Abstract
In this study, effect of tangential blowing through slits opened on the surface of a cylinder is investigated, in order to reduce aerodynamic noise from the cylinder placed in the mainstream of a wind tunnel. When blow-ing through slits is faster than mainstream of the wind tunnel, the intense narrow-band noise radiated from the cylinder in case of no blowing is attenuated significantly. At this time, reverse-flow region behind the model disappears and vortices released alternately from each side o the cylinder become small and weak, which seems to cause reduction of aerodynamic noise. Further increase of blowing does not bring further attenuation of the narrow-band noise, but generates rather loud noise in high-frequency.
