To increase the head of a pump in a small flow area without largely lowering a pump efficiency in a centrifugal pump having an impeller with a spiral inner flow passage.
The impeller is formed in an approximately cylindrical shape, a suction port is formed at one end of the impeller, and a discharge port 34 is formed at the other end-side thereof. A spiral primary flow passage 35 connecting the suction port to the discharge port is formed in the impeller. The impeller comprises a secondary vane 38 of such a shape that a part of the outer peripheral portion thereof is cut inward. The secondary vane 38 is continued with the primary flow passage 35 and divides a secondary flow passage 37 turning around the outer peripheral surface thereof. A passing grain size A at the inlet P1 of the secondary vane 38 is larger than a passing grain size B at the outlet P2 of the vane where the spiral flow line S1 of the primary flow passage 35 crosses the outer peripheral edge of a flange part 40 as viewed in the axial direction.
TAKEBE TSUTOMU
TAMAOKI YOICHI
ANDO AKIHIRO
FUNASAKA ARATA
