| 摘要 |
PROBLEM TO BE SOLVED: To prevent separation of an air flow from a guide and suppress deterioration of noise performance when an air passage between the slope of a guide mounted downstream from an impeller and the discharge surface of a fan casing is operated as a diffuser. SOLUTION: A guide 10 situated in the vicinity of an impeller 4 and vertically to the rotary shaft of an impeller 4 and gradually increased in diameter from approximately the same diameter as diameter of the end face, situated downstream, of the hub part 3 of the impeller 4 is mounted in a position situated downstream from the impeller 4. An annular groove 13 having a central axis being the rotary shaft of the impeller 4 is formed in the slope of the guide 10. The groove of the slope of the guide 10 is brought into a negative pressure, an air flow is attracted to the slope of the guide 10, separation of an air flow is suppressed, and deterioration of noise performance is prevented from occurring.
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