| 摘要 |
PROBLEM TO BE SOLVED: To provide an air current blowing device having an improved reduction effect to a background noise. SOLUTION: As for the air current from an air current blowing part 38, a fast flow of a main current is guided to the outside by a first guide part 39, and a slow flow of a wake is guided to the inside by a second guide part 40, and the main current and the wake are mixed together. The rates of change of velocities of the main current and the wake are mitigated by mixing, and hereby a jet noise caused by a shear flow is reduced. The first guide part 39 and the second guide part 40 are provided on the air current blowing part 38 on the flowing direction downstream side of the air current, and a boundary layer in the air current blowing part 38 is changed from a laminar-flow boundary layer to a turbulent-flow boundary layer, and simultaneity of hydrodynamic behavior of the flow is weakened in the peripheral direction, and the flow discharged from the air current blowing part is changed into a non-uniform flow, and a noise caused by vortex discharge is suppressed, and both the jet noise and the vortex noise are reduced together, and the behavior of the shear flow and the vortex generated by the air current blown out from the air current blowing part 38 is weakened, to thereby reduce the background noise. |
