抄録
The transitional change of flow field at the beginning of separation on an NACA0020 airfoil with an angle of attack of 25 degree was investigated experimentally. The generation of separation was controlled by using a wall jet ejected from a thin slit near the leading edge of the airfoil. Velocity fluctuations near the surface were measured by using a split-film probe, so that the instantaneous separation could be determined an reverse flow was detected. It was found that the large vortical structure was formed at the beginning of separation and it induced a strong reverse flow with a value of a half of the free stream velocity.
