| 摘要 |
Generation and growth of a wing tip vortex in a part of an outer peripheral portion of a blade not surrounded by a bell mouth is restrained to reduce noise (i.e., operation noise) generated by collision of the wing tip vortex and a fan guard on a blowoff side of a propeller fan. A ratio H1/H0 is set in a range of H1/H0 = 0.40 to 0.65 where H1 denotes a height of a portion of an axis directional height of the bell mouth 5 that is overlapped with an outer peripheral portion P of the blade 13, while H0 denotes an axis directional height of the outer peripheral portion P of the blade 13, so as to restrain growth of a leakage flow (i.e., a wing tip vortex) from a positive pressure surface to a negative pressure surface of the blade 13 in a part of the outer peripheral portion P of the blade 13 not surrounded by the bell mouth 5 while maintaining a suction flow from the outer peripheral portion P of the blade 13. <IMAGE> |
