Turbine stator blade

Abstract

To provide a turbine stationary blade structure capable of reducing thermal deformation and thermal stress.SOLUTION: A turbine stationary blade 100 disposed in a casing of a gas turbine includes: a blade effective part 110 which is arranged in a working fluid flow passage 16; an outer ring 120 which has an end wall 123 connected to a radially outer side end thereof and having four side surfaces, and an upstream side hook 121 and a downstream side hook 122 extending to a radially outer side from the end wall 123, having a width in a circumferential direction, and having distal ends respectively engaged with the casing; and an inner wall 130 which is connected with a radially inner side end of the blade effective part 110. A space surrounded by the end wall 123, the upstream side hook 121, and the downstream side hook 122 forms a cooling medium space 126 for a cooling medium from the casing side. A thermal stress relaxation part 150 for relaxing thermal stress at a joint between a blade effective part downstream side edge 112 of the blade effective part 110 and the end wall 123 is formed in the end wall 123.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to turbine stator blades used in gas turbines.

Background Art

[0002] In recent gas turbines, a hollow cooling structure is formed in the moving blades and stator blades manufactured by precision casting. By supplying a cooling medium to these hollow parts, an increase in the metal temperature of the moving blades and stator blades due to heat input from a high-temperature and high-pressure working medium is prevented.

[0003] In order to configure the casing with an inexpensive material, it is also necessary to lower the temperature of the outer ring of the stator blade that fits with the casing. For this reason, a cooling medium is supplied to the space surrounded by the casing and the outer ring of the stator blade.

[0004] Furthermore, in order to cool the stator blade itself, as described above, the stator blade has a hollow structure, and cooling holes penetrating from the hollow part to the main flow part are provided radially. The stator blade is cooled by the cooling medium passing through the hollow part and the cooling holes.

[0005] A temperature gradient occurs radially in the outer ring due to the temperature difference between the main flow and the cooling medium, and thermal deformation of the outer ring occurs due to this. At this time, in particular, large thermal stress is generated due to stress concentration at the root of the blade effective part attached to the outer ring.

[0006] Supercritical CO 2 The operating temperature of the turbine is as high as that of a conventional gas turbine, and a cooling structure similar to that of a gas turbine is required. On the other hand, supercritical CO 2 The operating pressure of the turbine is as high as that of a steam turbine, and the pressure difference is about 10 times that of a conventional gas turbine. In a steam turbine, it has a thick-walled structure and can withstand a large pressure difference. Supercritical CO 2 The turbine also needs to have a structure with similar strength. Thus, the stator blade of a supercritical CO 2 turbine has a larger thermal stress than a gas turbine and is used under severe high-temperature and high-pressure conditions in terms of strength.

Prior Art Documents

Patent Document

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] The turbine stator vane is attached to the casing with a hook. Supercritical CO 2 Since the stator vane of the turbine is used at high pressure, it is necessary to ensure sufficient rigidity. For this reason, compared with conventional gas turbines, the thickness of the end wall and the hook becomes thicker, and the hook has a structure that is long in the radial direction. Supercritical CO 2 During the operation of the turbine, the temperature difference between the radially inner part of the end wall that touches the main flow gas and becomes high temperature, and the metal at the tip of the hook which is the radially outer part of the end wall that touches the cooling medium and becomes low temperature becomes large. Therefore, when thermal deformation occurs, there is a problem that the thermal stress at the attachment root of the vane effective part to the end wall becomes high and damage occurs early.

[0009] An object of the present invention is to provide a turbine stator vane structure that reduces thermal deformation and thermal stress.

Means for Solving the Problems

[0010] To achieve the above object, a turbine stator vane according to an embodiment of the present invention is a turbine stator vane disposed in a casing of a gas turbine, and includes a vane effective part disposed in a working fluid flow path, an end wall having four side surfaces including an upstream side surface of the end wall, a downstream side surface of the end wall, and end wall circumferential side surfaces on both circumferential sides, which is connected to the radially outer end of the vane effective part, an outer ring having an upstream hook and a downstream hook that extend radially outward from the end wall, have a width in the circumferential direction, and whose tips are respectively engaged with the casing, and an inner wall connected to the radially inner end of the vane effective part andcomprising, the space surrounded by the end wall, the upstream hook, and the downstream hook forms a cooling medium space for the cooling medium supplied from the casing side, and a thermal stress relaxation portion for relaxing the thermal stress at the connection portion between the downstream edge of the effective blade portion of the blade and the end wall is formed on the end wall The thermal stress relaxation part is formed inside the end wall so as to communicate one side surface and the other side surface of the four side surfaces of the end wall, and has thermal stress relaxation cooling holes for allowing the cooling medium to pass through. The thermal stress relaxation cooling holes communicate a cooling hole inlet provided on the circumferential side surface of the end wall communicating with the cooling medium space and a cooling hole outlet provided on the downstream side surface of the end wall, and have at least one first cooling hole passing near the connection part of the end wall with the downstream side edge of the blade effective part in the end wall. .

Brief Description of the Drawings

[0011]

Figure 1

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, with reference to the drawings, a turbine stator blade according to an embodiment of the present invention will be described. Here, the same or similar parts are denoted by common reference numerals, and redundant descriptions are omitted.

[0013] [First Embodiment] FIG. 1 is a partial cross-sectional view along the turbine axis C of a gas turbine 10 showing the mounting state of a turbine stator blade according to the first embodiment. Hereinafter, the direction parallel to the turbine axis C is referred to as the turbine axis direction.

[0014] The gas turbine 10 has a casing 20, a rotor shaft 11 penetrating the casing 20 in the turbine axis direction, and a plurality of turbine stages 14 arranged in the turbine axis direction and forming a working fluid flow path 16, that is, a flow path for the working fluid.

[0015] Each of the plurality of turbine stages 14 has a stator blade row 101 having a plurality of turbine stator blades 100 and a rotor blade row 13a having a plurality of rotor blades 13 arranged immediately behind the stator blade row 101 in the flow direction of the working fluid in the working fluid flow path 16. Hereinafter, the directions of the respective members of the gas turbine 10 will be expressed using the directions in the state where they are installed in the gas turbine 10. Specifically, as expressions when viewed from the flow direction of the working fluid, they are referred to as the upstream side and the downstream side.

[0016] The plurality of turbine stator blades 100 constituting the stator blade row 101 are provided adjacent to each other in the circumferential direction. Each turbine stator blade 100 has a blade effective portion 110 arranged in the working fluid flow path 16, an outer ring 120 connected to the radially outer end of the blade effective portion 110, and an inner wall 130 connected to the radially inner end of the blade effective portion 110.

[0017] The outer ring 120 has an end wall 123 having a partial shape of an annular plate, an upstream hook 121 extending radially outward from the upstream end side of the end wall 123 and having a width in the circumferential direction, and a downstream hook 122 extending radially outward from the downstream end side and having a width in the circumferential direction. On the other hand, a first hook 20f and a second hook 20r are also formed on the casing 20.

[0018] The upstream hook 121 has an upstream hook wall portion 121a extending in the radial direction and an upstream hook protrusion 121b provided at the outermost portion in the radial direction of the upstream hook wall portion 121a and extending upstream. The upstream hook protrusion 121b engages with the first hook 20f of the casing 20. Further, the downstream hook 122 has a downstream hook wall portion 122a extending in the radial direction, and a downstream hook protrusion 122b provided at the outermost portion in the radial direction of the downstream hook wall portion 122a and extending downstream engages with the second hook 20r of the casing 20. As a result, the turbine stator blade 100 is supported by the casing 20.

[0019] A cooling medium space 126 surrounded by the end wall 123, the upstream hook 121, and the downstream hook 122 is formed in each of the plurality of outer rings 120, and they communicate with each other in the circumferential direction in the stator blade row 101. The casing 20 is formed with a refrigerant supply hole 20a communicating with a supply source (not shown) of the cooling medium. The cooling medium is supplied to the cooling medium space 126 through the refrigerant supply hole 20a. As a result, the turbine stator blade 100 is cooled.

[0020] A plurality of rotor disks 12 are formed on the rotor shaft 11 at intervals in the turbine axial direction. Each rotor disk 12 is formed to project annularly in the radial direction from the rotor shaft 11. The plurality of rotor blades 13 constituting the rotor blade row 13a are implanted adjacent to each other in the circumferential direction on each rotor disk 12.

[0021] A shroud 15 is provided via a gap between the tip of the moving blade row 13a and the radially outer side of the moving blade row 13a. The shroud 15 is supported by the outer rings 120 on its upstream side and downstream side.

[0022] FIG. 2 is a side view seen from the circumferential direction showing the turbine stator blade according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line A-A of FIG. 2 showing the turbine stator blade according to the first embodiment. Note that FIG. 2 is a side view taken along the line B-B of FIG. 3.

[0023] The end wall 123 of the outer ring 120 has an upstream protruding portion 124 that protrudes upstream of the portion where the upstream hook 121 is attached and a downstream protruding portion 125 that protrudes downstream of the portion where the downstream hook 122 is attached. The upstream protruding portion 124 and the downstream protruding portion 125 of the turbine stator blade 100 in the upstream side paragraph support the shroud 15 (FIG. 1) from the radially inner side as described above.

[0024] As shown in FIGS. 2 and 3, the end wall 123 has four side surfaces and is surrounded by these. Specifically, the end wall 123 has an upstream end wall upstream side surface 123a on the upstream side, end wall circumferential side surfaces 123b and 123c that are circumferential side surfaces, and a downstream end wall downstream side surface 123d on the downstream side. The upstream end wall upstream side surface 123a is a surface facing upstream of the upstream protruding portion 124. The downstream end wall downstream side surface 123d is a surface facing downstream of the downstream protruding portion 125. The end wall circumferential side surfaces 123b and the end wall circumferential side surfaces 123c face the end wall circumferential side surfaces 123c and the end wall circumferential side surfaces 123b of the end wall 123 of the adjacent turbine stator blade 100, respectively.

[0025] As described above, the plurality of turbine stator blades 100 constituting the stator blade row 101 are provided adjacent to each other in the circumferential direction. Therefore, the outer rings 120 of the respective turbine stator blades 100 are also arranged adjacent to each other. The end wall circumferential side surface 123b faces the end wall circumferential side surface 123c of the adjacent turbine stator blade 100 in the circumferential direction, and the end wall circumferential side surface 123c faces the end wall circumferential side surface 123b of the adjacent turbine stator blade 100 in the circumferential direction.

[0026] At this time, a seal plate (not shown) is provided so that the space having the cooling medium supplied to the cooling medium space 126 does not communicate with the working fluid flow path 16 through the gap between the adjacent outer rings 120. Further, in order to attach the seal plate, seal grooves 127 are formed on the end wall circumferential side surface 123b and the end wall circumferential side surface 123c as shown in FIG. 2. As a result, the space where the cooling medium exists is isolated from the space on the working fluid flow path 16 side.

[0027] FIG. 2 shows a case where the space where the cooling medium supplied to the cooling medium space 126 of the turbine stator blade 100 in the turbine stage 14 exists is isolated from the intermediate space 18 (FIG. 1) in the same turbine stage 14 (FIG. 1), and the space where this cooling medium exists is isolated from the intermediate space 18 (FIG. 1) on the upstream turbine stage 14 (FIG. 1) side.

[0028] The end wall 123 of the outer ring 120 is provided with a thermal stress relaxation cooling hole 151 as a thermal stress relaxation portion 150. For the purpose of distinction from the case described later, the thermal stress relaxation cooling hole 151 in the present embodiment is referred to as a first cooling hole 152. Hereinafter, although the case where there is one first cooling hole 152 is shown as in FIGS. 2 and 3, a plurality of first cooling holes 152 may be provided.

[0029] The first cooling hole 152 penetrates the end wall 123. The cooling hole inlet 152a, which is the inlet of the first cooling hole 152, is formed on one end wall circumferential side surface 123b that communicates with the cooling medium space 126. Therefore, the cooling hole inlet 152a is formed outside the radial direction of the sealing groove portion 127.

[0030] Also, the cooling hole outlet 152b, which is the outlet of the first cooling hole 152, is formed on the end wall downstream side surface 123d.

[0031] That is, the thermal stress relaxation cooling hole 151 as the thermal stress relaxation portion 150 is formed inside the end wall 123 so as to communicate the end wall circumferential side surface 123b, which is one of the four side surfaces of the end wall 123, with the end wall downstream side surface 123d, which is another side surface.

[0032] The first cooling hole 152 passes near the outer attachment root portion 112a (FIG. 2), which is the connection portion with the downstream edge 112 of the blade effective portion 110 in the end wall 123. Specifically, as shown in FIG. 3, on the plane viewed from the radial outside, the first cooling hole 152 passes near the downstream edge 112 of the blade effective portion. Here, the case where the first cooling hole 152 passes near the downstream edge 112 of the blade effective portion means a position where the temperature of the region including the outer attachment root portion 112a can be reduced. Specifically, on the plane viewed from the radial direction, a part of the center line CL of the hole of the first cooling hole 152 passing through the inside of the end wall 123 exists within a range of a predetermined distance d 0 from the downstream edge 112 of the blade effective portion. Here, the predetermined distance d 0 is 50% or less of the length Lb in the turbine axial direction of the blade effective portion 110, preferably about 20%, and more preferably about 10% as a range where an effect of reducing the temperature of the region including the outer attachment root portion 112a can be expected.

[0033] In FIG. 2, an example is shown in which the cooling hole inlet 152a and the cooling hole outlet 152b have the same radial position, and the first cooling hole 152 is formed so as to maintain the same radial position. However, the present invention is not limited to this, and the radial positions of the cooling hole inlet 152a and the cooling hole outlet 152b may be different. Further, the first cooling hole 152 does not necessarily have to be formed so as to linearly connect the cooling hole inlet 152a and the cooling hole outlet 152b. For example, it may be formed so as to change direction midway.

[0034] Regarding the direction passing through the end wall 123 of the first cooling hole 152 on the plane viewed in perspective from the radial direction, the longer the length in the end wall 123, the better the cooling effect of the end wall 123. Therefore, the direction may be determined from such a viewpoint. Alternatively, for example, it may be set in a direction perpendicular to the camber line of the blade effective portion 110 on the plane viewed in perspective from the radial direction.

[0035] In FIG. 2, as described above, the case where the cooling hole outlet 152b is formed on the downstream side surface 123d of the end wall is shown, and the cooling medium that has passed through the first cooling hole 152 is discharged to the radially inner side of the shroud 15, that is, the working fluid flow path 16. However, the present invention is not limited to this, and the position of the cooling hole outlet 152b may be set so that the cooling medium that has passed through the first cooling hole 152 is discharged to the radially outer side of the shroud 15, that is, the intermediate space 18.

[0036] Next, the effects of the turbine stator blade 100 according to the present embodiment will be described.

[0037] FIG. 4 is a conceptual diagram schematically showing an example of the temperature distribution in a conventional turbine stator blade. Further, FIG. 5 is a conceptual diagram schematically showing an example of the temperature distribution for explaining the effects of the turbine stator blade 100 according to the first embodiment. Each broken line indicates an isotherm.

[0038] As shown in the conventional example of FIG. 4, the radially inner surface of the outer ring 120 faces the working fluid flow path 16 (FIG. 1) through which the high-temperature working fluid passes, and the radially outer side is cooled by the low-temperature cooling medium passing through the cooling medium space 126 (FIG. 2). As a result, the radially inner side of the outer ring 120 is at a high temperature, and there is a temperature distribution such that the temperature decreases toward the radially outer side. For this reason, the amount of thermal expansion of the radially inner side of the outer ring 120 becomes larger than the amount of thermal expansion of the radially outer side, and the outer ring 120 tends to deform in a direction of warping toward the radially inner side.

[0039] As a result, at the connection portion with the blade effective portion 110, the amount of deformation tending to occur as described above is the largest at the positions of the upstream edge 111 and the downstream edge 112 of the blade effective portion. In particular, since the width (thickness) of the blade effective portion 110 is small at the downstream edge 112 of the blade effective portion, the thermal stress at the outer attachment root portion 112a due to the deformation of the outer ring 120 in the direction of warping in the radial direction becomes the largest.

[0040] On the other hand, in the present embodiment, as shown in FIG. 5, the radially inner portion of the outer ring 120 is cooled by the thermal stress relaxation cooling holes 151 as the thermal stress relaxation portion 150, so that the amount of thermal expansion of the radially inner portion is reduced. For this reason, the amount of deformation of the outer ring 120 in the direction of warping in the radial direction is reduced, and the thermal stress at the outer attachment root portion 112a is reduced.

[0041] Furthermore, by reducing the temperature in the region near the downstream edge 112 of the blade effective portion, a decrease in the allowable stress of the metal material in the region near the downstream edge 112 of the blade effective portion is suppressed, and the likelihood of structural soundness can be ensured.

[0042] [Second Embodiment] FIG. 6 is a cross-sectional view showing a turbine stator blade according to the second embodiment. This embodiment is a modification of the first embodiment. In this embodiment, in addition to two first cooling holes 152 described in the first embodiment as the thermal stress relaxation cooling holes 151 as the thermal stress relaxation portion 150, a second cooling hole 153 is further provided. Other than this point, it is the same as the first embodiment.

[0043] The second cooling hole 153 is formed in the end wall 123. In FIG. 6, the case where one second cooling hole 153 is provided is shown, but a plurality of them may be provided.

[0044] The cooling hole outlet 153b, which is the outlet of the second cooling hole 153, is formed in the end wall circumferential side surface 123c on the side opposite to the end wall circumferential side surface 123b where the cooling hole inlet 152a of the first cooling hole 152 is formed.

[0045] On the side opposite to the cooling hole outlet 153b of the second cooling hole 153, a cooling hole direction changing portion 153a is formed in the upstream side protrusion 124 (FIG. 2). The second cooling hole 153 communicates with a cooling hole inlet (not shown) formed on the radially outer surface of the upstream side protrusion 124 toward the radially outer side at the cooling hole direction changing portion 153a. This cooling hole inlet communicates with a flow path of the cooling medium that penetrates the shroud 15 (FIG. 1) provided on the radially outer side of the upstream side protrusion 124 in the radial direction.

[0046] Note that the cooling hole inlet may be formed on the upstream side surface of the upstream side hook 121 (FIG. 1) facing the intermediate space 18 of the upstream paragraph of the turbine paragraph 14.

[0047] With the above configuration, the cooling medium in the intermediate space 18 of the upstream paragraph of the turbine paragraph 14 is supplied to the cooling hole inlet through the flow path formed in the shroud 15 or directly to the cooling hole inlet. The cooling medium that has flowed into the cooling hole inlet passes through the second cooling hole 153 formed in the end wall 123 and flows out from the cooling hole outlet 153b into the space communicating with the cooling medium space 126 of the paragraph.

[0048] As described above, in the present embodiment, by further cooling the end wall 123, the amount of thermal expansion on the radially inner side of the outer ring 120 is further reduced. As a result, the amount of deformation of the outer ring 120 in the direction of warping in the circumferential direction is reduced, and the thermal stress at the outer attachment root portion 112a is further reduced.

[0049] [Third Embodiment] FIG. 7 is a cross-sectional view showing a turbine stator blade according to the third embodiment. This embodiment is a modification of the first embodiment.

[0050] This embodiment is applied when a plurality of blade effective portions 110 are connected to one outer ring 120.

[0051] In this embodiment, a first cooling hole 152 is provided as a thermal stress relaxation cooling hole 151, which is a thermal stress relaxation portion 150, in the end wall 123 of the outer ring 120.

[0052] Similar to the first embodiment, a cooling hole inlet 152a, which is an inlet of the first cooling hole 152, is formed on one end wall circumferential side surface 123b that communicates with a cooling medium space 126 (FIG. 2). Further, a cooling hole outlet 152b, which is an outlet of the first cooling hole 152, is formed on the end wall downstream side surface 123d.

[0053] However, since the first cooling hole 152 is formed on the upstream side compared to the first embodiment, the length of the first cooling hole 152 becomes longer, and the effect of cooling the end wall 123 becomes greater. As a result, the amount of deformation of the outer ring 120 in the direction of warping in the circumferential direction is further reduced, and further reduction of the thermal stress at the outer attachment root portion 112a can be achieved.

[0054] [Fourth Embodiment] FIG. 8 is a front view of a turbine stator blade 100 according to the fourth embodiment as viewed from the direction along the turbine axis. FIG. 9 is a cross-sectional view taken along the C-C arrow in FIG. 8 showing the turbine stator blade 100 according to the fourth embodiment. Further, FIG. 10 is a cross-sectional view taken along the D-D arrow in FIG. 9 showing the turbine stator blade 100 according to the fourth embodiment.

[0055] In this embodiment, as the thermal stress relaxation portion 150, a thermal stress relaxation groove 155 is provided instead of the thermal stress relaxation cooling hole 151 in the first to third embodiments.

[0056] The thermal stress relief groove 155 is formed from the downstream side surface 123d of the end wall 123 of the end wall towards the upstream direction of the flow, that is, axially into the inside of the end wall 123. As shown in FIG. 10, the thermal stress relief groove 155 is formed in the vicinity of the downstream edge 112 of the effective blade portion on a plane viewed through in the radial direction. Here, being in the vicinity means, for example, being formed such that the downstream edge 112 of the effective blade portion exists within the range of the thermal stress relief groove 155 on a plane viewed through in the radial direction.

[0057] Alternatively, even if the downstream edge 112 of the effective blade portion does not exist within the range of the thermal stress relief groove 155, the distance between the downstream edge 112 of the effective blade portion and the outer contour of the thermal stress relief groove 155 is a predetermined distance d 0 in the following cases may also be sufficient. Here, the predetermined distance d 0 is about 20% of the length Lb of the effective blade portion 110 in the turbine axial direction, more preferably about 10%.

[0058] In FIGS. 8 to 10, the case where the thermal stress relief groove 155 is formed on the downstream side surface 123d side of the end wall 123 of the end wall is shown as an example, but it is not limited thereto. If the downstream edge 112 of the effective blade portion is formed so as to exist within the range of the thermal stress relief groove 155 on a plane viewed through in the radial direction, for example, it may be formed on the side of the circumferential side surface 123b of the end wall.

[0059] Next, the effects of the present embodiment will be described.

[0060] FIG. 11 is a conceptual diagram schematically showing an example of the temperature distribution for explaining the effects of the turbine stator blade 100 according to the fourth embodiment. Each broken line indicates an isotherm.

[0061] As shown in Fig. 11, by providing the thermal stress relief groove 155, the temperature distribution in the vicinity of the outer attachment root portion 112a of the end wall 123 can be relaxed and the temperature of the outer ring 120 can be made uniform, compared to the case where the thermal stress relief portion 150 shown in Fig. 4 is not provided. As a result, the amount of thermal deformation of the outer ring 120 is reduced.

[0062] Furthermore, by providing the thermal stress relief groove 155, the rigidity of the end wall 123 is reduced. As a result, the influence of the thermal deformation of the outer ring 120 alone on the thermal deformation of the outer ring 120 in the entire turbine stator blade 100 is reduced.

[0063] As a result of the above, the thermal stress at the outer attachment root portion 112a is relaxed.

[0064] Also, when the cooling refrigerant is actively flowed in the vicinity of the thermal stress relief groove 155, the temperature of the region near the downstream side edge 112 of the blade effective portion is reduced, so that a decrease in the allowable stress of the metal material in the region near the downstream side edge 112 of the blade effective portion is suppressed, and it is possible to expect ensuring the likelihood of structural soundness.

[0065] Note that this embodiment may be combined with the features of the first to third embodiments.

[0066] [Fifth Embodiment] Fig. 12 is a front view seen from the direction along the turbine axis showing the turbine stator blade according to the fifth embodiment. Fig. 13 is a cross-sectional view taken along the line E-E of Fig. 12 showing the turbine stator blade according to the fifth embodiment.

[0067] This embodiment is a modification of the first embodiment. In this embodiment, in addition to the first embodiment, as shown in Figs. 12 and 13, a heat insulation coating 160 is provided on the portion of the outer ring 120 that contacts the high-temperature working fluid. Specifically, a radially inner coating 161 as the heat insulation coating 160 is provided on the portion of the inner surface 123f of the end wall that is not connected to the blade effective portion 110. Also, an axially downstream coating 162 as the heat insulation coating 160 is provided on the downstream side surface 123d of the end wall.

[0068] As the heat shield coating 160, for example, TBC is used. TBC is formed of a metal layer having oxidation resistance and a ceramic layer having a lower thermal conductivity than the metal. TBC is formed into a film on the surface to be applied by thermal spraying.

[0069] In the turbine stator blade 100 according to the present embodiment formed as described above, the heat input from the working fluid side is reduced, the temperature gradient of the end wall 123 is reduced, and thermal deformation can be reduced.

[0070] In addition, although the above shows the case of being combined with the features of the first embodiment, the present embodiment may be combined with the features of the second to fourth embodiments.

[0071] According to the embodiment described above, it is possible to provide a turbine stator blade structure that reduces thermal deformation and thermal stress.

[0072] [Other Embodiments] Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. For example, the embodiments of the present invention are applicable to both cases where the blade effective portion 110 of the turbine stator blade 100 has a hollow structure for cooling and cases where it does not. In addition, the embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Description of Reference Numerals

[0073] 10…Gas turbine, 11…Rotating shaft, 12…Rotating disk, 13…Moving blade, 13a…Moving blade row, 14…Turbine stage, 15…Shroud, 16…Working fluid flow path, 18…Intermediate space, 20…Casing, 20a…Refrigerant supply hole, 20f…First hook, 20r…Second hook, 21…Casing downstream hook, 22…Casing upstream hook, 100…Turbine stator blade, 101…Stator blade row, 110…Blade effective part, 111…Upstream edge of blade effective part, 112…Downstream edge of blade effective part, 112a…Outer attachment root, 120…Outer ring, 121…Upstream hook, 121a…Upstream hook wall part, 121b…Upstream hook protrusion, 122…Downstream hook, 122a…Downstream hook wall part, 122b…Downstream hook protrusion, 123…End wall, 123a…Upstream side surface of end wall, 123b, 123c…Circumferential side surfaces of end wall, 123d…Downstream side surface of end wall, 123f…Inner side surface of end wall, 124…Upstream protrusion, 125…Downstream protrusion, 126…Cooling medium space, 127…Sealing groove, 130…Inner wall, 131…End wall, 132…Labyrinth teeth, 150…Thermal stress relaxation part, 151…Thermal stress relaxation cooling hole, 152…First cooling hole, 152a…Cooling hole inlet, 152b…Cooling hole outlet, 153…Second cooling hole, 153a…Cooling hole direction conversion part, 153b…Cooling hole outlet, 155…Thermal stress relaxation groove, 160…Heat insulation coating, 161…Radial inner coating, 162…Axial downstream coating, C…Turbine axis

Claims

1. A turbine stator blade disposed within a casing of a gas turbine, comprising: a blade effective portion disposed in a working fluid flow path; an end wall having four side surfaces including an end wall upstream side surface, an end wall downstream side surface, and end wall circumferential side surfaces on both circumferential sides, connected to a radially outer end of the blade effective portion; and an outer ring extending radially outward from the end wall and having a circumferential width, the tips of which engage with the casing, respectively, including an upstream hook and a downstream hook; an inner wall connected to a radially inner end of the blade effective portion; and comprising: a space surrounded by the end wall, the upstream hook, and the downstream hook forms a cooling medium space for a cooling medium supplied from the casing side; a thermal stress relief portion is formed on the end wall to relieve thermal stress at a connection portion between a downstream edge of the blade effective portion of the blade effective portion and the end wall; the thermal stress relief portion is formed inside the end wall to communicate one of the four side surfaces of the end wall with another side surface to allow the cooling medium to pass therethrough, and has a thermal stress relief cooling hole; the thermal stress relief cooling hole communicates a cooling hole inlet provided on the end wall circumferential side surface communicating with the cooling medium space and a cooling hole outlet provided on the end wall downstream side surface, and has at least one first cooling hole passing near the connection portion between the end wall and the downstream edge of the blade effective portion in the end wall. A turbine stator blade characterized by that.

2. The thermal stress relief portion has a thermal stress relief groove formed on the end wall circumferential side surface or the end wall downstream side surface of the end wall; The turbine stator blade according to claim 1, wherein the thermal stress relief groove is formed near the connection portion between the blade effective portion and the end wall.

3. A turbine stator blade disposed within a casing of a gas turbine, comprising: a blade effective portion disposed in a working fluid flow path; an end wall having four side surfaces including an end wall upstream side surface, an end wall downstream side surface, and end wall circumferential side surfaces on both circumferential sides, connected to a radially outer end of the blade effective portion; and an outer ring extending radially outward from the end wall and having a circumferential width, the tips of which engage with the casing, respectively, including an upstream hook and a downstream hook; An inner wall connected to the radially inner end of the effective wing portion; comprising; The space surrounded by the end wall, the upstream hook, and the downstream hook forms a cooling medium space for the cooling medium supplied from the casing side; A thermal stress relaxation portion for relaxing the thermal stress at the connection portion between the downstream edge of the effective wing portion of the wing and the end wall is formed on the end wall; The thermal stress relaxation portion has a thermal stress relaxation groove formed on the circumferential side surface or the downstream side surface of the end wall in the end wall; The turbine stator blade is characterized in that the thermal stress relaxation groove is formed in the vicinity of the connection portion of the effective wing portion with the end wall.

4. The thermal stress relaxation portion is formed inside the end wall so as to communicate one side surface and the other side surface of the four side surfaces of the end wall, and has a thermal stress relaxation cooling hole for allowing the cooling medium to pass through. The turbine stator blade according to claim 3, characterized by that.

5. The thermal stress relaxation cooling hole communicates a cooling hole inlet provided on the circumferential side surface of the end wall communicating with the cooling medium space and a cooling hole outlet provided on the downstream side surface of the end wall, and in the end wall, at least one first cooling hole passing through the vicinity of the connection portion of the downstream edge of the effective wing portion with the end wall. The turbine stator blade according to claim 4, characterized by that.

6. The turbine stator blade forms a turbine stage together with a turbine rotor blade adjacent to the downstream side; The thermal stress relaxation cooling hole further has at least one second cooling hole that communicates the upstream side surface of the end wall facing the space having the cooling medium of the upstream turbine stage and the circumferential side surface of the end wall. The turbine stator blade according to claim 1 or 5, characterized by that.

7. The outer ring is connected to a plurality of the effective wing portions and the inner wall. The turbine stator blade according to any one of claims 1 to 6, characterized by that.

8. The turbine stator blade according to any one of claims 1 to 7, characterized by having a heat insulation coating provided on the surface of the end wall facing the working fluid flow path.

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