Turbine vane, turbine, and turbine vane modification method

1. A turbine vane comprising:

a vane body extending in the radial direction of a turbine;

a plate-like inner shroud provided at a radially inner end of the vane body; and

a plate-like outer shroud provided at a radially outer end of the vane body, wherein

the vane body includes a serpentine channel which is formed so as to meander inside the vane body in the radial direction and through which a cooling medium flows,

the serpentine channel has a plurality of main channels extending in the radial direction and communicating with each other,

one shroud of the inner shroud and the outer shroud includes:

a terminal channel which has a first end open at a downstream end side of a most-downstream main channel of the plurality of main channels that is disposed farthest on a side of a trailing edge end of the vane body in the serpentine channel;

a first cooling path which has a first end open at the terminal channel and a second end open at a downstream-side end face of a trailing edge of the one shroud and through which the serpentine channel communicates with the outside of the one shroud; and

a second cooling path having a first end and a second end,

the one shroud has a first principal surface on which the vane body is disposed and a second principal surface which is located on an opposite side from the first principal surface,

the second principal surface defines, in part, a cavity,

the first end of the second cooling path opens to the cavity,

the second end of the second cooling path opens at the downstream-side end face of the trailing edge of the one shroud,

the second cooling path is configured to permit a cooling medium in the cavity to pass from the cavity to the downstream-side end face of the trailing edge of the one shroud, and

the second cooling path and the first cooling path are disposed at an interval in the circumferential direction of the turbine.

2. The turbine vane according to claim 1 , wherein

a downstream-side end face of the cavity in the axial direction is disposed farther on an upstream side in the axial direction than the most-downstream main channel of the serpentine channel.

3. The turbine vane according to claim 1 , wherein the first cooling path is formed along a direction of combustion gas flow and provided within an area, in the circumferential direction of the one shroud, where the most-downstream main channel of the serpentine channel is joined to the one shroud.

4. The turbine vane according to claim 1 , wherein the first cooling path is formed along a direction of combustion gas flow and provided so as to include, in the circumferential direction of the one shroud, at least a region where a terminal channel constituting a downstream end of the serpentine channel is disposed.

5. A turbine comprising:

a rotor;

a turbine casing surrounding a periphery of the rotor;

turbine blades fixed to an outer circumference of the rotor; and

turbine vanes, according to claim 1 , that are fixed to an inner circumference of the turbine casing and arrayed alternately with the turbine blades in the axial direction of the rotor.

6. The turbine vane according to claim 1 , wherein the one shroud is the inner shroud,

the inner shroud further includes a rib,

the rib protrudes radially inward from the second principal surface, and

the terminal channel extends from an area of the first principal surface located at a downstream end of the serpentine channel inside the rib located radially inward with respect to the second principal surface, and an end of the terminal channel is closed.