Rotor blade and gas turbine comprising same

Abstract

In the present invention, a cooling air passage of a rotor blade has a blade body passage and a plurality of tip discharge holes which are open at a tip surface of the blade body and which are capable of discharging cooling air from the blade body passage. A plurality of 2-3 region discharge holes, which are a portion of the plurality of tip discharge holes, are open in a 2-3 region of the tip surface. A plurality of 4-5 region discharge holes, which are another portion of the plurality of tip discharge holes, are open in a 4-5 region of the tip surface. The area density which is the number of outlets of the plurality of 4-5 region discharge holes per unit area of the 4-5 region is higher than the area density which is the number of outlets of the plurality of 2-3 region discharge holes per unit area of the 2-3 region.

Description

Rotor blade and gas turbine equipped with same

[0001] This application claims priority to Japanese Patent Application No. 2024-154077, filed on September 6, 2024, the contents of which are incorporated herein by reference.

[0002] A gas turbine includes a compressor that compresses air to generate compressed air, a combustor that combusts fuel in the compressed air to generate combustion gas, and a turbine driven by the combustion gas. The turbine includes a turbine rotor that rotates about an axis, a turbine casing that covers the rotor, and multiple stator blade rows. The turbine rotor has a rotor shaft that is centered on the axis and multiple rotor blade rows attached to the rotor shaft. The multiple rotor blade rows are aligned in the axial direction along which the axis extends. Each rotor blade row has multiple rotor blades aligned in the circumferential direction about the axis. The multiple stator blade rows are aligned in the axial direction and attached to the inner periphery of the turbine casing. Each of the multiple stator blade rows is arranged axially upstream of one of the multiple rotor blade rows. Each stator blade row has multiple stator blades aligned in the circumferential direction about the axis.

[0003] A rotor blade generally has a blade body, a platform, and a blade root. The blade body has an airfoil-shaped cross section perpendicular to the radial direction relative to the axis and extends radially. The platform is provided at the end of the blade body, radially inward. The blade root is provided radially inward of the platform. This blade root is the part that attaches the rotor blade to the rotor shaft.

[0004] The rotor blades of a gas turbine are exposed to high-temperature combustion gases, and therefore are generally cooled by air or the like.

[0005] For example, the rotor blade described in Patent Document 1 below has a cooling air passage formed in the blade body of the stationary blade through which cooling air can flow. The blade has an inlet passage that opens at the surface of the blade root and allows cooling air to flow in, and a blade body passage formed within the blade body and through which cooling air from the inlet passage can flow. The inlet passage extends in the blade height direction at least within the blade root and has two inlet passage sections aligned from the leading edge side to the trailing edge side. The blade body passage has a plurality of blade body passage sections that extend in the blade height direction within the blade body and are aligned along the camber line of the blade body from the leading edge side to the trailing edge side.

[0006] The plurality of blade passages include a first blade passage, a second blade passage, a third blade passage, a fourth blade passage, a fifth blade passage, and a sixth blade passage, and the first blade passage, the second blade passage, the third blade passage, the fourth blade passage, the fifth blade passage, and the sixth blade passage are arranged in this order from the leading edge to the trailing edge.

[0007] The hub-side portion of the first blade passage, which is the most leading of the six blade passages, communicates with the hub-side portion of the second blade passage adjacent to the first blade passage. The tip-side portion of the second blade passage and the tip-side portion of the third blade passage adjacent to the second blade passage communicate with each other. The tip-side portion of the fourth blade passage adjacent to the third blade passage and the tip-side portion of the fifth blade passage adjacent to the fourth blade passage. The hub-side portion of the fifth blade passage and the hub-side portion of the sixth blade passage, which is the most trailing of the six blade passages and adjacent to the fifth blade passage, communicate with each other.

[0008] Of the two inlet passage sections, the first inlet passage section on the leading edge side is connected to the hub side portion of the third blade passage section, and the second inlet passage section on the trailing edge side is connected to the hub side portion of the fourth blade passage section.

[0009] The cooling air that flows into the first inlet passage flows through the third, second, and first blade passages and is ejected from the leading edge of the blade, while the cooling air that flows into the second inlet passage flows through the fourth, fifth, and sixth blade passages and is ejected from the trailing edge of the blade.

[0010] JP 2014-001633 A (FIG. 3)

[0011] In the blade described in Patent Document 1, as described above, the cooling air that flows into the first inlet passage flows through the third blade passage, the second blade passage, and the first blade passage before being ejected from the leading edge of the blade. Also, in this blade, as described above, the cooling air that flows into the second inlet passage flows through the fourth blade passage, the fifth blade passage, and the sixth blade passage before being ejected from the trailing edge of the blade. Therefore, the blade described in Patent Document 1 can cool the blade while suppressing the amount of cooling air.

[0012] Incidentally, moving blades of gas turbines that are exposed to high-temperature combustion gases are required to have high durability while reducing the amount of cooling air used.

[0013] Therefore, an object of the present disclosure is to provide a rotor blade that can increase durability while reducing the amount of cooling air used, and a gas turbine including this rotor blade.

[0014] To achieve the above object, one aspect of the invention provides a rotor blade comprising: a blade body having an airfoil-shaped cross section and extending in a blade height direction including a directional component perpendicular to the cross section; a platform provided at the hub-side end of the blade body, a blade root provided on the hub side of the platform; and a cooling air passage formed across the blade root, the platform, and the blade body, through which cooling air can flow. The blade body has a blade surface facing a direction having a directional component perpendicular to the blade height direction and a tip surface facing the tip side in the blade height direction. The blade surface has leading and trailing edges extending in the blade height direction, and pressure and suction surfaces extending in the blade height direction from the leading edge to the trailing edge. The cooling air passage includes an introduction passage formed at least in the blade root, a blade body passage formed at least in the blade body, and a plurality of tip ejection holes having outlets opening at the tip surface and capable of ejecting cooling air from the outlets. The introduction passage has a first introduction passage portion and a second introduction passage portion. The first introduction passage portion and the second introduction passage portion both have inlets that open on the surface of the blade root and allow cooling air to flow in through the inlets. The blade-body passage extends in the blade height direction and has six blade-body passage portions lined up from the leading edge side to the trailing edge side along the camber line of the blade body, and a communication portion that connects two adjacent blade-body passage portions among the six blade-body passage portions. The six blade passage sections include a first blade passage section closest to the leading edge, a second blade passage section located closer to the trailing edge than the first blade passage section and adjacent to the first blade passage section, a third blade passage section located closer to the trailing edge than the second blade passage section and adjacent to the second blade passage section, a fourth blade passage section located closer to the trailing edge than the third blade passage section and adjacent to the third blade passage section, a fifth blade passage section located closer to the trailing edge than the fourth blade passage section and adjacent to the fourth blade passage section, and a sixth blade passage section located closest to the trailing edge and adjacent to the fifth blade passage section.The communication section includes a 1-2 hub-side communication section that communicates the hub-side portion of the first blade passage section with the hub-side portion of the second blade passage section, a 2-3 tip-side communication section that communicates the tip-side portion of the second blade passage section with the tip-side portion of the third blade passage section, a 4-5 tip-side communication section that communicates the tip-side portion of the fourth blade passage section with the tip-side portion of the fifth blade passage section, and a 5-6 hub-side communication section that communicates the hub-side portion of the fifth blade passage section with the hub-side portion of the sixth blade passage section. The first inlet passage section communicates with the hub-side portion of the third blade passage section, and the second inlet passage section communicates with the hub-side portion of the fourth blade passage section. The tip surface has a 2-3 region, closer to the hub than the tip surface, in which the second blade passage portion, the 2-3 tip-side communicating portion, and the third blade passage portion are present, and a 4-5 region, closer to the hub than the tip surface, in which the fourth blade passage portion, the 4-5 tip-side communicating portion, and the fifth blade passage portion are present. Of the plurality of tip jet holes, a portion of the 2-3 region jet holes have their outlets open in the 2-3 region in the tip surface. Of the plurality of tip jet holes, a portion of the 4-5 region jet holes have their outlets open in the 4-5 region in the tip surface. An area density, which is the number of outlets in the plurality of 4-5 region jet holes per unit area in the 4-5 region, is higher than an area density, which is the number of outlets in the plurality of 2-3 region jet holes per unit area in the 2-3 region.

[0015] In the blade of this embodiment, the cooling air that flows into the first introduction passage flows through the third blade passage, the 2-3 tip side communicating portion, the second blade passage, the 1-2 hub side communicating portion, and the first blade passage, and convectively cools the areas around these passages and communicating portions as it flows through these passages and communicating portions. In the blade of this embodiment, the cooling air that flows into the second introduction passage flows through the fourth blade passage, the 4-5 tip side communicating portion, the fifth blade passage, the 5-6 hub side communicating portion, and the sixth blade passage, and convectively cools the areas around these passages and communicating portions as it flows through these passages and communicating portions. Therefore, in the blade of this embodiment, the amount of cooling air required can be reduced while still cooling the blade.

[0016] A portion of the combustion gases coming toward the blade from the leading edge side flows along the pressure surface of the blade toward the trailing edge side, and another portion flows along the suction surface of the blade toward the trailing edge side. With respect to the blade, the combustion gas pressure on the pressure surface side is higher than that on the suction surface side. A circumferential force acts on the blade due to this combustion gas pressure difference. There is a gap between the tip surface of the blade and the turbine casing. As mentioned above, since the combustion gas pressure on the pressure surface side is higher than that on the suction surface side with respect to the blade, a portion of the combustion gas on the pressure surface side flows into the gap between the tip surface and the turbine casing and then flows out to the suction surface side. Therefore, the tip surface of the blade is also exposed to the high-temperature combustion gases.

[0017] The rotor blade in this embodiment has a plurality of tip jet holes. A portion of the cooling air flowing through the blade-body passage flows into the plurality of tip jet holes. As this cooling air flows through the tip jet holes, it convectively cools the area around the tip jet holes. The cooling air that has flowed through the plurality of tip jet holes is ejected from the outlets of the tip jet holes that open on the tip surface. The cooling air ejected from the plurality of tip jet holes provides film cooling to the tip surface.

[0018] Therefore, in this embodiment, thermal damage to the tip surface due to combustion gas can be suppressed, and the durability of the rotor blade can be improved.

[0019] As mentioned above, there is a pressure difference between the combustion gas on the pressure side and the combustion gas on the suction side of the blade body. This pressure difference gradually increases and then decreases as you move from the leading edge of the blade body toward the trailing edge. The position where this pressure difference is greatest is within the region of the blade body where the fourth blade passage and the 4-5 tip communication are present. Therefore, the pressure difference in the region of the blade body where the fourth blade passage, the 4-5 tip communication, and the fifth blade passage are present is greater than the pressure difference in the region of the blade body where the third blade passage, the 2-3 tip communication, and the second blade passage are present. In this case, the flow velocity of the combustion gas passing through the 4-5 region on the tip surface is higher than the flow velocity of the combustion gas passing through the 2-3 region on the tip surface. When the flow velocity of the combustion gas is high, the heat transfer coefficient between the combustion gas and the blade body increases, so the heat transfer coefficient between the 4-5 region on the tip surface and the combustion gas is higher than the heat transfer coefficient between the 2-3 region on the tip surface and the combustion gas.

[0020] In this embodiment, the area density of the outlets of the 2-3 region nozzle holes that open in the 2-3 region on the tip surface, where the heat transfer coefficient is low, is reduced, while the area density of the outlets of the 4-5 region nozzle holes that open in the 4-5 region on the tip surface, where the heat transfer coefficient is high, is increased. As a result, in this embodiment, the amount of cooling air that is ejected from the outlets of the 2-3 region, which is relatively hard to heat up on the tip surface, is reduced, and the cooling performance for the 4-5 region, which is relatively easy to heat up on the tip surface, is improved. Therefore, in this embodiment, the durability of the rotor blade can be improved while reducing the amount of cooling air used.

[0021] According to one aspect of the present invention, a gas turbine includes a rotor shaft having a plurality of the rotor blades according to the above aspect, the rotor shaft being rotatable about an axis and having the plurality of rotor blades attached in a circumferential direction about the axis, and a turbine casing covering the plurality of rotor blades and an outer periphery of the rotor shaft. The rotor blades are attached to the rotor shaft so that the blade height direction is radial with respect to the axis and the tip side is radially outward with respect to the axis.

[0022] According to one aspect of the present disclosure, it is possible to increase the durability of the rotor blade while reducing the amount of cooling air used.

[0023] FIG. 1 is a schematic cross-sectional view of a gas turbine according to an embodiment of the present disclosure. FIG. 2 is a perspective view of a rotor blade according to an embodiment of the present disclosure. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a view seen from an arrow IV in FIG. 2. FIG. 5 is a cross-sectional view taken along line V-V in FIG. 4. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. FIG. 6 is a cross-sectional view of a main portion of a rotor blade according to a first modified example of an embodiment of the present disclosure. FIG. 7 is a view of a rotor blade according to a second modified example of an embodiment of the present disclosure, viewed from the radial outside. FIG. 8 is a view of a rotor blade according to a third modified example of an embodiment of the present disclosure, viewed from the radial outside.

[0024] Hereinafter, embodiments of a rotor blade and a gas turbine including the rotor blade according to the present disclosure will be described in detail with reference to the drawings.

[0025] Gas Turbine Embodiment An embodiment of a gas turbine will be described with reference to FIG.

[0026] As shown in FIG. 1 , the gas turbine 10 of this embodiment includes a compressor 20 that compresses air A, a combustor 30 that burns fuel F in the air A compressed by the compressor 20 to generate combustion gas G, and a turbine 40 that is driven by the combustion gas G.

[0027] The compressor 20 includes a compressor rotor 21 that rotates about an axis Ar, a compressor casing 25 that covers the compressor rotor 21, and a plurality of stator vane rows 26. The turbine 40 includes a turbine rotor 41 that rotates about the axis Ar, a turbine casing 45 that covers the turbine rotor 41, and a plurality of stator vane rows 46. In the following, the direction in which the axis Ar extends is referred to as the axial direction Da, the circumferential direction about the axis Ar is simply referred to as the circumferential direction Dc, and the direction perpendicular to the axis Ar is referred to as the radial direction Dr. One side of the axial direction Da is referred to as the axial upstream side Dau, and the opposite side is referred to as the axial downstream side Dad. The side of the radial direction Dr that approaches the axis Ar is referred to as the radially inner side Dri, and the opposite side is referred to as the radially outer side Dro.

[0028] The compressor 20 is disposed on the axial upstream side Dau relative to the turbine 40 .

[0029] The compressor rotor 21 and the turbine rotor 41 are located on the same axis Ar and are connected to each other to form the gas turbine rotor 11. To this gas turbine rotor 11, for example, a rotor of a generator GEN is connected. The gas turbine 10 further includes an intermediate casing 14. This intermediate casing 14 is disposed between the compressor casing 25 and the turbine casing 45 in the axial direction Da. The compressor casing 25, the intermediate casing 14, and the turbine casing 45 are connected to each other to form the gas turbine casing 15.

[0030] The compressor rotor 21 has a rotor shaft 22 extending in the axial direction Da centered on the axis Ar, and a plurality of rotor blade rows 23 attached to the rotor shaft 22. The plurality of rotor blade rows 23 are aligned in the axial direction Da. Each rotor blade row 23 is composed of a plurality of rotor blades aligned in the circumferential direction Dc. One of a plurality of stator blade rows 26 is arranged on the axial downstream side Dad of each of the plurality of rotor blade rows 23. Each stator blade row 26 is provided inside the compressor casing 25. Each stator blade row 26 is composed of a plurality of stator blades aligned in the circumferential direction Dc.

[0031] The turbine rotor 41 has a rotor shaft 42 that extends in the axial direction Da centered on the axis Ar, and a plurality of rotor blade rows 43 attached to the rotor shaft 42. The plurality of rotor blade rows 43 are aligned in the axial direction Da. Each rotor blade row 43 is made up of a plurality of rotor blades aligned in the circumferential direction Dc. One of the plurality of stator blade rows 46 is arranged on the axial upstream side Dau of each of the plurality of rotor blade rows. Each stator blade row 46 is provided inside the turbine casing 45. Each stator blade row 46 is made up of a plurality of stator blades aligned in the circumferential direction Dc.

[0032] The combustor 30 is attached to the intermediate casing 14 .

[0033] The compressor 20 compresses air A to generate compressed air. This compressed air flows into the combustor 30. Fuel F is supplied to the combustor 30. In the combustor 30, the fuel F is burned in the compressed air to generate high-temperature, high-pressure combustion gas G. This combustion gas G is sent from the combustor 30 to an annular combustion gas flow path 49 in the turbine casing 45. The combustion gas G rotates the turbine rotor 41 as it flows through the combustion gas flow path 49 toward the axial downstream side Dad. The rotation of this turbine rotor 41 rotates the rotor of the generator GEN connected to the gas turbine rotor 11. As a result, the generator GEN generates electricity.

[0034] Hereinafter, embodiments and modifications of the rotor blades that constitute the rotor blade row 43 of the turbine 40 will be described.

[0035] One Embodiment of a Rotor Blade One embodiment of a rotor blade will be described with reference to FIGS.

[0036] As shown in FIGS. 2 to 4, the rotor blade 50 in this embodiment includes a blade body 51 , a platform 58 , a blade root 59 , and a cooling air passage 60 .

[0037] The blade body 51 has an airfoil-shaped cross section and extends in a blade height direction that includes a directional component perpendicular to the cross section. The blade body 51 has a blade surface 52 facing a direction that includes a directional component perpendicular to the blade height direction, and a tip surface 55 facing the tip side of the tip side and hub side in the blade height direction. The blade surface 52 has a leading edge 53f and a trailing edge 53b that extend in the blade height direction, and a pressure surface 54p and a suction surface 54n that extend from the leading edge 53f to the trailing edge 53b. The pressure surface 54p and the suction surface 54n are back-to-back. The pressure surface 54p is a concave curved surface, and the suction surface 54n is a convex curved surface.

[0038] When this rotor blade 50 is attached to the rotor shaft 42, the blade body 51 is present in the combustion gas flow path 49 described above with reference to Figure 1. For this reason, the rotor blade 50 in this embodiment is provided with a cooling air passage 60 through which cooling air Ac flows in order to cool the blade body 51.

[0039] When this rotor blade 50 is attached to the rotor shaft 42, the blade height direction corresponds to the radial direction Dr, the tip side corresponds to the radially outer side Dro, and the hub side corresponds to the radially inner side Dri. The front side, where the leading edge 53f is located relative to the trailing edge 53b, corresponds to the axially upstream side Dau, and the rear side, where the trailing edge 53b is located relative to the leading edge 53f, corresponds to the axially downstream side Dad. The direction in which the pressure surface 54p and the suction surface 54n are aligned corresponds to the circumferential direction Dc. Therefore, hereinafter, the blade height direction is referred to as the blade height direction Dr, the tip side is referred to as the tip side Dro, and the hub side is referred to as the hub side Dri. The front side, where the leading edge 53f is located relative to the trailing edge 53b, is referred to as the front side Dau, and the rear side, where the trailing edge 53b is located relative to the leading edge 53f, is referred to as the rear side Dad.

[0040] The platform 58 is provided on the hub side Dri of the blade body 51. The platform 58 is a rectangular plate-shaped member (see FIG. 4) that extends in a direction including a directional component perpendicular to the blade height direction Dr.

[0041] The blade root 59 is provided on the hub side Dri of the platform 58. The blade root 59 is a portion for attaching the rotor blade 50 to the rotor shaft 42. The blade root 59 has a cross section shaped like a Christmas tree.

[0042] The cooling air passage 60 is formed through the blade root 59, the platform 58, and the blade body 51, and is a passage through which cooling air Ac can flow. The cooling air passage 60 has an introduction passage 61, a blade body passage 63, a plurality of front ejection holes 66, a plurality of rear ejection holes 67, a plurality of tip ejection holes 68, a plurality of pressure side corner ejection holes 69p, and a plurality of suction side corner ejection holes 69n.

[0043] 2 and 3, the introduction passage 61 has two introduction passage sections 62 that extend in the blade height direction Dr at least within the blade root 59 and are aligned along the camber line CL of the blade body 51. Of the two introduction passage sections 62, the first introduction passage section 62a on the front side Dau and the second introduction passage section 62b on the rear side Dad both have inlets 62i that open to the bottom surface 59b of the blade root 59, and cooling air Ac can flow in through these inlets 62i. The bottom surface 59b of the blade root 59 is the surface of the blade root 59 that faces the hub side Dri and is located closest to the hub side Dri.

[0044] The blade body passage 63 extends in the blade height direction Dr within the blade body 51 and has six blade body passage sections 64 lined up from the forward side Dau to the aft side Dad along the camber line CL, and a communication section 65 that connects two adjacent blade body passage sections 64 among the six blade body passage sections 64. Here, of the six blade body passage sections 64, the blade body passage section 64 located most forward Dau is referred to as the first blade body passage section 64a, the blade body passage section 64 located more aft than the first blade body passage section 64a and adjacent to the first blade body passage section 64a is referred to as the second blade body passage section 64b, and the blade body passage section 64 located more aft than the second blade body passage section 64b and adjacent to the second blade body passage section 64b is referred to as the third blade body passage section 64c. Furthermore, of the six blade body passage sections 64, the blade body passage section 64 located on the rear side Dad of the third blade body passage section 64c and adjacent to the third blade body passage section 64c is designated as the fourth blade body passage section 64d, the blade body passage section 64 located on the rear side Dad of the fourth blade body passage section 64d and adjacent to the fourth blade body passage section 64d is designated as the fifth blade body passage section 64e, and the blade body passage section 64 located on the most rear side Dad and adjacent to the fifth blade body passage section 64e is designated as the sixth blade body passage section 64f.

[0045] The communication section 65 includes a 1-2 hub-side communication section 65a, a 2-3 tip-side communication section 65c, a 4-5 tip-side communication section 65d, and a 5-6 hub-side communication section 65e. The 1-2 hub-side communication section 65a communicates the hub-side Dri portion of the first blade passage section 64a with the hub-side Dri portion of the second blade passage section 64b. The 2-3 tip-side communication section 65c communicates the tip-side Dro portion of the second blade passage section 64b with the tip-side Dro portion of the third blade passage section 64c. The 4-5 tip-side communication section 65d communicates the tip-side Dro portion of the fourth blade passage section 64d with the tip-side Dro portion of the fifth blade passage section 64e. The 5-6 hub side communication section 65e communicates the hub side Dri portion of the fifth blade passage section 64e with the hub side Dri portion of the sixth blade passage section 64f.

[0046] The first introduction passage 62a communicates with the hub-side Dri portion of the third blade passage 64c, and the second introduction passage 62b communicates with the hub-side Dri portion of the fourth blade passage 64d.

[0047] Each of the plurality of front ejection holes 66 has an outlet that opens at the leading edge 53 f in the blade surface 52 and in the region near the leading edge 53 f, and is able to eject a portion of the cooling air Ac flowing through the first blade body passage section 64 a from this outlet. The plurality of rear ejection holes 67 has an outlet that opens at the trailing edge 53 b in the blade surface 52, and is able to eject a portion of the cooling air Ac flowing through the sixth blade body passage section 64 f from this outlet.

[0048] 2 to 6, each of the plurality of tip ejection holes 68 has an outlet 68o (see FIG. 2) that opens at the tip surface 55, and the cooling air Ac from the blade-body passage 63 can be ejected from this outlet 68o. The outlets 68o of each of the plurality of tip ejection holes 68 are aligned along the camber line CL from the front side Dau to the rear side Dad.

[0049] As shown in FIGS. 2, 4, and 5, each of the pressure side corner nozzles 69p has an outlet that opens at a pressure side corner 56p, which is the boundary between the pressure surface 54p and the tip surface 55, and cooling air Ac from the blade-body passage 63 can be ejected from this outlet. The outlets of each of the pressure side corner nozzles 69p are aligned from the front side Dau to the rear side Dad at the pressure side corner 56p. The suction side corner nozzles 69n each have an outlet that opens at a suction side corner 56n, which is the boundary between the suction surface 54n and the tip surface 55, and cooling air Ac from the blade-body passage 63 can be ejected from this outlet. The outlets of each of the suction side corner nozzles 69n are aligned from the front side Dau to the rear side Dad at the suction side corner 56n.

[0050] Here, the region of the tip surface 55 where the first blade passage 64a exists, closer to the hub than the tip surface 55 (Dri), is referred to as region 1 55a. The region of the tip surface 55 where the second blade passage 64b, the 2-3 tip-side communicating portion 65c, and the third blade passage 64c exist, closer to the hub than the tip surface 55 (Dri), is referred to as region 2-3 55c. The region of the tip surface 55 where the fourth blade passage 64d, the 4-5 tip-side communicating portion 65d, and the fifth blade passage 64e exist, closer to the hub than the tip surface 55 (Dri), is referred to as region 4-5 55d. The region of the tip surface 55 where the sixth blade passage 64f exists, closer to the hub than the tip surface 55 (Dri), is referred to as region 6 55f. The number of outlets 68o in the tip ejection holes 68 per unit length of the camber line CL is referred to as the linear density. In this embodiment, the length of the 4-5 region 55d in the direction along the camber line CL is longer than the length of the 2-3 region 55c in the direction along the camber line CL.

[0051] The outlets 68o of some of the tip ejection holes 68, the 1-region ejection holes 68a, open in the 1-region 55a of the tip surface 55. The 1-region ejection holes 68a are capable of ejecting the cooling air Ac that has flowed through the first blade body passage section 64a from these outlets 68o. The outlets 68o of some of the tip ejection holes 68, the 2-3-region ejection holes 68c, open in the 2-3 region 55c of the tip surface 55. The 2-3-region ejection holes 68c are capable of ejecting a portion of the cooling air Ac that flows through the third blade body passage section 64c, the 2-3 tip-side communicating section 65c, and the second blade body passage section 64b from these outlets 68o. The outlets 68o of some of the tip ejection holes 68, the 4-5-region ejection holes 68d, open in the 4-5 region 55d of the tip surface 55. The plurality of 4-5 region ejection holes 68d are capable of ejecting from this outlet 68o a portion of the cooling air Ac that flows through the fourth blade passage section 64d, the 4-5 tip side communication section 65d, and the fifth blade passage section 64e.

[0052] The linear density of the outlets 68o in the 4-5 region jet holes 68d is higher than the linear density of the outlets 68o in the 2-3 region jet holes 68c. Specifically, the linear density of the outlets 68o in the 4-5 region jet holes 68d is 1.5 times or more and 2.5 times or less than the linear density of the outlets 68o in the 2-3 region jet holes 68c. For example, the linear density of the outlets 68o in the 4-5 region jet holes 68d is twice the linear density of the outlets 68o in the 2-3 region jet holes 68c.

[0053] Furthermore, the area density, which is the number of outlets 68o of the multiple 4-5 region ejection holes 68d per unit area in the 4-5 region 55d, is higher than the area density, which is the number of outlets 68o of the multiple 2-3 region ejection holes 68c per unit area in the 2-3 region 55c. Specifically, the area density of the outlets 68o of the 4-5 region ejection holes 68d is at least two times but not more than ten times the area density of the outlets 68o of the 2-3 region ejection holes 68c. For example, the area density of the outlets 68o of the 4-5 region ejection holes 68d is five times the area density of the outlets 68o of the 2-3 region ejection holes 68c.

[0054] The cooling air Ac that flows into the first introduction passage 62a flows into the third blade passage 64c. This cooling air Ac flows through the third blade passage 64c toward the tip side Dro, and in the process, convectively cools the area around the third blade passage 64c. The cooling air Ac that flows through the third blade passage 64c flows into the 2-3 tip side communicating portion 65c. This cooling air Ac flows through the 2-3 tip side communicating portion 65c toward the front side Dau, and in the process, convectively cools the area around the 2-3 tip side communicating portion 65c. The cooling air Ac that flows through the 2-3 tip side communicating portion 65c flows into the second blade passage 64b. This cooling air Ac flows through the second blade passage 64b toward the hub side Dri, and in the process, convectively cools the area around the second blade passage 64b. The cooling air Ac that flows through the second blade body passage 64b flows into the 1-2 hub side communicating portion 65a. This cooling air Ac flows through the 1-2 hub side communicating portion 65a to the front side Dau, and in this process, convectively cools the area around the 1-2 hub side communicating portion 65a. The cooling air Ac that flows through the 1-2 hub side communicating portion 65a flows into the first blade body passage 64a. This cooling air Ac flows through the first blade body passage 64a to the tip side Dro, and in this process, convectively cools the area around the first blade body passage 64a. A portion of the cooling air Ac flowing through the first blade body passage 64a flows into the multiple front ejection holes 66. This cooling air Ac flows through the multiple front ejection holes 66, and in this process, convectively cools the area around the multiple front ejection holes 66. The cooling air Ac that has flowed through the plurality of front injection holes 66 is ejected from the outlets of the plurality of front injection holes 66. The cooling air Ac ejected from the plurality of front injection holes 66 performs film cooling around the leading edge 53f in the blade surface 52.

[0055] The cooling air Ac that flows into the second introduction passage 62b flows into the fourth blade passage 64d. This cooling air Ac flows through the fourth blade passage 64d to the tip side Dro, and in the process, convectively cools the area around the fourth blade passage 64d. The cooling air Ac that flows through the fourth blade passage 64d flows into the 4-5 tip side communicating portion 65d. This cooling air Ac flows through the 4-5 tip side communicating portion 65d to the rear side Dad, and in the process, convectively cools the area around the 4-5 tip side communicating portion 65d. The cooling air Ac that flows through the 4-5 tip side communicating portion 65d flows into the fifth blade passage 64e. This cooling air Ac flows through the fifth blade passage 64e to the hub side Dri, and in the process, convectively cools the area around the fifth blade passage 64e. The cooling air Ac that flows through the fifth blade passage 64e flows into the 5-6 hub-side communicating portion 65e. This cooling air Ac flows through the 5-6 hub-side communicating portion 65e toward the rear side (Dad), and in the process, convectively cools the area around the 5-6 hub-side communicating portion 65e. The cooling air Ac that flows through the 5-6 hub-side communicating portion 65e flows into the sixth blade passage 64f. This cooling air Ac flows through the sixth blade passage 64f toward the tip side (Dro), and in the process, convectively cools the area around the sixth blade passage 64f. A portion of the cooling air Ac flowing through the sixth blade passage 64f flows into the multiple rear ejection holes 67. This cooling air Ac flows through the multiple rear ejection holes 67, and in the process, convectively cools the area around the multiple rear ejection holes 67. The cooling air Ac that has flowed through the multiple rear injection holes 67 is ejected from the outlets of the multiple rear injection holes 67. The cooling air Ac ejected from the multiple rear injection holes 67 performs film cooling around the trailing edge 53b in the blade surface 52.

[0056] As described above, in the blade 50 of this embodiment, as previously described, the cooling air Ac that flows into the first introduction passage 62a flows through the third blade passage 64c, the 2-3 tip side communicating portion 65c, the second blade passage 64b, the 1-2 hub side communicating portion 65a, and the first blade passage 64a, before being ejected from the leading edge 53f of the blade body 51. Also, in this blade 50, as previously described, the cooling air Ac that flows into the second introduction passage 62b flows through the fourth blade passage 64d, the 4-5 tip side communicating portion 65d, the fifth blade passage 64e, the 5-6 hub side communicating portion 65e, and the sixth blade passage 64f, before being ejected from the trailing edge 53b of the blade body 51. Therefore, in the blade 50 of this embodiment, the blade 50 can be cooled while suppressing the amount of cooling air Ac.

[0057] 4, part of the combustion gas G coming toward the blade body 51 from the front side Dau flows along the pressure surface 54p of the blade body 51 to the rear side Dad, and the other part flows along the suction surface 54n of the blade body 51 to the rear side Dad. With the blade body 51 as the reference, the pressure of the combustion gas G on the pressure surface 54p side is higher than the pressure of the combustion gas G on the suction surface 54n side. A force in the circumferential direction Dc acts on the blade body 51 due to this pressure difference of the combustion gas G.

[0058] 5 and 6 , there is a gap between the tip surface 55 of the blade body 51 and the turbine casing 45. As described above, the pressure of the combustion gas G on the pressure surface 54p side is higher than the pressure of the combustion gas G on the suction surface 54n side, so part of the combustion gas G on the pressure surface 54p side flows into the gap between the tip surface 55 and the turbine casing 45 and then flows out to the suction surface 54n side. Therefore, the tip surface 55 of the blade body 51 is also exposed to the high-temperature combustion gas G.

[0059] The rotor blade 50 in this embodiment has a plurality of tip ejection holes 68. A portion of the cooling air Ac flowing through the blade-body passage 63 flows into the plurality of tip ejection holes 68. This cooling air Ac convectively cools the area around the tip ejection holes 68 as it flows through the tip ejection holes 68. The cooling air Ac that has flowed through the plurality of tip ejection holes 68 is ejected from outlets 68o of the tip ejection holes 68 that open on the tip surface 55. The cooling air Ac ejected from the plurality of tip ejection holes 68 film-cools the tip surface 55.

[0060] Therefore, in this embodiment, thermal damage to the tip surface 55 due to the combustion gas G can be suppressed, and the durability of the rotor blade 50 can be improved.

[0061] As described above, the pressure of the combustion gas G on the pressure surface 54p side is higher than the pressure of the combustion gas G on the suction surface 54n side, and a pressure difference exists between the combustion gas G on the pressure surface 54p side and the combustion gas G on the suction surface 54n side, with the blade 51 as the reference. This pressure difference gradually increases and then gradually decreases from the leading edge 53f of the blade 51 toward the trailing edge 53b. The position where this pressure difference is greatest is within the region of the blade 51 where the fourth blade passage 64d and the 4-5 tip communicating portion 65d are present. Therefore, the pressure difference in the region of the blade 51 where the fourth blade passage 64d, the 4-5 tip communicating portion 65d, and the fifth blade passage 64e are present is greater than the pressure difference in the region of the blade 51 where the third blade passage 64c, the 2-3 tip communicating portion 65c, and the second blade passage 64b are present. In this case, the flow velocity of the combustion gas G passing through the 4-5 region 55d on the tip surface 55 is higher than the flow velocity of the combustion gas G passing through the 2-3 region 55c on the tip surface 55. When the flow velocity of the combustion gas G is high, the heat transfer coefficient between the combustion gas G and the blade body 51 increases, so the heat transfer coefficient between the 4-5 region 55d on the tip surface 55 and the combustion gas G is higher than the heat transfer coefficient between the 2-3 region 55c on the tip surface 55 and the combustion gas G.

[0062] In this embodiment, the linear density of the outlets 68o of the 2-3 region ejection holes 68c that open in the 2-3 region 55c, which has a low heat transfer coefficient in the tip surface 55, is reduced, while the linear density of the outlets 68o of the 4-5 region ejection holes 68d that open in the 4-5 region 55d, which has a high heat transfer coefficient in the tip surface 55, is increased. As a result, in this embodiment, the amount of cooling air Ac ejected from the outlets 68o in the 2-3 region 55c, which is relatively difficult to heat in the tip surface 55, is reduced, thereby improving the cooling performance for the 4-5 region 55d, which is relatively easy to heat in the tip surface 55. Therefore, in this embodiment, the durability of the rotor blade 50 can be improved while reducing the amount of cooling air Ac used.

[0063] The flow of combustion gas G along the pressure side corner 56p and the suction side corner 56n is turbulent. This is because the pressure side corner 56p is the position where the combustion gas G on the pressure surface 54p side flows into the narrow gap between the tip surface 55 and the turbine casing 45, and the suction side corner 56n is the position where the combustion gas G flows out from the narrow gap between the tip surface 55 and the turbine casing 45 into the wide space on the suction surface 54n side. The heat transfer coefficient between the combustion gas G and the blade body 51 is high even in the position where the flow of combustion gas G is turbulent as described above. The rotor blade 50 in this embodiment has pressure side corner ejection holes 69p that open at the pressure side corner 56p, where the heat transfer coefficient is relatively higher than in the surrounding area, and suction side corner ejection holes 69n that open at the suction side corner 56n, where the heat transfer coefficient is relatively higher than in the surrounding area. This improves the cooling performance of the positive pressure side corners 56p and negative pressure side corners 56n, which are more likely to heat up than the surrounding areas.

[0064] The blade width, which is the distance between the pressure surface 54p and the suction surface 54n, gradually increases and then decreases from the leading edge 53f toward the trailing edge 53b of the blade body 51. The position where this blade width is greatest is closer to the leading edge 53f, in the region where the 2-3 tip side communicating portion 65c and the second blade body passage portion 64b are present. In this relationship, the width of the 4-5 tip side communicating portion 65d in the blade span direction is narrower than the width of the 2-3 tip side communicating portion 65c in the blade span direction. Therefore, the flow velocity of the cooling air Ac flowing through the 4-5 tip side communicating portion 65d is higher than the flow velocity of the cooling air Ac flowing through the 2-3 tip side communicating portion 65c, and the convective cooling effect of the cooling air Ac flowing through the 4-5 tip side communicating portion 65d is higher than the convective cooling effect of the cooling air Ac flowing through the 2-3 tip side communicating portion 65c. In this embodiment, as described above, the length of the 4-5 region 55d on the tip surface 55 in the direction along the camber line CL is longer than the length of the 2-3 region 55c on the tip surface 55 in the direction along the camber line CL. However, in this embodiment, the convective cooling effect on the 4-5 region 55d on the tip surface 55, which is relatively easily heated, is greater than the convective cooling effect on the 2-3 region 55c on the tip surface 55, which is relatively less easily heated. Therefore, in this embodiment, the durability of the rotor blade 50 can be improved from this perspective as well.

[0065] "First Modified Example of Blade" As shown in FIG. 7, the plurality of 4-5 region ejection holes 68d may be inclined with respect to the tip surface 55 so as to gradually approach the trailing edge 53b as they move toward the tip side Dro. In this case, the length of the plurality of 4-5 region ejection holes 68d is longer than the length of the plurality of 4-5 region ejection holes 68d when the plurality of 4-5 region ejection holes 68d extend in a direction perpendicular to the tip surface 55. Furthermore, the projected area of ​​the plurality of 4-5 region ejection holes 68d on the tip surface 55 is larger than the projected area of ​​the plurality of 4-5 region ejection holes 68d when the plurality of 4-5 region ejection holes 68d extend in a direction perpendicular to the tip surface 55. Therefore, in this modified example, the convective cooling effect of the cooling air Ac flowing through the plurality of 4-5 region ejection holes 68d can be applied over a wide area of ​​the tip surface 55.

[0066] All of the plurality of tip ejection holes 68 may be inclined with respect to the tip surface 55, as in the above modified example.

[0067] "Second and Third Modified Examples of Blade" In the above embodiments, the outlets 68o of the multiple tip ejection holes 68 are all located on the camber line CL. However, the multiple tip ejection holes 68 do not have to be located on the camber line CL. For example, as in a second modified example shown in FIG. 8 , among the outlets 68o of the multiple 2-3 region ejection holes 68c in the 2-3 region 55c, one of the outlets 68o may be located closer to the pressure surface 54p than the camber line CL, and the other outlets 68o may be located closer to the suction surface 54n than the camber line CL. Furthermore, among the outlets 68o of the multiple 4-5 region ejection holes 68d in the 4-5 region 55d, one of the outlets 68o may be located closer to the pressure surface 54p than the camber line CL, and the other outlets 68o may be located closer to the suction surface 54n than the camber line CL. Furthermore, for example, as in a third modified example shown in Figure 9, both the outlets 68o of the multiple 2-3 region ejection holes 68c in the 2-3 region 55c and the outlets 68o of the multiple 4-5 region ejection holes 68d in the 4-5 region 55d may be located on the negative pressure surface 54n side of the camber line CL.

[0068] In the second and third modified examples, as in the above embodiment, the area density, which is the number of outlets 68o of the multiple 4-5 region ejection holes 68d per unit area in the 4-5 region 55d, is higher than the area density, which is the number of outlets 68o of the multiple 2-3 region ejection holes 68c per unit area in the 2-3 region 55c. Specifically, the area density of the outlets 68o of the 4-5 region ejection holes 68d is at least two times and at most ten times the area density of the outlets 68o of the 2-3 region ejection holes 68c.

[0069] "Other Modifications" The rotor blade 50 in the above embodiment has both a plurality of pressure side corner ejection holes 69p and a plurality of suction side corner ejection holes 69n. However, at least one of the plurality of positive pressure side corner ejection holes 69p and the plurality of suction side corner ejection holes 69n may be omitted. When only one of the plurality of positive pressure side corner ejection holes 69p and the plurality of suction side corner ejection holes 69n is omitted, it is preferable to omit the plurality of suction side corner ejection holes 69n and leave the plurality of positive pressure side corner ejection holes 69p.

[0070] The present disclosure is not limited to the above-described embodiments and modifications, and various additions, modifications, substitutions, partial deletions, etc. are possible within the scope of the conceptual idea and spirit of the present invention as derived from the content defined in the claims and their equivalents.

[0071] [Additional Notes] The rotor blade 50 in the above-described embodiment and modified examples can be understood, for example, as follows.

[0072] (1) A rotor blade 50 in a first aspect comprises: a blade body 51 having an airfoil-shaped cross section and extending in a blade height direction Dr including a directional component perpendicular to the cross section, a tip side Dro and a hub side Dri in the blade height direction Dr, a platform 58 provided at an end of the hub side Dri of the blade body 51, a blade root 59 provided on the hub side Dri of the platform 58, and a cooling air passage 60 formed across the blade root 59, the platform 58, and the blade body 51 and through which cooling air Ac can flow. The blade body 51 has a blade surface 52 facing in a direction having a directional component perpendicular to the blade height direction Dr, and a tip surface 55 facing the tip side Dro in the blade height direction Dr. The blade surface 52 has a leading edge 53 f and a trailing edge 53 b extending in the blade height direction Dr, and a pressure surface 54 p and a suction surface 54 n extending in the blade height direction Dr from the leading edge 53 f to the trailing edge 53 b. The cooling air passage 60 includes an introduction passage 61 formed at least in the blade root 59, a blade body passage 63 formed at least in the blade body 51, and a plurality of tip ejection holes 68 having outlets 68 o opening at the tip surface 55 and capable of ejecting cooling air Ac from the outlets 68 o. The introduction passage 61 includes a first introduction passage portion 62 a and a second introduction passage portion 62 b. Both the first introduction passage portion 62 a and the second introduction passage portion 62 b have inlets 62 i opening at the surface of the blade root 59, and the cooling air Ac can flow in through the inlets 62 i. The blade passage 63 extends in the blade height direction Dr and has six blade passage sections 64 lined up along the camber line CL of the blade body 51 from the leading edge 53 f side to the trailing edge 53 b side, and a communication section 65 that connects two adjacent blade passage sections 64 among the six blade passage sections 64.The six blade passages 64 include a first blade passage 64a closest to the leading edge 53f, a second blade passage 64b located closer to the trailing edge 53b than the first blade passage 64a and adjacent to the first blade passage 64a, a third blade passage 64c located closer to the trailing edge 53b than the second blade passage 64b and adjacent to the second blade passage 64b, a fourth blade passage 64d located closer to the trailing edge 53b than the third blade passage 64c and adjacent to the third blade passage 64c, a fifth blade passage 64e located closer to the trailing edge 53b than the fourth blade passage 64d and adjacent to the fourth blade passage 64d, and a sixth blade passage 64f located closest to the trailing edge 53b and adjacent to the fifth blade passage 64e. The communicating portion 65 includes a 1-2 hub side communicating portion 65a that communicates the hub side Dri portion of the first blade body passage portion 64a with the hub side Dri portion of the second blade body passage portion 64b, a 2-3 tip side communicating portion 65c that communicates the tip side Dro portion of the second blade body passage portion 64b with the tip side Dro portion of the third blade body passage portion 64c, a 4-5 tip side communicating portion 65d that communicates the tip side Dro portion of the fourth blade body passage portion 64d with the tip side Dro portion of the fifth blade body passage portion 64e, and a 5-6 hub side communicating portion 65e that communicates the hub side Dri portion of the fifth blade body passage portion 64e with the hub side Dri portion of the sixth blade body passage portion 64f. The first introduction passage 62a communicates with the hub-side Dri portion of the third blade passage 64c, and the second introduction passage 62b communicates with the hub-side Dri portion of the fourth blade passage 64d. The tip surface 55 has a 2-3 region 55c, located closer to the hub-side Dri than the tip surface 55, where the second blade passage 64b, the 2-3 tip-side communicating portion 65c, and the third blade passage 64c are present, and a 4-5 region 55d, located closer to the hub-side Dri than the tip surface 55, where the fourth blade passage 64d, the 4-5 tip-side communicating portion 65d, and the fifth blade passage 64e are present. Of the plurality of tip ejection holes 68, some of the 2-3 region ejection holes 68c have their outlets 68o open in the 2-3 region 55c in the tip surface 55.Of the plurality of tip ejection holes 68, the outlets 68o of another portion of the plurality of 4-5 region ejection holes 68d open in the 4-5 region 55d in the tip surface 55. The area density, which is the number of the outlets 68o of the plurality of 4-5 region ejection holes 68d per unit area in the 4-5 region 55d, is higher than the area density, which is the number of the outlets 68o of the plurality of 2-3 region ejection holes 68c per unit area in the 2-3 region 55c.

[0073] In the blade 50 of this embodiment, the cooling air Ac that flows into the first inlet passage 62a flows through the third blade passage 64c, the 2-3 tip-side communicating portion 65c, the second blade passage 64b, the 1-2 hub-side communicating portion 65a, and the first blade passage 64a, convectively cooling the areas around these passages and communicating portions as it flows through these passages and communicating portions. In the blade 50 of this embodiment, the cooling air Ac that flows into the second inlet passage 62b flows through the fourth blade passage 64d, the 4-5 tip-side communicating portion 65d, the fifth blade passage 64e, the 5-6 hub-side communicating portion 65e, and the sixth blade passage 64f, convectively cooling the areas around these passages and communicating portions as it flows through these passages and communicating portions. Therefore, the blade 50 of this embodiment can cool the blade 50 while suppressing the amount of cooling air Ac.

[0074] A portion of the combustion gas G coming toward the blade body 51 from the leading edge 53f side flows along the pressure surface 54p of the blade body 51 toward the trailing edge 53b, and the other portion flows along the suction surface 54n of the blade body 51 toward the trailing edge 53b. With respect to the blade body 51, the pressure of the combustion gas G on the pressure surface 54p side is higher than the pressure of the combustion gas G on the suction surface 54n side. This pressure difference in the combustion gas G causes a circumferential force Dc to act on the blade body 51. There is a gap between the tip surface 55 of the blade body 51 and the turbine casing 45. As described above, with respect to the blade body 51, the pressure of the combustion gas G on the pressure surface 54p side is higher than the pressure of the combustion gas G on the suction surface 54n side. Therefore, a portion of the combustion gas G on the pressure surface 54p side flows into the gap between the tip surface 55 and the turbine casing 45 and then flows out toward the suction surface 54n side. Therefore, the tip surface 55 of the blade body 51 is also exposed to the high-temperature combustion gas G.

[0075] The rotor blade 50 in this embodiment has a plurality of tip ejection holes 68. A portion of the cooling air Ac flowing through the blade-body passage 63 flows into the plurality of tip ejection holes 68. This cooling air Ac convectively cools the area around the tip ejection holes 68 while flowing through the tip ejection holes 68. The cooling air Ac that has flowed through the plurality of tip ejection holes 68 is ejected from outlets 68o of the tip ejection holes 68 that open on the tip surface 55. The cooling air Ac ejected from the plurality of tip ejection holes 68 film-cools the tip surface 55.

[0076] Therefore, in this embodiment, thermal damage to the tip surface 55 due to the combustion gas G can be suppressed, and the durability of the rotor blade 50 can be improved.

[0077] As described above, there is a pressure difference between the combustion gas G on the pressure surface 54p side and the combustion gas G on the suction surface 54n side of the blade body 51. This pressure difference gradually increases and then decreases from the leading edge 53f toward the trailing edge 53b of the blade body 51. The position where this pressure difference is greatest is within the region of the blade body 51 where the fourth blade passage 64d and the 4-5 tip communication 65d are present. Therefore, the pressure difference in the region of the blade body 51 where the fourth blade passage 64d, the 4-5 tip communication 65d, and the fifth blade passage 64e are present is greater than the pressure difference in the region of the blade body 51 where the third blade passage 64c, the 2-3 tip communication 65c, and the second blade passage 64b are present. In this case, the flow velocity of the combustion gas G passing through the 4-5 region 55d on the tip surface 55 is higher than the flow velocity of the combustion gas G passing through the 2-3 region 55c on the tip surface 55. When the flow velocity of the combustion gas G is high, the heat transfer coefficient between the combustion gas G and the blade body 51 increases, so the heat transfer coefficient between the 4-5 region 55d on the tip surface 55 and the combustion gas G is higher than the heat transfer coefficient between the 2-3 region 55c on the tip surface 55 and the combustion gas G.

[0078] In this embodiment, the area density of the outlets 68o of the 2-3 region ejection holes 68c that open in the 2-3 region 55c, where the heat transfer coefficient is low, is reduced, while the area density of the outlets 68o of the 4-5 region ejection holes 68d that open in the 4-5 region 55d, where the heat transfer coefficient is high, is increased. As a result, in this embodiment, the amount of cooling air Ac ejected from the outlets 68o of the 2-3 region 55c, which is relatively difficult to heat up in the tip surface 55, is reduced, thereby improving the cooling performance for the 4-5 region 55d, which is relatively easy to heat up in the tip surface 55. Therefore, in this embodiment, the durability of the rotor blade 50 can be improved while reducing the amount of cooling air Ac used.

[0079] (2) In a second aspect of the rotor blade 50, in the rotor blade of the first aspect, the area density of the outlets in the plurality of 4-5 region holes is at least twice the area density of the outlets in the plurality of 2-3 region holes.

[0080] (3) In a third aspect, the rotor blade 50 of the second aspect is such that the area density of the outlets in the plurality of 4-5 region holes is 10 times or less than the area density of the outlets in the plurality of 2-3 region holes.

[0081] (4) A fourth aspect of the rotor blade 50 is the rotor blade 50 of any one of the first to third aspects, wherein the outlets 68o of each of the plurality of tip ejection holes 68 are aligned along the camber line CL from the leading edge 53f to the trailing edge 53b. If the number of the outlets 68o in the plurality of tip ejection holes 68 per unit length of the camber line CL is defined as a linear density, the linear density of the outlets 68o in the plurality of 4-5 region ejection holes 68d is higher than the linear density of the outlets 68o in the plurality of 2-3 region ejection holes 68c.

[0082] (5) In a fifth aspect, the blade 50 of the fourth aspect is such that the length of the 4-5 region 55d in the direction along the camber line CL is longer than the length of the 2-3 region 55c in the direction along the camber line CL.

[0083] The blade width, which is the distance between the pressure surface 54p and the suction surface 54n, gradually increases and then decreases from the leading edge 53f toward the trailing edge 53b of the blade body 51. The position where this blade width is greatest is closer to the leading edge 53f, in the region where the 2-3 tip side communicating portion 65c and the second blade body passage portion 64b are present. In this relationship, the width of the 4-5 tip side communicating portion 65d in the blade span direction is narrower than the width of the 2-3 tip side communicating portion 65c in the blade span direction. Therefore, the flow velocity of the cooling air Ac flowing through the 4-5 tip side communicating portion 65d is higher than the flow velocity of the cooling air Ac flowing through the 2-3 tip side communicating portion 65c, and the convective cooling effect of the cooling air Ac flowing through the 4-5 tip side communicating portion 65d is higher than the convective cooling effect of the cooling air Ac flowing through the 2-3 tip side communicating portion 65c. In this embodiment, the length of the 4-5 region 55d on the tip surface 55 in the direction along the camber line CL is longer than the length of the 2-3 region 55c on the tip surface 55 in the direction along the camber line CL. However, in this embodiment, the convective cooling effect on the 4-5 region 55d on the tip surface 55, which is relatively easily heated, is greater than the convective cooling effect on the 2-3 region 55c on the tip surface 55, which is relatively less easily heated. Therefore, in this embodiment, the durability of the rotor blade 50 can be improved.

[0084] (6) A sixth aspect of the rotor blade 50 is the rotor blade 50 of the fourth or fifth aspect, wherein the linear density of the outlets 68o in the plurality of 4-5 region ejection holes 68d is 1.5 times or more the linear density of the outlets 68o in the plurality of 2-3 region ejection holes 68c.

[0085] (7) A seventh aspect of the rotor blade 50 is the rotor blade 50 of the sixth aspect, wherein the linear density of the outlets 68o in the plurality of 4-5 region ejection holes 68d is 2.5 times or less than the linear density of the outlets 68o in the plurality of 2-3 region ejection holes 68c.

[0086] (8) In the eighth aspect of the rotor blade 50, in the rotor blade 50 of any one of the first to seventh aspects, at least the plurality of 4-5 region jet holes 68d among the plurality of tip jet holes 68 are inclined with respect to the tip surface 55 so as to gradually approach the trailing edge 53b as they move toward the tip side Dro.

[0087] In this embodiment, the length of the plurality of 4-5 region ejection holes 68d is longer than the length of the plurality of 4-5 region ejection holes 68d when the plurality of 4-5 region ejection holes 68d extend in a direction perpendicular to the tip surface 55. Also, in this embodiment, the projected area of ​​the plurality of 4-5 region ejection holes 68d on the tip surface 55 is larger than the projected area of ​​the plurality of 4-5 region ejection holes 68d when the plurality of 4-5 region ejection holes 68d extend in a direction perpendicular to the tip surface 55. Therefore, in this embodiment, the convection cooling effect of the cooling air Ac flowing through the plurality of 4-5 region ejection holes 68d can be achieved over a wide area of ​​the tip surface 55.

[0088] (9) A ninth aspect of the blade 50 is the blade 50 of any one of the first to eighth aspects, wherein the cooling air passage 60 has an outlet that opens at a pressure side corner 56p, which is the boundary between the pressure surface 54p and the tip surface 55, and has a plurality of pressure side corner outlet holes 69p aligned from the leading edge 53f side to the trailing edge 53b side, through which the cooling air Ac from the blade-body passage 63 can be ejected from the outlet of the pressure side corner 56p.

[0089] The flow of combustion gas G is turbulent at a position along the pressure side corner 56p. This is because the pressure side corner 56p is the position where the combustion gas G on the pressure surface 54p side flows into the narrow gap between the tip surface 55 and the turbine casing 45. The heat transfer coefficient between the combustion gas G and the blade body 51 is high even at the location where the flow of combustion gas G is turbulent as described above. The rotor blade 50 in this embodiment has pressure side corner outlet holes 69p that open at the pressure side corner 56p, where the heat transfer coefficient is relatively higher than in the surrounding areas. Therefore, in this embodiment, the cooling performance of the pressure side corner 56p, which is more easily heated than the surrounding areas, can be improved.

[0090] (10) A tenth aspect of the blade 50 is the blade 50 of any one of the first to ninth aspects, wherein the cooling air passage 60 has an outlet that opens at a negative pressure side corner 56n, which is the boundary between the negative pressure surface 54n and the tip surface 55, and has a plurality of negative pressure side corner outlet holes 69n aligned from the leading edge 53f side to the trailing edge 53b side, through which the cooling air Ac from the blade-body passage 63 can be ejected from the outlet of the negative pressure side corner 56n.

[0091] The flow of combustion gas G is turbulent at a position along the suction side corner 56n. This is because the suction side corner 56n is the position where the combustion gas G flows out from the narrow gap between the tip surface 55 and the turbine casing 45 into the wide space on the suction surface 54n side. The heat transfer coefficient between the combustion gas G and the blade body 51 is high even at the location where the flow of combustion gas G is turbulent as described above. The rotor blade 50 in this embodiment has suction side corner outlet holes 69n that open at the suction side corner 56n, where the heat transfer coefficient is relatively higher than in the surrounding areas. Therefore, in this embodiment, the cooling performance of the suction side corner 56n, which is more easily heated than the surrounding areas, can be improved.

[0092] The gas turbine 10 in the above embodiments and modified examples can be understood, for example, as follows. (11) The gas turbine 10 in an eleventh aspect includes a rotor shaft 42 having a plurality of the rotor blades 50 in any one of the first to tenth aspects, the rotor shaft 42 being rotatable about an axis Ar and having the plurality of rotor blades 50 attached to it in a line in a circumferential direction Dc about the axis Ar, and a turbine casing 45 covering the outer periphery of the plurality of rotor blades 50 and the rotor shaft 42. The rotor blades 50 are attached to the rotor shaft 42 such that the blade height direction Dr is radial to the axis Ar and the tip side Dro is radially outward from the axis Ar.

[0093] According to one aspect of the present disclosure, it is possible to increase the durability of the rotor blade while reducing the amount of cooling air used.

[0094] 10: Gas turbine 11: Gas turbine rotor 14: Intermediate casing 15: Gas turbine casing 20: Compressor 21: Compressor rotor 22: Rotor shaft 23: Row of moving blades 25: Compressor casing 26: Row of stationary blades 30: Combustor 40: Turbine 41: Turbine rotor 42: Rotor shaft 43: Row of moving blades 45: Turbine casing 49: Combustion gas flow path 50: Moving blade 51: Blade body 52: Blade surface 53f: Leading edge 53b: Trailing edge 54n: Suction surface 54p: Pressure surface 55: Tip surface 55a: Region 1 55c: Region 2-3 55d: Region 4-5 55f: Region 6 56n: Suction side corner 56p: Pressure side corner 58: Platform 59: Blade root 59b: Bottom surface 60: Cooling air passage 61: Introduction passage 62: Introduction passage section 62a: First introduction passage section 62b: Second introduction passage section 62i: Inlet 63: Blade passage 64: Blade passage section 64a: First blade passage section 64b: Second blade passage section 64c: Third blade passage section 64d: Fourth blade passage section 64e: Fifth blade passage section 64f: Sixth blade passage section 65: Communication section 65a: 1-2 hub side communication section 65c: 2-3 tip side communication section 65d: 4-5 tip side communication section 65e: 5-6 hub side communication section 66: Front injection hole 67: Rear injection hole 68: Tip injection hole 68o: Outlet 68a: 1 region injection hole 68c: 2-3 region injection hole 68d: 4-5 region injection hole 69n: Negative pressure side corner nozzle 69p: Pressure side corner nozzle A: Air Ac: Cooling air F: Fuel G: Combustion gas Ar: Axis CL: Camber line Da: Axial direction Dau: Front side (or axial upstream side) Dad: Rear side (or axial downstream side) Dc: Circumferential direction Dr: Blade height direction (or radial direction) Dri: Hub side (or radially inner side) Dro: Tip side (or radially outer side)

Claims

1. A blade body having an airfoil-shaped cross section and extending in a blade height direction including a directional component perpendicular to the cross section; a platform provided at the hub end of the blade body, of a tip side and a hub side in the blade height direction; a blade root provided on the hub side of the platform; and a cooling air passage formed across the blade root, the platform and the blade body, through which cooling air can flow, wherein the blade body has a blade surface facing a direction having a directional component perpendicular to the blade height direction and a tip surface facing the tip side in the blade height direction, and the blade surface has leading and trailing edges extending in the blade height direction, and pressure and suction surfaces extending in the blade height direction and spreading from the leading edge to the trailing edge, and the cooling air passage comprises an introduction passage formed at least in the blade root, a blade body passage formed at least in the blade body, and a plurality of tip ejection holes having outlets opening at the tip surface from which cooling air can be ejected, the introduction passage has a first introduction passage section and a second introduction passage section, each of the first introduction passage section and the second introduction passage section having an inlet opening on the surface of the blade root and through which cooling air can flow, the blade-body passage extending in the blade height direction has six blade-body passage sections aligned along the camber line of the blade from the leading edge side to the trailing edge side, and a communication section connecting two adjacent blade-body passage sections among the six blade-body passage sections, the six blade passage sections include a first blade passage section closest to the leading edge, a second blade passage section located closer to the trailing edge than the first blade passage section and adjacent to the first blade passage section, a third blade passage section located closer to the trailing edge than the second blade passage section and adjacent to the second blade passage section, a fourth blade passage section located closer to the trailing edge than the third blade passage section and adjacent to the third blade passage section, a fifth blade passage section located closer to the trailing edge than the fourth blade passage section and adjacent to the fourth blade passage section, and a sixth blade passage section located closest to the trailing edge and adjacent to the fifth blade passage section; the communication section includes a 1-2 hub side communication section that communicates between a hub side portion of the first blade passage section and a hub side portion of the second blade passage section;the tip surface has a 2-3 tip side communicating portion which communicates the tip side portion of the second blade passage portion with the tip side portion of the third blade passage portion, a 4-5 tip side communicating portion which communicates the tip side portion of the fourth blade passage portion with the tip side portion of the fifth blade passage portion, and a 5-6 hub side communicating portion which communicates the hub side portion of the fifth blade passage portion with the hub side portion of the sixth blade passage portion, the first introduction passage portion communicates with the hub side portion of the third blade passage portion, and the second introduction passage portion communicates with the hub side portion of the fourth blade passage portion, the tip surface has a 2-3 region on the hub side of the tip surface where the second blade passage portion, the 2-3 tip side communicating portion, and the third blade passage portion are present, and a 4-5 region on the hub side of the tip surface where the fourth blade passage portion, the 4-5 tip side communicating portion, and the fifth blade passage portion are present, a rotor blade, wherein among the plurality of tip jet holes, a portion of a plurality of 2-3 region jet holes have outlets that open in the 2-3 region in the tip surface, and another portion of the plurality of tip jet holes, a portion of a plurality of 4-5 region jet holes have outlets that open in the 4-5 region in the tip surface, and an area density that is the number of outlets in the plurality of 4-5 region jet holes per unit area in the 4-5 region is higher than an area density that is the number of outlets in the plurality of 2-3 region jet holes per unit area in the 2-3 region.

2. A rotor blade according to claim 1, wherein the area density of the outlets in the plurality of 4-5 region holes is at least twice the area density of the outlets in the plurality of 2-3 region holes.

3. A rotor blade according to claim 2, wherein the area density of the outlets in the plurality of 4-5 region holes is 10 times or less the area density of the outlets in the plurality of 2-3 region holes.

4. A blade according to any one of claims 1 to 3, wherein the outlets for each of the plurality of tip jet holes are aligned along the camber line from the leading edge side to the trailing edge side, and when the number of the outlets in the plurality of tip jet holes per unit length of the camber line is taken as linear density, the linear density of the outlets in the plurality of 4-5 region jet holes is higher than the linear density of the outlets in the plurality of 2-3 region jet holes.

5. A blade according to claim 4, wherein the length of the 4-5 region in the direction along the camber line is longer than the length of the 2-3 region in the direction along the camber line.

6. A rotor blade according to claim 4, wherein the linear density of the outlets in the plurality of 4-5 region holes is 1.5 times or more the linear density of the outlets in the plurality of 2-3 region holes.

7. A rotor blade according to claim 6, wherein the linear density of the outlets in the plurality of 4-5 region jet holes is 2.5 times or less the linear density of the outlets in the plurality of 2-3 region jet holes.

8. A rotor blade according to any one of claims 1 to 3, wherein at least the plurality of 4-5 region nozzle holes among the plurality of tip nozzle holes are inclined with respect to the tip surface so as to gradually approach the trailing edge side as they move toward the tip side.

9. A rotor blade according to any one of claims 1 to 3, wherein the cooling air passage has an outlet that opens at a pressure side corner that is the boundary between the pressure surface and the tip surface, and has a plurality of pressure side corner outlet holes aligned from the leading edge side to the trailing edge side, which are able to eject cooling air from the blade body passage from the outlet at the pressure side corner.

10. A rotor blade according to any one of claims 1 to 3, wherein the cooling air passage has an outlet opening at a suction side corner which is the boundary between the suction surface and the tip surface, and has a plurality of suction side corner ejection holes aligned from the leading edge side to the trailing edge side, which are capable of ejecting cooling air from the blade body passage from the outlet at the suction side corner.

11. A gas turbine comprising a plurality of rotor blades according to any one of claims 1 to 3, a rotor shaft rotatable about an axis and having a plurality of said rotor blades attached in a circumferential direction about said axis, and a turbine casing covering the outer periphery of said rotor blades and said rotor shaft, wherein said rotor blades are attached to said rotor shaft so that the blade height direction is radial to said axis and said tip side is radially outward from said axis.

Images