| 摘要 |
PROBLEM TO BE SOLVED: To provide a centrifugal pump with an improved casing shape, which has been an impediment to pump suction performance. SOLUTION: In the centrifugal pump, a suction flow passage part 54 is formed between an outward rotation face part 51a and an inward rotation face part 51b rotating around a rotational axis center of an impeller 53 in a cross-sectional shape of the casing 51 intersecting with the rotational axis center of the impeller 53. A circulation terminal end of the outward rotation face part 51a forms a tongue part 63, and is continuous to the inward rotation face part 51a through the tongue part 63 as a boundary therebetween. The tongue part 63 is positioned to a side opposed to a pump suction port 54a, across a flat surface that is a face including the rotational axis center of the impeller 53 and in parallel with a flow direction of a main flow in the pump suction port 54a. A ratio r/r<SB>0</SB>of a shortest distance r from the rotational axis center of the impeller 53 to a tip of a top of the tongue part 63, and a minimum radius r<SB>0</SB>from the rotational axis center of the impeller 53 to an inner peripheral face of a suction port part 60 of the impeller 53 is within a range of 1.13 to 1.22. COPYRIGHT: (C)2010,JPO&INPIT
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