迎角对扑翼运动气动性能影响的高性能数值研究

Numerical study of high performance on the influence of angle of attack on aerodynamic performance of wing flapping

为了设计更高效、高机动性的扑翼飞行器,需要对扑翼运动机理进行细致的动力学研究。其中,迎角是影响扑翼运动气动性能的关键因素。本文结合格子Boltzmann法与Level-Set动边界识别法,建立了含有动边界的流场模拟方法,并采用GPU加速,数值研究了迎角对扑翼运动气动性能的影响。结果表明:增大迎角,扑翼运动的升阻比呈现先增大后减小的趋势,当迎角θ=10°时,能够获得最佳气动性能。θ=0°~40°范围内,随着迎角的增大,扑翼翼尖处的上下翼面压差比翼根、翼中处大,在翼尖处提供了更大的升力。随着迎角的增大,扑翼的前缘涡附着于翼面的面积明显增大,扑翼后方脱落的涡旋也较难耗散,提高了扑翼的升力;同时,翼尖涡的强度和影响范围变大,增加了扑翼的阻力。

In order to design a more efficient and highly maneuverable flapping-wing aircraft, it is necessary to conduct meticulous aerodynamics research on the flapping-wing motion mechanism. The angle of attack is a key factor affecting the aerodynamic performance of a flapping-wing motion. Based on the Lattice Boltzmann method and the Level-Set moving boundary recognition method with the GPU acceleration, this work carries out the aerodynamic performance of flapping-wing with the angle of attack(θ) from 0° to 60°. The results show that with increasing of θ,the lift-to-drag ratio of the flapping-wing increases and then decreases.Whenθ=10?,flapping-wing exhibits the best aerodynamic performance.In the range ofθ=0?~40?,with increasing of θ,the pressure difference between the upper and lower wing surfaces at the tip of the flapping-wing is greater than that at the root and middle of the wing,which provide greater lift force at the wing tip.As the θ increasing,the area where the leading edge vortex attaches to the wing surface increases,and the vortices that fall off behind the flapping-wing are also difficult to dissipate,which lead to the increasing of the lift force of the flapping-wing.At the same time,the strength and range of influence of the wingtip vortex become larger,which lead to the increasing of the drag force of the flapping-wing.