US Patent 10087950 Centrifugal rotation machine

A centrifugal rotation machine includes a rotation shaft, a plurality of impellers rotating along with the rotation shaft, a casing defining a return flow channel configured to guide the fluid from the front-stage impeller to the rear-stage impeller, and a plurality of return vanes installed in the return flow channel, the return flow channel includes a return bend section guiding the fluid G, which has been sent from the front-stage impeller to the outside in the radial direction, to the inside in the radial direction, the return bend section includes a first curved portion and a second curved portion connected to the downstream side of the first curved portion, and the radius of curvature of an inside wall surface of the second curved portion in the radial direction is greater than the radius of curvature of an inside wall surface of the first curved portion in the radial direction.