| 摘要 |
PROBLEM TO BE SOLVED: To effectively suppress the leakage of an air stream flowing inward in the radial direction by forming recessed sections radially in the inclined direction along the rotating direction of a centrifugal fan on the opposite face side to the centrifugal fag of a fan casing. SOLUTION: Recessed sections 20 are formed radially in the inclined direction along the rotating direction of a centrifugal fan 12 with the opposite face side to the centrifugal fan 12 of a fan casing 15 recessed. The air near the centrifugal fan 12 in the space between the centrifugal fan 12 and the fan casing 15 flows outward in the radial direction while revolving around the rotary shaft of the centrifugal fan 12, and the air near the fan casing 15 tends to flow inward in the radial direction while revolving around the rotary shaft of the centrifugal fan 12. The recessed sections 20 function to guide the air flowing inward in the radial direction while revolving around the rotary shaft of the centrifugal fan 12 to the outside in the radial direction and suppresses the air flowing inward in the radial direction from being leaked to a suction hole side.
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