Turbine blades and gas turbines

Abstract

A turbine blade according to one embodiment comprises: a first internal passage extending in a blade height direction and opening at the root of the blade; a second internal passage that extends in the blade height direction, that is formed nearer to the leading edge of a profile part than the first internal passage, and that is connected to the first internal passage at a first turn-back part on the tip-end side of the profile part; a third internal passage that extends in the blade height direction, that is formed nearest to the leading edge, and that is connected to the second internal passage at a second turn-back part on the base-end side of the profile part; and a fourth internal passage which extends in the blade height direction, and of which the end part on the tip-end side of the profile part is connected to the second turn-back part.

Description

[Technical Field]

[0001] The present disclosure relates to turbine blades and gas turbines. This application claims priority based on Japanese Patent Application No. 2022-082725, filed with the Japan Patent Office on May 20, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] For example, turbine blades used in gas turbines and the like are used in high-temperature combustion gases, so they are equipped with cooling channels inside for cooling purposes, and the temperature rise of the blade metal is suppressed by circulating cooling air through the cooling channels (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-046853 Summary of the Invention [Problem to be solved by the invention]

[0004] In the turbine blade described in Patent Document 1, the cooling passage is formed as a serpentine passage in which multiple internal passages are connected. However, when the cooling passage located closest to the leading edge is the most downstream internal passage among the multiple internal passages that make up the serpentine passage, as in the turbine blade described in Patent Document 1, the cooling air flowing through the serpentine passage is heated and its temperature rises before it reaches the internal passage. As a result, there is a risk of insufficient cooling capacity in the leading edge region of the airfoil.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to optimize the distribution of metal temperature of a turbine blade. [Means for solving the problem]

[0006] (1) A turbine blade according to at least one embodiment of the present disclosure includes: a first internal passage extending in the blade height direction and opening at the blade root; a second internal passage extending in the blade height direction, formed closer to the leading edge of the airfoil than the first internal passage, and connected to the first internal passage at a first turning portion on the tip side of the airfoil; a third internal passage extending in the blade height direction, formed closest to the leading edge, and connected to the second internal passage at a second turning portion on the base end side of the airfoil portion; a fourth internal passage extending in the blade height direction, the tip end of the airfoil portion being connected to the second folded portion; Equipped with.

[0007] (2) A gas turbine according to at least one embodiment of the present disclosure includes: The turbine blade has the configuration described in (1) above. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, the distribution of metal temperature of a turbine blade can be optimized. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically illustrating a partial cross-sectional structure of a gas turbine according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the airfoil taken along section II-II of FIGS. 3A, 3B, and 3C. [Figure 3A] FIG. 3 is a cross-sectional view of the turbine blade of FIG. 2 taken along line III-III. [Figure 3B] FIG. 3 is a cross-sectional view of the turbine blade of FIG. 2 taken along line III-III. [Figure 3C] FIG. 3 is a cross-sectional view of the turbine blade of FIG. 2 taken along line III-III. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0011] (Gas Turbine Overview) FIG. 1 is a schematic diagram illustrating a partial cross-sectional structure of a gas turbine 6 according to one embodiment. The gas turbine 6 includes a compressor 91 and a turbine 92 that are directly connected to each other. The compressor 91 is configured as, for example, an axial-flow compressor, and draws atmospheric air or a predetermined gas as a working fluid through an inlet port and pressurizes the working fluid. A combustor 8 is connected to a discharge port of the compressor 91, and the working fluid discharged from the compressor 91 is heated to a predetermined turbine inlet temperature by the combustor 8. The working fluid heated to the predetermined temperature is then supplied to the turbine 92. As shown in FIG. 1 , gas turbine stator vanes 5 are provided in multiple stages inside a casing of the turbine 92. Furthermore, gas turbine moving blades 4 are attached to a rotor 64 so as to form a set of stages with each stator vane 5. One end of the rotor 64 is connected to a rotating shaft 65 of the compressor 91, and the other end is connected to a rotating shaft of a generator (not shown).

[0012] With this configuration, when high-temperature, high-pressure working fluid is supplied from the combustor 8 into the casing of the turbine 92, the working fluid expands inside the casing, causing the rotor 64 to rotate and driving a generator (not shown) connected to the gas turbine 6. That is, the pressure is reduced by the stator vanes 5 fixed to the casing, and the kinetic energy generated thereby is converted into rotational torque via the rotor blades 4 attached to the rotor 64. The generated rotational torque is then transmitted to the rotor 64 to drive the generator.

[0013] (Outline of turbine blades) Turbine blades according to some embodiments of the present disclosure are shown in Figures 2, 3A, 3B, and 3C, where Figure 2 is a cross-sectional view of the airfoil taken along section II-II of Figures 3A, 3B, and 3C, and Figures 3A, 3B, and 3C are cross-sectional views of the turbine blade of Figure 2 taken along section III-III, each showing a different embodiment.

[0014] The turbine blade 50 according to some embodiments is a gas turbine rotor blade 4 of a gas turbine 6 according to one embodiment, and includes an airfoil portion 81, a platform 83, and a blade root 85. The blade root 85 is embedded in a rotor 64 of the gas turbine 6, and the turbine blade 50 rotates together with the rotor 64. The platform 83 is configured integrally with the blade root 85.

[0015] 2, the turbine blade 50 according to some embodiments has a serpentine flow passage (leading-edge-side serpentine flow passage 21) that extends in a serpentine manner from the blade central portion toward the leading edge 51, and a serpentine flow passage (trailing-edge-side serpentine flow passage 22) that extends in a serpentine manner from the blade central portion toward the trailing edge 52. In the turbine blade 50 according to some embodiments, the leading-edge-side serpentine flow passage 21 and the trailing-edge-side serpentine flow passage 22 are flow passages independent of each other. In some embodiments of the turbine blade 50, six cooling passages 42 to 47, for example, which are passages that constitute the leading edge side serpentine passage 21 and the trailing edge side serpentine passage 22, are arranged in order from the leading edge 51 side, and a cooling passage 48 with a large number of pin fins 7 is provided on the trailing edge side.

[0016] 2 has a plurality of cooling holes 1b that open near the leading edge 51 as film cooling holes that blow out film cooling air. For example, the plurality of cooling holes 1b are connected to a cooling flow path .

[0017] In a turbine blade 50 according to some embodiments, cooling passages 42, 43, and 44, which are provided in this order from the leading edge 51 side, are sequentially connected to form a serpentine passage (leading-edge-side serpentine passage 21) that extends in a serpentine manner from the blade central portion toward the leading edge 51. In addition, cooling passages 45, 46, and 47 are sequentially connected to form a serpentine passage (trailing-edge-side serpentine passage 22) toward the trailing edge 52.

[0018] The cooling flow passage 44 constituting the leading-edge-side serpentine flow passage 21 has an opening 44a, which is an opening on one end side (inlet side), formed at the base of the blade, i.e., at the bottom 85a of the blade root 85. Similarly, the cooling flow passage 45 constituting the trailing-edge-side serpentine flow passage 22 has an opening 45a, which is an opening on one end side (inlet side), formed at the bottom 85a of the blade root 85.

[0019] In the following description, the cooling passage 42, the cooling passage 43, and the cooling passage 44 that constitute the leading edge side serpentine passage 21 will be referred to as, in order from the upstream side along the flow of cooling air, the cooling passage 44 will also be referred to as the first internal passage 31, the cooling passage 43 will also be referred to as the second internal passage 32, and the cooling passage 42 will also be referred to as the third internal passage 33.

[0020] In the turbine blade 50 according to some embodiments, the first internal passage 31 extends in the blade height direction, i.e., in the radial direction of the rotor 64 of the gas turbine 6, and opens at the root of the blade as described above. The second internal passage 32 extends in the blade height direction and is formed closer to the leading edge 51 of the airfoil portion 81 than the first internal passage 31, and is connected to the first internal passage 31 at the first turn-back portion 61 on the tip 53 side of the airfoil portion 81. The third internal passage 33 extends in the blade height direction, is formed closest to the leading edge 51, and is connected to the second internal passage 32 at the second folded portion 62 on the base end 54 side of the blade-shaped portion 81.

[0021] The turbine blade 50 according to some embodiments includes a fourth internal passage 34 that extends in the blade height direction, and whose end 34b on the tip 53 side (radially outer side) of the airfoil portion 81 is connected to the second folded-back portion 62. Similar to the first internal passage 31, the fourth internal passage 34 has an opening 34a, which is an opening on one end side (inlet side), formed at the base of the blade.

[0022] In some embodiments of the turbine blade 50, in the leading edge side serpentine flow passage 21, the cooling air supplied from the opening 44a, which is the cooling air intake, flows from the first internal passage 31 through the second internal passage 32 toward the third internal passage 33, i.e., toward the leading edge 51. The leading-edge-side serpentine flow passage 21 is also configured to be supplied with cooling air from the fourth internal passage 34. That is, the cooling air that flows into the fourth internal passage 34 from the opening 34a, which is the cooling air intake of the fourth internal passage 34, is supplied to the second turning portion 62. Then, the cooling air that flows in from the fourth internal passage 34 flows into the third internal passage 33 together with the cooling air from the second internal passage 32.

[0023] A portion of the cooling air that has flowed into the third internal passage 33 is blown out as film cooling air 11 from the multiple cooling holes 1b to film cool the airfoil portion 81 from the outside. In addition, a portion of the cooling air that has flowed into the third internal passage 33 is blown out to the outside of the turbine blade 50 from the openings 42a formed at the tip of the airfoil portion 81. Furthermore, part of the cooling air that has flowed into the third internal passage 33 is also used to cool the platform 83, as will be described later.

[0024] In the turbine blade 50 according to some embodiments, in the trailing-edge-side serpentine passage 22, cooling air supplied from the opening 45a, which is an intake port for cooling air, flows from the cooling passage 45 through the cooling passage 46 and the cooling passage 47 in this order toward the cooling passage 48, i.e., toward the trailing edge 52. This cooling air is blown out as trailing-edge blown air 12 from the cooling passage 48, which is provided with a large number of pin fins 7.

[0025] In the turbine blade 50 according to some embodiments configured as described above, by supplying relatively low-temperature cooling air from the opening 34a formed at the end of the fourth internal passage 34 opposite the end 34b connected to the second turn portion 62, it is possible to lower the temperature of the cooling air flowing through the third internal passage 33 compared to when the fourth internal passage 34 is not provided. This makes it possible to suppress the metal temperature in the region on the leading edge 51 side of the airfoil portion 81, where the metal temperature is higher than in the region closer to the trailing edge 52. This makes it possible to optimize the distribution of the metal temperature in the turbine blade 50. Furthermore, according to a gas turbine 6 equipped with a turbine blade 50 according to some embodiments, the metal temperature distribution of the turbine blade 50 can be optimized to improve the life of the turbine blade 50, thereby reducing the frequency of maintenance of the gas turbine 6 and reducing the maintenance costs of the gas turbine 6.

[0026] In some embodiments, the turbine blade 50 is provided with a plurality of cooling holes 1b formed in the blade wall 33w that forms the third internal passage 33, communicating with the third internal passage 33 and opening to the blade surface 81s of the blade-shaped portion 81. This allows film cooling of the blade surface 81s of the airfoil portion 81 with cooling air at a lower temperature than when the fourth internal passage 34 is not provided.

[0027] As shown in Figures 3A, 3B, and 3C, in some embodiments of the turbine blade 50, the third internal passage 33 has a third internal passage opening 33a for supplying cooling air within the third internal passage 33 to the platform 83. This allows a portion of the cooling air flowing through the third internal passage 33 after the cooling air from the fourth internal passage 34 joins with it to be supplied to the platform 83 via the third internal passage opening 33a. Therefore, the platform 83 can be cooled by a portion of the cooling air flowing through the third internal passage 33.

[0028] 3A, 3B, and 3C, the turbine blade 50 according to some embodiments includes side cooling passages 71 formed in a side portion 83a on the pressure 81a side and a side portion 83b on the suction 81b side in the suction-ventral direction of the airfoil portion 81 of the platform 83. The side cooling passages 71 include a pressure-side side cooling passage 72 formed in the side portion 83a on the pressure 81a side in the suction-ventral direction, and a suction-side side cooling passage 73 formed in the side portion 83b on the suction 81b side in the suction-ventral direction. In some embodiments of the turbine blade 50, one end (upstream end) of the side cooling passage 71 is connected to the other end (downstream end) of the supply passage 76 described later, and the other end (downstream end) of the side cooling passage 71 opens at the end of the platform 83 on the trailing edge 52 side.

[0029] 3A, 3B, and 3C, the turbine blade 50 according to some embodiments includes a supply passage 76 that communicates between the leading-edge-side serpentine passage 21 and the side cooling passage 71. The supply passage 76 includes a pressure-side supply passage 77 that communicates between the leading-edge-side serpentine passage 21 and the pressure-side side cooling passage 72, and a suction-side supply passage 78 that communicates between the leading-edge-side serpentine passage 21 and the suction-side side cooling passage 73.

[0030] 3A, one end (upstream end) of the pressure-side supply passage 77 is connected to the third internal passage opening 33a, and the other end (downstream end) is connected to one end of the pressure-side side cooling passage 72. In the turbine blade 50 shown in FIG. 3A, one end (upstream end) of the suction-side supply passage 78 is connected to the third internal passage opening 33a, and the other end (downstream end) is connected to one end of the suction-side side cooling passage 73.

[0031] In the turbine blade 50 shown in FIG. 3B, the first internal passage 31 has a first internal passage opening 31 a for supplying the cooling air in the first internal passage 31 to the platform 83 . 3B, one end of the pressure-side supply passage 77 is connected to the third internal passage opening 33a, and the other end is connected to one end of the pressure-side side cooling passage 72. In the turbine blade 50 shown in FIG. 3B, one end of the suction-side supply passage 78 is connected to the first internal passage opening 31a, and the other end is connected to one end of the suction-side side cooling passage 73.

[0032] In the turbine blade 50 shown in FIG. 3C, the second internal passage 32 has a second internal passage opening 32 a for supplying the cooling air in the second internal passage 32 to the platform 83 . 3C, one end of the pressure-side supply passage 77 is connected to the third internal passage opening 33a, and the other end is connected to one end of the pressure-side side cooling passage 72. In the turbine blade 50 shown in FIG. 3C, one end of the suction-side supply passage 78 is connected to the second internal passage opening 32a, and the other end is connected to one end of the suction-side side cooling passage 73.

[0033] As shown in Figures 3A, 3B, and 3C, the turbine blade 50 according to some embodiments includes a side cooling passage 71 formed on at least one side in the ventral direction of the airfoil portion 81 at the platform 83, and a supply passage 76 that connects the third internal passage opening 33a to the side cooling passage 71. This allows a portion of the cooling air flowing through the third internal passage 33 after the cooling air from the fourth internal passage 34 joins with it to be supplied to the side cooling passage 71. Therefore, the platform 83 can be cooled by a portion of the cooling air flowing through the third internal passage 33, the temperature of which has been lowered by the cooling air from the fourth internal passage 34.

[0034] As shown in FIGS. 3A, 3B, and 3C, in some embodiments of the turbine blade 50, the side cooling passages 71 may include ventral side cooling passages 72. This allows for efficient cooling of the region on the belly 81a side of the platform 83, where the metal temperature tends to be higher than on the back 81b side.

[0035] As shown in FIGS. 3A, 3B, and 3C, in some embodiments of the turbine blade 50, the side cooling passages 71 may include suction side cooling passages 73. This allows efficient cooling of the suction side region of the platform 83. Furthermore, if the ventral side cooling passages 72 are formed in the platform 83, the suction side region of the platform 83 can be cooled by the suction side cooling passages 73, thereby suppressing the difference in metal temperature between the ventral side region and the suction side region of the platform 83 and suppressing the difference in thermal elongation between the two regions. This suppresses deformation of the platform 83 caused by the difference in thermal elongation between the two regions, thereby suppressing the accumulation of low cycle thermal fatigue and improving the life of the turbine blade 50.

[0036] As shown in Fig. 3B , in the turbine blade 50 of one embodiment, the first internal passage 31 may have a first internal passage opening 31a for supplying cooling air in the first internal passage 31 to the platform. As shown in Fig. 3B , the turbine blade 50 of one embodiment may be provided with a ventral supply passage 77 that connects the third internal passage opening 33a and the ventral side cooling passage 72, and a suction side supply passage 78 that connects the first internal passage opening 31a and the suction side cooling passage 73.

[0037] According to the turbine blade 50 shown in FIG. 3B , a portion of the cooling air flowing through the third internal passage 33 after the cooling air from the fourth internal passage 34 joins with it can be supplied to the pressure-side side cooling passage 72. This allows the pressure-side region of the platform 83 to be efficiently cooled by a portion of the cooling air flowing through the third internal passage 33, the temperature of which has been lowered by the cooling air from the fourth internal passage 34. Furthermore, according to the turbine blade 50 shown in FIG. 3B , a portion of the cooling air flowing through the first internal passage 31 can be supplied to the suction-side side cooling passage 73. This allows the suction-side region of the platform 83 to be efficiently cooled by a portion of the cooling air flowing through the first internal passage 31, which has a relatively low temperature.

[0038] 3C , in one embodiment of the turbine blade 50, the second internal passage 32 may have a second internal passage opening 32a for supplying cooling air in the second internal passage 32 to the platform 83. The turbine blade 50 shown in FIG. 3C may be provided with a pressure-side supply passage 77 that connects the third internal passage opening 33a and the pressure-side side cooling passage 72, and a suction-side supply passage 78 that connects the second internal passage opening 32a and the suction-side side cooling passage 73.

[0039] According to the turbine blade 50 shown in FIG. 3C , a portion of the cooling air flowing through the third internal passage 33 after the cooling air from the fourth internal passage 34 joins with the third internal passage 33 can be supplied to the pressure-side side cooling passage 72. As a result, the pressure-side region of the platform 83 can be efficiently cooled by a portion of the cooling air flowing through the third internal passage 33 whose temperature has been lowered by the cooling air from the fourth internal passage 34. According to the turbine blade 50 shown in FIG. 3C , it is easier to set the cooling start position of the suction-side side cooling passage 73 toward the leading edge 51, compared to a configuration in which a portion of the cooling air flowing through the first internal passage 31 is supplied to the suction-side side cooling passage 73. Furthermore, according to the turbine blade 50 shown in FIG. 3C , the length of the suction-side supply passage 78 can be shortened, compared to a configuration in which a portion of the cooling air flowing through the third internal passage 33 is supplied to the suction-side side cooling passage 73. This makes it possible to suppress a temperature increase in the cooling air while it flows through the suction-side supply passage 78, thereby efficiently cooling the suction-side region of the platform 83.

[0040] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0041] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A turbine blade 50 according to at least one embodiment of the present disclosure comprises: a first internal passage 31 extending in the blade height direction and opening at the base of the blade; a second internal passage 32 extending in the blade height direction and formed closer to the leading edge 51 of the airfoil portion 81 than the first internal passage 31 and connected to the first internal passage 31 at a first turn-back portion 61 on the tip 53 side of the airfoil portion 81; a third internal passage 33 extending in the blade height direction and formed closest to the leading edge 51 and connected to the second internal passage 32 at a second turn-back portion 62 on the base end 54 side of the airfoil portion 81; and a fourth internal passage 34 extending in the blade height direction and having an end portion 34b on the tip 53 side of the airfoil portion 81 connected to the second turn-back portion 62.

[0042] According to the configuration (1) above, by supplying cooling air with a relatively low temperature from the end of the fourth internal passage 34 opposite to the end 34b connected to the second turning portion 62, it is possible to lower the temperature of the cooling air flowing through the third internal passage 33 compared to when the fourth internal passage 34 is not provided. This makes it possible to suppress the metal temperature in the region on the leading edge 51 side of the airfoil section 81, where the metal temperature is higher than in the region closer to the trailing edge 52. This makes it possible to optimize the distribution of the metal temperature in the turbine blade 50.

[0043] (2) In some embodiments, in the configuration of (1) above, the third internal passage 33 may have a third internal passage opening 33a for supplying cooling air within the third internal passage 33 to the platform 83.

[0044] According to the configuration (2) above, a portion of the cooling air flowing through the third internal passage 33 after joining with the cooling air from the fourth internal passage 34 can be supplied to the platform 83 via the third internal passage opening 33a. This allows the platform 83 to be cooled by a portion of the cooling air flowing through the third internal passage 33, the temperature of which has been lowered by the cooling air from the fourth internal passage 34.

[0045] (3) In some embodiments, the configuration of (2) above may include a side cooling passage 71 formed on at least one side of the platform 83 in the ventral-suction direction of the airfoil portion 81, and a supply passage 76 connecting the third internal passage opening 33a and the side cooling passage 71.

[0046] According to the above configuration (3), a portion of the cooling air flowing through the third internal passage 33 after joining with the cooling air from the fourth internal passage 34 can be supplied to the side cooling passage 71. This allows the platform 83 to be cooled by a portion of the cooling air flowing through the third internal passage 33, the temperature of which has been lowered by the cooling air from the fourth internal passage 34.

[0047] (4) In some embodiments, in the configuration of (3) above, the side cooling passages 71 may include a ventral side cooling passage 72 formed in the side portion 83a on the ventral side 81a side in the back-to-ventral direction.

[0048] According to the above configuration (4), it is possible to efficiently cool the region on the belly 81a side of the platform 83, where the metal temperature tends to be higher than that on the back 81b side.

[0049] (5) In some embodiments, in the configurations (3) or (4) above, the side cooling passages 71 may include dorsal side cooling passages 73 formed in the side portions 83b on the dorsal 81b side in the dorsal-ventral direction.

[0050] According to the configuration (5) above, it is possible to efficiently cool the region on the suction 81b side of the platform 83. Furthermore, if the platform 83 is formed with the pressure-side side cooling passages 72, the region on the suction 81b side of the platform 83 can be cooled by the suction-side side cooling passages 73, thereby suppressing the difference in metal temperature between the region on the pressure 81a side and the region on the suction 81b side of the platform 83 and suppressing the difference in thermal elongation between the two regions. This suppresses deformation of the platform 83 due to the difference in thermal elongation between the two regions, thereby suppressing the accumulation of low-cycle thermal fatigue and improving the life of the turbine blade 50.

[0051] (6) In some embodiments, in the configuration of (2) above, the first internal passage 31 may have a first internal passage opening 31 a for supplying cooling air in the first internal passage 31 to the platform 83. In some embodiments, the airfoil 81 may include a pressure-side side cooling passage 72 formed in a side portion 83 a on the pressure-side 81 a side in the dorsal-ventral direction of the platform 83, a suction-side side cooling passage 73 formed in a side portion 83 b on the dorsal-ventral side 81 b side in the dorsal-ventral direction of the platform 83, a pressure-side supply passage 77 connecting the third internal passage opening 33 a and the pressure-side side cooling passage 72, and a suction-side supply passage 78 connecting the first internal passage opening 31 a and the suction-side side cooling passage 73.

[0052] According to the above configuration (6), a portion of the cooling air flowing through the third internal passage 33 after the cooling air from the fourth internal passage 34 joins can be supplied to the pressure-side side cooling passage 72. As a result, the region on the pressure 81a side of the platform 83 can be efficiently cooled by a portion of the cooling air flowing through the third internal passage 33, the temperature of which has been lowered by the cooling air from the fourth internal passage 34. Furthermore, according to the above configuration (6), a portion of the cooling air flowing through the first internal passage 31 can be supplied to the pressure-side side cooling passage 73. As a result, the region on the pressure 81b side of the platform 83 can be efficiently cooled by a portion of the cooling air flowing through the first internal passage 31, which has a relatively low temperature.

[0053] (7) In some embodiments, in the configuration of (2) above, the second internal passage 32 may have a second internal passage opening 32a for supplying cooling air in the second internal passage 32 to the platform 83. In some embodiments, the airfoil may include a pressure-side side cooling passage 72 formed in a side portion 83a on the pressure 81a side of the airfoil portion 81 in the dorsal-ventral direction of the platform 83, a suction-side side cooling passage 73 formed in a side portion 83b on the dorsal-ventral side of the platform 83 in the dorsal-ventral direction, a pressure-side supply passage 77 connecting the third internal passage opening 33a and the pressure-side side cooling passage 72, and a suction-side supply passage 78 connecting the second internal passage opening 32a and the suction-side side cooling passage 73.

[0054] According to the configuration of (7) above, a portion of the cooling air flowing through the third internal passage 33 after the cooling air from the fourth internal passage 34 joins can be supplied to the pressure-side side cooling passage 72. As a result, the pressure-81a side region of the platform 83 can be efficiently cooled by a portion of the cooling air flowing through the third internal passage 33, the temperature of which has been lowered by the cooling air from the fourth internal passage 34. According to the configuration of (7) above, compared to a configuration in which a portion of the cooling air flowing through the first internal passage 31 is supplied to the suction-side side cooling passage 73, it is easier to set the cooling start position of the suction-side side cooling passage 73 toward the leading edge 51. Furthermore, according to the configuration of (7) above, compared to a configuration in which a portion of the cooling air flowing through the third internal passage 33 is supplied to the suction-side side cooling passage 73, the length of the suction-side supply passage 78 can be shortened, which can suppress a temperature increase of the cooling air while flowing through the suction-side supply passage 78, and can efficiently cool the suction-side 81b side region of the platform 83.

[0055] (8) In some embodiments, in any of the configurations (1) to (7) above, it is preferable to provide a plurality of cooling holes 1b formed in the blade wall 33w that forms the third internal passage 33, communicating with the third internal passage 33 and opening to the blade surface 81s of the blade-shaped portion 81.

[0056] According to the above configuration (8), the blade surface 81s of the airfoil portion 81 can be film-cooled with cooling air at a lower temperature than when the fourth internal passage 34 is not provided.

[0057] (9) A gas turbine 6 according to at least one embodiment of the present disclosure includes a turbine blade 50 having any one of the configurations described in (1) to (8) above.

[0058] According to the configuration (9) above, the distribution of the metal temperature of the turbine blades 50 can be optimized to improve the life of the turbine blades 50, so that the frequency of maintenance of the gas turbine 6 can be reduced, and the maintenance costs of the gas turbine 6 can be reduced. [Explanation of symbols]

[0059] 1b cooling hole 6. Gas turbine 4 Gas turbine rotor blades (rotor blades) 21 Serpentine channel (leading edge side serpentine channel) 31 1st internal passage 31a 1st internal passage opening 32 Second internal passage 32a 2nd internal passage opening 33 Third internal passage 33a Third internal passage opening 33w wing wall 34 4th internal passage 42~48 Cooling passage 50 turbine blades 61 First fold 62 Second fold 71 Side cooling passage 72 Ventral side cooling passage 73 Back side cooling passage 76 Supply passage 77 Ventral supply passage 78 Dorsal supply passage 81 Airfoil 81a Belly 81b back 81s wing surface 83 Platform 85 Wing root

Claims

1. a first internal passage extending in the blade height direction and opening at the blade root; a second internal passage extending in the blade height direction, formed closer to the leading edge of the airfoil than the first internal passage, and connected to the first internal passage at a first turning portion on the tip side of the airfoil; a third internal passage extending in the blade height direction, formed closest to the leading edge, and connected to the second internal passage at a second turning portion on the base end side of the airfoil portion; a fourth internal passage extending in the blade height direction, the tip end of the airfoil portion being connected to the second turn-back portion; Equipped with the third internal passage has a third internal passage opening for supplying cooling air in the third internal passage to the platform; a side cooling passage formed on at least one side of the platform in a ventral direction of the airfoil; a supply passage communicating the third internal passage opening with the side cooling passage; Equipped with the side cooling passage includes a ventral-side cooling passage formed on a ventral side in the dorsal-ventral direction, The supply passage includes a ventral supply passage that communicates the third interior passage opening and the ventral side cooling passage. Turbine blades.

2. The connection position between the ventral supply passage and the ventral side cooling passage is located at a position farther from the trailing edge end of the airfoil portion on the platform than the connection position between the third internal passage opening and the ventral supply passage. The turbine blade of claim 1 .

3. the side cooling passages include a dorsal-side side cooling passage formed in a dorsal side in the dorsal-ventral direction, The turbine blade according to claim 1 or 2.

4. the first internal passage has a first internal passage opening for supplying cooling air in the first internal passage to the platform; the side cooling passages include a dorsal-side side cooling passage formed in a dorsal side in the dorsal-ventral direction, The supply passage includes a suction side supply passage that communicates the first interior passage opening and the suction side cooling passage. The turbine blade according to claim 1 or 2.

5. the second internal passage has a second internal passage opening for supplying cooling air in the second internal passage to the platform; the side cooling passages include a dorsal-side side cooling passage formed in a dorsal side in the dorsal-ventral direction, The supply passage includes a suction side supply passage that communicates the second internal passage opening and the suction side cooling passage. The turbine blade according to claim 1 or 2.

6. a plurality of cooling holes formed in a blade wall that defines the third internal passage, the cooling holes communicating with the third internal passage and opening on the blade surface of the airfoil portion; Equipped with The turbine blade according to claim 1 or 2.

7. A gas turbine comprising the turbine blade according to claim 1 or 2.

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