To reduce a leakage flow amount from a clearance between a shroud and a bell-mouth in a centrifugal blower such as a turbo fan to improve fan efficiency, and to suppress separation and reduce separation noise of a blade negative pressure face caused by interference with a main flow.
The centrifugal blower includes: a circular hub fixed to a rotary drive shaft; a plurality of backward blades fixed in parallel in a circumferential direction of the hub; the shroud fixed to a side opposite to a fixed end of the blade, and forming an air suction port; and the bell-mouth to which an air outlet port is play-fitted with a predetermined clearance in an air suction side end part of the shroud. An outer periphery of the air flow outlet part of the bell-mouth play-fitted to the inside of the shroud is provided with a seal wall covering the air suction side end part of the shroud to have structure with U-shaped cross-section, so that the leakage flow amount from the clearance between the shroud and the bell-mouth is reduced.
IWATA TORU
NAGAE TAKANORI
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