Gas turbine blade and gas turbine having the same

A gas turbine blade comprising:

• a serpentine channel in which a plurality of cooling channels, extending from the base end to the distal end of the blade, are provided from the leading edge to the trailing edge of the blade, at least two of these cooling channels being connected in a folded manner at the base end or the distal end,
• a first wall portion that partitions a first cooling channel located at the leading edge side and a second cooling channel located adjacent to the trailing edge side of the first cooling channel;
• a second wall portion that partitions the second cooling channel and a third cooling channel located adjacent to the trailing edge side of the second cooling channel;
• and
• a third wall portion that partitions the third cooling channel and a fourth cooling channel located adjacent to the trailing edge side of the third cooling channel;
• wherein the serpentine channel is formed by the second to fourth cooling channels such that the second cooling channel is provided at the extreme downstream side;
• the first wall portion and the third wall portion are arranged such that the distance therebetween becomes greater from the pressure side towards the suction side of the blade;
• the second wall portion extends substantially parallel to the second first wall portion;
• the second channel, having a substantially square lateral cross-section, is formed by the first wall portion, the suction side wall portion of the blade, the second wall portion, and the pressure side wall portion of the blade;
• and
• the third channel, having a substantially triangular lateral cross-section, is formed by the second wall portion, the suction side wall portion of the blade, and the third wall portion;
• and
• wherein the serpentine channel is formed such that the channel cross-sectional area becomes sequentially smaller from the cooling channel at the extreme upstream side of the serpentine channel to the cooling channel at the extreme downstream side.