Multistage centrifugal compressor

Abstract

A multistage centrifugal compressor capable of maintaining and improving efficiency while having a static flow path with a reduced outer diameter is provided. Each of return flow paths is provided with a plurality of return vanes disposed in a circular cascade form centered on a center line of a rotational shaft. Each of the return vanes is disposed as a leading vane (A) and a trailing vane (B). The trailing vanes are offset toward the pressure surface side of the leading vanes in a circumferential direction and provided so as to guide a flow from the pressure surface side of the leading vanes to negative pressure surfaces of the trailing vanes. At least one of (1) maximum camber positions (I) of the leading vanes (A), (2) circumferential angles γ formed by trailing edges (A) of the leading vanes and leading edges (B) of the trailing vanes in the circumferential direction centered on the center line of the rotational shaft, and (3) circumferential angles θ formed by the leading edges (B) of the trailing vanes and trailing edges (B) of the trailing vanes in the circumferential direction centered on the center line of the rotational shaft is changed in accordance with the positions of centrifugal compressor stages of the multistage centrifugal compressor.