| 摘要 |
PURPOSE:To restrict generation of blade end vortex and reduce noise without decreasing an axial flow speed near the tip end of the blade by a method wherein both of the suction and delivery side surfaces of the tip end of the blade are provided with guides to change the direction of airflow. CONSTITUTION:When the fan blade 2 rotates into the arrow sign direction in the diagram, the angles of incidence at both ends 5, 9 in the front side of the rotating direction of the fan are zero degree. A flowout angle alpha at the end part 6 in the rear side of the rotating direction of the fan and the flowout angle beta at the end part 10 are about 10-80 degrees and 20-30 degrees are the optimum among those angles. Accordingly, the guide 5 of the suction side surface 3 is concave with respect to the centrifugal direction while the guide 8 of the delivery side surface 7 is convex with respect to the centrifugal direction. The widths of the guides 5, 9 are 2-10mm.. Air flows along the guide 4 at the suction side surface 3 centrifugally by the rotation of the fan, but the same flows centripetally along the guide 8 at the delivery side surface 7, and these airflows are cancelled mutually. Accordingly, the blade end vortex may be attenuated remarkably and the noise may be reduced. |
