多段翼绕流中前缘缝道旋涡结构的时间演化与频率特性研究

多段翼是大型民用客机上常用的增升装置，其前缘缝道流动中的旋涡结构与客机的气动力和气动声学特性密切相关。现有研究已从前缘缝道流动中提取了多种典型旋涡结构，但缺乏对旋涡结构时间演化与频率特性（时频特性）的认识，并且尚未掌握雷诺数、翼型攻角等对时频特性的影响规律。因此，本项目拟采用实验测量和数值模拟等手段对前缘缝道中旋涡结构的时频特性开展研究。通过时间解析粒子图像测速（PIV）与尺度自适应模拟（SAS）分别获取前缘缝道流动在较低与较高雷诺数下的时间解析速度场，综合运用模态分解、旋涡识别以及小波分析等多种数据后处理技术分析旋涡结构的时频特性，探讨雷诺数和翼型攻角对时频特性的影响规律，进而为大型民用客机的气动力和气动声学特性优化与控制提供依据。

As a traditional high-lift configuration, the multi-element airfoil is extensively employed in large passenger aircrafts for lift augmentation. The gap flow between the leading-edge slat and the main element contains complex vortical structures and could affect the aerodynamic and aeroacoustic performances of large passenger aircrafts prominently. Although classical vortical structures have been identified from gap flows, the understanding of their joint time-frequency properties is lacking. In addition, the effects of Reynolds number and angle of attack on the joint time-frequency properties have not yet been revealed. This proposal therefore intends to investigate the joint time-frequency properties of the vortical structures in gap flows via experimental measurements and numerical simulations. PIV and SAS are employed to obtain the time-resolved velocity fields of gap flows at low and high Reynolds numbers, respectively. The combined analyses of modal decomposition, vortex identification method and wavelet transform are then used to demonstrate the joint time-frequency properties of vortical structures, finally revealing the effects of Reynolds number and angle of attack on these joint time-frequency properties. It is hoped that the current proposal could provide theoretical references to the aerodynamic and aeroacoustic optimizations of large passenger aircrafts.