| 摘要 |
A propeller fan includes a hub 1 and a plurality of blades 2, which are radially arranged on the outer circumference of the hub 1. A plurality of bent surface-shaped recesses 21 to 23 are formed on the positive pressure surface at a trailing edge 2b of each blade 2. The recesses 21 to 23 extend in the rotation direction of the fan and are arranged in a radial direction. Protrusions 24, 25 are each formed between adjacent pair of the recesses 21 to 23. The bent surfaces of the recesses 21 to 23 and the protrusions 24, 25 reduces air flow caused by centrifugal force. This allows the air flow on the positive pressure surface of the blade 2 to easily flow along the recesses 21 to 23. As a result, air flow does not concentrate on the outer periphery of the blade 2, which reduces the differences in the velocity and volume of air flow between the outer tip 2c of the blade 2 and the hub 1. Accordingly, the blade 2 functions as a whole. Therefore, the air blowing performance (efficiency and air blowing noise) of the propeller fan is improved.
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