扑动轨迹对扑翼气动特性影响的数值研究

国内外对扑翼飞行的气动性能进行了大量研究,这些研究大多针对特定运动轨迹下的扑翼,然而大量观察发现,昆虫在飞行时其翅膀会出现各种不同的运动形式,这些不同的翅膀运动方式必定对其气动性能产生重要影响。该文基于对昆虫的实验和数值模拟中常用的几种扑动轨迹模型分析,建立了三种具有相同准稳态气动力的扑翼扑动轨迹,并采用数值求解N-S 方程的方法,研究了前飞状态下不同扑动轨迹对扑翼气动特性产生的影响。结果显示扑动和转动均为简谐函数轨迹形式的扑翼具有较高的升举效率和推进效率。进一步通过对不同扑动轨迹扑翼流场分析得出,扑动轨迹不能改变扑翼产生的尾流性质,但可以影响涡的强度,从而使扑翼产生不同的气动性能。

NUMERICAL STUDY ON THE EFFECT OF KINEMATICS OF A FLAPPING WING ON ITS AERODYNAMIC PERFORMANCE

The kinematics of flapping wings has strong influence on their aerodynamic performance. However, most previous studies focus on wings under specific flapping kinematics. In this paper, the effects of kinematics of a forward flight wing on its aerodynamic performance were studied. Three types of flapping kinematics with identical quasi-steady aerodynamic forces were considered, and the flow fields of the wings were obtained by solving the N-S equation using the finite volume method. Results showed that wings with simple harmonic translation and rotation displacement presented enhanced lifting and propulsive efficiency. By examining the flow field of different kinematic wings, similar patterns of vortex were observed in the wake with different strength, which led to different aerodynamic performance of the wings.