Labyrinth seal and gas turbine

Abstract

Provided is a labyrinth seal including a first structure; and a second structure opposing the first structure. The first structure includes seal fins located at intervals in an axial direction and extending toward the second structure; a downstream wall surface located most downstream one of the seal fins and extending toward the second structure. A tip of the downstream wall surface located at a side of a tip of the most downstream seal fin, the side being close to the second structure in a radial direction and having a first outlet surface extending from the tip of the downstream wall surface toward a downstream side. The second structure includes a second outlet surface opposing the first outlet surface, a radial gap between the first outlet surface and the second outlet surface; and a cavity surface located upstream of the second outlet surface recessed away from the first structure.