Patent ID: 7625181

Claim:
A turbine blade cascade structure comprising: a plurality of blades having respective blade bodies and provided in series on a wall surface in a circumferential direction, the wall surface connecting the blade bodies so that connected portions of the wall surface and blade bodies form corner portions, respectively; and a cover portion disposed only at a portion near a front edge portion of each of the blade bodies corresponding to a flow of a working fluid in the corner portions formed to the connected portion, extending to an upstream side of the flow of the working fluid and formed as a protruded portion having a concave curved surface toward a height direction of the front edge portion of the blade body from a base portion on the upstream side of the flow of the working fluid, wherein the protruded portion having the concave curved surface is formed to establish relationships of L 0 =(2-5)H 0 and H 0 =(0.5-2.0)T, in which L 0 represents a distance from the base portion to the front edge portion of the blade body, H 0 represents a distance from the wall surface to the height direction of the front edge portion, and T represents a thickness of a boundary layer of the working fluid in a steady operation.