Abstract: In order to study the triggering conditions of the intersecting instability of the flap wingtip vortex and the main-wing vortex， the rectangular wing model is used to generate a pair of wingtip vortices with different flap widths and attack angles and the optimal vortex parameters for triggering R-L (Rayleigh-Ludwig) instability are investigated within 35 wingspans. The flow visualization experiments show that the single main-wing vortex has not changed significantly at 35th wingspan， and the energy attenuation is very slow. The wake flow instability is activated after the flap installation and the main-wing vortex energy dissipates much more quickly with the increase of the flap attack angle in certain extent. The PIV (particle image velocimetry) analysis (statistical radius for the wake flow circulation [Rd]=50mm) has found that the wake flow energy dissipates most quickly while the main-wing attack angle α=8°， the flap attack angle β=28°， the flap width b=55mm and the flow velocity V=0.5m/s， and the main-wing’s 35th wingspan vortex circulation reduced to the 28% of 1st wingspan. The aircraft wake flow can be controlled effectively by installing the suitable flaps and the fracture and dissipation of the main-wing vortex can be accelerated.

Key words: Wingtip vortex；Instability；Flow visualization；Particle image velocimetry；Circulation

摘要： 为了研究襟翼小涡与主翼尖涡相交不稳定性触发条件，采用矩形机翼模型产生一对翼尖涡，同时在机翼上安装不同宽度及攻角的襟翼，对35个翼展下诱发R-L(Rayleigh-Ludwig)不稳定性的最佳涡系参数组合进行了研究。结果表明:通过水槽流动显示实验发现，单主翼尾涡在第35个翼展处未发生明显变化，能量衰减缓慢；加装襟翼后尾流不稳定性被触发，衰减效果明显，在一定范围内尾涡能量衰减值随着襟翼攻角的增大而增大；环量统计半径[Rd]=50mm时，对主翼尖涡环量进行PIV(Particle Image Velocimetry)分析时发现，当主翼攻角α=8°，襟翼攻角β=28°，襟翼宽度b=55mm，来流速度V=0.5m/s时尾涡能量消散最快，主翼尖涡环量在第35个翼展时衰减为第一个翼展的28%；证实通过安装合适的襟翼可以有效地控制飞机尾流，加速其破裂和消散。

关键词: 翼尖涡；不稳定性；流动显示；粒子图像测速；环量