Gas turbine stator blade, combined blade unit, and method for manufacturing gas turbine stator blade

Abstract

Provided are a gas turbine stator blade, a combined blade unit, and a method for manufacturing a gas turbine stator blade, whereby damage to the gas turbine stator blade due to oxidation can be efficiently suppressed with a small amount of oxidation-resistant coating. The gas turbine stator blade is provided with a blade-shaped part, the surface of the blade-shaped part includes a front edge, a rear edge, a pressure surface connecting the front edge and the rear edge, and a negative pressure surface connecting the front edge and the rear edge, and an oxidation-resistant coating layer is formed on at least a part of the surface of the blade-shaped part on the pressure surface side, and in a cross section orthogonal to the blade height direction of the blade-shaped part, the oxidation-resistant coating layer is formed on the surface of the blade-shaped part. When the distance from the leading edge to the trailing edge in the axial direction of the gas turbine is defined as Xmax and the position in the axial direction with the leading edge as the origin is defined as X, the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side in the range of 0.90 < = X / Xmax < = 1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side in the range of 0.0 < = X / Xmax < = 0.50.

Description

Technical Field

[0001] The present disclosure relates to a gas turbine stator blade, a grouped blade unit, and a method for manufacturing a gas turbine stator blade. This application claims priority based on Japanese Patent Application No. 2023-133751 filed on August 21, 2023, the contents of which are incorporated herein by reference. Background Art

[0002] Patent Document 1 discloses that foreign matter reflected by colliding with a gas turbine rotor blade collides with the trailing edge of the gas turbine vane and damages the gas turbine vane, and that a protective film is partially formed only on the trailing edge of the gas turbine vane to solve such a problem.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 10-148101 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, if the gas turbine stator blade is exposed to high-temperature atmospheric gas, the wall thickness reduction due to oxidation may progress and damage the gas turbine stator blade. Therefore, it is considered to apply oxidation-resistant coating to the surface of the gas turbine stator blade, but if the oxidation-resistant coating is applied to the entire surface of the gas turbine stator blade, a lot of labor and cost are required for coating.

[0008] In this regard, Patent Document 1 does not disclose any knowledge for efficiently suppressing damage to gas turbine vanes caused by oxidation with a small amount of oxidation-resistant coating.

[0009] In view of the above, an object of at least one embodiment of the present disclosure is to provide a gas turbine vane, a combined blade unit, and a method for manufacturing a gas turbine vane that can effectively suppress damage to the gas turbine vane caused by oxidation with a small amount of oxidation-resistant coating.

[0010] Solutions to Solve Problems

[0011] In order to achieve the above-mentioned object, a gas turbine stator blade according to at least one embodiment of the present disclosure includes a blade portion, wherein:

[0012] The surface of the blade-shaped portion includes a leading edge, a trailing edge, a pressure surface connecting the leading edge and the trailing edge, and a negative pressure surface connecting the leading edge and the trailing edge.

[0013] An oxidation-resistant coating layer is formed on at least a portion of the surface of the blade portion on the pressure surface side.

[0014] In the cross section of the blade portion orthogonal to the blade height direction, the distance from the leading edge to the trailing edge in the axial direction of the gas turbine is defined as Xmax, and the position in the axial direction with the leading edge as the origin is defined as X.

[0015] Then, the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.90≤X / Xmax≤1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.0≤X / Xmax≤0.50.

[0016] In order to achieve the above-mentioned object, at least one embodiment of the present disclosure includes a plurality of gas turbine stationary blades, wherein the combined blade unit is formed by integrally forming the plurality of gas turbine stationary blades, wherein:

[0017] The plurality of gas turbine stationary blades are respectively the above-mentioned gas turbine stationary blades.

[0018] To achieve the above object, a method for manufacturing a gas turbine vane according to at least one embodiment of the present disclosure includes the steps of: applying an oxidation-resistant coating layer to at least a portion of a pressure surface side of a vane portion of the gas turbine vane;

[0019] In a cross section of the blade portion orthogonal to the blade height direction, a position in the axial direction of the gas turbine is defined by a distance X from the leading edge of the blade portion in the axial direction to the position, and a position of the trailing edge of the blade portion in the axial direction is defined as Xmax.

[0020] In the step, the oxidation-resistant coating layer is formed on at least a portion of the pressure surface side of the surface of the blade portion in such a manner that the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side in the range of 0.90≤X / Xmax≤1.0 is less than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface in the range of 0.0≤X / Xmax≤0.50.

[0021] Effects of the Invention

[0022] According to at least one embodiment of the present disclosure, there are provided a gas turbine vane, a combined blade unit, and a method for manufacturing a gas turbine vane, which are capable of efficiently suppressing damage to the gas turbine vane caused by oxidation with a small amount of oxidation-resistant coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram schematically showing a cross-sectional shape perpendicular to the blade height direction in a combined blade unit 2 for a gas turbine according to an embodiment.

[0024] Figure 2It is schematically shown Figure 1 The illustrated diagram is an enlarged view of a cross-sectional shape of a blade portion 6 of a gas turbine stator blade 4, which is perpendicular to the blade height direction.

[0025] Figure 3 This is a diagram for explaining an example of a method of performing oxidation-resistant coating on a gas turbine vane 4 .

[0026] Description of reference numerals:

[0027] 2Combined blade unit

[0028] 4 Gas turbine stator blades

[0029] 6-leaf

[0030] 7 Surface

[0031] 8 Outer shroud

[0032] 9 Cavity

[0033] 10Inner shroud

[0034] 12 Front Edge

[0035] 14 trailing edge

[0036] 16 Pressure surface

[0037] 18 Negative pressure surface

[0038] 20 Oxidation resistant coating

[0039] 20h1, 20s1 oxidation resistant coating leading edge side

[0040] 20h2, 20s3 oxidation resistant coating trailing edge side

[0041] 20s2 oxidation resistant coating middle part

[0042] 30 spray gun. DETAILED DESCRIPTION

[0043] Hereinafter, several embodiments of the present disclosure will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the invention but are merely illustrative examples.

[0044] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" that indicate relative or absolute configurations not only indicate such configurations in a strict sense, 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.

[0045] For example, expressions such as “same”, “equal”, and “homogeneous” indicating a state in which things are equal not only indicate a state of being strictly equal but also indicate a state in which there is a tolerance or a difference to the extent that the same function can be obtained.

[0046] For example, expressions indicating shapes such as a quadrilateral and a cylindrical shape not only indicate shapes such as a quadrilateral and a cylindrical shape in a strict geometric sense, but also indicate shapes including concave-convex portions, chamfered portions, and the like within a range that can obtain the same effect.

[0047] On the other hand, expressions such as “having”, “containing”, “equipped with”, “including” or “having” a constituent element are not exclusive expressions that exclude the existence of other constituent elements.

[0048] Figure 1 This is a diagram schematically showing a cross-sectional shape perpendicular to the blade height direction in a combined blade unit 2 for a gas turbine according to an embodiment.

[0049] like Figure 1 As shown, the combined blade unit 2 includes a plurality of gas turbine vanes 4, and is integrally formed by integrally molding the plurality of gas turbine vanes 4. The plurality of gas turbine vanes 4 each includes a vane portion 6, an outer shroud 8, and an inner shroud 10. The plurality of vanes 6 of the combined blade unit 2 are arranged at intervals in the circumferential direction of the gas turbine, the outer shrouds 8 of the adjacent gas turbine vanes 4 among the plurality of gas turbine vanes 4 are connected to each other, and the inner shrouds 10 of the adjacent gas turbine vanes 4 among the plurality of gas turbine vanes 4 are connected to each other.

[0050] Figure 2 It is schematically shown Figure 1 An enlarged view of the cross-sectional shape of the blade portion 6 of the gas turbine stator blade 4, which is perpendicular to the blade height direction, is shown. It should be noted that, in the present specification, the blade height direction may also coincide with the radial direction of the gas turbine. In addition, since the structures of the blade portions 6 of the plurality of gas turbine stator blades 4 provided in the combined blade unit 2 are the same, the structures of the blade portions 6 of the gas turbine stator blades 4 are described below without specifically distinguishing them. In addition, in the following, unless otherwise specified, "axial direction" refers to the axial direction of the gas turbine, unless otherwise specified, "circumferential direction" refers to the circumferential direction of the gas turbine, and unless otherwise specified, "radial direction" refers to the radial direction of the gas turbine.

[0051] like Figure 2 As shown, the surface 7 of the blade portion 6 of the gas turbine stator blade 4 includes a leading edge 12, a trailing edge 14, a pressure surface 16 connecting the leading edge 12 and the trailing edge 14, and a suction surface 18 connecting the leading edge 12 and the trailing edge 14. In the illustrated embodiment, a cavity 9 extending in the blade height direction is formed inside the blade portion 6.

[0052] like Figure 2 As shown, an oxidation-resistant coating layer 20 is formed on the pressure surface 16 and the suction surface 18 of the blade portion 6 of the gas turbine stator blade 4. In the illustrated embodiment, the oxidation-resistant coating layer 20 is formed on a portion of the pressure surface 16 side of the surface 7 of the blade portion 6 and the entire suction surface 18 side of the surface 7 of the blade portion 6.

[0053] Here, the oxidation-resistant coating layer 20 may be, for example, a coating layer made of CoNiCrAlY, NiCrAlY, CoCrAlY or MCrAlX (wherein M is Ni, Co or an alloy of Ni and Co, namely NiCo, and X is Hf, Si or Ta).

[0054] exist Figure 2 In the illustrated embodiment, the oxidation-resistant coating layer 20 on the pressure surface 16 side is formed in the range from the position of the leading edge 12 to the position P1 near the trailing edge 14 on the pressure surface 16, and is not formed in the range from the position P1 near the trailing edge 14 to the trailing edge 14 on the pressure surface 16. Here, the position P1 is a position between the position P2 on the pressure surface 16 where the blade thickness t of the blade portion 6 of the gas turbine stator blade 4 becomes maximum and the trailing edge 14.

[0055] The oxidation-resistant coating layer 20 formed on the pressure surface 16 side in the surface 7 of the blade-shaped portion 6 includes: an oxidation-resistant coating layer leading edge side portion 20h1 formed in the range from the leading edge 12 to the position P3 on the trailing edge 14 side in the pressure surface 16; and an oxidation-resistant coating layer trailing edge side portion 20h2 formed in the range from the position P3 to the position P1 in the pressure surface 16. Here, the thickness dh1 of the oxidation-resistant coating layer leading edge side portion 20h1 is greater than the thickness dh2 of the oxidation-resistant coating layer trailing edge side portion 20h2. The thickness dh1 of the oxidation-resistant coating layer leading edge side portion 20h1 may be constant from the leading edge 12 to the position P3, and the thickness dh2 of the oxidation-resistant coating layer trailing edge side portion 20h2 may decrease as it approaches the position P1 from the position P3.

[0056] exist Figure 2In the illustrated embodiment, in the cross section of the blade 6 orthogonal to the blade height direction, if the position on the suction surface 18 where the blade thickness t of the blade 6 becomes the largest is set as P4, the oxidation-resistant coating layer 20 formed on the suction surface 18 side of the surface 7 of the blade 6 includes: an oxidation-resistant coating layer middle portion 20s2 formed in the range including the position P4 in the suction surface 18; an oxidation-resistant coating layer leading edge side portion 20s1 formed in the range between the oxidation-resistant coating layer middle portion 20s2 and the leading edge 12 in the suction surface 18; and an oxidation-resistant coating layer trailing edge side portion 20s3 formed in the range between the oxidation-resistant coating layer middle portion 20s2 and the trailing edge 14 in the suction surface 18. The thickness ds2 of the oxidation-resistant coating layer middle portion 20s2 is smaller than the thickness ds1 of the oxidation-resistant coating layer leading edge side portion 20s1, and smaller than the thickness ds3 of the oxidation-resistant coating layer trailing edge side portion 20s3.

[0057] exist Figure 2 In the illustrated embodiment, the leading edge side portion 20S1 of the oxidation-resistant coating layer is an oxidation-resistant coating layer formed in the range from position P5 between the leading edge 12 and position P4 to the leading edge 12 in the surface 7 of the blade-shaped portion 6, and the thickness ds1 of the leading edge side portion 20s1 of the oxidation-resistant coating layer can be constant from the leading edge 12 to the position P5.

[0058] exist Figure 2 In the illustrated embodiment, the oxidation-resistant coating layer trailing edge side portion 20s3 is an oxidation-resistant coating layer formed in the range from position P6 between the trailing edge 14 and position P4 to the trailing edge 14 on the surface 7 of the blade portion 6, and the thickness ds3 of the oxidation-resistant coating layer trailing edge side portion 20s3 can be constant from the trailing edge 14 to the position P6.

[0059] exist Figure 2In the illustrated embodiment, in a cross section of the blade-shaped portion 6 that is orthogonal to the blade height direction, the axial position is defined by the axial distance X from the leading edge 12 to the position, and the axial position of the trailing edge 14 (i.e., the axial distance from the leading edge 12 to the trailing edge 14) is defined as Xmax, then the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side within the range of 0.90≤X / Xmax≤1.0 is less than the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side within the range of 0.0≤X / Xmax≤0.50. That is, in the cross section orthogonal to the blade height direction in the blade-shaped portion 6, with respect to the XY coordinate system (orthogonal coordinate system) with the position of the leading edge 12 as the origin, when the coordinate axis parallel to the axial direction of the gas turbine is set as the X axis, the downstream side of the gas flow in the axial direction (X axis direction) is set as the positive direction of the X axis, and the X coordinate of the trailing edge 14 is set as Xmax, the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side in the range where the X coordinate satisfies 0.90≤X / Xmax≤1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side in the range where the X coordinate satisfies 0.0≤X / Xmax≤0.50. Here, X / Xmax is a value obtained by dividing X by Xmax.

[0060] Generally, in the blade portion of a gas turbine stator blade, as a physical strength, the bending strength relative to the gas flow (gas bending strength) is important from the viewpoint of suppressing damage. However, when the blade portion is exposed to the flow of high-temperature gas and the wall thickness reduction of the blade portion due to oxidation proceeds, the bending strength of the blade portion decreases.

[0061] In contrast, according to the above-mentioned gas turbine stator blade 4, the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side within the range of 0.90≤X / Xmax≤1.0, which has a small influence on the bending strength with respect to the gas flow, is smaller than the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side within the range of 0.0≤X / Xmax≤0.50, which has a large influence on the bending strength with respect to the gas flow. Therefore, damage to the gas turbine stator blade 4 caused by oxidation (for example, bending or chipping on the side of the suction surface 18) can be effectively suppressed with a small amount of oxidation-resistant coating, and the cost required for oxidation-resistant coating can be reduced. In addition, by improving the durability of the gas turbine stator blade 4, the maintenance cycle can be extended.

[0062] In addition, Figure 2 In the illustrated embodiment, the thickness of the oxidation-resistant coating layer 20 formed on the negative pressure surface 18 side decreases from a position on the leading edge 12 side of the negative pressure surface 18 toward a position P4 where the blade thickness t of the gas turbine stator 4 becomes maximum, and decreases from a position on the trailing edge 14 side of the negative pressure surface 18 toward a position P4 where the blade thickness t of the gas turbine stator 4 becomes maximum.

[0063] According to this configuration, the thickness of the oxidation-resistant coating layer 20 of the suction surface 18 decreases from the position on the leading edge 12 side of the suction surface 18 toward the position P4 where the blade thickness t of the gas turbine vane 4 becomes maximum, so that damage to the gas turbine vane 4 caused by oxidation can be effectively suppressed with a small amount of oxidation-resistant coating. In addition, generally, the blade thickness is thinner on the trailing edge 14 side of the gas turbine vane 4 than on the leading edge 12 side, so when the wall thickness reduction due to oxidation advances, the blade profile and the chord length of the blade change significantly, and there is a possibility that the aerodynamic performance will be greatly reduced. However, according to the above-mentioned gas turbine vane 4, the thickness of the oxidation-resistant coating layer 20 decreases from the position on the trailing edge 14 side of the suction surface 18 toward the position P4 where the blade thickness of the gas turbine vane 4 becomes maximum, so that on the suction surface 18, the thickness of the oxidation-resistant coating layer 20 becomes relatively large at the trailing edge 14 side relative to the position P4, and the reduction in the aerodynamic performance of the gas turbine vane 4 caused by oxidation can be effectively suppressed with a small amount of oxidation-resistant coating.

[0064] In addition, Figure 2 In the illustrated embodiment, in the cross section of the blade-shaped portion 6 that is orthogonal to the blade height direction, the axial distance from position P7 on the negative pressure surface 18 to the leading edge 12 at which the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side is minimum in the range from the leading edge 12 to the trailing edge 14 is defined as X1, and the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side varies between the leading edge 12 and the trailing edge 14 in a manner that satisfies 0.25≤X1 / Xmax≤0.70.

[0065] According to this structure, within the range of 0.25≤X / XmaX≤0.70 where the influence on damage to the gas turbine stator blade 4 and reduction in aerodynamic performance is relatively small, the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side becomes the smallest at position P7, so that damage to the gas turbine stator blade 4 and reduction in aerodynamic performance can be efficiently suppressed with a smaller amount of oxidation-resistant coating.

[0066] exist Figure 2 In the illustrated embodiment, in a cross section orthogonal to the blade height direction in the blade-shaped portion 6, an average value of the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side within the range of 0.25≤X / Xmax≤0.70 is smaller than an average value of the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side within the range of 0.0≤X / XmaX≤0.25, and is smaller than an average value of the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side within the range of 0.70≤X / Xmax≤1.0.

[0067] According to this structure, within the range of 0.25≤X / Xmax≤0.70, in which the influence on damage to the gas turbine stator blade 4 and reduction in aerodynamic performance is relatively small, the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side is made relatively smaller than that in other ranges, thereby enabling the damage to the gas turbine stator blade 4 and reduction in aerodynamic performance to be efficiently suppressed with a smaller amount of oxidation-resistant coating.

[0068] It should be noted that, for example Figure 3 As shown, the gas turbine stator blade 4 can also be formed by spraying the material of the oxidation-resistant coating layer 20 (for example, CoNiCrAlY, NiCrAlY, CoCrAlY or MCrAlX (wherein M is Ni, Co or an alloy of Ni and Co, and X is Hf, Si or Ta) onto the surface 7 of the blade portion 6 of the gas turbine stator blade 4 using a spraying gun 30, thereby forming the above-mentioned oxidation-resistant coating layer 20 (20s1, 20s2, 20s3, 20h1, 20h2) on the surface 7 of the blade portion 6. In this case, for example, Figure 3 As shown, the oxidation-resistant coating leading edge side portion 20h1 on the pressure surface 16 side may be formed by spraying the material of the oxidation-resistant coating 20 on the range from the leading edge 12 to the position P3 of the pressure surface 16 of the blade 6 using the spray gun 30 from the position axially upstream of the blade 6 of the gas turbine stator blade 4. In addition, the oxidation-resistant coating trailing edge side portion 20h2 on the pressure surface 16 side may be formed by spraying (sweeping) the material of the oxidation-resistant coating 20 on the range from the position P3 to the position P1 of the pressure surface 16 of the blade 6 using the spray gun 30 from the position axially upstream of the blade 6 of the gas turbine stator blade 4.

[0069] Alternatively, the oxidation resistant coating layer leading edge side portion 20s1 on the negative pressure surface 18 side may be formed by thermally spraying the material of the thermal oxidation resistant coating on the range from the leading edge 12 to the position P5 of the negative pressure surface 18 of the blade portion 6 from a position upstream in the axial direction of the gas turbine relative to the blade portion 6 of the gas turbine stator blade 4 using the thermal oxidation resistant coating spray gun 30. Alternatively, the oxidation resistant coating layer intermediate portion 20s2 on the negative pressure surface 18 side may be formed by thermally spraying the material of the thermal oxidation resistant coating on the range from the position P5 to the position between the position P5 and the position P6 of the negative pressure surface 18 of the blade portion 6 from a position upstream in the axial direction of the gas turbine relative to the blade portion 6 of the gas turbine stator blade 4 using the thermal oxidation resistant coating spray gun 30, and thermally spraying the material of the thermal oxidation resistant coating on the range from the position P6 to the position between the position P6 and the position P5 of the negative pressure surface 18 of the blade portion 6 from a position downstream in the axial direction of the gas turbine stator blade 4 using the thermal oxidation resistant coating spray gun 30. In addition, the oxidation-resistant coating layer trailing edge side portion 20s3 on the negative pressure surface 18 side can be formed by using a spraying gun 30 to spray the material of the oxidation-resistant coating layer 20 on the negative pressure surface 18 of the blade portion 6 from the trailing edge 14 to the position P6 from a position axially downstream of the blade portion 6 of the gas turbine stator blade 4.

[0070] Therefore, even if you use Figure 1 and Figure 2 The small combined blade unit 2 in which the interval between adjacent gas turbine vanes 4 is small can also be manufactured while avoiding interference between the spraying gun and the gas turbine vane 4. In addition, compared with the case where a plurality of gas turbine vanes formed separately are subjected to oxidation-resistant coating and then assembled, by subjecting the combined blade unit 2 formed of a plurality of gas turbine vanes 4 as a whole to oxidation-resistant coating, it is not necessary to assemble the plurality of gas turbine vanes, thereby reducing the labor and cost required for assembly.

[0071] The present disclosure is not limited to the above-described embodiments, and also includes modified embodiments of the above-described embodiments and embodiments in which these embodiments are appropriately combined.

[0072] For example, in Figure 2In the illustrated embodiment, the oxidation-resistant coating layer 20 is not formed in the range from the position P1 to the trailing edge 14 of the pressure surface 16 of the blade portion 6, but the oxidation-resistant coating layer 20 may also be formed in the range from the position P1 to the trailing edge 14 of the pressure surface 16 of the blade portion 6, or the oxidation-resistant coating layer 20 may be formed on the entire pressure surface 16 of the blade portion 6. In the gas turbine stator blade 4 of the present disclosure, the oxidation-resistant coating layer 20 is formed in at least a portion of the pressure surface 16 side of the surface 7 of the blade portion 6, and the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side in the range of 0.90≤X / Xmax≤1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer 20 on the pressure surface 16 side in the range of 0.0≤X / Xmax≤0.50, so that the damage of the gas turbine stator blade 4 caused by oxidation can be effectively suppressed with a small amount of oxidation-resistant coating.

[0073] The contents described in each of the above-mentioned embodiments can be understood, for example, as follows.

[0074] (1) A gas turbine vane according to at least one embodiment of the present disclosure (for example, the gas turbine vane 4 described above) includes a blade portion (for example, the blade portion 6 described above), wherein:

[0075] The surface of the blade portion includes: a leading edge (such as the leading edge 12 mentioned above); a trailing edge (such as the trailing edge 14 mentioned above); a pressure surface connecting the leading edge and the trailing edge (such as the pressure surface 16 mentioned above); and a negative pressure surface connecting the leading edge and the trailing edge (such as the negative pressure surface 18 mentioned above),

[0076] An oxidation-resistant coating layer (for example, the oxidation-resistant coating layer 20 of the pressure surface 16 described above) is formed on at least a portion of the pressure surface side of the surface of the blade-shaped portion.

[0077] The cross section of the blade portion that is perpendicular to the blade height direction (for example Figure 2 In the cross section shown in FIG. 1 , the axial position of the gas turbine is defined by the distance X from the leading edge to the position in the axial direction, and the position of the trailing edge in the axial direction is defined as Xmax.

[0078] Then, the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.90≤X / Xmax≤1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.0≤X / Xmax≤0.50.

[0079] In a turbine blade, as a physical strength, the bending strength relative to the gas flow (gas bending strength) is important from the viewpoint of suppressing damage. However, if the turbine blade is exposed to the flow of high-temperature gas and the wall thickness of the turbine blade is thinned due to oxidation, the bending strength of the turbine blade is reduced.

[0080] In contrast, according to the gas turbine stator blade described in (1), the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.90≤X / / Xmax≤1.0, which has a smaller influence on the bending strength with respect to the gas flow, is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.0≤X / Xmax≤0.50, which has a larger influence on the bending strength with respect to the gas flow. Therefore, damage to the gas turbine stator blade caused by oxidation (e.g., bending to the negative pressure surface side, chipping, etc.) can be effectively suppressed with a small amount of oxidation-resistant coating, and the cost required for oxidation-resistant coating can be reduced. In addition, by improving the durability of the gas turbine stator blade, the maintenance cycle of the gas turbine stator blade can be extended.

[0081] (2) In some embodiments, in addition to the gas turbine stator blade described in (1) above,

[0082] An oxidation-resistant coating layer (for example, the oxidation-resistant coating layer 20 of the above-mentioned suction surface 18) is formed on at least a portion of the surface of the blade-shaped portion on the suction surface side.

[0083] The thickness of the oxidation-resistant coating layer formed on the negative pressure surface side decreases from the leading edge side of the negative pressure surface toward the position where the blade thickness of the gas turbine stator blade is maximum, and decreases from the trailing edge side of the negative pressure surface toward the position where the blade thickness of the gas turbine stator blade is maximum.

[0084] According to the gas turbine stator blade described in (2), the thickness of the oxidation-resistant coating layer on the suction surface decreases from the leading edge on the suction surface toward the position where the blade thickness of the gas turbine stator blade becomes the largest, so that damage to the gas turbine stator blade caused by oxidation can be effectively suppressed with a small amount of oxidation-resistant coating. In addition, in general, the blade thickness is thinner on the trailing edge side of the gas turbine stator blade than on the leading edge side. Therefore, when the wall thickness reduction caused by oxidation advances, the blade profile and the chord length of the blade change significantly, and there is a possibility that the aerodynamic performance will be greatly reduced. However, according to the gas turbine stator blade described in (2), the thickness decreases from the trailing edge side on the suction surface toward the position where the blade thickness of the gas turbine stator blade becomes the largest. Therefore, on the suction surface, the thickness of the oxidation-resistant coating layer on the trailing edge side becomes relatively larger than the position where the blade thickness is the largest, and the reduction in the aerodynamic performance of the gas turbine stator blade caused by oxidation can be effectively suppressed with a small amount of oxidation-resistant coating.

[0085] (3) In some embodiments, in addition to the gas turbine stator blade described in (1) or (2) above,

[0086] An oxidation-resistant coating layer (for example, the oxidation-resistant coating layer 20 of the above-mentioned suction surface 18) is formed on at least a portion of the surface of the blade-shaped portion on the suction surface side.

[0087] In the cross section in the blade-shaped portion that is orthogonal to the blade height direction, the axial distance of the gas turbine from the position on the negative pressure surface where the thickness of the oxidation resistant coating layer on the negative pressure surface side is minimum to the leading edge is defined as X1, and the thickness of the oxidation resistant coating layer on the negative pressure surface side varies between the leading edge and the trailing edge in a manner that satisfies 0.25≤X1 / Xmax≤0.70.

[0088] According to the gas turbine stator described in (3) above, the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side is minimum within the range of 0.25≤X / Xmax≤0.70, where the influence on damage to the gas turbine stator 4 and reduction in aerodynamic performance is small. Therefore, as with the gas turbine stator described in (2) above, damage to the gas turbine stator blade and reduction in aerodynamic performance of the gas turbine stator blade caused by oxidation can be efficiently suppressed with a small amount of oxidation-resistant coating.

[0089] (4) In some embodiments, in the gas turbine stator blade described in any one of (1) to (3) above,

[0090] An oxidation-resistant coating layer (for example, the oxidation-resistant coating layer 20 described above) is formed on at least a portion of the surface of the blade-shaped portion on the negative pressure surface side.

[0091] In the cross-section orthogonal to the blade height direction in the leaf-shaped portion, the average value of the thickness of the oxidation-resistant coating layer on the negative pressure surface side within the range of 0.25≤X / Xmax≤0.70 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the negative pressure surface side within the range of 0.0≤X / XmaX≤0.25, and is smaller than the average value of the thickness of the oxidation-resistant coating layer on the negative pressure surface side within the range of 0.70≤X / Xmax≤1.0.

[0092] According to the gas turbine stator described in (4) above, within the range of 0.25≤X / Xmax≤0.70, in which the influence on damage to the gas turbine stator 4 and reduction in aerodynamic performance is small, the thickness of the oxidation-resistant coating layer 20 on the negative pressure surface 18 side is made relatively smaller than that in other ranges. Thus, as with the gas turbine stator described in (2) above, damage to the gas turbine stator blade and reduction in aerodynamic performance of the gas turbine stator blade caused by oxidation can be efficiently suppressed with a smaller amount of oxidation-resistant coating.

[0093] (5) In some embodiments, in the gas turbine stator blade described in any one of (1) to (4) above,

[0094] The oxidation-resistant coating layer is composed of CoNiCrAlY, NiCrAlY, CoCrAlY or MCrAlX (wherein M is Ni, Co or an alloy of Ni and Co, and X is Hf, Si or Ta).

[0095] According to the gas turbine stator blade described in (5) above, when the oxidation-resistant coating layer is composed of CoNiCrAlY, NiCrAlY, CoCrAlY or MCrAlX (wherein M is Ni, Co or an alloy of Ni and Co, and X is Hf, Si or Ta), damage to the gas turbine stator blade caused by oxidation can be efficiently suppressed with a smaller amount of oxidation-resistant coating.

[0096] (6) A combined blade unit according to at least one embodiment of the present disclosure (e.g., the combined blade unit 2 described above) includes a plurality of gas turbine stationary blades (e.g., the plurality of gas turbine stationary blades 4 described above), wherein the combined blade unit is formed integrally with the plurality of gas turbine stationary blades, wherein:

[0097] The plurality of gas turbine stationary blades are respectively the gas turbine stationary blades described in (1) above.

[0098] In a combined blade unit formed by integrally molding a plurality of gas turbine stator blades, if the gas turbine stator blades are miniaturized, when, for example, a spray gun is used to form an oxidation-resistant coating layer on the blade surface of the stator blade, interference between the spray gun and the gas turbine stator blade is likely to occur. However, in the combined blade unit described in (5), the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.90≤X / Xmax≤1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.0≤X / Xmax≤0.50, so that the combined blade unit can be manufactured while avoiding interference between the spray gun and the gas turbine stator blade. In addition, by applying oxidation-resistant coating to the combined blade unit formed by integrally molding a plurality of gas turbine stator blades 4, it is not necessary to assemble the plurality of gas turbine stator blades, thereby reducing the labor and cost required for assembly, compared with the case where oxidation-resistant coating is applied to a plurality of gas turbine stator blades formed separately and then the gas turbine stator blades are assembled.

[0099] (7) A method for manufacturing a gas turbine stator blade according to at least one embodiment of the present disclosure includes the following steps:

[0100] An oxidation-resistant coating layer (e.g., the oxidation-resistant coating layer 20) is formed on at least a portion of a pressure surface (e.g., the pressure surface 16) of a blade portion (e.g., the blade portion 6) of a gas turbine stator blade (e.g., the gas turbine stator blade 4).

[0101] The cross section of the blade portion that is perpendicular to the blade height direction (for example Figure 2 In the cross section shown in FIG. 1 , the axial position of the gas turbine is defined by the distance X from the leading edge of the blade portion in the axial direction to the position, and the position of the trailing edge of the blade portion in the axial direction is defined as Xmax.

[0102] In the step, the oxidation-resistant coating layer is formed on at least a portion of the pressure surface side of the surface of the blade portion in such a manner that the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side in the range of 0.90≤X / Xmax≤1.0 is less than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface in the range of 0.0≤X / Xmax≤0.50.

[0103] In a turbine blade, as a physical strength, the bending strength relative to the gas flow (gas bending strength) is important from the viewpoint of suppressing damage. However, if the turbine blade is exposed to the flow of high-temperature gas and the wall thickness of the turbine blade is thinned due to oxidation, the bending strength of the turbine blade is reduced.

[0104] In contrast, according to the method for manufacturing a gas turbine stator blade described in (7) above, the oxidation-resistant coating layer is formed on at least a portion of the pressure surface side of the surface of the blade portion in such a manner that the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.90≤X / Xmax≤1.0, where the influence on the bending strength relative to the gas flow is smaller, is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.0≤X / Xmax≤0.50, where the influence on the bending strength relative to the gas flow is larger. This makes it possible to realize a method for manufacturing a gas turbine stator blade that can efficiently suppress damage to the gas turbine stator blade caused by oxidation with a smaller amount of oxidation-resistant coating.

Claims

1. A gas turbine stator blade, comprising a blade portion, wherein: The surface of the blade-shaped portion includes a leading edge, a trailing edge, a pressure surface connecting the leading edge and the trailing edge, and a negative pressure surface connecting the leading edge and the trailing edge. An oxidation-resistant coating layer is formed on at least a portion of the surface of the blade portion on the pressure surface side. In the cross section of the blade portion orthogonal to the blade height direction, the position of the gas turbine in the axial direction is defined by the distance X from the leading edge to the position in the axial direction, and the position of the trailing edge in the axial direction is defined as Xmax, Then, the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.90≤X / Xmax≤1.0 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side within the range of 0.0≤X / Xmax≤0.

50.

2. The gas turbine stator blade according to claim 1, wherein: An oxidation-resistant coating layer is formed on at least a portion of the surface of the blade portion on the negative pressure surface side. The thickness of the oxidation-resistant coating layer formed on the negative pressure surface side decreases from the leading edge side of the negative pressure surface toward the position where the blade thickness of the gas turbine stator blade is maximum, and decreases from the trailing edge side of the negative pressure surface toward the position where the blade thickness of the gas turbine stator blade is maximum.

3. The gas turbine stator blade according to claim 1, wherein: An oxidation-resistant coating layer is formed on at least a portion of the surface of the blade portion on the negative pressure surface side. In the cross section in the blade-shaped portion that is orthogonal to the blade height direction, the axial distance of the gas turbine from the position on the negative pressure surface where the thickness of the oxidation resistant coating layer on the negative pressure surface side is minimum to the leading edge is defined as X1, and the thickness of the oxidation resistant coating layer on the negative pressure surface side varies between the leading edge and the trailing edge in a manner that satisfies 0.25≤X1 / Xmax≤0.

70.

4. The gas turbine stator blade according to claim 1, wherein: An oxidation-resistant coating layer is formed on at least a portion of the surface of the blade portion on the negative pressure surface side. In the cross-section in the leaf-shaped portion that is orthogonal to the blade height direction, the average value of the thickness of the oxidation-resistant coating layer on the negative pressure surface side within the range of 0.25≤X / Xmax≤0.70 is smaller than the average value of the thickness of the oxidation-resistant coating layer on the negative pressure surface side within the range of 0.0≤X / Xmax≤0.25, and is smaller than the average value of the thickness of the oxidation-resistant coating layer on the negative pressure surface side within the range of 0.70≤X / Xmax≤1.

0.

5. The gas turbine stator blade according to claim 1, wherein: The oxidation-resistant coating layer is composed of CoNiCrAlY, NiCrAlY, CoCrAlY or MCrAlX, wherein M is Ni, Co or an alloy of Ni and Co, and X is Hf, Si or Ta.

6. A combined blade unit comprising a plurality of gas turbine stationary blades, wherein the combined blade unit is formed by integrally forming the plurality of gas turbine stationary blades, wherein: The plurality of gas turbine stationary blades are respectively the gas turbine stationary blades according to claim 1 .

7. A method for manufacturing a gas turbine stator blade, wherein: The method for manufacturing a gas turbine stationary blade comprises the steps of: forming an oxidation-resistant coating layer on at least a portion of a pressure surface side of a blade portion of the gas turbine stationary blade; In a cross section of the blade portion orthogonal to the blade height direction, a position in the axial direction of the gas turbine is defined by a distance X from the leading edge of the blade portion in the axial direction to the position, and a position of the trailing edge of the blade portion in the axial direction is defined as Xmax. In the step, the oxidation-resistant coating layer is formed on at least a portion of the pressure surface side of the surface of the blade portion in such a manner that the average value of the thickness of the oxidation-resistant coating layer on the pressure surface side in the range of 0.90≤X / Xmax≤1.0 is less than the average value of the thickness of the oxidation-resistant coating layer on the pressure surface in the range of 0.0≤X / Xmax≤0.50.

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