| 摘要 |
A blower having an annular wall (2) formed so as to be spaced from free ends of blades of a fan (1), and slits (6) which are formed in the portions of the annular wall which are opposed to the free ends of the blades, and which allow communication between inner and outer circumferential portions of the annular wall, the air being sucked from the slits into the inner circumferential portion of the annular wall in accordance with the rotation of the fan, characterized in that a width (w) of each slit interval being varied in the radial and circumferential directions so that a flow rate of the air flowing from the slits into the inner circumferential portion of the annular wall becomes substantially equal over the whole circumference thereof, this structure enabling the occurrence of a leakage vortex flowing from a positive pressure side to a back pressure side at the free ends of the blades to be minimized, the P-Q characteristics to be improved, the noise occurring in the slit-carrying annular wall to be minimized, and the noise of a noise generating apparatus to be thereby reduced. |
