COOLING AXIAL FAN

摘要

PROBLEM TO BE SOLVED: To reduce a wind noises of blades without reducing a wind speed at operating time by arranging a large number of notches in a leading edge part of the blades of an impeller having a plurality of blades arranged in the frame center. SOLUTION: Sawtoothed notches 15 are arranged in a plurality in a leading edge part 14a of blades 14. These are to reduce a wind noise at rotating time of the blades 14. Here, the size (the depth) and the number of the notches 15 are optionally set by and specifications (the size and output) of a fan 10 and a degree of a wind noise reducing effect by preliminary measurement at design time. The most part of an inflow air current 19 becomes a flow 19a respectively passing through an upper surface or an under surface of the blades 14 by rotation of an impeller 13, but a part becomes an expanded flow 19b by the sawtoothed notches 15 arranged in the leading edge part 14a of the blades 14 to thereby reduce noise generated at fan operating time.