Scroll structure of centrifugal compressor and centrifugal compressor

Abstract

A scroll structure of a centrifugal compressor includes, of a flow passage connection section where a scroll start portion and a scroll end portion of a scroll flow passage intersect, a connection region where a first inner circumferential surface of the scroll end portion in the centrifugal compressor and a second inner circumferential surface of the scroll start portion in the centrifugal compressor are connected. The connection region includes a turning start point where a direction starts to change from the first inner circumferential surface toward the second inner circumferential surface, and a turning end point where the change in direction from the first inner circumferential surface toward the second inner circumferential surface comes to an end. Where a cross-section orthogonal to an extension direction of a center line of the scroll flow passage in the connection region is a first cross-section, the turning start point on the first cross-section is a first turning start point, a turning end point on the first cross-section is a first turning end point, and a tangent line to the first inner circumferential surface passing through the first turning start point on the first cross-section is a first direction, the first turning start point exists at a position away from the first turning end point along the first direction by a distance not less than 30% of a height dimension along an axial direction of the centrifugal compressor at a minimum cross-sectional area position of the scroll flow passage.