四涡系统构建及其特性的实验研究

Four-vortex system reconstruction and experimental study of its wake features

飞机尾涡是与升力相关的固有流动现象,威胁着机场附近的飞行安全,同时也限制了机场使用效率。在矩形机翼翼尖以一定方式安装涡流发生器,产生与主涡旋向相反的小涡,来构建一种具有自我消散机制的四涡系统,能实现尾涡集中能力的快速消散。结合流动显示和粒子成像测速(PIV)测量,探索了在不同的参数匹配下,下游25个翼展范围内该四涡系统的空间发展过程、涡量发展曲线,以及45个翼展范围内主涡环量的衰减程度。实验结果表明,受小涡诱导,尾涡出现了相交不稳定性,主涡提前破裂,涡量随之降低。当小涡和主涡的初始环量比为-0.581、初始距离比为0.5时,45个翼展范围内,主涡环量衰减34.7%。该实验结果为低尾流机翼的设计提供了一定的参考。

The aircraft wake vortex is a coherent flow phenomenon due to the lift generation mechanism, which threatens the flight safety and limits airport operation efficiency. By mounting a vortex generator onto the wingtip of a rectangular airfoil, a secondary vortex that rotated reversely to the primary vortex is produced, thereby constructing a self-destructed four-vortex system to accelerate the dissipation of the primary vortex. Combined with flow visualizations and particle image velocimetry （PIV） measurements, a parametric study of the spatial evolution and vorticity development of the four-vortex system in 25 wingspans, as well as the circulation reduction rate in 45 wingspans, is conducted. The results exhibit that the interaction in- stability of the wake vortex is triggered by the secondary vortex in advance, resulting in the premature breakdown of the pri- mary vortex, resulting in the decline of its vorticity. As the initial circulation ratio is -0. 581 and the initial distance ratio is 0.5, the circulation of the primary vortex is reduced most significantly （34.7 % ） in 45 wingspans. The results would provide a scheme for the design of airfoils with weaker vortices.