| 摘要 |
PROBLEM TO BE SOLVED: To suppress separation of air flow at front edges of blades by providing a peripheral direction sectional shape with thickness of width and height of specified values in the range of specified values from the front edges for chord lengths of the blades on the whole or a part of peripheral direction front edge sides of positive pressure surfaces of the blades arranged around a hub of an axial flow or diagonal flow impeller. SOLUTION: In an impeller in which a plurality of blades 3 are arranged around a hub, a peripheral direction sectional shape is constituted by being provided with thickness 4 of a width of 1 to 5% and a height of 1 to 5% in the range of 1 to 15% from front edges 3c for chord lengths B of the blades 3 on the whole or a part on peripheral direction front edges 3c sides of positive pressure surfaces 3a of the blades 3. When flow rate is changed by this constitution, air flow 5 flowed into the blades 3 with an inflow angleαsmoothly flows into the blades 3 along thickness 4 by a Coanda effect and separation at the front edges 3c is suppressed. Because thickness 4 is provided in the range of 1 to 15% from the front edges 3c, the front edges 3 are thin, air flow 5 toward the pressure surfaces 3a of the blades 3 collides against the front edges 3c and infiltrating into negative pressure surfaces 3b is suppressed.
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