| 摘要 |
PROBLEM TO BE SOLVED: To provide a high specific-speed pump in which an axial power in a small water volume area during a cutout operation or the like is reduced despite a simple structure.SOLUTION: The axial-flow pump P includes a spindle 2 rotatably disposed in a casing 1 and an impeller 20 rotated integrally with the spindle 2. The impeller 20 includes a hub 21 supported on the spindle 2, a plurality of blades 22 disposed around the hub 21, and an elastic member 25 which is installed on the hub 21 or the blades 22 and which autonomously changes the blade angle θ of the blade 2 according to a pressure with which a fluid acts on the blades 22. When the pressure is higher than a predetermined value, the elastic member 25 changes the blade angle θ from a first angle θ1 to a second angle θ2 smaller than the first angle θ1. When the pressure is reduced, the elastic member returns the blade angle θ to the first angle θ1. |
