To inhibit the separation of air flowing on the negative pressure surface side of a blade part and improve the blasting efficiency by forming a rough face from the counter rotating direction side of a negative pressure surface of a blade part over an outer peripheral surface, and widening the rough face toward the outer peripheral side.
A plurality of blade parts 3 are radially formed from an outer periphery of a boss part 1. A rough face 4 gradually widened toward the outer peripheral side is formed on the negative pressure surface side of the blade part 3 from a center of the counter rotating direction side edge with respect to the rotating direction, toward an outer peripheral edge. The rough face 4 has a number of irregularities like ground glass, sand paper or the like. When an axial flow fan is rotated, the air current flowing to the negative pressure surface of the blade part 3 forms the laminar flow to be apt to separate without going along the shape of the blade part 3. By forming the rough face 4 on the blade part 3 on the negative pressure surface side from the rotating direction side toward the outer peripheral side, the laminar is disturbed to form a turbulent boundary layer, and the separation of the air current can be inhibited. By moving an air current generation place backwardly, the use area of the blade part 3 is widened in comparison with a case not forming the rough face 4, and the blasting efficiency can be improved.
YANO KAZUYA
NOGUCHI KOJI
