Surface Flow and Vortex Shedding of an Impulsively Started Wing

• Main Authors: Jeng Yih Wu, 吳正義
• Other Authors: Rong Fung Huang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/18912332677841842695

碩士 === 國立臺灣科技大學 === 機械工程系 === 87 === The particle tracking flow visualization method (PTFV) and particle imagine velocimetry (PIV) were used to obtain a clear picture of the vortex evolution process on suction surface of an impulsively started NACA 0012 wing. The formation and evolution processes of the vortex system on the suction surface were observed and analyzed by streak pictures of the particle images. Five characteristic vortex evolution processes are identified on the domain of angle of attack and chord Reynolds number. The evolution processes of the streamline patterns, vorticities, traveling paths of vortices, velocities of vortex center, etc., are presented. Stable vortex shedding is eventually established in the wake after the initial period of complex vortex evolution process. The instabilities in the wake, including instability wave, surface vortex shedding, and bluff-body vortex shedding, correspond to different evolution modes of surface flow. The shedding frequency of the vortices is correlated and compared with several conventional results.