著者

大上 芳文 赤松 映明

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.510, pp.298-305, 1989-02-25

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A numerical investigation is carried out to examine the validity of the unsteady Kutta condition presented by many authors. Using a vortex method with a diffusion velocity model, the flow under a transient and oscillating motion of a NACA 0012 airfoil at Re=10000 is calculated. It is found that after the airfoil starts impulsively from rest, the rear stagnation point moves to the trailing edge instantly. Then the angle between the stream line from the trailing edge and the edge bisector decreases from 90° to 10° for the nondimensional time 0 to 0.1. After that time, the classical Kutta condition gradually becomes satisfied. In an oscillating motion, the rear stagnation point is always on the trailing edge and the amplitude of the angle of stream line direction from the trailing edge increases with the frequency. This result shows that the classical Kutta condition is always violated in an oscillating motion.