Turbine rotor blade and gas turbine

1. A turbine rotor blade, comprising

a leading edge portion having a plurality of cooling holes,

wherein the plurality of cooling holes includes:

m cooling holes arranged in a first range in a blade height direction, where m is an integer of 2 or more; and

n cooling holes arranged in a second range on a blade tip side of the first range in the blade height direction, where n is an integer of 2 or more, and

wherein n/b<m/a is satisfied, where a is a dimension of the first range in the blade height direction, and b is a dimension of the second range in the blade height direction,

wherein the plurality of cooling holes includes:

a plurality of cooling hole rows each of which is arranged along the blade height direction in the first range; and

at least one cooling hole row which or each of which is arranged along the blade height direction in the second range, and

wherein the number of cooling hole rows in the second range is less than the number of cooling hole rows in the first range,

wherein the plurality of cooling hole rows in the first range includes a pressure-side cooling hole row formed on a pressure surface and a suction-side cooling hole row formed on a suction surface,

wherein the pressure-side cooling hole row in the first range is arranged along a first virtual line which is linear,

wherein the suction-side cooling hole row in the first range is arranged along a second virtual line which is linear, and

wherein when X is defined as a distance between the first virtual line and the second virtual line at a same position in the blade height direction on the blade surface, the distance X decreases as the position in the blade height direction changes from the first range to the second range.

2. The turbine rotor blade according to claim 1 ,

wherein a curvature radius of a blade surface of the leading edge portion in a cross-section perpendicular to the blade height direction decreases toward a blade tip.

3. The turbine rotor blade according to claim 1 ,

wherein the second range is located between a position at one-half of a blade height and the blade tip.

4. The turbine rotor blade according to claim 3 ,

wherein the second range includes a range from a position at two-thirds of the blade height to the blade tip.

5. The turbine rotor blade according to claim 1 ,

wherein the number of cooling hole rows in the first range is 3, and

wherein the number of cooling hole rows in the second range is 2.

6. The turbine rotor blade according to claim 5 ,

wherein the plurality of cooling hole rows in the first range includes a pressure-side cooling hole row formed on a pressure surface, a suction-side cooling hole row formed on a suction surface, and a middle cooling hole row formed between the pressure-side cooling hole row and the suction-side cooling hole row, and

wherein the at least one cooling hole row in the second range includes a pressure-side cooling hole row formed on the pressure surface, and a suction-side cooling hole row formed on the suction surface.

7. A gas turbine, comprising:

a compressor for producing compressed air;

a combustor for producing combustion gas using the compressed air and fuel; and

a turbine configured to be driven by the combustion gas,

wherein the turbine includes the turbine rotor blade according to claim 1 .

8. A turbine rotor blade comprising,

a leading edge portion having a plurality of cooling holes,

wherein the plurality of cooling holes includes:

m cooling holes arranged in a first range in a blade height direction, where m is an integer of 2 or more; and

n cooling holes arranged in a second range on a blade tip side of the first range in the blade height direction, where n is an integer of 2 or more, and

wherein n/b<m/a is satisfied, where a is a dimension of the first range in the blade height direction, and b is a dimension of the second range in the blade height direction,

wherein the plurality of cooling holes includes:

a plurality of cooling hole rows each of which is arranged along the blade height direction in the first range; and

at least one cooling hole row which or each of which is arranged along the blade height direction in the second range, and

wherein the number of cooling hole rows in the second range is less than the number of cooling hole rows in the first range,

wherein the number of cooling hole rows in the first range is 3,

wherein the number of cooling hole rows in the second range is 2,

wherein the plurality of cooling hole rows in the first range includes a pressure-side cooling hole row formed on a pressure surface, a suction-side cooling hole row formed on a suction surface, and a middle cooling hole row formed between the pressure-side cooling hole row and the suction-side cooling hole row,

wherein the at least one cooling hole row in the second range includes a pressure-side cooling hole row formed on the pressure surface, and a suction-side cooling hole row formed on the suction surface,

wherein the pressure-side cooling hole row in the first range is arranged along a first virtual line which is linear,

wherein the suction-side cooling hole row in the first range is arranged along a second virtual line which is linear,

wherein the middle cooling hole row is arranged along a third virtual line which is linear, and

wherein when

X is defined as a distance between the first virtual line and the second virtual line at a same position in the blade height direction on the blade surface,

Y is defined as a distance between the second virtual line and the third virtual line at a same position in the blade height direction on the blade surface,

Ymax is defined as a maximum value of the distance Y in the first range, and

h 1 is defined as a position in the blade height direction such that the distance X is less than the distance Ymax,

the second range is located between the position h 1 and the blade tip.

9. The turbine rotor blade according to claim 8 ,

wherein each of the cooling holes of the pressure-side cooling hole row in the first range extends along a direction parallel to a first straight line intersecting the pressure surface,

wherein each of the cooling holes of the suction-side cooling hole row in the first range extends along a direction parallel to a second straight line intersecting the suction surface,

wherein each of the cooling holes of the pressure-side cooling hole row in the second range extends along a direction parallel to a third straight line intersecting the pressure surface,

wherein each of the cooling holes of the suction-side cooling hole row in the second range extends along a direction parallel to a fourth straight line intersecting the suction surface, and

wherein an angle between the third straight line and the fourth straight line is less than an angle between the first straight line and the second straight line.

10. A gas turbine, comprising:

a compressor for producing compressed air;

a combustor for producing combustion gas using the compressed air and fuel; and

a turbine configured to be driven by the combustion gas,

wherein the turbine includes the turbine rotor blade according to claim 8 .