| 摘要 |
PROBLEM TO BE SOLVED: To provide an impeller capable of improving efficiency. SOLUTION: The impeller 4 is equipped with a plurality of primary blades 10 and an intermediate blade 11. The primary blades 10 have a low pressure surface 12 and a high pressure surface 13, which are arranged circumferentially of the impeller 4 with equal interval. The primary blades 10 face the high pressure surface 13 to the corresponding low pressure surface 12. The intermediate blade 11 is formed, in length, to be equal to or shorter than the primary blades 10. The intermediate blade 11 is provided with a low pressure surface 14 and a high pressure surface 15. One intermediate blade 11 is placed between the mutually adjacent primary blades 10 in the condition that the high pressure surface 15 faces the low pressure surface 12 of the primary blade 10. An intervalλ0 between edges 10a of the mutually adjacent primary blades 10, and an intervalλ1 between an edge 11a of the intermediate blade 11 and the edge 10a of the primary blade 10 facing its low pressure surface 12 to this intermediate blade 11 meet the equation 0.35<=λ1/λ0<=0.50.
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