Turbine stator vane and gas turbine

Abstract

This invention provides a turbine stator blade comprising: a blade body; a shroud formed at the end of the blade body in the blade height direction; a rounded corner portion connecting the blade body and the shroud; and a base plate with a plurality of cooling holes in contact with the combustion gas flow path. In the turbine stator blade, the plurality of cooling holes are connected to an inlet opening and a downstream outlet opening formed on the base plate. The inclination of the center lines of the cooling holes connecting the inlet and outlet openings relative to the axial direction is the same, forming a set of cooling hole rows with a first straight opening center line connecting the center of the outlet opening and a second straight opening center line connecting the center of the inlet opening, which are parallel to each other. The plurality of cooling hole rows are arranged along the blade surface from the upstream side to the downstream side in the axial direction, and the inclination of the center lines of the cooling holes in the plurality of cooling hole rows decreases as they move towards the downstream side in the axial direction.

Description

Technical Field

[0001] This invention relates to a turbine stationary blade and a gas turbine.

[0002] This application claims priority based on Japanese Patent Application No. 2021-112476 filed with the Japan Patent Office on July 7, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] Gas turbines produce high-temperature combustion gases by mixing compressed air with fuel. Turbine stationary blades, which are part of the gas turbine, are positioned within these high-temperature combustion gases and are therefore susceptible to thermal damage. To prevent this thermal damage, the turbine stationary blades receive a portion of the compressed air from the outside as cooling air to cool the blade body and shroud. Patent Document 1 shows an example of a cooling structure using cooling air from turbine stationary blades. Patent Document 1 discloses an example in which cooling holes are provided in both the high-temperature and low-temperature regions of the blade body and shroud for appropriate cooling.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-185270 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, it is desirable to reduce the amount of cooling air by using a cooling mechanism that is more suitable than the cooling structure disclosed in Patent Document 1.

[0009] The purpose of this invention is to provide a turbine stator blade in which a more appropriate cooling mechanism is applied in the turbine stator blade shroud, particularly in the negative pressure side leading edge region of the shroud with high heat load, to further reduce the amount of cooling air.

[0010] Methods for solving problems

[0011] At least one embodiment of the present invention relates to a turbine stator blade, comprising: a blade body; a shroud formed at an end of the blade body in the blade height direction; and a rounded corner portion for joining the blade body and the shroud. In the turbine stator blade, the shroud includes: a base plate in contact with a combustion gas flow path; a peripheral wall extending along the periphery of the base plate in the blade height direction; and a recess forming a space surrounded by the peripheral wall and the base plate. The peripheral wall includes: a leading edge end portion extending along the leading edge side of the blade body; and a negative pressure surface end portion extending from the leading edge to the trailing edge of the negative pressure surface side of the blade body. The shroud includes: a plurality of cooling holes formed in the leading edge region of the negative pressure surface side of the shroud and formed on the base plate.

[0012] Of the plurality of cooling holes, the first end is connected to the inlet opening formed in the base plate.

[0013] The second end is connected to the gas path surface formed on the base plate and to the outlet opening which is located further downstream of the inlet opening. It is arranged at predetermined intervals from the blade surface of the blade body toward the leading edge end or the negative pressure surface end in the circumferential direction. The inclination of the cooling hole centerline connecting the inlet opening and the outlet opening relative to the axial direction is kept the same. A set of cooling hole rows is formed with a first opening centerline that is straight and connects the center of the outlet opening of the plurality of cooling holes and a second opening centerline that is straight and connects the center of the inlet opening of the cooling holes, which are parallel to each other. A plurality of cooling hole rows are arranged along the blade surface from the upstream side to the downstream side. The inclination of the cooling hole centerline of the plurality of cooling hole rows decreases as it moves toward the downstream side.

[0014] Invention Effects

[0015] According to at least one embodiment of the present invention, a suitable cooling structure is formed in the leading edge region of the negative pressure side of the shield to uniformly cool the gas path surface of the base plate. Furthermore, this reduces the amount of cooling air required and improves the efficiency of the gas turbine. Attached Figure Description

[0016] Figure 1 This is a structural diagram of a gas turbine in one embodiment of the present invention.

[0017] Figure 2 This is a perspective view of a gas turbine stationary blade in one embodiment of the present invention.

[0018] Figure 3 This is a top view of a protective cover according to one embodiment of the present invention.

[0019] Figure 4 It is along Figure 3 A cross-sectional view of the protective cover cut along line A-A.

[0020] Figure 5 Indicates along Figure 4 The planar cross-section of the gas path surface of the shield cut by the BB line.

[0021] Figure 6 Indicates along Figure 4 Another embodiment of the planar cross-section of the gas path surface of the shield cut by the BB line.

[0022] Figure 7 It means Figure 6 A detailed view of a portion of the planar cross-section of the gas path surface of the shield shown.

[0023] Figure 8 It means Figure 5 Top view and sectional view of the cooling holes in section C.

[0024] Figure 9 This is a flowchart illustrating the cooling method for turbine stationary blades. Detailed Implementation

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0026] <<Structure of Gas Turbines>>

[0027] refer to Figure 1 The structure of a gas turbine employing turbine stationary blades is explained. Additionally, Figure 1 This is a schematic structural diagram of a gas turbine 1 using one embodiment of the turbine stationary blades 24.

[0028] like Figure 1 As shown, one embodiment of the gas turbine 1 includes: a compressor 2 for generating compressed air; a combustor 4 for generating combustion gas G using compressed air and fuel; and a turbine 6 driven by the rotation of the combustion gas G. In the case of the gas turbine 1 for power generation, a generator (not shown) is connected to the turbine 6, and power is generated by the rotational energy of the turbine 6.

[0029] use Figure 1 The various structures in gas turbine 1 will be described.

[0030] The compressor 2 includes: a compressor housing 10; an intake chamber 12 disposed on the inlet side of the compressor housing 10 for drawing in air; a rotor 8 configured to penetrate both the compressor housing 10 and the turbine housing 22 (described later); and various blades disposed within the compressor housing 10. The various blades include: inlet guide vanes 14 disposed on the side of the intake chamber 12; a plurality of compressor stationary blades 16 fixed on the side of the compressor housing 10; and a plurality of compressor moving blades 18 arranged alternately in the axial direction relative to the compressor stationary blades 16 on the rotor 8. Additionally, the compressor 2 may include other components such as an extraction chamber (not shown). In such a compressor 2, air drawn in from the intake chamber 12 is compressed by the plurality of compressor stationary blades 16 and the plurality of compressor moving blades 18, thereby generating compressed air. The compressed air is then delivered from the compressor 2 to the burner 4 on the axially downstream side.

[0031] The burner 4 is housed within the casing 20. For example... Figure 1 As shown, multiple burners 4 are arranged in a ring around the rotor 8 within the housing 20. Fuel and compressed air generated by the compressor 2 are supplied to the burners 4, causing the fuel to burn and thereby producing high-temperature, high-pressure combustion gas G, which serves as the working fluid of the turbine 6. The produced combustion gas G is transported from the burners 4 to the turbine 6 on the axial downstream side.

[0032] The turbine 6 includes a turbine housing (casing) 22 and various turbine blades disposed within the turbine housing 22. The various turbine blades include: a plurality of turbine stationary blades 24 fixed to the side of the turbine housing 22; and a plurality of turbine moving blades 26, which are mounted on the rotor 8 in an axially alternating manner relative to the turbine stationary blades 24.

[0033] In turbine 6, rotor 8 extends axially, and combustion gas G discharged from turbine housing 22 is discharged to exhaust housing 28 on the downstream side of the axial direction. Figure 1 In the diagram, the left side represents the upstream side of the axial direction, and the right side represents the downstream side of the axial direction. Furthermore, in the following description, when simply referred to as radial, it indicates the direction orthogonal to the rotor 8. And when referred to as circumferential, it indicates the direction of rotation of the rotor 8. Radial direction is sometimes also referred to as the blade height direction.

[0034] The turbine moving blades 26 are configured to generate rotational driving force from the high-temperature, high-pressure combustion gas G flowing together with the turbine stationary blades 24 within the turbine housing 22. This rotational driving force is transmitted to the rotor 8, which drives a generator (not shown) connected to the rotor 8.

[0035] Downstream of the turbine housing 22, an exhaust chamber 29 is connected via an exhaust housing 28. The combustion gas G after driving the turbine 6 is discharged to the outside through the exhaust housing 28 and the exhaust chamber 29.

[0036] <<Structure of Turbine Stationary Blades>>

[0037] Figure 2 A perspective view showing turbine stationary blade 24. (Example) Figure 2 As shown, the stationary blade 24 of the turbine 6 has a blade body 40 extending along the blade height direction and shrouds 60 at both ends of the blade body 40 at its outer and inner ends in the blade height direction. The shrouds 60 include: an outer shroud 60a formed on the outer side of the blade body 40 in the blade height direction; and an inner shroud 60b formed on the inner side of the blade body 40 in the blade height direction. The blade body 40 is disposed within a combustion gas flow path 47 through which the combustion gas G flows. The outer shroud 60a defines the outer position of the combustion gas flow path 47, which is formed in an annular shape around the rotor 8, in the blade height direction. The inner shroud 60b defines the inner position of the annular combustion gas flow path 47 in the blade height direction.

[0038] On the trailing edge 43 side of the blade body 40 in the outer shroud 60a of the blade body 40, a hook 76 is provided for supporting the turbine stationary blade 24 in the turbine housing 22. The hook 76 of the turbine stationary blade 24 is provided on the peripheral wall 62 on the trailing edge 43 side of the outer shroud 60a.

[0039] like Figure 2 As shown, the blade body 40 extends along the blade height direction, and is connected to the outer shroud 60a via a rounded corner 46 on the outer side of the blade height direction, and to the inner shroud 60b via a rounded corner 46 on the inner side of the blade height direction. The blade body 40, the outer shroud 60a, and the inner shroud 60b are integrated to form the turbine stationary blade 24.

[0040] Figure 3 This represents a planar cross-section of the outer shroud 60a as viewed from the outside of the blades on the reverse flow side relative to the combustion gas flow path 47. In the following description, the outer shroud 60a side will be explained as an example. Figure 2 and Figure 3 As shown, the blade body 40, connected to the outer shroud 60a via the rounded corner 46, forms a blade shape. The blade body 40 has a leading edge 42 at its upstream axial end and a trailing edge 43 at its downstream axial end. The blade body 40 has a convex negative pressure surface 44 and a concave positive pressure surface 45 on its circumferential surface facing the blade surface 41. The negative pressure surface 44 and the positive pressure surface 45 are joined at the leading edge 42 and the trailing edge 43, becoming a single unit to form a blade body 40. Furthermore, in the following description, the side of the blade body 40 with the positive pressure surface 45 is sometimes referred to as the ventral side, and the side of the blade body 40 with the negative pressure surface 44 is sometimes referred to as the dorsal side.

[0041] The blade body 40 extends along the blade height direction and has a blade body cavity 51 (first cavity) through which cooling air Ac flows. The blade body cavity 51 extends along the blade height direction from the outer shroud 60a to the inner shroud 60b, and forms multiple internal spaces connected between the leading edge 42 and the trailing edge 43. Figure 2 and Figure 3 In the embodiment shown, as an example, three blade body cavities 51 (blade body leading edge cavity 52, blade body middle cavity 53, and blade body trailing edge cavity 54) are arranged in the leading edge-to-trailing edge direction connecting the leading edge 42 and the trailing edge 43 of the blade body 40.

[0042] Regarding the blade body cavity 51, it is divided into multiple internal spaces by multiple blade body partitions 49, one end of which is connected to the inner wall 62a of the blade wall 40b on the negative pressure surface 44 side and the other end of which is connected to the inner wall 62a of the blade wall 40b on the positive pressure surface 45 side. The blade body cavity 51 is divided via the blade body partitions 49 on the leading edge 42 side of the blade body 40 into a blade body leading edge cavity 52 disposed on the leading edge 42 side of the blade body 40 and a blade body intermediate cavity 53 disposed adjacent to the axially downstream side of the leading edge cavity 52. ​​Similarly, the blade body cavity 51 is divided via the blade body partitions 49 on the trailing edge 43 side of the blade body 40 into a blade body intermediate cavity 53 and a blade body trailing edge cavity 54 disposed adjacent to the axially downstream side of the intermediate cavity 53.

[0043] Each blade body cavity 51 is not interconnected, but is open in either the outer shroud 60a or the inner shroud 60b, while the blade body end 40a of the other blade body cavity 51 is sealed by a cover 56 or the like. All blade body cavities 51 are supplied with cooling air Ac from either the outer shroud 60a or the inner shroud 60b to cool the blade body 40, and the air is discharged from the blade surface 41 to the combustion gas flow path 47. Alternatively, the blade body cavities 51 can be interconnected to form a serpentine flow path, with cooling air Ac supplied from an opening 56a in the blade height direction of the leading edge cavity 52, flowing through the intermediate cavity 53 and the trailing edge cavity 54 of the blade body, and discharged from a cooling passage (not shown) formed in the trailing edge 43 to the combustion gas flow path 47.

[0044] Figure 4 Indicates along Figure 3 The cross-section of the blade body 40, including the leading edge cavity 52 and the outer shroud 60a surrounding the leading edge cavity 52, is shown along line AA. Figure 2 , Figure 3 and Figure 4As shown, the outer shield 60a is composed of the following: a base plate 69, forming the bottom surface of the outer shield 60a; a peripheral wall 62, formed on the entire circumference of the outer periphery of the base plate 69, erected from the inner surface 70 of the base plate 69 along the blade height direction; a partition 73, dividing the recess 75 formed by the base plate 69 and the peripheral wall 62 into a plurality of cavities 80; and a collision plate 85, dividing the cavity 80 (recess 75) into an outer cavity 82 (third cavity) on the outer side in the blade height direction and an inner cavity 83 (fourth cavity) on the inner side in the blade height direction.

[0045] The collision plate 85 disposed in the cavity 80 has a plurality of through holes 86 communicating with the outer cavity 82 and the inner cavity 83. The outer cavity 82 forms part of the recess 75, and a space is formed by the outer shroud 60a. On the other hand, regarding the inner cavity 83, the recess 75 is divided into a plurality of spaces in the blade height direction by the collision plate 85, and the collision plate 85 is sandwiched in the middle and disposed on the inner side of the outer cavity 82 in the blade height direction.

[0046] The peripheral wall 62 is composed of: a leading edge end 64, formed on the axial upstream side of the leading edge 42; a trailing edge end 65, which is disposed opposite to the leading edge end 64 on the axial downstream side and extends circumferentially along the trailing edge 43 side; a negative pressure surface end 66, formed on the circumferential end of the blade body 40 on the negative pressure surface 44 side; and a positive pressure surface end 67, which is disposed opposite to the negative pressure surface end 66 in the circumferential direction and formed on the positive pressure surface 45 side of the blade body 40.

[0047] The base plate 69 includes: an outer surface (gas path surface) 71, which contacts the combustion gas G on the inner side of the combustion gas flow path 47 in the blade height direction; and an inner surface (reverse flow path) 70, which is on the reverse flow path side opposite to the outer surface (gas path surface) 71 in the blade height direction, facing outward in the blade height direction. The base plate 69 includes a plurality of cooling holes 89, the details of which will be described later. The cooling holes 89 penetrate the base plate 69 along the blade height direction and communicate with the inner cavity 83 and the combustion gas flow path 47 facing the outer surface 71. The outer end of the blade body 40 in the blade height direction (in the case of the inner shroud 60b) has a blade body end 40a that slightly protrudes from the inner surface 70 of the base plate 69 of the outer shroud 60a towards the outer or inner side in the blade height direction.

[0048] like Figure 3As shown, the region on the leading edge 42 side of the negative pressure surface 44 side of the outer shroud 60a has a plurality of protruding ribs 73 with a cross-section protruding from the inner surface 70 of the base plate 69 toward the reverse flow path side opposite to the outer surface (gas path surface) 71. In this embodiment, the ribs 73 include: a leading edge rib 73a, connecting the blade body end 40a and the leading edge end 64 on the leading edge 42 side of the blade body 40 formed in the recess 75 of the shroud 60; and a negative pressure surface side intermediate rib 73b, connecting the blade body end 40a and the negative pressure surface side end 66 of the blade body 40. By configuring leading-edge spacers 73a and negative-pressure-side intermediate spacers 73b in the region on the leading edge 42 side of the negative-pressure-side side of the outer shield 60a, an inner cavity 83 is formed, constituting a part of the space surrounded by the blade body end 40a, the leading edge end 64, the negative-pressure-side end 66, the leading-edge spacers 73a, and the negative-pressure-side intermediate spacers 73b, namely, the negative-pressure-side leading-edge cavity 81 (second cavity). Therefore, the inner cavity 83 communicates with the outer cavity 82 on the outer side in the blade height direction via the through hole 86 of the collision plate 85, and communicates with the combustion gas flow path 47 on the inner side in the blade height direction via the cooling hole 89 of the base plate 69.

[0049] The inner protective cover 60b has a structure that is substantially the same as the outer protective cover 60a described above. That is, Figure 3 and Figure 4 The structure shown is an example of the outer shield 60a, but the structure of the inner shield 60b can also be applied. Figure 3 and Figure 4 The structure is shown. Therefore, unless otherwise specified, the names and symbols of the structures of the inner shield 60b can be directly borrowed from the descriptions of the structures of the outer shield 60a. In the following... Figures 4 to 8 Unless otherwise specified, the description relating to the outer shield 60a can also be applied to the inner shield 60b. Furthermore, in the case of the inner shield 60b, the outer side in the blade height direction of the outer shield 60a is replaced with the inner side in the blade height direction, and the inner side in the blade height direction is replaced with the outer side in the blade height direction.

[0050] Typically, in the region of the combustion gas flow path 47 formed between the shrouds 60 at both ends of the turbine stationary blade 24 in the blade height direction, high-temperature combustion gas G flowing into the turbine stationary blade 24 from the axial upstream side flows along the blade surface 41 and the gas path surface 71, thus causing the gas path surface 71 of the shroud 60 to overheat. In particular, the flow velocity of combustion gas G is faster on the gas path surface 71 on the negative pressure surface 44 side of the leading edge 42 side compared to the positive pressure surface 45 side, thus the tendency to overheat is obvious. Therefore, a cooling mechanism is needed to suppress thermal damage to the shroud 60 from the combustion gas G. In the following description, some embodiments of the cooling structure for the leading edge cavity 81 on the negative pressure surface side of the shroud 60 of the turbine stationary blade 24 will be described. In the following description of the embodiments, the shroud 60 including the outer shroud 60a and the inner shroud 60b will be described. Therefore, unless otherwise specified, the shroud 60 can be applied to both the outer shroud 60a and the inner shroud 60b.

[0051] <<First Embodiment>>

[0052] The cooling structure around the negative pressure side leading edge cavity 81 of the shield 60 in this embodiment is shown in the figure. Figure 3 , Figure 4 and Figure 5 In addition, Figure 5 , Figure 6 and Figure 7 This represents a planar cross-section of the leading edge 42 of the negative pressure surface 44, obtained by viewing the outer shroud 60a from the inner gas path surface (outer surface) 71 along the blade height direction, and is along... Figure 4 A sectional view cut along the BB line.

[0053] The cooling structure of this embodiment comprises: a collision plate 85 having a plurality of through holes 86; a base plate 69 having a plurality of cooling holes 89; an outer cavity 82 formed on the outer side of the collision plate 85 in the blade height direction; and an inner cavity 83 formed on the inner side of the collision plate 85 in the blade height direction. Through the combination of these structures, the shield 60 forms a cooling structure comprising: an impact cooling structure in which cooling air Ac supplied from the outer cavity 82 through the through holes 86 formed in the collision plate 85 is injected into the inner cavity 83 and collides with the inner surface 70 of the base plate 69, thereby performing impact cooling (collision cooling); and a thin-film cooling structure in which the outer surface (gas path surface) 71 of the base plate 69 is cooled as the cooling air Ac after impact cooling is discharged through the cooling holes 89 formed in the base plate 69 into the combustion gas flow path 47.

[0054] The following is based on Figure 3 , Figure 4 , Figure 5 and Figure 9The cooling structure formed by the combination of impact cooling and thin film cooling of the cavity 81 at the front edge of the negative pressure surface is specifically described.

[0055] On the outer surface (gas path surface) 71 of the negative pressure side leading edge cavity 81 of the shroud 60, a plurality of cooling holes 89 are arranged along the blade surface 41 of the blade body 40 in a manner that surrounds the blade surface 41. On the negative pressure side leading edge cavity 81 of the shroud 60, a plurality of cooling hole rows 90, each containing a plurality of cooling holes 89, are arranged at predetermined intervals along the curvature of the blade surface 41, surrounding the outer periphery of the blade body cavity 51 on the negative pressure side of the blade body 40. The plurality of cooling hole rows 90 are formed by gradually changing their inclination relative to the axial direction as they move towards the downstream side.

[0056] Figure 5 The cooling hole rows 90 (91, 92, 93, 94) shown extend axially from the upstream side to the downstream side, and are composed of a first cooling hole row 91, a second cooling hole row 92, a third cooling hole row 93, and a fourth cooling hole row 94. Each cooling hole row 91, 92, 93, and 94 has a plurality of cooling holes 89. Furthermore, regarding the symbols for the cooling holes 89 constituting the third cooling hole row 93 and the fourth cooling hole row 94, only the cooling holes 89 closest to the blade surface 41 and the cooling holes 89 furthest from the blade surface 41 are shown, and the symbols for the other cooling holes 89 are omitted.

[0057] The structures of each cooling hole row 91, 92, 93, and 94 are based on the cooling hole 89 located closest to the blade surface 41, extending from the blade surface 41 side of the blade body 40 toward the leading edge end 64 or the negative pressure surface end 66, and are composed of multiple cooling holes 89 arranged at predetermined intervals. Here, if the straight line connecting the center of the inlet opening 89a and the center of the outlet opening 89b of the cooling hole 89 is defined as the cooling hole centerline FL, then the direction in which the cooling hole 89 extends is consistent with the direction in which the cooling hole centerline FL extends. As described above, the combustion gas G flowing from the axial upstream side into the gas path surface 71 of the turbine stationary blade 24 flows along the blade surface 41 of the blade body 40, on the negative pressure surface 44 side and the positive pressure surface 45 side. The blade surface 41 on the negative pressure surface 44 side of the blade body 40 forms a convex curved surface, and the shape of the blade surface 41 changes as it moves toward the axial downstream side. Therefore, the flow direction of the combustion gas G flowing along the blade surface 41 changes with the curvature of the blade surface 41 of the blade body 40. On the other hand, the cooling air Ac discharged from the cooling holes 89 of the base plate 69 of the shroud 60 to the combustion gas flow path 47 is preferably discharged in the direction of the flow of the combustion gas G, which changes along with the flow direction, so as not to disturb the flow of the combustion gas G. Therefore, the plurality of cooling holes 89 forming the plurality of cooling hole rows 90 are configured such that their inclination relative to the axial direction gradually changes according to the change in the flow direction of the combustion gas G as they move toward the axial downstream side. That is, the inclination of the cooling hole centerline FL of the plurality of cooling holes 89 forming the plurality of cooling hole rows 90 relative to the axial line AL gradually decreases as they move toward the axial downstream side.

[0058] Here, for reference Figure 5 The structure of the cooling hole array 90 (91, 92, 93, 94) will be described. As mentioned above, Figure 5 The cooling hole rows 91, 92, 93, and 94 shown are preferably structured as follows: taking the position of the cooling hole 89 closest to the blade surface 41 as a reference, from the position of the cooling hole 89 closest to the blade surface 41 toward the leading edge end 64 or the negative pressure side end 66, in a direction separate from the blade surface 41, the plurality of cooling holes 89 constituting the same cooling hole row 90 extend at the same interval and with the same inclination relative to the axial line AL. Furthermore, the direction in which each group of cooling hole rows 91, 92, 93, and 94 extends is preferably arranged parallel to the direction in which the isobaric line IBL of the combustion gas G extends, as described later.

[0059] like Figure 5As shown, the cooling hole centerline FL of the aforementioned cooling hole 89 is represented by a solid straight line connecting the center of the inlet opening 89a and the center of the outlet opening 89b of the plurality of cooling holes 89 forming each cooling hole row 91, 92, 93, 94. The plurality of cooling holes 89 forming each cooling hole row 91, 92, 93, 94 have a first opening centerline OL1, represented by a dashed line connecting the centers of the outlet openings 89b of adjacent cooling holes 89, relative to the direction from the blade surface 41 near the plurality of cooling holes 89 arranged in each cooling hole row 91, 92, 93, 94 toward the leading edge end 64 or the negative pressure side end 66. Similarly, the plurality of cooling holes 89 forming the same cooling hole rows 90 have a second opening center line OL2, which is a straight line representing the center of the inlet opening 89a of adjacent cooling hole rows 91, 92, 93, 94, relative to the direction from the blade surface 41 of the plurality of cooling holes 89 arranged in the cooling hole rows 91, 92, 93, 94 toward the leading edge end 64 or the negative pressure side end 66. The first opening center line OL1 and the second opening center line OL2 are collectively referred to as the opening center line OL.

[0060] The structure of cooling hole 89 is as Figure 5 The details of section C of the cooling hole are shown. Figure 8 In the middle. For example Figure 8 As shown in detail in section C, the cooling hole 89 formed in the base plate 69 has an inlet opening 89a opening on the inner surface 70 and an outlet opening 89b opening on the outer surface (gas path surface) 71. The outlet opening 89b is formed at a position further downstream of the inlet opening 89a on the trailing edge 43 side. The inclination of the cooling hole 89 relative to the inner surface 70 or the outer surface (gas path surface) 71 of the base plate 69 is the same, and the length of the cooling hole centerline FL, which connects the length of the cooling hole 89 to the length of the inlet opening 89a and the outlet opening 89b, is also the same.

[0061] Here, if we define the cooling hole array 90 in this embodiment, the cooling hole array 90 extends from the position of the cooling hole 89 closest to the blade surface 41 toward the leading edge end 64 or the negative pressure surface side end 66, in a direction separate from the blade surface 41, based on the position of the cooling hole 89 closest to the blade surface 41. Each cooling hole array 91, 92, 93, 94, including a plurality of cooling holes 89, can be regarded as a group of a plurality of cooling holes 89 extending simultaneously while maintaining the same spacing and the same inclination relative to the axial line AL. Moreover, the cooling hole center lines FL of the plurality of cooling holes 89 constituting the same cooling hole array 91, 92, 93, 94 are arranged parallel to each other in the same cooling hole array 91, 92, 93, 94, maintaining the same spacing and the same inclination relative to the axial line AL. Furthermore, the first opening center lines OL1 and the second opening center lines OL2 of the plurality of cooling holes 89 forming the same cooling hole array 91, 92, 93, 94 are formed parallel to each other and extend with the same inclination relative to the cooling hole center line FL. In addition, the inclination of the cooling hole centerline FL relative to the first opening centerline OL1 remains the same at any position in the axial direction in the same cooling hole rows 91, 92, 93, and 94.

[0062] like Figure 5 As shown, when comparing multiple cooling hole rows 90 (91, 92, 93, 94) arranged from the upstream side to the downstream side of the axial direction, the direction in which the groups of cooling holes 89 forming each cooling hole row 91, 92, 93, 94 extend is consistent with the direction in which the first opening center line OL1 and the second opening center line OL2 extend. As they move towards the downstream side of the axial direction, the inclination relative to the axial direction increases, while the inclination relative to the axial line AL decreases. Furthermore, when comparing the cooling hole center lines FL of the cooling holes 89 in the cooling hole rows 90, the direction in which the cooling hole center lines FL forming each cooling hole row 91, 92, 93, 94 extend is consistent with the direction in which the cooling hole center lines FL of each individual cooling hole 89 extend. As they move towards the downstream side of the axial direction, the inclination relative to the axial direction decreases, while the inclination relative to the axial line AL decreases. Furthermore, the first opening center line OL1 and the second opening center line OL2 of each cooling hole row 91, 92, 93, and 94 also become more inclined relative to the axial direction as they move towards the downstream side of the axial direction, while their inclination relative to the axial line AL becomes less.

[0063] For example, the first cooling hole row 91, located on the upstream side of the axial direction, is composed of five cooling holes 91a, 91b, 91c, 91d, and 91e, with the same spacing and the same inclination of the cooling hole centerline FL relative to the axial direction, based on the cooling hole 91a closest to the blade surface 41 and facing the leading edge end 64 or the negative pressure surface end 66. On the other hand, the second cooling hole row 92, located adjacent to the first cooling hole row 91 on the downstream side of the axial direction, is composed of five cooling holes 92a, 92b, 92c, 92d, and 92e, with the same spacing and the same inclination of the cooling hole centerline FL relative to the axial direction, based on the cooling hole 92a closest to the blade surface 41 and facing the negative pressure surface end 66. Furthermore, the first opening centerline OL1 of the first cooling hole row 91 is arranged parallel to the isobaric line IBL1 of the combustion gas G (described later), and the first opening centerline OL1 of the second cooling hole row 92 is arranged parallel to the isobaric line IBL2 of the combustion gas G.

[0064] When comparing the first cooling hole row 91 and the second cooling hole row 92, the inclination of the first opening centerline OL1 of the second cooling hole row 92 relative to the axial direction is greater than that of the first opening centerline OL1 of the first cooling hole row 91, while its inclination relative to the axial line AL is smaller. Furthermore, the inclination of the cooling hole centerline FL of the second cooling hole row 92 relative to the axial direction is greater than that of the cooling hole centerline FL of the first cooling hole row 91, while its inclination relative to the axial line AL is smaller.

[0065] That is, as the isobaric line IBL of the combustion gas G (described later) moves towards the downstream side of the axial direction and closer to the negative pressure surface end 66, its inclination relative to the axial direction increases, while its inclination relative to the axial line AL decreases. On the other hand, the opening center lines (first opening center line OL1) of each cooling hole row 91, 92, 93, 94 are preferably arranged parallel to the isobaric line IBL of the combustion gas G. Therefore, the directions in which each cooling hole row 91, 92, 93, 94 extends—that is, the opening center line OL and the cooling hole center line FL—preferably change the inclination of the opening center line (first opening center line OL1) of each cooling hole row 91, 92, 93, 94 relative to the axial line AL as the inclination of the isobaric line IBL of the combustion gas G changes. In other words, the inclination of the opening center lines OL and the cooling hole center lines FL of each cooling hole row 91, 92, 93, 94 relative to the axial line AL gradually decreases as they move towards the downstream side of the axial direction. Here, the inclination or angle of the opening center line OL (first opening center line OL1, second opening center line OL2) or cooling hole center line FL of the plurality of cooling holes 89 constituting the cooling hole row 90 relative to the axial line AL refers to the inclination or angle formed by the axial line AL and the opening center line OL or cooling hole center line FL in the counterclockwise direction when viewed from a position further downstream of the axial line AL than the position where the opening center line OL or cooling hole center line FL intersects with the axial line AL.

[0066] The number and configuration of the multiple cooling holes 89 that make up each cooling hole row 90 are selected taking into account the metal temperature of the gas path surface 71 of the shield 60. Figure 5 The illustrated embodiment is as follows: In the negative pressure surface-side leading edge cavity 81, four rows of cooling holes 90 (first cooling hole row 91, second cooling hole row 92, third cooling hole row 93, and fourth cooling hole row 94) are arranged at predetermined intervals from the upstream side to the downstream side. The number of cooling hole rows 90 is not limited to four; it can be three or fewer, or five or more. Furthermore, the configuration... Figure 5 The number of cooling holes 89 in each of the cooling hole rows 91, 92, 93, and 94 shown is an example. For instance, the number of cooling holes 89 constituting the first cooling hole row 91 and the second cooling hole row 92 can be more than 5 or less than 4.

[0067] The number of cooling holes 89 in the third cooling hole row 93 and the fourth cooling hole row 94 can be more than three.

[0068] Next, the relationship between the configuration of the cooling holes 89 formed on the gas path surface 71 and the pressure distribution of the combustion gas G flowing through the combustion gas flow path 47 will be explained. Figure 5The diagram shows a portion of the pressure distribution of combustion gas G flowing through the gas path surface 71 of the leading edge 42 on the negative pressure side 44 of the shroud 60. The isobaric lines IBL representing the pressure (static pressure) of the combustion gas G are represented by dashed lines. As the combustion gas G flows into the turbine stator blade 24, its pressure decreases as it flows through the combustion gas flow path 47 from the leading edge 42 to the trailing edge 43 on the negative pressure side 44 and the positive pressure side 45. The isobaric lines IBL of the combustion gas G are drawn, for example, as a gentle curve starting from the blade surface 41 on the negative pressure side 44 of the turbine stator blade 24 and ending at the blade surface 41 on the adjacent (not shown) positive pressure side of the turbine stator blade 24 in the circumferential direction.

[0069] Here, the isobaric line IBL refers to the curve that connects the combustion gas G flowing through the combustion gas flow path 47, where the pressure (static pressure) shows the same position.

[0070] As an example of the isobaric line IBL for combustion gas G Figure 5 The isobaric line IBL1 shown connects the starting point Xa on the blade surface 41 of the blade body 40 to the midpoint Xb on the end face located at the negative pressure side end 66, represented by a gentle curve indicated by a dashed line. IBL1 represents a portion of the entire length of the isobaric line, although not shown, it is a curve extending further from the midpoint Xb to the blade surface 41 on the positive pressure side 45 of the adjacent turbine stationary blade 24. The pressure (static pressure) of the combustion gas G decreases axially downstream towards the gas path surface 71. IBL1, from the starting point Xa towards the midpoint Xb, moves axially downstream and separates from the blade surface 41, near the negative pressure side end 66, with a greater inclination relative to the axial direction and a smaller inclination relative to the axial line AL. Figure 5 In comparing isobar IBL1 with isobar IBL2, which is formed further downstream of isobar IBL1, the pressure (static pressure) of isobar IBL2 is lower than that of isobar IBL1. Furthermore, as the combustion gas G flows axially downstream of the gas path surface 71, closer to the negative pressure surface end 66, the axial distance between isobar IBL1 and isobar IBL2 increases. Regarding the tendency of this increasing axial distance of isobar IBL, the axial distance is small near the starting point Xa of the blade surface 41, gradually increasing as it separates from the blade surface 41, reaching its maximum near the midpoint Xb. The inclination of isobar IBL relative to the axial direction varies greatly near the blade surface 41, but the variation is small as it moves away from the blade surface 41 and towards the midpoint Xb of the negative pressure surface end 66.

[0071] exist Figure 5Taking the first cooling hole row 91, located near the leading edge end 64 of the axially upstream side within the plurality of cooling hole rows 90, as an example, the relationship between the arrangement of the cooling hole rows 90 and the isobaric line IBL of the combustion gas G will be explained. The first cooling hole row 91 consists of a group of five cooling holes 89 (91a, 91b, 91c, 91d, 91e), arranged at equal intervals from a position near the blade surface 41 along the direction of the negative pressure surface end 66. As an example of the isobaric line IBL of the combustion gas G near the first cooling hole row 91, isobaric line IBL1 can be given. Isobaric line IBL1 is formed by drawing a gentle curve from the starting point Xa on the blade surface 41 on the negative pressure surface 44 side of the leading edge 42 side of the blade body 40 to the midpoint Xb on the end face of the negative pressure surface end 66.

[0072] On the other hand, the arrangement of the plurality of cooling holes 89 in the first cooling hole row 91 is configured such that the first opening center line OL1 connecting the outlet openings 89b of the plurality of cooling holes 89 in the first cooling hole row 91 is approximately parallel to the isobaric line IBL1. However, the isobaric line IBL1 is a gently curving line, so in order to ensure that the opening center line OL (first opening center line OL1) of the cooling hole 89 is strictly parallel to the isobaric line IBL1, it is preferable that the opening center line OL is not a straight line, but a curve. However, since the cooling holes 89 are formed by machining or electrical discharge machining, from the viewpoint of simplifying the machining operation, it is preferable to arrange the plurality of cooling holes 89 such that the first opening center line OL1 is a straight line. Therefore, in Figure 5 In this context, relative to the isobaric line IBL1 extending from the starting point Xa on the blade surface 41 on the leading edge 42 side of the blade body 40 to the midpoint Xb of the negative pressure side end 66, the first opening center line OL1 of the plurality of cooling holes 89 arranged near it is preferably selected from the two cooling holes 89, namely the cooling hole 91a arranged closest to the blade surface 41 side and the cooling hole 91b adjacent to each other on the blade surface 41 in the direction of the negative pressure side end 66. The first opening center line OL1 is a straight line that connects the center of the outlet opening 89b of the cooling hole 91a and the cooling hole 91b and extends parallel to the isobaric line IBL1.

[0073] In the above description, the cooling hole 91b adjacent to the cooling hole 91a closest to the blade surface 41 was selected. However, a combination of two other adjacent cooling holes 89 from the same cooling hole row 90 can also be selected. That is, the configuration of the cooling holes 89 in the first cooling hole row 91 can be selected such that the first opening centerline OL1, determined by the combination of other cooling holes 89 constituting the same first cooling hole row 91, namely cooling holes 91d and cooling holes 91e, is parallel to the isobaric line IBL1. Simply selecting a straight first opening centerline OL1 based on the outlet openings 89b of two adjacent cooling holes 89 in the same cooling hole row 90 is a preferred choice from both the perspective of improving the cooling performance of the shield 60 and simplifying the processing operation. The same idea applies to the selection of the second opening centerline OL2. Furthermore, the two adjacent cooling holes 89 used when selecting the second opening centerline OL2 are preferably a combination of the two adjacent cooling holes 89 used when selecting the first opening centerline OL1.

[0074] As described above, the arrangement of the plurality of cooling holes 89 in the cooling hole array 90 is selected such that the metal temperature and thermal stress of the base plate 69 forming the shroud 60 are within allowable values. Furthermore, the selection of the inclination of the cooling holes 89 and the cooling hole array 90 relative to the axial direction is preferably taken into consideration while considering the relationship with the isobaric line IBL of the combustion gas G flowing through the gas path surface 71. As described above, the cooling structure of the shroud 60 includes a combination of impact cooling based on the impact plate 85 and thin-film cooling based on the cooling holes 89 of the base plate 69. By applying these two combinations, thermal damage to the base plate 69 of the shroud 60 from the combustion gas G can be suppressed. Figure 4 As shown, cooling air Ac supplied from the outside to the shroud 60 is supplied to the outer cavity 82 and then to the inner cavity 83 via a through hole 86 formed in the collision plate 85. The cooling air Ac is depressurized as it passes through the through hole 86 of the collision plate 85. Furthermore, as the cooling air Ac flows from the through hole 86 into the inner cavity 83, it becomes a jet and collides with the inner surface 70 of the base plate 69, performing impact cooling (impact cooling) on ​​the inner surface 70. The cooling air Ac, after impact cooling of the inner surface 70, then exits from the cooling hole 89 formed in the base plate 69 into the combustion gas flow path 47 on the gas path surface 71 side, thus performing thin-film cooling on the gas path surface 71.

[0075] The configuration of the cooling holes 89 in the cooling hole row 90 located in the negative pressure side leading edge cavity 81 is a characteristic feature affecting the cooling of the shroud 60, namely, thin-film cooling based on the cooling holes 89. As described above, as the combustion gas G flowing into the combustion gas flow path 47 of the turbine stationary blade 24 flows axially downstream on the gas path surface 71 of the shroud 60, the pressure (static pressure) decreases as shown by the change of the isobar IBL. On the other hand, the amount of cooling air discharged from the inner cavity 83 of the shroud 60 to the combustion gas flow path 47 via the cooling holes 89 is affected by the pressure difference between the inlet opening 89a and the outlet opening 89b of the cooling holes 89, that is, the pressure difference (pressure difference) between the inner cavity 83 of the cooling holes 89 and the combustion gas flow path 47.

[0076] Due to the difference in pressure drop of the combustion gas G as it flows through the gas path surface 71, the amount of cooling air flowing through the cooling hole array 90's cooling holes 89 varies. The inner cavity 83 connected to the upstream inlet opening 89a of the cooling hole 89 maintains the same pressure as long as it is within the same space. On the other hand, the pressure of the combustion gas G on the gas path surface 71 side connected to the downstream outlet opening 89b of the cooling hole 89 decreases as it moves axially downstream. Therefore, depending on the configuration of the multiple cooling holes 89 in the cooling hole array 90, differences in pressure difference may occur among the multiple cooling holes 89 constituting the same cooling hole array 90, resulting in deviations in the amount of cooling air discharged. These deviations in the amount of cooling air from the multiple cooling holes 89 constituting the cooling hole array 90 contribute to uneven thin-film cooling and result in uneven metal temperature distribution on the base plate 69. To improve this, it is preferable to select the configuration of the plurality of cooling holes 89 in the same cooling hole array 90 such that the center line OL1 of the first opening of the plurality of cooling holes 89 constituting the same cooling hole array 90 is approximately parallel to the isobaric line IBL of the combustion gas G near each cooling hole array 91, 92, 93, 94. If the configuration of the plurality of cooling holes 89 in the same cooling hole array 90 is set such that the center line OL1 of the first opening of the cooling hole array 90 is approximately parallel to the isobaric line IBL of the combustion gas G, the plurality of cooling holes 89 constituting the same cooling hole array 90 can maintain the same pressure difference. If the pressure difference of the plurality of cooling holes 89 in the same cooling hole array 90 is set to be the same, the amount of cooling air discharged from the plurality of cooling holes 89 in the same cooling hole array 90 to the gas path surface 71 is uniformized, and the thin film cooling on the axial downstream side is uniformized from the position of the plurality of cooling holes 89 in the same cooling hole array 90. As a result, the temperature distribution of the gas path surface 71 of the shield 60 is equalized, suppressing thermal damage to the base plate 69 and reducing thermal stress caused by the uneven temperature distribution of the base plate 69.

[0077] As described above, the pressure (static pressure) of the combustion gas G decreases as it moves axially downstream, but the axial spacing of the isobars IBL of the combustion gas G tends to increase as it moves axially downstream. Therefore, the axial spacing of the first opening centerline OL1 of each cooling hole row 91, 92, 93, 94, arranged parallel to the isobars IBL, also gradually increases axially downstream. As a result, the gas path surface 71 on the axially downstream side is uniformly cooled from the multiple cooling holes 89 of each cooling hole row 91, 92, 93, 94.

[0078] like Figure 5 As shown, the isobaric line IBL of the combustion gas G, as it moves downstream towards the axial direction and closer to the negative pressure side end 66, has a greater inclination relative to the axial direction. Therefore, the inclination of the straight first opening center line OL1 of the multiple cooling hole rows 90, relative to the axial direction, also increases as it moves downstream towards the axial direction, while its inclination gradually decreases relative to the axial line AL, depending on the change in the isobaric line IBL. As a result, as... Figure 5As shown, the first opening center line OL1, extending towards the leading edge 42 on the side opposite to the circumferential direction of the negative pressure surface end 66 relative to the position of the cooling holes 89 (91a, 92a, 93a, 94a) closest to the blade surface 41, has a smaller inclination relative to the axial line AL as it moves towards the axial downstream side. The first opening center line OL1 is the first opening center line of the plurality of cooling hole rows 90. On the other hand, assuming a circular leading edge region 42a (first region), indicated by a dashed line, centered on the leading edge 42 and tangent to the outer edge 46a of the rounded corner portion 46 formed axially upstream of the leading edge 42, the first opening center line OL1 of the plurality of cooling hole rows 90 passes through the leading edge region 42a (first region). From different perspectives, the plurality of cooling hole rows 90 (91, 92, 93, 94) formed by the plurality of cooling holes 89 formed in the negative pressure surface side leading edge cavity 81 take the circular leading edge region 42a (first region) centered on the leading edge 42 as the starting point, and have a first opening center line OL1 connecting at least two cooling hole 89 outlet openings 89b that are adjacent to each other in the direction of the extension of the plurality of cooling hole rows 90 in the negative pressure surface side end 66 of the plurality of cooling hole rows 89 forming the plurality of cooling hole rows 90. That is, the first opening center line OL1 of at least one cooling hole row 90 in the plurality of cooling hole rows 89 formed in the plurality of cooling hole rows 89 formed in the negative pressure surface side leading edge cavity 81 is formed by a straight line that starts from the leading edge region 42a (first region) centered on the leading edge 42, connects the center of the outlet openings 89b of the plurality of cooling hole 89 forming the same cooling hole row 90, and extends to the negative pressure surface side end 66. The reason for the configuration of the first opening centerline OL1 of the cooling hole row 90 is that the multiple cooling hole rows 90 formed in the negative pressure side leading edge cavity 81 are arranged radially along the blade surface 41 of the blade body 40 in a manner that surrounds the blade surface 41. While the first opening centerline OL1 of each cooling hole row 91, 92, 93, 94 is arranged parallel to the isobaric line IBL of the combustion gas G, the inclination relative to the axial line AL decreases as it moves toward the axial downstream side.

[0079] As a characteristic element affecting the configuration of the cooling hole array 90 in this embodiment, the isobaric line IBL of the combustion gas G has, in addition to having a point where the first opening center line OL1 of the cooling hole array 90 is parallel to the isobaric line IBL, as described above, the inclination of the cooling hole center line FL of the cooling hole array 90 relative to the axial direction.

[0080] like Figure 5As shown, the combustion gas G flowing through the gas path surface 71 on the negative pressure surface 44 side of the leading edge 42 side of the shroud 60 flows along the blade surface 41, which has a convex curved surface. The region where multiple cooling holes 89 formed in the leading edge cavity 81 on the negative pressure surface side is configured is such that, as the blade surface 41 of the blade body 40 approaches the negative pressure surface side end 66 from the upstream side to the downstream side, the inclination of the curved surface of the blade surface 41 relative to the axial line AL gradually decreases. In this region, the cooling hole centerline FL is positioned in a direction more inclined towards the blade surface 41 than the direction orthogonal to the opening centerline OL, relative to the direction in which the opening centerline OL of the multiple cooling holes 89 extends. Furthermore, as the opening centerline OL of the multiple cooling hole rows 90 moves towards the downstream side, the inclination of the cooling hole centerline FL of the same cooling hole row 90 relative to the axial line AL decreases, therefore the inclination of the cooling hole centerline FL relative to the axial line AL also decreases. Furthermore, the inclination or angle formed by the center line FL of the cooling holes 89 in each cooling hole row 91, 92, 93, and 94 and the opening center line OL (first opening center line OL1) is preferably maintained at the same inclination or angle at any position in the axial direction. If the inclination of the center line FL of the cooling holes 89 relative to the opening center line OL is not maintained at the same level, and the center line FL of the cooling holes is excessively inclined towards the blade surface 41 depending on the axial position of the cooling hole row 90, the flow of cooling air Ac discharged from the cooling holes 89 will disrupt the flow of combustion gas G.

[0081] Here, the positional relationship between the center line OL1 of the first opening and the center line OL2 of the second opening of the cooling hole array 90 will be explained using the first cooling hole array 91 as an example. As described above, the center lines FL of the multiple cooling holes 89 constituting the same cooling hole array 90 have the same length and the same inclination. Therefore, as Figure 5 As shown, if the center line OL1 of the first opening of the first cooling hole row 91 is a straight line starting from the front edge region (first region) 42a, then the center line OL2 of the second opening extending to the front edge 42 side of the inlet opening 89a of the multiple cooling holes 89 connected to the same cooling hole row 90 is also formed by a straight line.

[0082] Furthermore, the second opening centerline OL2 of the same first cooling hole row 91 is formed by a straight line originating from an upstream leading edge region (second region) 42b located at a predetermined position further upstream of the leading edge 42 on the axial line AL passing through the leading edge 42. Here, the upstream leading edge region (second region) 42b refers to a region located on the axial line AL further upstream of the leading edge 42, centered at a position equivalent to the axial length of the cooling hole centerline FL of the first cooling hole row 91, and formed as a circle with the same radius as the leading edge region 42a, indicated by a dashed line.

[0083] Regarding the above description, the configuration, function, effect, and impact of the cooling holes 89 have been explained with the first cooling hole row 91 as the center. However, the configuration of the cooling holes 89 in other cooling hole rows 90 (92, 93, 94) can also be set in the same way as the first cooling hole row 91. However, as mentioned above, the inclination of the opening center line OL of the other cooling hole rows 90 relative to the axial line AL changes as they move towards the downstream side. Therefore, the first opening center line OL1 of at least one cooling hole row 90 within all cooling hole rows 90 originates from the leading edge region (first region) 42a, and the second opening center line OL2 originates from the upstream leading edge region (second region) 42b, extending along the direction of the leading edge end 64 or the negative pressure surface side end 66. By selecting the above-mentioned configuration of the cooling holes 89, appropriate cooling of the negative pressure surface side leading edge cavity 81 is achieved, suppressing thermal damage and the generation of thermal stress on the base plate 69 of the shield 60. Furthermore, by configuring the appropriate cooling holes 89, the amount of cooling air required is reduced, thereby improving the efficiency of the gas turbine.

[0084] <<Second Implementation>>

[0085] The following description relates to a second embodiment of the cooling structure surrounding the negative pressure side leading edge cavity 81 of the shield 60, see reference. Figure 6 and Figure 7 Please provide an explanation. Figure 6 This indicates a planar cross-section of the shield 60 in this embodiment, and is along... Figure 4 A top view cut along the BB line. Figure 7 It means Figure 6 A detailed view of a portion of the top view of this embodiment of the protective cover 60 shown.

[0086] The cooling structure of this embodiment relates to the following embodiment: the arrangement of the cooling holes 89 is changed compared to the structure of the first embodiment, which has multiple cooling holes 89 formed in the cooling hole row 90 of the aforementioned shield 60. The cooling structure of this embodiment is such that the arrangement of the multiple cooling holes 89 constituting the thin-film cooling structure differs from that of the first embodiment, which combines the impact cooling structure and the thin-film cooling structure. Furthermore, Figure 3 and Figure 4 The impact cooling structure shown is also applied in this embodiment.

[0087] Figure 6 The cooling hole array 95 shown in this embodiment extends axially from the upstream side to the downstream side and is composed of a first cooling hole array 96, a second cooling hole array 97, a third cooling hole array 98, and a fourth cooling hole array 99. Each cooling hole array 96, 97, 98, and 99 has a plurality of cooling holes 89.

[0088] exist Figure 6 In the text, solid lines represent the arrangement of multiple cooling holes 89 in the multiple cooling hole rows 95 (96, 97, 98, 99) involved in this embodiment, and dashed lines represent the arrangement of multiple cooling holes 89 in the multiple cooling hole rows 90a (91, 92, 93, 94) as a modified example of the first embodiment described below.

[0089] In this embodiment, the structure is also as follows: the number of cooling hole rows 95 constituting the gas path surface 71 of the negative pressure side leading edge cavity 81 disposed on the shield 60 and the number of cooling holes 89 constituting each cooling hole row 96, 97, 98, 99 are the same as in the first embodiment.

[0090] As mentioned above, Figure 5 In the first embodiment shown, the cooling holes 89 of the plurality of cooling hole rows 90, indicated by solid lines, are arranged such that they are approximately parallel to the isobaric lines IBL1 of the combustion gas G near the first opening center line OL1 of each cooling hole row 91, 92, 93, 94. However, under different gas turbine operating conditions, such as differences in combustion gas temperature, the high-temperature portion of the gas path surface 71 of the shroud 60 is larger than in the first embodiment, and sometimes it is desirable to enhance cooling to a position further close to the blade surface 41. In such cases, it is sometimes desirable to arrange the group of cooling holes 89 of each cooling hole row 91, 92, 93, 94 closer to the blade surface 41 than in the first embodiment, while maintaining the direction in which the opening center lines OL (first opening center line OL1, second opening center line OL2) of the plurality of cooling holes 89 constituting the cooling hole row 90 of the first embodiment extend. In a variation of the first embodiment, the arrangement of the plurality of cooling holes 89 of the cooling hole row 90 of the first embodiment is further brought closer to the blade surface 41, which is the arrangement of the cooling holes 89 of the cooling hole row 90a.

[0091] However, the cooling holes 89 are sometimes machined by machining or electrical discharge machining, creating holes that penetrate the base plate 69 from the gas path surface 71 side toward the inner cavity 83 side. When performing such hole machining, depending on the position of the cooling hole 89 closest to the blade surface 41 in each cooling hole row 90a (91, 92, 93, 94) and the direction in which its centerline FL extends, the blade body 40 sometimes becomes an obstacle, making it difficult to machine the cooling holes 89. To avoid interference with the blade body 40 when machining such cooling holes 89, it is sometimes preferable to slightly change the direction in which the cooling holes 89 extend and modify the inclination of the cooling hole centerline FL relative to the axial direction.

[0092] Based on the above idea, the arrangement of the cooling holes 89 in the cooling hole row 90a, a modified example of the first embodiment, is compared with the arrangement of the plurality of cooling holes 89 in the modified cooling hole row 95 of this embodiment. Figure 6 In the modified example, the cooling hole row 90a is a virtual cooling hole row. Figure 6 The arrangement of the cooling holes 89 shown is a diagram comparing the arrangement of multiple cooling holes 89 in the cooling hole row 90a of the first embodiment (shown by dashed lines) with the arrangement of multiple cooling holes 89 in the cooling hole row 95 (96, 97, 98, 99) of this embodiment (shown by solid lines).

[0093] Figure 6 and Figure 7 The cooling hole rows 90a (91, 92, 93, 94) shown as a variation of the first embodiment are configured as follows: while maintaining the number of cooling holes 89 constituting each cooling hole row 91, 92, 93, 94 of the first embodiment, the extending direction of each group of cooling hole rows 91, 92, 93, 94, the spacing of the cooling holes 89 in the extending direction of the cooling hole row 90, and the inclination of the cooling hole centerline FL relative to the axial direction, each group of cooling holes 89 in each cooling hole row 91, 92, 93, 94 of the first embodiment is moved towards the blade surface 41. Therefore, the position and extending direction of the opening centerline OL (first opening centerline OL1, second opening centerline OL2) of each cooling hole row 90a (91, 92, 93, 94) constituting the variation of the first embodiment are the same as those in the first embodiment. Furthermore, the inclination of the cooling hole centerline FL of the plurality of cooling holes 89 in each cooling hole row 90a (91, 92, 93, 94) relative to the axial direction, the spacing of the cooling holes 89 in the direction in which each group of cooling hole rows 90a (91, 92, 93, 94) extends, and the inclination of the cooling hole centerline FL relative to the opening centerline OL are the same as in the first embodiment.

[0094] refer to Figure 6 and Figure 7The idea of ​​changing the configuration of the cooling holes 89 in the cooling hole row 90a, which is a variation of the first embodiment, to the configuration of the cooling holes 89 in the cooling hole row 95 of this embodiment will be explained. As described above, when machining the cooling holes 89 (91aa, 92aa, 93aa, 94a) closest to the blade surface 41 in each cooling hole row 90a (91, 92, 93, 94) of the variation of the first embodiment, it is preferable to modify the inclination of the cooling holes 89 relative to the axial direction to avoid interference with the blade body 40. However, the fourth cooling hole row 94 is located on the downstream side of the cooling hole row 90a in the axial direction, and the inclination of the cooling hole centerline FL relative to the axial line AL is smaller than that of the other cooling holes 89 (91aa, 92aa, 93aa) on the upstream side of the axial direction, so the possibility of interference with the blade body 40 is small. Therefore, the inclination of the cooling hole 94a closest to the blade surface 41 in the fourth cooling hole row 94 is not changed, and the configuration of the cooling hole 94a in the modified example is maintained.

[0095] On the other hand, in order to avoid interference with the blade body 40 during processing, the cooling holes 89 closest to the blade surface 41 in the other cooling hole rows 90a (91, 92, 93) of the modified example have their axial tilt angles changed. This is because the cooling holes 91aa of the first cooling hole row 91, 92aa of the second cooling hole row 92, and 93aa of the third cooling hole row 93 of the modified example's cooling hole rows 90a are positioned differently. By changing the position of the cooling holes 89 closest to the blade surface 41, the configuration of the cooling holes 89 is the same as that of the cooling holes 94a of the fourth cooling hole row 94 of the modified example's cooling hole rows 90a, with no change in position. Figure 6 The structure of the fourth cooling hole row 99 in this embodiment is the same as that of the fourth cooling hole row 94 in the modified example cooling hole row 90a. Therefore, the symbols for the cooling holes 89 are shown only for the cooling hole 99a closest to the blade surface 41 and the cooling hole 99c furthest from the blade surface 41 in this embodiment, and the symbols for the cooling holes 89 in the modified example are omitted.

[0096] Next, after setting the position of the cooling holes 89 (96a, 97a, 98a, 99a) closest to the blade surface 41 in the cooling hole row 95 of this embodiment, the positions of other cooling holes 89 arranged in each cooling hole row 96, 97, 98, 99 in the direction away from the blade surface 41 are selected. At this time, the cooling holes 89 constituting each cooling hole row 96, 97, 98, 99 are based on the cooling holes 89 (96a, 97a, 98a, 99a) closest to the blade surface 41 after the change in arrangement, and have the same inclination relative to the axial direction as the cooling holes 89 (96a, 97a, 98a, 99a), and are arranged with the same spacing and the same inclination and spacing of the cooling hole centerline FL as the cooling hole row 90a of the modified example of the first embodiment, and are formed toward the leading edge end 64 or the negative pressure surface side end 66 in the direction away from the blade surface 41.

[0097] Next, it is preferable that the direction in which each cooling hole row 96, 97, 98, 99 extends is not the same as the direction in which each cooling hole row 91, 92, 93, 94 extends in the first embodiment, that is, the direction in which the opening center line OL (first opening center line OL1, second opening center line OL2) of each cooling hole row 90a (91, 92, 93, 94) in the modified example extends, but is arranged to be further upstream in the axial direction than each cooling hole row 91, 92, 93, 94 in the first embodiment, and has a larger inclination relative to the axial direction and a larger inclination angle relative to the axial line AL. This is because, when the opening center lines OL (first opening center line OL1, second opening center line OL2) of the cooling holes 89 in each cooling hole row 96, 97, 98, 99 of this embodiment are extended in the same direction as the opening center lines OL of each cooling hole row 91, 92, 93, 94 of the first embodiment, the inclination of the cooling hole center line FL relative to the opening center line OL is more inclined toward the blade surface 41 than the inclination of the cooling hole center line FL in the first embodiment. The flow of cooling air discharged from the excessively inclined cooling holes 89 will disturb the flow of combustion gas G flowing along the blade surface 41.

[0098] On the other hand, when the cooling holes 89 of each cooling hole row 96, 97, 98, 99 in this embodiment are arranged to be further upstream in the axial direction and with a greater inclination relative to the axial direction than the cooling holes 89 of each cooling hole row 91, 92, 93, 94 in the first embodiment, the parallel relationship between the opening center line OL and the isobaric line IBL is slightly disrupted, as the direction in which the isobaric line IBL of the combustion gas G near the opening center line OL extends further upstream in the axial direction than the opening center line OL of the cooling hole row 90 in the first embodiment. However, since the opening center line OL is formed approximately parallel to other isobaric lines IBL that are further upstream in the axial direction than the isobaric line IBL, the variation in the amount of cooling air discharged from the cooling holes 89 of each cooling hole row can be minimized. Based on the idea of ​​changing the above-mentioned cooling hole 89 arrangement, the cooling hole 89 arrangement of the cooling hole rows 95 (96, 97, 98, 99 (94)) in this embodiment is selected. Furthermore, the fourth cooling hole row 99 has the same configuration as the fourth cooling hole row 94 in the modified example of the first embodiment, and no changes are required. Additionally, in Figure 7 In this embodiment, the center line OL of the cooling hole row 95 represents the first opening center line OL1 and the second opening center line OL2 of the cooling hole rows 96 and 97. Figure 6 In the diagram, only the first opening center line OL1 is shown as the center line OL of the cooling hole rows 98 and 99. The second opening center line OL2 of the cooling hole rows 98 and 99 can be considered as a straight line parallel to the first opening center line OL1, connecting the center of the inlet opening 89a of the cooling hole 89, and extending from the middle leading edge region 42d to the negative pressure side end 66.

[0099] Next, see below for reference. Figure 7 The specific ideas regarding the configuration and modification of the cooling hole array 95 in this embodiment will be explained. Figure 7 It is an excerpt Figure 6 The diagram shows a comparison of the combination of the first cooling hole row 96 and the second cooling hole row 97 within the cooling hole row 95 of this embodiment and the combination of the first cooling hole row 91 and the second cooling hole row 92 of the cooling hole row 90a of the modified first embodiment, illustrating the arrangement of the cooling holes 89. In the modified first embodiment, the first cooling hole row 91 of the cooling hole row 90a consists of a plurality of cooling holes 89 (91aa, 91bb, 91cc, 91dd, 91ee), and the second cooling hole row 92 consists of a plurality of cooling holes 89 (92aa, 92bb, 92cc, 92dd, 92ee). In this embodiment, the first cooling hole row 96 consists of a plurality of cooling holes 89 (96a, 96b, 96c, 96d, 96e), and the second cooling hole row 97 consists of a plurality of cooling holes 89 (97a, 97b, 97c, 97d, 97e).

[0100] The cooling holes 89 (91aa, 91bb, 91cc, 91dd, 91ee) of the first cooling hole row 91 in the cooling hole row 90a, a variation of the first embodiment, are listed below, and a specific idea for changing the configuration of the cooling holes 89 will be explained. As described above, the cooling hole 91aa, which is closest to the blade surface 41, is the one that is necessary to avoid interference with the blade body 40 when the cooling holes 89 are machined. Figure 7 As shown, to avoid interference with the blade body 40 during the machining of the cooling hole 91aa, it is preferable to make the following modification: with the position of the outlet opening 89b of the cooling hole 91aa as the center, the inclination of the cooling hole 91aa relative to the axial direction is further rotated by an angle α1 in a counterclockwise direction closer to the blade surface 41. The modified position of the new cooling hole 89 corresponds to the position of the cooling hole 96a, indicated by the solid line, closest to the blade surface 41 in the first cooling hole row 96 of the cooling hole row 95 of this embodiment.

[0101] The arrangement of the group of cooling holes 89 constituting the first cooling hole row 96 in this embodiment is based on the position of the cooling hole 96a closest to the blade surface 41, which is changed according to the modified method described above. From the blade surface 41 side towards the forward edge end 64, the arrangement maintains the same axial tilt as the cooling hole 96a and the same spacing as the cooling holes 89 in the first embodiment. The direction in which the first cooling hole row 96 extends is a direction further axially upstream of the isobaric line IBL1 than the direction in which the isobaric line IBL1 of the combustion gas G extends. This direction deviates slightly from the direction in which the first opening centerline OL1 is parallel to the isobaric line IBL1, but the first opening centerline OL1 is formed approximately parallel to the isobaric line IBL3, which is axially upstream of the isobaric line IBL1. Furthermore, the inclination (angle) of the cooling hole centerline FL of the first cooling hole row 96 relative to the opening centerline OL (first opening centerline OL1) is preferably the same as the inclination of the cooling hole centerline FL of the first cooling hole row 91 of the first embodiment relative to the opening centerline OL (first opening centerline OL1).

[0102] The direction in which the first cooling hole row 96 of this embodiment extends is not the same as the direction in which the first opening center line OL1 of the first cooling hole row 91 of the modified cooling hole row 90a extends. Instead, it is arranged in a direction that is further upstream of the first cooling hole row 91 in the axial direction and has a greater inclination relative to the axial direction. The reason for setting the inclination of the cooling hole center line FL of the first cooling hole row 91 of the first embodiment relative to the opening center line OL (first opening center line OL1) is that, as described above, keeping the inclination of the cooling hole center line FL of the cooling hole 89 relative to the opening center line OL the same avoids the flow of cooling air discharged from the cooling hole 89 that is excessively inclined towards the blade surface 41 side from disturbing the flow of combustion gas G.

[0103] The number of cooling holes 89 (96a, 96b, 96c, 96d, 96e) constituting the first cooling hole row 96 in this embodiment is the same as in the first embodiment. Compared with the first cooling hole row 91 in the first embodiment, the group of cooling holes 89 constituting the first cooling hole row 96 in this embodiment is arranged in a direction with a greater inclination relative to the axial direction, and is formed on the side near the leading edge end 64 on the upstream side of the axial direction.

[0104] Next, the idea of ​​changing the arrangement of the cooling holes 89 of the second cooling hole row 92, which is adjacent to the first cooling hole row 91 on the axial downstream side in the modified example of the first embodiment, is the same as that of the first cooling hole row 91. The cooling hole 92aa, which is closest to the blade surface 41, is chosen because it is necessary to avoid interference with the blade body 40 when drilling holes in the cooling holes 89 (92aa, 92bb, 92cc, 92dd, 92ee) of the second cooling hole row 92 in the modified example. Figure 7 As shown, to avoid interference with the blade body 40 during the processing of cooling holes 92aa, it is preferable to change the direction as follows: with the position of the outlet opening 89b of cooling hole 92aa as the center, the inclination of cooling hole 92aa relative to the axial direction is further rotated by an angle α2 towards the side closer to the blade surface 41. The position of the modified new cooling hole 89 corresponds to the position of the cooling hole 97a closest to the blade surface 41, indicated by the solid line, in the second cooling hole row 97 of this embodiment. The arrangement of cooling holes 89 constituting the second cooling hole row 97 in this embodiment is based on the position of the cooling hole 97a set above, and is arranged from the blade surface 41 side towards the negative pressure surface side end 66, maintaining the same inclination relative to the axial direction as cooling hole 97a and the same spacing as cooling holes 89 in the first embodiment. The number of cooling holes 89 (97a, 97b, 97c, 97d, 97e) constituting the second cooling hole row 97 is the same as in the first embodiment. In this embodiment, the second cooling hole row 97 is arranged in a direction with a greater inclination relative to the axial direction than the second cooling hole row 92 in the first embodiment, and is formed on the upstream side near the leading edge end 64. Furthermore, similar to the first cooling hole row 96 in this embodiment, the inclination of the cooling hole centerline FL relative to the opening centerline OL (first opening centerline OL1) in the second cooling hole row 97 is preferably the same as the inclination of the cooling hole centerline FL relative to the opening centerline OL (first opening centerline OL1) in the second cooling hole row 92 of the first embodiment.

[0105] The idea of ​​modifying the configuration of the third cooling hole row 93 and the fourth cooling hole row 94 in the modified example of the first embodiment, and selecting the configuration of the cooling holes 89 in the third cooling hole row 98 and the fourth cooling hole row 99 in this embodiment, is the same as the idea described above. However, the configuration of the fourth cooling hole row 99 in this embodiment remains the same as that of the fourth cooling hole row 94 in the modified example, and does not require modification. In addition, the number of cooling holes 89 in each cooling hole row 96, 97, 98, and 99 constituting this embodiment, and the number of cooling hole rows, may be different from those in the first embodiment, depending on the operating conditions of the gas turbine.

[0106] As described above, when the arrangement of the cooling holes 89 in the cooling hole row 90a of the modified example of the first embodiment is changed, and the arrangement of the cooling holes 89 in the cooling hole row 95 of this embodiment is selected, the arrangement of the plurality of cooling holes 89 in the new cooling hole row 95 is determined by rotating counterclockwise with the position of the outlet opening 89b of the cooling hole 89 closest to the blade surface 41 as the center. By rotating the arrangement of the cooling holes 89 counterclockwise, the parallel relationship between the first opening center line OL1 of the cooling hole row 90 of the first embodiment and the isobar IBL is disrupted, but the parallel relationship between the first opening center line OL1 of the cooling hole row 95 of this embodiment and the other isobars IBL on the upstream side is maintained after the change of arrangement. Therefore, the amount of cooling air discharged from the cooling holes 89 of each cooling hole row 96, 97, 98, 99 is uniform, and the variation in the amount of cooling air is small.

[0107] Furthermore, similar to the cooling hole array 90 in the first embodiment, in the cooling hole array 95 of this embodiment, the inclination of the cooling hole centerline FL of the plurality of cooling holes 89 constituting the cooling hole array 95 relative to the opening centerline OL (first opening centerline OL1, second opening centerline OL2) is preferably set to be the same at any position in the axial direction. This is because if the inclination of the cooling hole centerline FL relative to the opening centerline OL is changed due to the difference in the position of the cooling hole array 95 in the axial direction, the cooling hole centerline FL will be excessively inclined towards the blade surface 41 side or excessively inclined towards the reverse blade surface 41 side, and the flow of cooling air Ac discharged from the cooling hole 89 will disturb the flow of combustion gas G, which is therefore not preferred.

[0108] As described above, the arrangement of the cooling holes 89 in the cooling hole row 95 of this embodiment is based on the arrangement of the cooling holes 89 in the cooling hole row 90a of the modified example of the first embodiment. The arrangement of the cooling hole rows 96, 97, 98, and 99 in this embodiment is selected by rotating each group of cooling hole rows 90a (91, 92, 93, 94) counterclockwise, with the position of the outlet opening 89b closest to the blade surface 41 as the center. Furthermore, the angle of counterclockwise rotation of each cooling hole row 96, 97, 98, and 99 is smaller towards the downstream side of the axial direction. As a result, the opening center lines OL (first opening center line OL1, second opening center line OL2) of each cooling hole row 96, 97, 98, 99 of this embodiment, which are located at the outlet opening 89b or inlet opening 89a closest to the blade surface 41, have a larger inclination relative to the axial direction and a larger inclination relative to the axial line AL compared to the opening center lines OL of each cooling hole row 90a (91, 92, 93, 94) of the modified example. Furthermore, the points Y1 and Y2 where the opening center lines OL (first opening center line OL1, second opening center line OL2) of each cooling hole row 96, 97, 98, 99 intersect with the axial line AL on the side opposite to the leading edge 42 of the blade body 40 on the circumferentially opposite side of the negative pressure surface end 66 extending therefrom are located further to the trailing edge 43 than the points Y3 and Y4 where the opening center lines OL (first opening center line OL1, second opening center line OL2) of each cooling hole row 90a (91, 92, 93, 94) intersect with the axial line AL in the modified example. Additionally, point Y3 coincides with the leading edge 42.

[0109] The positions where the opening center lines OL of each cooling hole row 91, 92, 93, 94 in the first embodiment intersect with the axial line AL are the same as the positions where the opening center lines OL (first opening center line OL1, second opening center line OL2) of each cooling hole row 90a (91, 92, 93, 94) in the modified example of the first embodiment intersect with the axial line AL, i.e., points Y3 and Y4. Therefore, the positions where the opening center lines OL (first opening center line OL1, second opening center line OL2) of the cooling holes 89 in each cooling hole row 96, 97, 98, 99 in this embodiment intersect with the axial line AL, i.e., points Y1 and Y2, are located further to the rear edge 43 than the position where the opening center lines OL of the cooling hole row 90 in the first embodiment intersect. Furthermore, in the first embodiment, the point Y3 where the center line OL1 of the first opening of the cooling hole array 90 intersects with the axial line AL is the same as the position of the leading edge 42. Therefore, in this embodiment, the point Y1 where the center line OL1 of the first opening of the cooling hole array 95 intersects with the axial line AL is located further to the trailing edge 43 than the position of the leading edge 42.

[0110] In this embodiment, the point Y1 where the center lines OL1 of the first openings of at least two cooling hole rows intersect with the axial line AL is located in the downstream leading edge region 42c (third region) within the leading edge cavity 52 of the blade body, which is further downstream than the leading edge 42. Therefore, the center line OL1 of the first opening of the cooling hole row 95 in this embodiment is formed by a straight line that starts from the downstream leading edge region 42c, which is further downstream than the leading edge 42, and connects the center of the outlet opening 89b of at least two adjacent cooling holes 89 forming the cooling hole row 95, extending to the leading edge end 64 or the negative pressure surface end 66.

[0111] Here, the downstream leading edge region 42c refers to a circular region located on the axial line AL, having the same radius as the leading edge region 42a.

[0112] Next, the second opening centerline OL2 of the cooling hole row 95 is parallel to the first opening centerline OL1 and is positioned axially upstream of the cooling hole 89, separated from the first opening centerline OL1 by the length of the cooling hole 89. Therefore, the point Y2 where the second opening centerline OL2 of at least two cooling hole rows intersects the axial line AL is located further towards the leading edge 42 than the point Y1 where the first opening centerline OL1 intersects the axial line AL, and is positioned within the intermediate leading edge region 42d (fourth region) within the leading edge cavity 52 of the blade body. Here, the intermediate leading edge region 42d is a circular region with the same radius as the leading edge region 42a, positioned on the axial line AL, and located between the leading edge region 42a and the downstream leading edge region 42c.

[0113] The second opening centerline OL2 of at least two cooling hole rows within the cooling hole row 95 is formed by a straight line, starting from a circular intermediate leading edge region 42d formed at a position longer than the center of the downstream leading edge region 42c and axially upstream of the cooling hole 89, parallel to the first opening centerline OL1, connecting the centers of the inlet openings 89a of at least two adjacent cooling holes 89 forming the cooling hole row 95, and extending to the leading edge end 64 or the negative pressure surface end 66. Furthermore, the at least two adjacent cooling holes 89 forming the second opening centerline OL2 are preferably a combination of the same cooling holes 89 selected when the first opening centerline OL1 is chosen.

[0114] Furthermore, the positions of the center positions of the downstream leading edge region 42c and the middle leading edge region 42d, i.e., the positions of points Y1 and Y2, change according to the inclination angle α of the cooling hole centerline FL when the configuration of the cooling hole row 90a in the modified example of the first embodiment is changed to the cooling hole row 95 in this embodiment.

[0115] According to the cooling structure of the cooling hole array 95 in this embodiment, compared with the cooling structure of the cooling hole array 90 in the first embodiment, the arrangement of a group including multiple cooling holes 89 closer to the blade surface 41 suppresses thermal damage and thermal stress on the gas path surface 71 of the shroud 60, and the gas path surface 71 is properly cooled. Furthermore, the amount of cooling air is reduced, and the efficiency of the gas turbine is improved.

[0116] <<Third Implementation>>

[0117] according to Figure 9 The steps of the cooling method for the turbine stationary blade 24 shown in the first and second embodiments described above will be explained.

[0118] like Figure 9 As shown, the cooling method for the negative pressure side leading edge cavity 81 of the blade body 40 of the turbine stationary blade 24 includes: step S1, supplying cooling air Ac to the outer cavity 82 of the shroud 60; step S2, depressurizing the cooling air Ac using the through hole 86 of the impact plate 85, and supplying cooling air Ac to the inner cavity 83; step S3, using the cooling air Ac to perform impact cooling on the base plate 69; and step S4, using the cooling air to perform thin film cooling on the gas path surface 71 of the base plate 69.

[0119] In step S1, cooling air Ac is supplied to the outer cavity 82 of the negative pressure side leading edge cavity 81 of the shroud 60. Cooling air Ac is supplied from the outer casing 20 of the turbine stationary blade 24 or the turbine housing 22 to the shroud 60 (S1).

[0120] In step S2, where cooling air Ac is depressurized using the through holes 86 of the collision plate 85, the pressure in the inner cavity 83 is reduced as the air is discharged into the inner cavity 83 through the multiple through holes 86 formed in the collision plate 85 (S2).

[0121] In step S3, where cooling air Ac is used to impact-cool the base plate 69, the cooling air Ac, which is sprayed into the inner cavity 83 through multiple through holes 86 of the impact plate 85, collides with the inner surface 70 of the base plate 69, and impact-cools the inner surface 70 (collision cooling) (S3).

[0122] In step S4, where cooling air Ac is used to perform thin-film cooling on the base plate 69, cooling air Ac, after impact cooling of the inner surface 70 of the base plate 69, is supplied to a plurality of cooling holes 89 formed in the base plate 69. During the process of being discharged from the outlet opening 89b of the cooling holes 89 to the combustion gas flow path 47, thin-film cooling is performed on the gas path surface 71 of the base plate 69 of the shroud 60 (S4). Furthermore, as described above, the center line OL1 of the first opening of the multiple cooling hole rows 90, 95 are arranged parallel to the isobaric line IBL of the combustion gas G. Therefore, the pressure difference between the inner cavity 83 connected to the upstream side of each group of cooling holes 89 constituting the multiple cooling hole rows 90, 95 via the inlet opening 89a and the combustion gas flow path 47 connected to the downstream side via the outlet opening 89b is approximately the same, and the amount of cooling air discharged from each group of cooling holes 89 constituting the multiple cooling hole rows 90, 95 is homogenized to the same flow rate.

[0123] According to the cooling method of the turbine stator blade 24 in this embodiment, the center line OL1 of the first opening of the multiple cooling holes 89 formed on the base plate 69, the rows of cooling holes 90, 95, is arranged parallel to the isobaric line IBL of the combustion gas G, thereby stabilizing the internal pressure fluctuation of the inner cavity 83. Furthermore, the arrangement of the center line OL1 of the first opening of the multiple cooling holes 89, the rows of cooling holes 90, 95, parallel to the isobaric line IBL of the combustion gas G, ensures that the pressure difference between the inner cavity 83 connected upstream of the multiple cooling holes 89, the rows of cooling holes 90, 95, and the combustion gas flow path 47 connected downstream is approximately the same. As a result, the amount of cooling air discharged from the multiple cooling holes 89 of the rows of cooling holes 90, 95 is kept constant and homogenized. Therefore, excess cooling air discharged from the cooling holes 89 can be suppressed, and the amount of cooling air can be reduced. Furthermore, it makes the amount of cooling air discharged from the cooling holes 89 of the cooling hole rows 90 and 95 uniform, and makes the metal temperature distribution of the base plate 69 uniform, thereby suppressing the generation of thermal stress on the base plate 69 of the shield 60.

[0124] The dimensions, materials, shapes, and relative arrangements of the structural components described or illustrated in the above embodiments are not intended to limit the scope of the invention, but are merely illustrative examples. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only indicate such arrangement in a strict sense, but also indicate a state of relative displacement by an angle or distance with tolerances or to the extent that the same function can be obtained. For example, expressions indicating that things are in the same state such as "same," "equal," and "homogeneous" not only indicate the same state in a strict sense, but also indicate the state with differences in tolerances or to the extent that the same function can be obtained.

[0125] For example, expressions describing shapes such as quadrilaterals and cylinders not only refer to quadrilaterals and cylinders in a strict geometric sense, but also include shapes with concave and convex parts, chamfered parts, etc., within the range where the same effect can be obtained. On the other hand, the expression "possessing," "having," "completing," "including," or "having" a constituent element is not an exclusive expression that excludes the existence of other constituent elements.

[0126] The contents described in the above embodiments can be understood as follows.

[0127] (1) The turbine stationary blade according to the first embodiment comprises: a blade body; a shroud formed at the end of the blade body in the blade height direction; and a rounded corner portion for joining the blade body and the shroud. The shroud includes: a base plate in contact with the combustion gas flow path; a peripheral wall extending along the periphery of the base plate in the blade height direction; and a recess forming a space surrounded by the peripheral wall and the base plate. The peripheral wall includes: a leading edge end portion extending along the leading edge side of the blade body; and a negative pressure surface end portion extending from the leading edge to the trailing edge of the negative pressure surface side of the blade body. The shroud includes: a plurality of cooling holes formed in the leading edge region of the negative pressure surface side of the shroud and formed on the base plate. A first end of the plurality of cooling holes is connected to an inlet opening formed on the base plate. The second end is connected to the gas path surface formed on the base plate and to the outlet opening which is located further downstream of the inlet opening. It is arranged at predetermined intervals from the blade surface of the blade body toward the leading edge end or the negative pressure surface end in the circumferential direction. The inclination of the cooling hole centerline connecting the inlet opening and the outlet opening relative to the axial direction is kept the same. A set of cooling hole rows is formed with a first opening centerline that is straight and connects the center of the outlet opening of the plurality of cooling holes and a second opening centerline that is straight and connects the center of the inlet opening of the cooling holes, which are parallel to each other. A plurality of cooling hole rows are arranged along the blade surface from the upstream side to the downstream side. The inclination of the cooling hole centerline of the plurality of cooling hole rows decreases as it moves toward the downstream side.

[0128] According to the turbine stator blade described in (1) above, multiple rows of cooling holes are arranged along the blade surface in the leading edge region of the negative pressure side of the shroud. The inclination of the centerline of the cooling holes of the multiple rows of cooling holes relative to the axial direction decreases as they move towards the downstream side of the axial direction. On the other hand, the combustion gas flowing through the gas path surface flows along the blade surface towards the downstream side of the axial direction, and the inclination of the isobars of the combustion gas relative to the axial direction decreases as they move along the blade surface towards the downstream side of the axial direction.

[0129] Therefore, as the inclination of the isobars relative to the axial direction decreases, the inclination of the centerline of each cooling hole row also decreases along the blade surface towards the downstream side of the axial direction, and each cooling hole row is formed parallel to the isobars of the combustion gases. As a result, the amount of cooling air discharged from the cooling holes of each cooling hole row is homogenized, the gas path surface is properly cooled, and the amount of cooling air is reduced.

[0130] Furthermore, the cooling air exiting from the cooling holes flows in the same direction as the combustion gas flow, thus preventing disruption of the combustion gas flow. Therefore, the impact on the aerodynamic performance of the gas turbine can be suppressed.

[0131] (2) In the turbine stationary blade involved in the second method, the shield has: a first region, which is formed into a circle with the leading edge of the blade body as the center and the outer edge of the rounded corner as the inner edge, and the center line of the first opening extends from the first region.

[0132] According to the turbine stationary blade described in (2) above, the center line of the first opening of the plurality of cooling holes constituting the cooling hole array extends from the first region, and thus forms approximately parallel to the isobars of the combustion gas, and the amount of cooling air discharged from the cooling hole array is homogenized.

[0133] (3) In the turbine stationary blade of the third method, the shroud includes: a third region disposed in a first cavity formed inside the blade body, disposed further downstream of the leading edge on the axial line of the blade body, and having a size equivalent to a region formed as a circle tangent to the outer edge of the rounded corner with the leading edge of the blade body as the center, and the center lines of the first openings of at least two cooling hole rows in the cooling hole row extend from the third region.

[0134] According to the turbine stator blade described above (3), in a cooling structure that avoids interference between the cooling holes and the blade body during hole machining, including a configuration where the inclination of the cooling holes is close to the inclination of the blade surface, the center lines of the first openings of at least two rows of cooling holes extend from the third region. Therefore, the center lines of the first openings of each row of cooling holes are formed approximately parallel to the isobars of the combustion gases, and the amount of cooling air discharged from the rows of cooling holes is homogenized. Furthermore, the machining of the cooling holes becomes easier.

[0135] (4) In the turbine stationary blade according to the fourth method, the shroud includes: a second region formed as a circle with the same radius as the first region on an axial line further upstream of the leading edge of the blade body.

[0136] The center line of the second opening extends from the second region.

[0137] According to the turbine stationary blade described above (4), the center line of the second opening of the multiple cooling holes constituting the cooling hole array is formed parallel to the center line of the first opening on the upstream side of the axial direction. The center line of the second opening extends from the second region. Therefore, the center line of the second opening is also formed approximately parallel to the isobar of the combustion gas, and the amount of cooling air discharged from the cooling hole array is homogenized.

[0138] (5) In the turbine stationary blade of the fifth embodiment, the shroud includes: a fourth region disposed in the first cavity, disposed on the axial downstream side of the leading edge on the axial line of the blade body and on the axial upstream side of the third region, and formed as a circle with the same radius as the third region, wherein the center line of the second opening of at least two cooling hole rows in the cooling hole row extends from the fourth region.

[0139] According to the turbine stationary blade described above (5), the center line of the second opening of the multiple cooling holes constituting the cooling hole array is formed parallel to the center line of the first opening on the upstream side of the axial direction. The center line of the second opening extends from the fourth region. Therefore, the center line of the second opening is also formed approximately parallel to the isobar of the combustion gas, and the amount of cooling air discharged from the cooling hole array is homogenized.

[0140] (6) In the turbine stationary blade involved in the sixth method, the first opening centerline or the second opening centerline is formed by at least two adjacent cooling holes in the direction in which the first opening centerline or the second opening centerline extends.

[0141] According to the turbine stator blade described above (6), the first opening centerline or the second opening centerline of the cooling hole array is formed by at least two adjacent cooling holes in the direction in which the first opening centerline or the second opening centerline extends, thus making the processing of the cooling holes easier.

[0142] (7) In the turbine stationary blade involved in the seventh method, the center line of the cooling hole is more inclined toward the blade surface than the direction orthogonal to the center line of the first opening or the center line of the second opening.

[0143] According to the turbine stator blade described above (7), the cooling hole centerline is more inclined toward the blade surface than the direction orthogonal to the centerline of the first opening or the centerline of the second opening, so the cooling air discharged from the cooling hole will not disturb the flow of combustion gas flowing through the gas path surface.

[0144] (8) In the turbine stationary blade involved in the eighth method, the inclination of the center line of the cooling hole row relative to the center line of the first opening is the same in any position of the cooling hole row in the axial direction.

[0145] According to the turbine stationary blade described above (8), for any cooling hole row located in the axial direction, the inclination of the cooling hole centerline of the cooling hole row relative to the first opening centerline is kept the same, so the cooling air discharged from the cooling hole will not disturb the flow of combustion gas flowing through the gas path surface.

[0146] (9) In the turbine stationary blade of the ninth method, the axial spacing between the first opening centerline of the plurality of cooling hole rows and the first opening centerline of the cooling hole rows arranged axially adjacent to each other increases as the shaft moves toward the axially downstream side.

[0147] According to the turbine stationary blade described above (9), the spacing of the isobars of the combustion gas in the second cavity increases towards the axial downstream side. On the other hand, the center line of the first opening of each cooling hole row is arranged parallel to the isobars of the combustion gas. Therefore, as the axial downstream side increases, the spacing of the center lines of the first opening of the cooling hole row also increases, and the gas path surface of the exhaust cooling air is uniformly cooled.

[0148] (10) In the turbine stator blades of the 10th method, the plurality of cooling holes in the cooling hole array are arranged at the same intervals in the direction in which the first opening centerline or the second opening centerline extends.

[0149] According to the turbine stationary blade described above (10), the cooling holes constituting the cooling hole array are arranged at the same interval in the direction extending from the center line of the first opening or the center line of the second opening, so that the gas path surface of the exhaust cooling air is uniformly cooled.

[0150] (11) In the turbine stationary blades involved in the 11th method, the plurality of cooling hole groups constituting the plurality of cooling hole rows extend radially toward the leading edge end or the negative pressure side end, starting from at least one region from the first region to the fourth region.

[0151] According to the turbine stator blade described in (11) above, the multiple cooling hole groups constituting the multiple cooling hole rows extend radially from at least one region from the first region to the fourth region toward the leading edge end or the negative pressure surface side end. As a result, the cooling hole groups constituting the cooling hole rows expand radially with the inclination of the blade surface, so the gas path surface is uniformly cooled and the flow of the discharged cooling air does not disturb the flow of the combustion gas flow.

[0152] (12) In the turbine stationary blade involved in the 12th method, either the first opening centerline or the second opening centerline of the plurality of cooling hole rows extends radially toward the leading edge end or the negative pressure side end, starting from at least one region from the first region to the fourth region.

[0153] According to the turbine stator blade described in (12) above, either the centerline of the first or second opening of the plurality of cooling hole rows extends radially toward the leading edge or the negative pressure side end, starting from at least one region from the first to the fourth region. As a result, the centerline of the first or second opening of the cooling hole row extends radially with the inclination of the blade surface, so the gas path surface is cooled uniformly and the flow of the discharged cooling air does not disturb the flow of the combustion gas.

[0154] (13) In the turbine stationary blade of the 13th embodiment, the shield includes: a second cavity, the recess being divided by the blade body, a leading edge partition connecting the leading edge end and a negative pressure side partition connecting the blade body and the negative pressure side end, and being surrounded by the outer wall surface of the blade body, the leading edge partition and the negative pressure side partition; and a collision plate, dividing the second cavity into a third cavity formed on the outer side in the blade height direction and a fourth cavity formed on the inner side of the third cavity, and having a plurality of through holes connecting the third cavity and the fourth cavity.

[0155] According to the turbine stationary blade described in (13) above, the shroud includes: a second cavity, the recess being divided by the blade body, a leading edge rib connecting the leading edge end, and a negative pressure side rib connecting the blade body and the negative pressure side end, and formed by the outer wall surface of the blade body, the leading edge rib, and the negative pressure side rib. Furthermore, the shroud includes: a collision plate, dividing the second cavity into a third cavity formed on the outer side in the blade height direction and a fourth cavity formed on the inner side of the third cavity, and having a plurality of through holes connecting the third cavity and the fourth cavity. As a result, the base plate is effectively cooled by a combination of impact cooling of the inner surface of the base plate and thin-film cooling of the gas path surface based on the cooling holes of the base plate, using cooling air supplied to the inner shroud via the collision plate.

[0156] (14) In the turbine stationary blade of the 14th embodiment, the shield includes: an outer shield formed at the outer end of the blade body in the blade height direction; and an inner shield formed at the inner end of the blade body in the blade height direction.

[0157] (15) The gas turbine of the 15th method comprises: a turbine stator blade as described in any one of (1) to (13); and a combustor that generates combustion gas flowing through a combustion gas flow path provided with the turbine stator blade.

[0158] In the gas turbine described above (15), the thermal stress on the turbine stationary blades is reduced, thus improving reliability. Furthermore, the amount of cooling air is reduced, thereby improving the efficiency of the gas turbine.

[0159] (16) In the cooling method for a turbine stator blade according to the 16th embodiment, the turbine stator blade comprises: a blade body; and a shroud formed at the end of the blade body in the blade height direction, the shroud comprising: a base plate in contact with the combustion gas flow path; a peripheral wall formed along the periphery of the base plate in the blade height direction; a recess forming a space surrounded by the peripheral wall and the base plate; a second cavity divided by the base plate, the blade body and a plurality of ribs connecting the peripheral wall, and formed in the leading edge region of the negative pressure surface; and a collision plate dividing the second cavity into a third cavity formed on the outer side in the blade height direction and a fourth cavity formed on the inner side of the third cavity, and having a plurality of through holes connecting the third cavity and the fourth cavity, the turbine stator blade having a cooling hole array, the cooling hole array having a via shape The turbine stationary blade cooling method includes the following steps: supplying cooling air to the third cavity from the outside; supplying the cooling air to the fourth cavity through the through hole formed in the collision plate disposed in the negative pressure side leading edge cavity, thereby reducing the pressure of the cooling air in the fourth cavity; subjecting the inner surface of the base plate to impact cooling; and discharging the cooling air from the multiple cooling holes formed in the base plate and constituting the cooling hole array to the combustion gas flow path, thereby subjecting the gas path surface to thin-film cooling, wherein the cooling hole array has a first opening centerline disposed parallel to the isobaric line of the combustion gas.

[0160] According to the turbine stator blade cooling method described above (16), the shroud has a second cavity with a collision plate in the negative pressure side region of the shroud. Cooling air supplied from the outside is depressurized through the through hole of the collision plate and impacts the inner surface of the base plate for cooling. Furthermore, the center line of the first opening of the cooling hole array connecting the outlet openings of the cooling holes is arranged parallel to the isobaric line of the combustion gas flow, so the pressure at the outlet openings of the cooling holes constituting the cooling hole array remains the same, suppressing pressure fluctuations in the fourth cavity connected to the upstream side of the cooling holes. Therefore, the amount of cooling air discharged from the cooling holes is stable, the gas path surface is appropriately cooled, and the amount of cooling air is reduced.

[0161] Symbol Explanation

[0162] 1-Gas turbine, 2-Compressor, 4-Burner, 6-Turbine, 8-Rotor, 10-Compressor housing, 12-Inlet chamber, 14-Inlet guide vane, 16-Compressor stationary blade, 18-Compressor moving blade, 20-Casing, 22-Turbine housing, 24-Turbine stationary blade, 26-Turbine moving blade, 28-Exhaust housing, 29-Exhaust chamber, 40-Blade body, 40a-Blade body tip, 40b-Blade wall, 41-Blade surface, 42-Leading edge, 42a-Leading edge region (Region 1), 42b-Upstream leading edge region (Region 2), 42c-Downstream leading edge region (Region 3), 4 2d - Middle leading edge region (region 4), 43 - Trailing edge, 44 - Negative pressure surface, 45 - Positive pressure surface, 46 - Rounded corner, 46a - Outer edge, 47 - Combustion gas flow path, 49 - Blade body rib, 51 - Blade body cavity (cavity 1), 52 - Blade body leading edge cavity, 53 - Blade body middle cavity, 54 - Blade body trailing edge cavity, 56 - Cover, 56a - Opening, 60 - Shield (outer shield 60a, inner shield 60b), 62 - Peripheral wall, 62a - Inner wall, 64 - Leading edge end, 65 - Trailing edge end, 66 - Negative pressure surface side end, 67 - Positive pressure surface side end, 69 - Base plate, 7 0-Inner surface, 71-Outer surface (gas path surface), 73-Rib, 73a-Leading edge rib, 73b-Middle rib on negative pressure side, 75-Recess, 76-Hook, 80-Cavity, 81-Leading edge cavity on negative pressure side (second cavity), 82-Outer cavity (third cavity), 83-Inner cavity (fourth cavity), 85-Collision plate, 86-Through hole, 89-Cooling hole, 89a-Inlet opening, 89b-Outlet opening, 90-Cooling hole row (first cooling hole row 91 (91a~91e), second cooling hole row 92 (92a~92e), third cooling hole row 93 (93a~93c), the... 4 Cooling hole rows 94 (94a~94c)), 90a - Cooling hole row (variant example), 95 - Cooling hole row (first cooling hole row 96 (96a~96e), second cooling hole row 97 (97a~97e), third cooling hole row 98 (98a~98c), fourth cooling hole row 99 (99a~99c)), G - Combustion gas, Ac - Cooling air, AL - Axial line, FL - Cooling hole center line, OL - Opening center line, OL1 - First opening center line, OL2 - Second opening center line, IBL, IBL1, IBL2, IBL3 - Isobars, Xa - Starting point, Xb - Intermediate point.

Claims

1. A turbine stator blade, comprising: Blade body; A protective cover is formed at the end of the blade body in the blade height direction; and The rounded corners connect the blade body to the protective cover. In the turbine stationary blades The protective cover includes: The base plate is in contact with the combustion gas flow path; The peripheral wall extends along the periphery of the base plate toward the height of the blade; and The recess forms a space surrounded by the peripheral wall and the bottom plate. The peripheral wall includes: The leading edge extends along the leading edge side of the blade body; and The negative pressure surface end extends from the leading edge to the trailing edge of the negative pressure surface side of the blade body. The protective cover has the following features: Multiple cooling holes are formed in the negative pressure side leading edge region of the shield and in the base plate. Among the plurality of cooling holes The first end is connected to the inlet opening formed in the base plate. The second end is connected to the gas path surface formed on the base plate and to the outlet opening which is located further downstream axially than the inlet opening. They are arranged at predetermined intervals from the blade surface of the blade body toward the leading edge end or the negative pressure surface end in the circumferential direction. The inclination of the centerline of the cooling hole connecting the inlet opening and the outlet opening relative to the axial direction is kept the same. A set of cooling holes is formed, with a first opening centerline that is parallel to each other and forms a straight line connecting the center of the outlet opening of the plurality of cooling holes, and a second opening centerline that is parallel to the center of the inlet opening of the cooling holes. A plurality of cooling hole rows are arranged along the blade surface from the upstream side to the downstream side in the axial direction. The inclination of the centerline of the cooling holes in the plurality of cooling hole rows decreases as they move toward the axial downstream side.

2. The turbine stationary blade according to claim 1, wherein, The protective cover has the following features: The first region is circular, centered on the leading edge of the blade body and internally tangent to the outer edge of the rounded corner portion. The center line of the first opening extends from the first region.

3. The turbine stationary blade according to claim 1, wherein, The protective cover has the following features: The third region is disposed within the first cavity formed inside the blade body, positioned further downstream of the leading edge along the axial line of the blade body, and has a size equivalent to a region centered on the leading edge of the blade body and internally tangent to the outer edge of the rounded corner. The center lines of the first openings of at least two of the cooling hole rows extend from the third region.

4. The turbine stationary blade according to claim 2, wherein, The protective cover has the following features: The second region is formed as a circle with the same radius as the first region on an axial line further upstream of the leading edge of the blade body. The center line of the second opening extends from the second region.

5. The turbine stationary blade according to claim 3, wherein, The protective cover has the following features: The fourth region, disposed within the first cavity, is located further downstream along the axial direction than the leading edge of the blade body and further upstream along the axial direction than the third region, and is formed as a circle with the same radius as the third region. The center lines of the second opening of at least two of the cooling hole rows extend from the fourth region.

6. The turbine stationary blade according to any one of claims 1 to 5, wherein, The first opening centerline or the second opening centerline is formed by at least two adjacent cooling holes in the direction in which the first opening centerline or the second opening centerline extends.

7. The turbine stationary blade according to any one of claims 1 to 5, wherein, The centerline of the cooling hole is more inclined toward the blade side than the direction orthogonal to the centerline of the first opening or the centerline of the second opening.

8. The turbine stationary blade according to any one of claims 1 to 5, wherein, The inclination of the center line of the cooling holes relative to the center line of the first opening remains the same at any position in the axial direction of the cooling hole array.

9. The turbine stationary blade according to any one of claims 1 to 5, wherein, The axial spacing between the first opening centerline of the plurality of cooling hole rows and the first opening centerline of the cooling hole rows arranged axially adjacent to each other increases as the rows move axially downstream.

10. The turbine stationary blade according to any one of claims 1 to 5, wherein, The plurality of cooling holes in the cooling hole array are arranged at the same intervals in the direction extending from the center line of the first opening or the center line of the second opening.

11. The turbine stationary blade according to claim 6, wherein, The plurality of cooling hole groups constituting the plurality of cooling hole rows extend radially toward the leading edge end or the negative pressure surface side end, starting from at least one region from the first region to the fourth region.

12. The turbine stationary blade according to claim 6, wherein, The center line of either the first or second opening of the plurality of cooling hole rows extends radially toward the leading edge end or the negative pressure surface end, starting from at least one region from the first to the fourth region.

13. The turbine stationary blade according to any one of claims 1 to 5, wherein, The protective cover includes: The second cavity, the recess, is divided by the blade body, the leading edge rib connecting the leading edge end, and the negative pressure surface side rib connecting the blade body and the negative pressure surface side end, and is formed by being surrounded by the outer wall surface of the blade body, the leading edge rib, and the negative pressure surface side rib; and The collision plate divides the second cavity into a third cavity formed on the outer side of the blade height direction and a fourth cavity formed on the inner side of the third cavity, and has a plurality of through holes connecting the third cavity and the fourth cavity.

14. The turbine stationary blade according to any one of claims 1 to 5, wherein, The protective cover includes: An outer protective cover is formed at the outer end of the blade body in the blade height direction; and An inner protective cover is formed on the inner end of the blade body in the blade height direction.

15. A gas turbine comprising: The turbine stationary blade according to any one of claims 1 to 5; and The burner generates combustion gas that flows through a combustion gas path provided with the turbine stationary blades.

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