In former studies of flapping wing,the change of flapping velocity and the deformation of wing are ignored.This paper defined a new trans-speed factor to take into account change of flapping velocity,and build up a deform model of flapping wing which considered the deformation along span and chord respectively on the base of observation the deformation of birds wing.So a new flexible flapping wing model is developed,which can simulate the actual bird's fly better than former rigid flapping wing model.To find a flapping wing that is more suitable for MAV,the aerodynamic forces of flapping wing before and after deformation were computed using unsteady vortex lattice method.It is found that the wing's flexibility will affect the aerodynamic characteristic of flapping wing seriously.The deformation along span is useful to increase lift,while twist along chord is helpful to enlarge thrust,if controlled properly.