Scroll structure of centrifugal compressor and centrifugal compressor

Abstract

A scroll structure of a centrifugal compressor according to an embodiment is a scroll structure of a centrifugal compressor having a scroll passage formed in spiral shape, comprising: a tongue portion separating the scroll passage from an outlet passage connected to the downstream side of the scroll passage at the most downstream position of the scroll passage in a passage connecting portion where a winding start portion and a winding end portion of the scroll passage intersect; and a ridge portion protruding from an inner peripheral surface of the scroll passage on the axially downstream side of the centrifugal compressor toward the axially upstream side of the centrifugal compressor, with a protruding height toward the axially upstream side gradually increasing toward the tongue portion from a starting position that is located upstream from the tongue portion in the scroll passage. The starting position is a position at an angle of 8 degrees or less in the circumferential direction of the centrifugal compressor from the tongue portion toward the upstream side of the scroll passage.