| 摘要 |
PROBLEM TO BE SOLVED: To reduce an axial thrust acting on an impeller of a pump as much as possible by installing a balance hole to reduce a manufacturing cost of the pump, prevent deterioration of anti-cavitation ability due to effluent from an opening portion of the balance hole at the time of operating in a large flow rate range of the pump, and further, prevent reduction in a pump efficiency due to an increase in the leak losses due to installation of the balance hole. SOLUTION: A center position of the opening portion of the balance hole in a hub face on the front side of the hub (i.e., the side where the blades are present) is made closer to a straight line connecting a rotational axis center and a leading edge of a blade negative pressure face, and a curve representing a negative pressure face of the blade, rather than a straight line connecting the rotational axis center and a leading edge of the blade positive pressure face, and a curve representing the blade positive pressure face, within a pitch interval of the blades when viewed the impeller of the pump from a suction side. COPYRIGHT: (C)2009,JPO&INPIT
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