Turbine blade and gas turbine

A turbine blade comprising:

• a blade body;
• a plurality of cooling passages that extend along a blade height direction inside the blade body and are connected to each other via a folded portion;
• and
• a bypass portion that is provided in a partition wall portion for partitioning a pair of adjacent cooling passages among the plurality of cooling passages and allows the pair of cooling passages to communicate with each other, wherein
• the pair of cooling passages includes an upstream-side passage and a downstream-side passage located on a downstream side of the upstream-side passage with respect to a flow of a cooling fluid,
• the turbine blade includes a plurality of turbulators, the plurality of turbulators being provided on an inner wall surface of the downstream-side passage and arranged along the blade height direction,
• values of parameters indicating characteristics of the plurality of turbulators are different between an upstream-side region and a downstream-side region, the upstream-side region being located on an upstream side of a position corresponding to the bypass portion in the blade height direction with respect to the flow of the cooling fluid in the downstream-side passage, and the downstream-side region being located on a downstream side of the upstream-side region with respect to the flow of the cooling fluid in the downstream-side passage, and
• at least one of the following conditions (i) to (iii) is satisfied:
• (i) the plurality of turbulators are provided such that a heat transfer coefficient between the cooling fluid and the inner wall surface of the downstream-side passage is smaller in the downstream-side region than in the upstream-side region;
• (ii) a pitch of the plurality of turbulators in the blade height direction is larger in the downstream-side region than in the upstream-side region;
• and
• (iii) a height of the turbulators with reference to the inner wall surface of the downstream-side passage is lower in the downstream-side region than in the upstream-side region.

A turbine blade comprising:

• a blade body;
• a plurality of cooling passages that extend along a blade height direction inside the blade body and are connected to each other via a folded portion;
• and
• a bypass portion that is provided in a partition wall portion for partitioning a pair of adjacent cooling passages among the plurality of cooling passages and allows the pair of cooling passages to communicate with each other, wherein
• the pair of cooling passages includes an upstream-side passage and a downstream-side passage located on a downstream side of the upstream-side passage with respect to a flow of a cooling fluid,
• the turbine blade includes a thermal barrier coating that covers a surface of the blade body,
• values of parameters indicating characteristics of the plurality of cooling holes are different between an upstream-side region and a downstream-side region, the upstream-side region being located on an upstream side of a position corresponding to the bypass portion in the blade height direction with respect to the flow of the cooling fluid in the downstream-side passage, and the downstream-side region being located on a downstream side of the upstream-side region with respect to the flow of the cooling fluid in the downstream-side passage, and
• a thickness of the thermal barrier coating is smaller in the downstream-side region than in the upstream-side region.