四涡系统构建及其特性的实验研究

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。

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

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 instability of the wake vortex is triggered by the secondary vortex in advance, resulting in the premature breakdown of the primary 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.