Abstract: A centrifugal turbomachinery in accordance with the present invention can lower a fluid loss in a return flow path. In the centrifugal turbomachinery, a plurality of centrifugal impellers is attached to a rotating shaft, and the centrifugal turbomachinery is provided with a diffuser having a plurality of blades introducing a fluid boosted by a front stage impeller to a rear stage impeller, and a return flow path means. The return flow path means has a side plate arranged in a back surface side of the front stage impeller, a plate opposing the side plate and arranged in a front surface side of the rear stage impeller, and a plurality of blades arranged between the side plate and the plate so as to be spaced in a peripheral direction. A maximum diameter portion of the side plate is changed in the peripheral direction.

Abstract: A prewhirl type inlet casing for inducing a spiral stream in fluid has a suction passage arranged on an upstream side, being orthogonal to a rotary shaft of fluid machinery, and an internal passage connected to the suction passage, the internal passage being formed in a spiral shape so as to induce a swirl stream orthogonal to the rotary shaft in the fluid. A guide vane provided in the fluid passage in the inlet casing has a rectifying function capable of distributing flow rates in the swirl stream of the fluid in the internal passage between the swirl center side and the swirl outer peripheral side, and causing the fluid to deflect into the swirling direction of the swirl stream induced by the internal passage.

Abstract: A centrifugal turbomachinery in accordance with the present invention can lower a fluid loss in a return flow path. In the centrifugal turbomachinery, a plurality of centrifugal impellers is attached to a rotating shaft, and the centrifugal turbomachinery is provided with a diffuser having a plurality of blades introducing a fluid boosted by a front stage impeller to a rear stage impeller, and a return flow path means. The return flow path means has a side plate arranged in a back surface side of the front stage impeller, a plate opposing the side plate and arranged in a front surface side of the rear stage impeller, and a plurality of blades arranged between the side plate and the plate so as to be spaced in a peripheral direction. A maximum diameter portion of the side plate is changed in the peripheral direction.

Abstract: A prewhirl type inlet casing for inducing a spiral stream in fluid comprising a suction passage arranged on an upstream side, being orthogonal to a rotary shaft of fluid machinery, and an internal passage connected to the suction passage, the internal passage being formed in a spiral shape so as to induce a swirl stream orthogonal to the rotary shaft in the fluid. A guide vane is provided in the fluid passage in the inlet casing. The guide vane has a rectifying function capable of distributing flow rates in the swirl stream of the fluid in the internal passage between the swirl center side and the swirl outer peripheral side and has a rectifying function capable of causing the fluid to deflect into the swirling direction of the swirl stream induced by the internal passage. With these rectifying functions, a rectified swirl stream can be easily created in the in internal passage so as to prevent occurrence of a deviation of a cavitations inducing zone.