来流湍流度对翼尖双涡系统不稳定演化的影响机理研究

飞机尾涡是由于飞行时机翼上下表面压力差所导致的一种大尺度涡结构，因它对周围空气的强烈诱导，会对经过其后方的飞机造成尾迹遭遇灾害。削弱尾涡强度、加速尾涡衰减一直是飞机设计和研究人员所追求的目标。然而，现有研究缺乏对更贴近工程实际飞行条件和参数条件下的尾涡不稳定演化的研究，导致无法进一步加快尾涡的衰减破碎。在此背景下，本项目将以考虑不同湍流度来流条件下的翼尖双涡系统为研究对象，通过时间解析的体式PIV实验技术和全局线性稳定性分析方法揭示中、远场尾迹区内双涡系统不稳定时空演化机理和发展机制。进一步地，针对典型涡对强度和间距参数配比，在不同来流湍流度下，通过层析PIV实验和DMD模态分解方法揭示双涡系统的衰减机理，并结合体式PIV实验结果建立预测尾涡衰减的物理模型。项目的预期成果对认识双涡系统的不稳定演化、衰减破碎具有重要意义，同时还可为指导尾涡耗散装置研发，缩短飞机起降间隔提供理论支撑。

The trailing vortex is a large-scale vortex structure caused by the pressure difference between the upper and lower surfaces of the wing of an aircraft. Its strong induction effect on the surrounding air will bring about the wake encounter problem where the following aircraft is passing through. Therefore, aircraft designers and researchers always aim to weaken the trailing vortex and accelerate it. However, it should be recognized that the investigation of the instability mechanism on the trailing vortex closer to the engineering practice is still insufficient and inadequate, which makes it full of challenges to attenuate the trailing vortex more effectively. Aiming at revealing the spatio-temporal instability mechanism, the dual-trailing vortex system generated under different turbulence levels is considered in this program. The time-resolved stereo particle image velocimetry (SPIV) and time-resolved PIV technology are adopted to experimentally measure its flow field up to middle and far wake. The global linear stability analysis is performed to calculate its instability characteristics. In further, the proper orthogonal decomposition (POD) and dynamic modal decomposition (DMD) methods are used to reveal the underlying decay mechanism by analyzing the characteristics of POD modes and DMD modes of vortex pairs under different flow configurations with different turbulence intensities, circulation ratios and separated distance ratios of vortex pair. The expected results of this project are of great significance for understanding the instability mechanism of the dual-trailing vortex system and providing theoretical support for guiding the design of vortex waken device, which can also contribute to further shortening the take-off and landing interval of aircraft.