Diffuser and centrifugal pump

Abstract

The present invention is capable of suppressing occurrence of turning stall while suppressing reduction in efficiency of a centrifugal pump.　This diffuser 7 is disposed adjacent to an impeller 6 in the axial direction of a rotary shaft 4 of a centrifugal pump 1. The diffuser includes: a flow passage formation part 84; and a plurality of vanes 9 that partition a plurality of diffuser flow passages. Each vane is provided with positive pressure surfaces 91a to 98a, negative pressure surfaces 91b to 98b, and front end parts 91c to 98c and 95d to 98d. The vane comprises a plurality of long vanes 91 to 94 and at least one of short vanes 95 to 98 shorter than the long vanes. The long vanes are provided with at least one specific length vane disposed adjacent to the positive-pressure surface side of the short vane corresponding to the long vane. In the axial direction, the front end part of the short vane is disposed further in the rear direction than a front end portion of the long vane. The specific length vane is provided with communication flow paths 91d to 94d that are open to the positive pressure surface and negative pressure surface of the specific length vane.

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