Gas turbine

A gas turbine comprising:

• a compressor which compresses air;
• a combustor which mixes compressed air compressed by the compressor and fuel and combusts the fuel;
• a turbine which produces rotary power from combustion gas generated by the combustor;
• and
• a rotating shaft which is driven by the combustion gas to rotate around a rotation axis, wherein
• the turbine includes:
• a turbine casing forming a ring shape around the rotation axis;
• a blade ring which forms a ring shape around the rotation axis and is coupled on the inner circumference of the turbine casing so as to define an annular first cavity;
• a plurality of heat shield rings which form a ring shape around the rotation axis and are coupled on the inner circumference of the blade ring at predetermined intervals in the axial direction;
• a plurality of ring segments which form a ring shape around the rotation axis and are coupled on the inner circumference of the plurality of heat shield rings;
• a plurality of blade bodies which are fixed on the outer circumference of the rotating shaft at predetermined intervals in the axial direction and disposed so as to radially face the ring segments;
• a plurality of vane bodies of which a shroud forming a ring shape around the rotation axis between the plurality of blade bodies is fixed on the adjacent heat shield rings so as to define an annular second cavity;
• a second cooling air supply channel which supplies a part of the compressed air compressed by the compressor to the second cavity;
• a cooling air flow passage which is provided inside the blade ring and of which one end communicates with the first cavity;
• a first cooling air supply channel which supplies cooling air having a lower temperature than the compressed air compressed by the compressor to one of the other end of the cooling air flow passage and the first cavity;
• and
• a cooling air discharge channel which discharges the cooling air from the other one of the other end of the cooling air flow passage and the first cavity.