微型扑翼飞行器扑翼/尾翼气动干扰的数值研究

以二维刚性约束条件下的微型扑翼飞行器模型为研究对象,在动网格技术基础上,应用非定常数值分析手段对比分析了单翼/纵列翼布局的气动性能,深入研究了纵列翼缩减频率、扑翼—尾翼无量纲水平间距、来流攻角对其气动性能的影响.结果表明:①纵列翼尾翼对扑翼产生正效应干扰,相对于单翼布局,扑翼—尾翼无量纲水平间距为0.5倍翼型弦长时的纵列翼布局的推力系数和推进效率分别增加28.7%和5.7%;②缩减频率是影响推力的关键参数,随着缩减频率的增加,脱落涡的强度增加,推力系数增大.对于单翼、纵列翼两种布局模式,当缩减频率在1.0附近时推进效率达到最优;③对于纵列翼布局,在扑翼—尾翼无量纲水平间距为1.1倍翼型弦长时推进效率达到峰值;④在0°~20°来流攻角变化范围内,随着来流攻角的增加,升力系数增加,推力系数减小,当来流攻角大于9°时,两种布局的推力均为负值. 

Numerical study of flapping wing/tail aerodynamic interaction for flapping wing micro air vehicle

Taking the two-dimensional rigid flapping wing micro air vehicles model as research object, the aerodynamic characteristics of both single wing and tandem wing configurations were numerically evaluated. The numerical analysis methodology was transient and based on the dynamic grid technology. Simulation was conducted on the influence of reduced frequency of tandem wing, flapping wing to tail dimensionless horizontal distance and angle of attack on the aerodynamic performance. Results show that: (1) The tail of tandem wing is beneficial to the overall aerodynamic performance. Compared with the single wing configuration, the thrust coefficient and propulsive efficiency of tandem wing configuration are increased by 28.7% and 5.7% when the flapping wing to tail dimensionless horizontal distance is half of the wing length, respectively. (2) Reduced frequency is the key parameter that significantly influences the thrust. The higher reduced frequency strengthens the vortex-shedding and then results in an increase in thrust coefficient. The propulsive efficiency of single and tandem wings approaches maximal value when reduced frequency is about 1.0. (3) For the tandem wing configuration, the propulsive efficiency is optimized when the wing to tail flapping dimensionless horizontal distance is 1.1. (4) As the angle of attack increases from 0 degree to 20 degree, the lift coefficient increases and the thrust coefficient decreases. The flapping wing of the two configuration is predominated by drag at the moment angle of attack being 9 degree.