CAJ | 학술논문

研究湍流边界层精细流动结构特征，有助于建立流动结构特征与壁面摩阻、流噪声之间的关联，从而为湍流边界层减阻降噪机理的深层次研究奠定基础。该文应用PIV（粒子图像测速）技术，对平板湍流边界层中发卡涡在流向-展向平面的涡迹特征进行研究。利用PIV瞬时速度场，捕捉到明显的低速条带，通过统计分析获得对数层范围低速条带间距随壁面法向距离的变化以及雷诺数的影响规律。同时，通过涡识别准则，提取在流向-展向平面内长低速条带两侧的反向漩涡带，揭示了发卡涡包与长低速条带的内在关系。此外，还研究了流向-展向平面发卡涡涡腿间距随壁面法向距离的变化规律以及雷诺数的影响。
연구단류변계층정세류동결구특정，유조우건립류동결구특정여벽면마조、류조성지간적관련，종이위단류변계층감조강조궤리적심층차연구전정기출。해문응용PIV（입자도상측속）기술，대평판단류변계층중발잡와재류향-전향평면적와적특정진행연구。이용PIV순시속도장，포착도명현적저속조대，통과통계분석획득대수층범위저속조대간거수벽면법향거리적변화이급뢰낙수적영향규률。동시，통과와식별준칙，제취재류향-전향평면내장저속조대량측적반향선와대，게시료발잡와포여장저속조대적내재관계。차외，환연구료류향-전향평면발잡와와퇴간거수벽면법향거리적변화규률이급뢰낙수적영향。
The analysis of detailed flow structure of a turbulent boundary layer is of great significance for establishing the link among the detailed flow structure characteristics, flow noise and wall friction, which can help lay the foundation for deeper research of the drag and noise reduction mechanism. PIV (particle image velocimetry) technique is applied in this paper to study the hairpin vortex signatures in the streamwise-spanwise plane in turbulent boundary layer flow on a flat plate. The experiment successfully identifies low-speed streaks from PIV instantaneous velocity field and the distributions of spanwise spacing of low-speed streaks along with wall-normal distance and Reynolds number are obtained through statistical analysis in the logarithmic layer. Meanwhile, the counter-rotating vortices surrounding the long low-speed streaks in the streamwise-spanwise plane are extracted through vortex identification criterion, which reveals the relationship between hairpin packets and long low-speed streaks. Besides, this paper performs a research about the distribution of spanwise spacing of hairpin vortex legs, considering various wall-normal distances and the effect of Reynolds numbers.