Turbine stator blade and gas turbine

Abstract

A turbine stator blade according to at least one embodiment of the present invention is provided with: a blade-shaped part; an inner shield; a pair of peripheral wall parts extending in the extending direction of the end parts at the end parts of one side and the other side in the circumferential direction of the inner shield; a vertical wall portion extending in the circumferential direction, one end and the other end of the vertical wall portion in the circumferential direction being connected to the pair of circumferential wall portions, and protruding from the inner shield; a connecting part for connecting the pair of peripheral wall parts and the vertical wall part with a smooth curved surface; and a first plate member that forms a cavity together with a surface on the opposite side of the inner shield and the pair of peripheral wall portions. The first plate member has a first flat surface portion along the pair of peripheral wall portions, a second flat surface portion along the vertical wall portion, and a curved surface portion along the connecting portion. The curved surface portion includes a thick portion that is thicker than the first flat surface portion and the second flat surface portion at least at one end portion and the other end portion in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a turbine stator blade and a gas turbine.

[0002] This application claims priority based on Japanese Patent Application No. 2023-031598 filed with the Japan Patent Office on March 2, 2023, and uses the contents thereof herein. Background Art

[0003] A gas turbine comprises: a compressor that compresses atmospheric air to generate compressed air; a combustor that burns fuel in the compressed air to generate combustion gas; and a turbine driven by the combustion gas. The turbine comprises: a turbine rotor that rotates about an axis; a plurality of stator blade layers arranged in an axial direction along which the axis extends; and a turbine chamber that rotatably covers the turbine rotor. The turbine rotor comprises: a rotor shaft that extends in an axial direction about the axis; and a plurality of moving blade layers fixed to the rotor shaft. Each of the plurality of moving blade layers comprises a plurality of moving blades arranged circumferentially about the axis. Any one of the plurality of stator blade layers is arranged upstream of the plurality of moving blade layers. Each of the plurality of stator blade layers comprises a plurality of stator blades arranged circumferentially about the axis.

[0004] Examples of the stator blade include the stator blade described in Patent Document 1. The stator blade includes a blade body extending radially relative to the axis, an outer shroud formed radially outside the blade body, and an inner shroud formed radially inside the blade body.

[0005] The inner shroud includes a pair of circumferentially opposed side walls, an upstream wall disposed upstream in the axial direction of the turbine rotor, and a retainer disposed axially opposed to the upstream wall, each projecting radially inward from the inner shroud toward the blade body. A recess is formed in the inner shroud by the pair of side walls, the upstream wall, and the retainer.

[0006] Previous technical literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-011649 Summary of the Invention

[0009] Technical issues to be solved by the invention

[0010] Sometimes a plate member is provided to cover and seal the recess of the inner shroud. In this case, when the plate member is connected to a pair of side walls or a retainer by welding, the plate member is also connected to the connection portion from the pair of side walls to the retainer which is smoothly connected by a curved surface.

[0011] However, if the retainer is deformed by the heat from the combustion gas, the stress becomes relatively high near the portion connected to the connecting portion within the plate member, which may cause damage due to low-cycle fatigue.

[0012] In view of the above circumstances, an object of at least one embodiment of the present invention is to improve the durability of turbine stator blades.

[0013] Means for solving technical problems

[0014] (1) At least one embodiment of the present invention relates to a turbine stator blade comprising: a blade-shaped portion; an inner shroud provided on the inner side of the blade-shaped portion in the blade height direction; a pair of peripheral wall portions, at end portions on one side and the other side of the circumferential direction in the inner shroud, extending along the extension direction of the end portions and protruding from the inner shroud toward the side opposite to the blade-shaped portion in the blade height direction; a longitudinal wall portion extending in the circumferential direction, with end portions on one side and the other side of the circumferential direction connected to the pair of peripheral wall portions, protruding from the inner shroud toward the side opposite to the blade-shaped portion in the blade height direction, and protruding toward the side opposite to the blade height direction relative to the pair of peripheral wall portions; a connecting portion connecting the pair of peripheral wall portions and the longitudinal wall portion with a smooth curved surface; and a first plate member forming a mold cavity together with the opposite side surface of the inner shroud and the pair of peripheral wall portions, the first plate member having a first flat portion along the pair of peripheral wall portions, a second flat portion along the longitudinal wall portion, and a curved portion along the connecting portion.

[0015] The curved surface portion includes thick portions thicker than the first planar portion and the second planar portion at least at end portions on one side and the other side in the circumferential direction.

[0016] (2) A gas turbine according to at least one embodiment of the present invention includes turbine stator blades having the structure of (1) above.

[0017] Effects of the Invention

[0018] According to at least one embodiment of the present invention, the durability of a turbine stator blade can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram showing the overall structure of a gas turbine.

[0020] Figure 2 It is a cross-sectional view showing a gas flow path of a turbine.

[0021] Figure 3 This is a schematic front view showing a stationary blade according to one embodiment.

[0022] Figure 4 It is a schematic perspective view of the inner shroud, showing a state before the first plate member and the second plate member are attached.

[0023] Figure 5 This is a schematic perspective view of the inner shroud, showing a state after the first plate member is mounted and before the second plate member is mounted.

[0024] Figure 6 yes Figure 5 VI-VI sectional view.

[0025] Figure 7 It is a schematic perspective view of the inner shroud, showing a state after the second plate member is attached.

[0026] Figure 8 yes Figure 7 Enlarged view of the main part.

[0027] Figure 9 yes Figure 7 Cross-sectional view taken along the IX-IX direction.

[0028] Figure 10 This is a diagram for explaining the welded portion between the first plate member and the inner shroud. DETAILED DESCRIPTION

[0029] Several embodiments of the present invention are described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

[0030] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" indicate relative or absolute configurations, and not only strictly indicate such configurations, but also indicate a state of relative displacement at an angle or distance with a tolerance or a degree that can achieve the same function.

[0031] For example, “identical,” “equal,” and “homogeneous” are expressions indicating the equal state of objects, and they not only indicate a strictly equal state but also a state in which there is a tolerance or a degree of difference to achieve the same function.

[0032] For example, expressions indicating shapes such as a quadrilateral and a cylinder not only indicate shapes such as a quadrilateral and a cylinder in a strict geometric sense, but also indicate shapes including concave and convex portions, chamfered portions, etc., within a range that can achieve the same effect.

[0033] On the other hand, the expressions “have”, “have”, “complete”, “include” or “have” are not exclusive expressions that exclude the existence of other constituent elements.

[0034] Figure 1 This is a schematic diagram showing the overall structure of a gas turbine. Figure 2 It is a cross-sectional view showing a gas flow path of a turbine.

[0035] In this embodiment, if Figure 1 As shown, the gas turbine 10 is composed of a compressor 11, a combustor 12, and a turbine 13 arranged coaxially by a rotor 14, and a generator 15 is connected to one end of the rotor 14. Figure 2 As shown, the direction in which the axis of the rotor 14 extends is defined as the axial direction Da, the circumferential direction centered on the axis of the rotor 14 is defined as the circumferential direction Dc, and the direction perpendicular to the axis Ax of the rotor 14 is defined as the radial direction Dr. The radial direction Dr is also referred to as the blade height direction h.

[0036] The compressor 11 compresses air AI entering through an air inlet by passing it through a plurality of stator blades and rotor blades, generating high-temperature, high-pressure compressed air AC. The combustor 12 supplies a predetermined fuel FL to the compressed air AC and combusts the fuel, generating high-temperature, high-pressure combustion gas FG. The turbine 13 drives a rotating rotor 14 by passing the high-temperature, high-pressure combustion gas FG generated in the combustor 12, which serves as a working fluid, through a plurality of stator blades and rotor blades, thereby driving a generator 15 connected to the rotor 14.

[0037] And, as Figure 2 As shown, in the turbine 13, the turbine stator blades (stator blades) 21 are configured by having the blade body (blade-shaped portion) 23 secured to the inner shroud 25 on the hub side (inward in the radial direction Dr) and to the outer shroud 27 on the tip side (outward in the radial direction Dr). The turbine rotor blades (moving blades) 41 are configured by having the base end of the blade-shaped portion 43 secured to the platform 45. Furthermore, the outer shroud 27 and the split ring 51 disposed on the tip side of the rotor blade 41 are supported by the casing (turbine casing) 30 via a heat shield ring 53, while the inner shroud 25 is supported by the support ring 31. Consequently, a combustion gas flow path 32, through which the combustion gas FG passes, is formed along the axial direction Da as a space enclosed by the inner shroud 25, the outer shroud 27, the platform 45, and the split ring 51.

[0038] The inner shroud 25 and the outer shroud 27 function as gas passage surface forming members that partition the combustion gas flow path 32 and have a gas passage surface with which the combustion gas FG contacts.

[0039] The stationary blade 21 according to one embodiment will be described, particularly the structure of the inner shroud 25 and each portion inside the inner shroud 25 in the radial direction Dr.

[0040] Figure 3This is a schematic front view showing a stationary blade according to one embodiment.

[0041] Figure 4 It is a schematic perspective view of the inner shield, showing a state before a first plate member and a second plate member, which will be described later, are attached.

[0042] Figure 5 It is a schematic perspective view of the inner shroud, showing a state after a first plate member (to be described later) is attached and before a second plate member (to be described later) is attached.

[0043] Figure 6 yes Figure 5 VI-VI sectional view.

[0044] Figure 7 It is a schematic perspective view of the inner shroud, showing a state after the second plate member described later is mounted.

[0045] Figure 8 yes Figure 7 Enlarged view of the main part.

[0046] Figure 9 yes Figure 7 Cross-sectional view taken along the IX-IX direction.

[0047] Figure 10 This is a diagram for explaining the welded portion between the first plate member and the inner shroud.

[0048] like Figure 3 As shown, the stationary blade 21 involved in one embodiment is provided with an inner shroud 25 on the hub side of the blade shape portion 23, that is, one end portion in the blade height direction (the inner end portion in the radial direction Dr), and an outer shroud 27 on the front end side, that is, the other end portion in the blade height direction (the outer end portion in the radial direction Dr).

[0049] (Surrounding Wall 251, Leading Edge Side Retainer 61, and Trailing Edge Side Retainer 63)

[0050] like Figure 4 As shown, the stationary blade 21 involved in one embodiment has a pair of circumferential wall portions 251, and the pair of circumferential wall portions 251 have end portions 25c on one side and the other side in the circumferential direction Dc in the inner shroud 25, extending along the extension direction of the end portion 25c, and protruding from the inner shroud 25 toward the side opposite to the blade shape portion 23 in the blade height direction h (inner side of the radial direction Dr).

[0051] The stationary blade 21 according to one embodiment includes a leading edge retainer 61 and a trailing edge retainer 63 extending inward in the radial direction Dr on the side opposite to the blade-shaped portion 23 across the gas passage surface 25a. The leading edge retainer 61 is formed on the leading edge 23a side of the blade-shaped portion 23, and the trailing edge retainer 63 is formed on the trailing edge 23b side of the blade-shaped portion 23. The leading edge retainer 61 and the trailing edge retainer 63 are connected to each other via the support ring 31 (see FIG. Figure 2 ) is installed in the machine room 30.

[0052] The leading edge side retainer 61 and the trailing edge side retainer 63 are longitudinal wall portions, which extend along the circumferential direction Dc. The end portions 61a and 63a on one side and the other side of the circumferential direction Dc are connected to a pair of circumferential wall portions 251, and protrude from the inner shroud 25 toward the side opposite to the blade shape portion 23 in the blade height direction h (the inner side of the radial direction Dr), and protrude further toward the opposite side of the blade height direction h (the inner side of the radial direction Dr) than the pair of circumferential wall portions 251.

[0053] An opening 65 penetrating in the axial direction Da is formed in the trailing edge side retainer 63 .

[0054] (Connection 253)

[0055] Furthermore, the stationary blade 21 according to one embodiment includes a connecting portion 253 that connects the pair of peripheral wall portions 251 with the leading edge retainer 61 and the trailing edge retainer 63, which serve as vertical wall portions, via a smooth curved surface 253a. The curved surface 235a connects the end surfaces 251a of the pair of peripheral wall portions 251 that face inward in the radial direction Dr with the surfaces 61b and 63b of the leading edge retainer 61 and the trailing edge retainer 63.

[0056] The connection portion 253 includes a leading edge side connection portion 253L connecting the pair of peripheral wall portions 251 and the leading edge side retainer 61 , and a trailing edge side connection portion 253T connecting the pair of peripheral wall portions 251 and the trailing edge side retainer 63 .

[0057] (recess 67)

[0058] In the stationary blade 21 according to one embodiment, a recessed portion 67 is formed by the surface 25 b on the side opposite to the gas passage surface 25 a of the inner shroud 25 , the pair of peripheral wall portions 251 , and the leading edge retainer 61 .

[0059] (First Plate Member 70)

[0060] For example, Figure 7As shown, the stationary blade 21 according to one embodiment includes a first plate member 70 arranged to cover the recessed portion 67. The first plate member 70, together with the surface 25b on the side opposite to the gas passage surface 25a of the inner shroud 25, the pair of peripheral wall portions 251, and the leading edge retainer 61, forms a cavity 69 surrounded by these portions (see FIG. Figure 9 ).

[0061] The first plate member 70 includes a first flat portion 71 along the pair of peripheral wall portions 251 , a second flat portion 72 along the leading edge retainer 61 and the trailing edge retainer 63 as vertical walls, and a curved surface portion 73 along the connecting portion 253 .

[0062] The second flat surface portion 72 includes a leading edge side second flat surface portion 72L along the leading edge side retainer 61 and a trailing edge side second flat surface portion 72T along the trailing edge side retainer 63 .

[0063] The curved surface portion 73 includes a front edge side curved surface portion 73L along the front edge side connecting portion 253L and a rear edge side curved surface portion 73T along the rear edge side connecting portion 253T.

[0064] exist Figure 7 and Figure 8 Although not shown in the figure, the end surface of the first plate member 70 is connected to the pair of peripheral wall portions 251, the leading edge side retainer 61, the trailing edge side retainer 63 and the connecting portion 253 by welding over the entire circumference.

[0065] Therefore, if the leading edge side retainer 61 and the trailing edge side retainer 63 are deformed due to the heat from the combustion gas FG, if the strength near the end portions 73a on one side and the other side of the inner circumference Dc of the curved surface portion 73 is insufficient, relatively high stress is likely to be generated near the end portions 73a, which may cause damage due to low cycle fatigue near the end portions 73a.

[0066] (Thick wall portion 75)

[0067] Therefore, if Figure 7 and Figure 8 As shown, in the stationary blade 21 according to one embodiment, the curved surface portion 73 is formed so as to include a thick portion 75 having a thickness t3 thicker than the thicknesses t1 and t2 of the first and second planar portions 71 and 72 at least at the end portions 73a on one side and the other side in the circumferential direction Dc.

[0068] In the stationary blade 21 according to one embodiment, the thick portion 75 includes a leading edge thick portion 75L formed at one end portion 73a of the leading edge curved surface portion 73L and the other end portion 73a, and a trailing edge thick portion 75T formed at one end portion 73a of the trailing edge curved surface portion 73T.

[0069] This improves the strength of the ends 73a on the one and other sides of the curved surface portion 73. Therefore, even if the leading edge retainer 61 or the trailing edge retainer 63 deforms due to heat from the combustion gas FG, stresses near the ends 73a on the one and other sides of the curved surface portion 73 can be suppressed. Consequently, the low-cycle fatigue strength near the ends 73a on the one and other sides of the curved surface portion 73 is improved, thereby improving the durability of the vane 21.

[0070] Furthermore, according to the gas turbine 10 according to one embodiment, the durability of the turbine vanes 21 is improved, and thus the reliability of the gas turbine 10 is improved.

[0071] In the stationary blade 21 according to one embodiment, the thick wall portion 75 may be provided in the entire region from the end 73a on one side of the curved surface portion 73 to the end 73a on the other side, as shown in FIG. Figure 7 and Figure 8 As shown, the curved surface portion 73 may be provided only at the end portion 73a on one side and near the end portion 73a on the other side. That is, the curved surface portion 73 may include a non-thick portion 76 located between the thick portion 75 at the end portions 73a on one side and the other side in the circumferential direction Dc and thinner than the thickness t3 of the thick portion 75.

[0072] This effectively reinforces the vicinity of the end portions 73 a on one side and the other side of the curved surface portion 73 , where the strength needs to be increased.

[0073] In addition, if the thicknesses t1 and t2 of the first planar portion 71 and the second planar portion 72 are equal, and the thickness of the non-thick-walled portion 76 is equal to the thicknesses t1 and t2 of the first planar portion 71 and the second planar portion 72, the first plate member 70 can be formed by bending a plate member, thereby reducing the cost of the first plate member 70.

[0074] In the stationary blade 21 according to one embodiment, the thick portion 75 may be provided, for example, with a predetermined width Wc extending in the circumferential direction Dc from one end 73a and the other end 73a of the curved surface portion 73. The width Wc of the thick portion 75 may be, for example, 2.5 times or greater than the thickness t1 of the first planar portion 71.

[0075] Furthermore, in the stationary blade 21 according to one embodiment, although the thick portion 75 extends in the axial direction Da and the radial direction Dr, its extension length L (refer to Figure 8 ) can be set to a length that reaches from the first planar portion 71 to the second planar portion 72, or can be set to a length that at least one of the two end portions 75a is located within the curved surface portion 73.

[0076] (Regarding Connection of First Plate Member 70 by Welding)

[0077] As described above, the end surface of the first plate member 70 is connected to the pair of peripheral wall portions 251, the leading edge side retainer 61, the trailing edge side retainer 63, and the connecting portion 253 by welding over the entire circumference.

[0078] like Figure 10 As shown, in the first plate member 70 , end portions 73 a on one side and the other side in the circumferential direction of the curved surface portion 73 are welded to the curved surface 253 a of the connecting portion 253 .

[0079] That is, the first plate member 70 is welded and fixed to the curved surface 253 a of the connecting portion 253 in the vicinity of the thick portion 75 .

[0080] In addition, Figure 10 In FIG, the cross-sectional shapes of the welded portions 91, 92, and 93 described later are indicated by hatching. Figure 10 In the figure, for the convenience of illustration, the shapes of the welds 91, 92, 93 change sharply at the boundaries between each other, but in fact, the welds 91, 92, 93 are smoothly connected to each other at the boundaries between each other.

[0081] In the first plate member 70, the first flat portion 71 is welded to the end faces 251a of the pair of peripheral wall portions 251, and the second flat portion 72 is welded to the surfaces 61b and 63b of the leading edge retainer 61 and the trailing edge retainer 63. The weld leg length Ls3 of the welded portions 93 between the end portions 73a on one side and the other side in the circumferential direction Dc of the curved portion 73 and the curved surface 253a of the connecting portion 253 can be longer than the weld leg length Ls1 of the welded portions 91 between the first flat portion 71 and the end faces 251a of the pair of peripheral wall portions 251, and the weld leg length Ls2 of the welded portions 92 between the second flat portion 72 and the surfaces 61b and 63b of the leading edge retainer 61 and the trailing edge retainer 63.

[0082] As a result, the leading edge side retainer 61 and the trailing edge side retainer 63 are deformed by the heat from the combustion gas FG, and the stress tends to become relatively large, so that the stress can be suppressed in the weld 93 between the end portions 73a on one side and the other side of the circumferential direction Dc of the curved surface portion 73 and the curved surface 253a of the connecting portion 253.

[0083] The thick portion 75 may be formed by welding a member on an arc to the curved surface portion 73 , or may be formed by welding the surface of a plate portion constituting the curved surface portion 73 to increase the thickness.

[0084] This makes it relatively easy to reinforce the vicinity of the end portions 73 a on one side and the other side of the curved surface portion 73 , where the strength needs to be increased.

[0085] (Second Plate Member 80)

[0086] The stationary blade 21 according to one embodiment includes the second plate member 80 that partitions the cavity 69 into an outer region 69 o in the blade height direction h and an inner region 69 i in the blade height direction h.

[0087] The second plate member 80 is a porous plate extending in the circumferential direction Dc and the axial direction Da, and has a plurality of through-holes 80 a extending in the plate thickness direction (radial direction Dr) of the second plate member 80 .

[0088] Although not shown, the stator blade 21 according to one embodiment is configured so that cooling air is supplied from the outside to the inner region 69i. The cooling air supplied from the outside to the inner region 69i is ejected through the plurality of through-holes 80a toward the surface 25b of the inner shroud 25 opposite the gas passage surface 25a, thereby providing impingement cooling to the surface 25b.

[0089] According to the stator blade 21 according to one embodiment, the second plate member 80 can partition the cavity 69 into an outer region 69o in the blade height direction and an inner region 69i in the blade height direction h. Furthermore, by supplying cooling air from the outside to the inner region 69i, impingement cooling can be performed on the surface 25b of the inner shroud 25 opposite the gas passage surface 25a.

[0090] In the second plate member 80, an end portion 81 in the circumferential direction Dc is folded back inward in the radial direction Dr, and an end surface 81a facing inward in the radial direction Dr is connected by corner welding to the inner surfaces 251i of the pair of peripheral wall portions 251 that face the cavity 69. In other words, the second plate member 80 is welded to the inner surfaces 251i of the pair of peripheral wall portions 251 that face each other in the circumferential direction Dc.

[0091] The welded portion 94 between the second plate member 80 and the pair of peripheral wall portions 251 is located further outward in the radial direction Dr than the end surfaces 251 a on the inner side in the radial direction Dr of the pair of peripheral wall portions 251 .

[0092] As described above, in the first plate member 70, the first flat surface portion 71 is connected to the end surfaces 251a of the pair of peripheral wall portions 251 (see FIG. Figure 9 and Figure 10 ).

[0093] For example, consider the following case: the first plate member 70 and the second plate member 80 are arranged so as to overlap on the end surface 251a of the pair of peripheral wall portions 251, and the corner portions of the end portions of the first plate member 70 and the second plate member 80 in the circumferential direction Dc are welded to the end surface 251a. In this case, compared to the case where only the corner portions of the end portions of the first plate member 70 in the circumferential direction Dc are welded to the end surface 251a, the amount of molten metal in the weld increases by an amount corresponding to the increase in the height in the blade height direction h by the thickness of the second plate member 80, and thus welding strain is more likely to occur.

[0094] According to the stationary blade 21 according to one embodiment, the amount of molten metal in the weld portion 91 when the corner portion of the first plate member 70 is welded to the end surface 251 a can be reduced, and thus welding strain in the weld portion 91 can be suppressed.

[0095] The present invention is not limited to the above-described embodiment, and includes additional modifications to the above-described embodiment and appropriate combinations of these embodiments.

[0096] For example, the stationary blade 21 according to the above embodiment includes the leading edge thick portion 75L and the trailing edge thick portion 75T, but only one of the leading edge thick portion 75L and the edge thick portion 75T may be provided.

[0097] The contents described in each of the above-mentioned embodiments can be understood, for example, as follows.

[0098] (1) A turbine vane 21 according to at least one embodiment of the present invention includes:

[0099] blade-shaped portion 23;

[0100] An inner shroud 25 is provided on the inner side of the blade-shaped portion 23 in the blade height direction h;

[0101] A pair of peripheral wall portions 251 extend along the extending direction of the end portions 25c at one and the other ends 25c of the inner shroud 25 in the circumferential direction Dc, and protrude from the inner shroud 25 toward the side opposite to the blade-shaped portion 23 in the blade height direction h (inward in the radial direction Dr);

[0102] The longitudinal wall portions (the leading edge retainer 61 and the trailing edge retainer 63) extend in the circumferential direction Dc, with end portions 61a and 63a on one and the other sides in the circumferential direction Dc connected to the pair of peripheral wall portions 251. The longitudinal wall portions protrude from the inner shroud 25 toward the side opposite to the blade-shaped portion 23 in the blade height direction h (inward in the radial direction Dr), and further toward the side opposite to the blade height direction h (inward in the radial direction Dr) from the pair of peripheral wall portions 251.

[0103] The connecting portion 253 connects the pair of peripheral wall portions 251 and the longitudinal wall portion (the leading edge retainer 61 and the trailing edge retainer 63) with a smooth curved surface 253a; and

[0104] The first plate member 70, together with the opposite surface 25b of the inner shroud 25 and the pair of peripheral walls 251, forms the cavity 69. The first plate member 70 includes a first flat portion 71 extending along the pair of peripheral walls 251, a second flat portion 72 extending along the longitudinal walls (the leading edge retainer 61 and the trailing edge retainer 63), and a curved surface portion 73 extending along the connecting portion 253. The curved surface portion 73 includes thicker portions 75 at at least one end portion 73a on one side and the other side in the circumferential direction Dc than the thicknesses t1 and t2 of the first and second flat portions 71 and 72.

[0105] According to the configuration (1), since the strength of the ends 73a on the one side and the other side of the curved surface portion 73 can be increased, even if the vertical wall portion (the leading edge retainer 61 and the trailing edge retainer 63) is deformed by heat from the combustion gas FG, stresses in the vicinity of the ends 73a on the one side and the other side of the curved surface portion 73 can be suppressed. As a result, the low-cycle fatigue strength in the vicinity of the ends 73a on the one side and the other side of the curved surface portion 73 is improved, thereby improving the durability of the turbine blade 21.

[0106] (2) Several embodiments In the structure of (1) above, the curved surface portion 73 may include a non-thick-walled portion 76, which is located between the thick-walled portions 75 of the end portions 73a on one side and the other side in the circumferential direction Dc and is thinner than the thick-walled portion 75.

[0107] According to the configuration of (2) above, the vicinity of the ends 73a on the one side and the other side of the curved surface portion 73 where the strength needs to be increased can be effectively reinforced.

[0108] (3) Several Embodiments In the structure of (2) above, the thick-walled portion 75 may be formed by thickening the surface of the plate portion constituting the curved portion 73 by welding.

[0109] According to the configuration of (3) above, the vicinity of the end portions 73a on the one side and the other side of the curved surface portion 73 where the strength needs to be increased can be reinforced relatively easily.

[0110] (4) Several Embodiments In any of the structures (1) to (3) above, the curved surface 253a of the connecting portion 253 may connect the end surfaces 251a on the opposite sides of the pair of peripheral wall portions 251 to the surfaces 61b and 63b of the longitudinal wall portions (the leading edge retainer 61 and the trailing edge retainer 63). In the first plate member 70, at least the end portions 73a on one side and the other side of the curved surface portion 73 of the first plate member 70 in the circumferential direction Dc may be welded to the curved surface 253a of the connecting portion 253.

[0111] According to the configuration of (4) above, the first plate member 70 is welded and fixed to the curved surface 253 a of the connecting portion 253 in the vicinity of the thick portion 75 .

[0112] (5) Several Embodiments In the structure of (4) above, in the first plate member 70, the first flat portion 71 may be welded to the end surfaces 251a on the opposite sides of the pair of peripheral wall portions 251, and the second flat portion 72 may be welded to the surfaces 61b and 63b of the longitudinal wall portions (the leading edge retainer 61 and the trailing edge retainer 63). The weld leg length Ls3 of the welded portion 93 between the end portions 73a on one side and the other side in the circumferential direction Dc of the curved portion 73 and the curved surface 253a of the connecting portion 253 may be longer than the weld leg length Ls1 of the welded portion 91 between the first flat portion 71 and the end surfaces 251a on the opposite sides of the pair of peripheral wall portions 251, and the weld leg length Ls2 of the welded portion 92 between the second flat portion 72 and the surfaces 61b and 63b of the longitudinal wall portions (the leading edge retainer 61 and the trailing edge retainer 63).

[0113] According to the structure of (5) above, stress can be suppressed in the welded portion (i.e., the welded portion 93 between the end portions 73a on one side and the other side of the circumferential direction Dc in the curved portion 73 and the above-mentioned curved surface 253a in the connecting portion 253) where stress tends to become relatively large due to deformation of the longitudinal wall portion (the leading edge side retainer 61 and the trailing edge side retainer 63) due to heat from the combustion gas FG.

[0114] (6) Several embodiments In any of the structures (1) to (5) above, a second plate member 80 may be provided, and the second plate member 80 divides the cavity 69 into an outer region 69o in the blade height direction h and an inner region 69i in the blade height direction h.

[0115] According to the configuration of (6) above, the second plate member 80 can partition the cavity 69 into the outer region 69 o in the blade height direction h and the inner region 69 i in the blade height direction h.

[0116] (7) Several Embodiments In the structure of (6) above, the second plate member 80 may be welded to surfaces (inner surfaces 251 i ) facing each other in the circumferential direction Dc in the pair of peripheral wall portions 251 .

[0117] According to the configuration of (7), the amount of molten metal in the welded portion 91 when the corner portion of the first plate member 70 is welded to the end surfaces 251 a of the pair of peripheral wall portions 251 can be reduced, thereby suppressing welding strain in the welded portion 91 .

[0118] (8) The gas turbine 10 according to at least one embodiment of the present invention includes the turbine stator blade 21 having any one of the structures of (1) to (7) above.

[0119] According to the configuration of (8) above, the durability of the turbine vanes 21 is improved, and thus the reliability of the gas turbine 10 is improved.

[0120] Explanation of symbols

[0121] 10-gas turbine, 21-turbine stator blade (stator blade), 23-blade body (blade shape portion), 25-inner shroud, 25a-gas passing surface, 25b-surface, 25c-end, 61-leading edge side retainer, 61a-end, 61b-surface, 63-trailing edge side retainer, 63a-end, 63b-surface, 67-recess, 69-cavity, 69i-inner area, 69o-outer area, 70-first plate component, 71-first plane portion, 72-second plane portion, 73-curved portion, 73a-end, 75-thick wall portion, 75a-end, 76-non-thick wall portion, 80-second plate component, 91, 92, 93, 94-welding portion, 251-circumferential wall portion, 251a-end face, 253-connecting portion, 253a-curved surface.

Claims

1. A turbine stator blade comprising: blade shape portion; an inner shroud provided on the inner side of the blade-shaped portion in the blade height direction; a pair of peripheral wall portions, at end portions on one side and the other side in the circumferential direction of the inner shroud, extending along the extending direction of the end portions and protruding from the inner shroud toward a side opposite to the blade-shaped portion in the blade height direction; a longitudinal wall portion extending in the circumferential direction, having ends on one side and the other side of the circumferential direction connected to the pair of circumferential wall portions, and projecting from the inner shroud toward a side opposite to the blade-shaped portion in the blade height direction, and projecting toward a side opposite to the pair of circumferential wall portions in the blade height direction; a connecting portion connecting the pair of peripheral wall portions and the longitudinal wall portion with a smooth curved surface; and The first plate member forms a cavity together with the opposite side surface of the inner shroud and the pair of peripheral wall portions. The first plate member has a first flat surface portion along the pair of peripheral wall portions, a second flat surface portion along the vertical wall portion, and a curved surface portion along the connecting portion. The curved surface portion includes thick portions thicker than the first planar portion and the second planar portion at least at end portions on one side and the other side in the circumferential direction.

2. The turbine stator blade according to claim 1, wherein: The curved surface portion includes a non-thick portion that is located between the thick portions at each of the end portions on one side and the other side in the circumferential direction and is thinner than the thick portion.

3. The turbine stator blade according to claim 2, wherein: The thick portion is formed by welding to thicken the surface of the plate portion constituting the curved portion.

4. The turbine stator blade according to claim 1 or 2, wherein: The curved surface in the connecting portion connects the end surfaces on the opposite sides of the pair of peripheral wall portions and the surface of the vertical wall portion. In the first plate member, at least the ends on one side and the other side in the circumferential direction of the curved surface portion are welded to the curved surface of the connecting portion.

5. The turbine stator blade according to claim 4, wherein: In the first plate member, the first flat portion is welded to the end surfaces on the opposite sides of the pair of peripheral wall portions, and the second flat portion is welded to the surface of the vertical wall portion. The weld leg lengths of the welds between the ends on one circumferential side and the other circumferential side of the curved portion and the curved surface in the connecting portion are longer than the weld leg lengths of the welds between the first planar portion and the end faces on the opposite sides of the pair of peripheral wall portions, and the weld leg lengths of the welds between the second planar portion and the surface of the longitudinal wall portion.

6. The turbine stator blade according to claim 1 or 2, wherein: A second plate member is provided, the second plate member partitioning the cavity into an outer region in the blade height direction and an inner region in the blade height direction.

7. The turbine stator blade according to claim 6, wherein: The second plate member is welded to surfaces of the pair of peripheral wall portions that face each other in the circumferential direction.

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

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