Method of manufacturing centrifugal rotary machine and centrifugal rotary machine

A method of manufacturing a centrifugal rotary machine, wherein the centrifugal rotary machine includes a rotation shaft rotatable around an axis, a plurality of impellers fixed to the rotation shaft, a casing provided with a diffuser flow path covering the impeller from an outside and extending from an outer peripheral side of the impeller outward in a radial direction, a return bend portion turning from an outer radial end portion of the diffuser flow path inward in the radial direction, and a guide flow path extending from the return bend portion inward in the radial direction, and a plurality of return vanes provided on the guide flow path at intervals in a rotation direction of the rotation shaft, the method comprising:

• a fixing step of fixing a return vane body having a virtual airfoil curved forward in the rotation direction as it goes inward in the radial direction and formed by a positive pressure surface recessed forward in the rotation direction and a negative pressure surface protruding forward in the rotation direction onto the guide flow path;
• and
• a cutting step of cutting a portion including an inner radial end portion of the return vane body from the positive pressure surface to the negative pressure surface so as to form a cut surface.