一様流中に置かれた翼まわりの流れの周期的変動現象に関する実験的研究

概要

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The mechanism of the fluctuating phenomena in the wake was investigated to NACA0008 and NACA0015 blades with experimentally. It's found that when the attack angle a is small, the periodic fluctuating phenomenon emerges in the wake for both type blades. This phenomenon is the Karman vortex street which generates from the separation of a laminar boundary layer upstream of the trailing edge and from the formation of a dead air region. At NACA0008 blade the frequency of the Karman vortex formation falls with the attack angle increasing, because the separation of the laminar boundary layer occurs mainly on the suction surface and the dead air region becomes large as a attack angle increases. At NACA0015 blade, the frequency of the Karman vortex formation increases with the attack angle in'creasing, because the separation occurs mainly on the pressure surface and the dead air region becomes small as the attack angle increases. When the attack angle more increases, the Karman vortex street disappers for both blades because of the boundary layer on both surface of the blade attached before the trailing edge and no dead air region formed. When the attack angle is very large, the flow of suction side separates near the leading edge and the large dead air region forms so the Karman vortex street emerges and it's frequersy is very low.
長崎大学工学部,Faculty of Engineering, Nagasaki Universityの論文