Turbine blade and gas turbine

1. A turbine blade comprising:

a platform;

a blade body including at least one cooling flow channel including a meandering serpentine cooling flow channel;

a fillet portion provided in a joint surface between the blade body and the platform; and

a base portion including a supply flow channel communicating with the cooling flow channel of the blade body,

wherein a bypass flow channel is branched off from a high-pressure part of the cooling flow channel and is connected to a low-pressure part of the cooling flow channel,

wherein the bypass flow channel is provided so as to run along the fillet portion in a rotor axis direction,

wherein the bypass flow channel is formed in a wall of the blade body in sectional view when the blade body is seen from a leading edge toward a trailing edge of the turbine blade, and

wherein a portion of the wall of the blade body in which the bypass flow channel is formed is surrounded by a fillet upper end line and a fillet lower end line, the fillet upper end line defining a boundary between an outer wall surface of the blade body and the fillet portion, and the fillet lower end line defining a boundary between a platform outer surface and the fillet portion.

2. The turbine blade according to claim 1 , wherein

the bypass flow channel has an entrance and an exit both of which are provided in a portion of the fillet portion.

3. The turbine blade according to claim 1 , wherein

the bypass flow channel has an entrance provided on an inner side in a radial direction from a portion of the fillet portion and an exit provided on an outer side in the radial direction from the portion of the fillet portion.

4. The turbine blade according to claim 1 , wherein

the bypass flow channel has an entrance provided on an outer side in a radial direction from a portion of the fillet portion and an exit provided on an inner side in the radial direction from the portion of the fillet portion.

5. The turbine blade according to claim 1 , wherein

the at least one cooling flow channel includes cooling flow channels in a plurality of systems, and

the high-pressure part and the low-pressure part are provided in cooling flow channels in different systems.

6. The turbine blade according to claim 1 , wherein

the at least one cooling flow channel includes cooling flow channels in a plurality of systems, and

the high-pressure part and the low-pressure part are provided in a cooling flow channel in the same system.

7. The turbine blade according to claim 1 , wherein

the bypass flow channel is provided in at least one of a pressure side and a suction side of the blade body.

8. The turbine blade according to claim 1 , wherein

the cooling flow channel of the blade body includes cooling flow channels in three systems,

a first-system cooling flow channel is formed of a first cooling flow channel, which is located at a most leading edge side,

a second-system cooling flow channel is formed of a serpentine cooling flow channel including a second cooling flow channel, a third cooling flow channel, and a fourth cooling flow channel that are arranged in the stated order from the leading edge toward a trailing edge, the second cooling flow channel being located adjacent to the first cooling flow channel,

a third-system cooling flow channel is formed of a serpentine cooling flow channel including a fifth cooling flow channel, a sixth cooling flow channel, and a seventh cooling flow channel that are arranged in the stated order from the leading edge toward the trailing edge, the fifth cooling flow channel being adjacent to the fourth cooling flow channel,

the high-pressure part is provided in the first cooling flow channel, and

the low-pressure part is provided in the second cooling flow channel.

9. A gas turbine comprising the turbine blade according to claim 1 .