Cooling method and cooling structure for stationary blade of gas turbine

Abstract

A shroud according to the present invention is provided with a shroud main body and a shroud end that is provided around the shroud main body and surrounds the shroud main body, the shroud end including a shroud end flow path therein, the shroud end flow path being provided along the periphery of the shroud main body. The shroud end is provided with: a plurality of cooling air inlets configured so as to introduce cooling air from the outside of the shroud end into the shroud end flow path; and a plurality of cooling air outlets configured so that cooling air flows out from the shroud end flow path to the outside of the shroud end. The shroud end flow path is divided into three or more sub-flow paths by the plurality of cooling air inlets and the plurality of cooling air outlets.

Description

Technical Field

[0001] The present invention relates to a cooling method for a stationary blade of a gas turbine and also relates to a cooling structure for a stationary blade of a gas turbine. Background Art

[0002] The stationary blades of a gas turbine and the rotor blades of a gas turbine are exposed to high temperature combustion gas. Therefore, the stationary blades and the rotor blades need to be cooled by cooling air. For example, the following Patent Document 1 describes the cooling of turbine stationary blades. Figure 4 The following describes the case where cooling air is taken in from two air intake ports near the front end of the shroud arranged in the ventral passage and the dorsal passage. The cooling air then flows along the ventral passage and the dorsal passage toward the rear end of the shroud, and then is discharged from two exhaust ports arranged in the rear end of the shroud to the high-temperature gas flow path.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 6418667 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In recent years, the inlet temperature of the gas turbine has increased, and therefore, it is desired to further promote the cooling of the first-stage stationary blades. One method for coping with the above problem is to supply cooling air of higher pressure and lower temperature to the first-stage stationary blades (compared with the conventional technology). According to the inventor's research, when the cooling air of higher pressure and lower temperature is used to cool the first-stage stationary blades, even after the cooling air is used to cool the airfoil or the shroud end, it is possible to reuse it for cooling other components of the first-stage stationary blades.

[0008] However, in the conventional technology, the utilization efficiency of cooling air is limited.

[0009] It is desirable to provide a cooling method or a cooling structure for a gas turbine vane that can improve the efficiency of using cooling air.

[0010] Means for solving problems

[0011] According to a first aspect of the present disclosure, a shroud for a turbine stator blade is provided. The shroud includes a shroud body and a shroud end portion, the shroud end portion is arranged around the shroud body and surrounds the shroud body, the shroud end portion includes a shroud end flow path inside, the shroud end flow path is arranged along the shroud body, the shroud end portion includes: a plurality of cooling air inlets configured to introduce cooling air from the outside of the shroud end portion into the shroud end flow path; and a plurality of cooling air outlets configured to allow cooling air to flow out from the shroud end flow path to the outside of the shroud end portion, the shroud end flow path being divided into three or more secondary flow paths by the plurality of cooling air inlets and the plurality of cooling air outlets.

[0012] According to the above features, by using three or more secondary flow paths, the number of flow paths at the shroud end can be increased, and the flow rate of cooling air in each secondary flow path can be reduced. Thus, by reducing the cross-sectional area of ​​the flow path at the shroud end, a space for allowing the expansion of the shroud body is provided, and the necessary components can be easily arranged in the expanded space of the shroud body. Furthermore, according to the above features, by providing a shorter secondary flow path, the pressure loss of cooling air inside the shroud end flow path can be reduced.

[0013] According to a second aspect of the present disclosure, a method for cooling the stator blades of a turbine having a shroud is provided. The shroud includes a shroud body and a shroud end portion, the shroud end portion is arranged around the shroud body and surrounds the shroud body, the shroud end portion includes a shroud end flow path inside, the shroud end flow path is arranged along the shroud body, and the shroud end portion includes: a front shroud end portion, which is arranged at the upstream end portion of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; a rear shroud end portion, which is arranged at the downstream end portion of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; a dorsal shroud end portion, which is arranged on the dorsal side of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; and a ventral shroud end portion. , which is arranged on the ventral side of the shroud end relative to the flow direction of the high-temperature gas of the turbine, the dorsal shroud end includes a dorsal shroud end flow path inside, and the ventral shroud end includes a ventral shroud end flow path inside, and the cooling method is processed as follows: cooling air is caused to flow from the upstream side to the downstream side inside the dorsal shroud end flow path relative to the flow direction of the high-temperature gas of the turbine; cooling air is caused to flow from the downstream side to the upstream side inside the dorsal shroud end flow path relative to the flow direction of the high-temperature gas of the turbine; and cooling air is caused to flow out from a cooling air outlet arranged in the middle part of the dorsal shroud end flow path.

[0014] According to the above features, the number of shield end flow paths can be increased in the back shield end flow path, and the flow rate of cooling air in each secondary flow path can be reduced. Thus, by reducing the cross-sectional area of ​​the shield end flow path and providing a space for allowing the shield body to be expanded, it is possible to easily arrange the necessary components in the expanded space of the shield body. Furthermore, according to the above features, by providing a short secondary flow path in the back shield end flow path, the pressure loss of cooling air inside the shield end flow path can be reduced.

[0015] Significant advantages of the present disclosure will become apparent from the following drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic cross-sectional view of a gas turbine according to an embodiment of the present disclosure.

[0017] Figure 2 It is a perspective view of the stationary blade according to the first embodiment.

[0018] Figure 3 It is along Figure 2 Cross-sectional view along line III-III.

[0019] Figure 4 This is a partial enlarged view of the stationary blade.

[0020] Figure 5 It is a partial perspective view of the stationary blade according to the first embodiment.

[0021] Figure 6 It is a partial perspective view of a stationary blade according to another embodiment.

[0022] Figure 7 This is a flowchart illustrating the cooling method of the stationary blade according to the first embodiment.

[0023] Figure 8 This is a flowchart illustrating a method for cooling a stationary blade according to the second embodiment.

[0024] Fig. 9 It is a diagram schematically illustrating the cooling step of the second embodiment.

[0025] Fig.10 This is a flowchart illustrating a method for cooling a stationary blade according to a third embodiment.

[0026] Fig.11 It is a schematic cross-sectional view of a stationary blade according to a fourth embodiment.

[0027] Fig. 12A It is a schematic cross-sectional view of a stationary blade according to a fifth embodiment.

[0028] Fig. 12B It is a schematic cross-sectional view of a stationary blade according to a fifth embodiment.

[0029] Fig.13 It is a partially enlarged view of a stationary blade according to the fifth embodiment.

[0030] Fig.14A It is a schematic cross-sectional view of a stationary blade according to the sixth embodiment.

[0031] Fig. 14B It is a schematic cross-sectional view of a stationary blade according to the sixth embodiment.

[0032] Fig.15 It is a partial schematic diagram of a stationary blade according to the seventh embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Figure 1 : is a schematic cross-sectional view of a gas turbine in an embodiment of the present disclosure. Figure 1 As shown, the gas turbine 10 of this embodiment includes a turbine 20 driven by combustion gas generated by a combustor 30. The turbine 20 includes a rotor shaft 24, a turbine rotor 26 rotating about an axis Ar, a turbine casing 22 covering the turbine rotor 26, and a plurality of stator blades 28.

[0034] Figure 2 A stationary blade of a gas turbine according to an embodiment of the present disclosure will be schematically described. Figure 2 It is a perspective view of the stationary blade in the first embodiment. Figure 3 It is along Figure 2 Cross-sectional view along line III-III. Figure 4 This is a partial enlarged view of the stationary blade. Figure 2 As shown, the stationary blade 50 includes a stationary blade body (air foil) 51 extending in the radial direction of the gas turbine, an inner shroud 60 arranged on the radial inner side of the stationary blade body 51, and an outer shroud 70 arranged on the radial outer side of the stationary blade body 51. The stationary blade body 51 is arranged in a combustion gas flow path (high-temperature gas flow path) through which the combustion gas passes. Generally, the radial inner side of the annular combustion gas flow path is defined by the inner shroud 60, and the radial outer side thereof is defined by the outer shroud 70. The inner shroud 60 and the outer shroud 70 are plate-shaped members that define a part of the combustion gas flow path.

[0035] like Figure 2 As shown, the upstream end of the stationary blade body 51 has a leading edge portion 52, and the downstream end of the stationary blade body 51 has a trailing edge portion 53. The convex surface of the surface of the stationary blade body 51 is a dorsal side surface 54 (negative pressure surface), and the concave surface is a ventral side surface 55 (positive pressure surface). For convenience, in the following description, the ventral side (positive pressure surface side) of the stationary blade body 51 and the dorsal side (negative pressure surface side) of the stationary blade body 51 are respectively referred to as the ventral side and the dorsal side.

[0036] The inner shroud 60 and the outer shroud 70 have basically the same structure. Therefore, the outer shroud 70 will be mainly described below.

[0037] like Figure 2 and Figure 3 As shown, the outer shroud 70 is a plate-shaped shroud member including a shroud body 72, shroud ends 74 disposed on the outer periphery of the shroud body 72, and a peripheral wall 76 extending along the shroud ends 74. The peripheral wall 76 protrudes from the shroud body 72 toward the radially outer side of the gas turbine.

[0038] The outer shroud 70 has a front end face as an upstream end face, a rear end face as a downstream end face, a ventral end face as a ventral end face, and a ventral end face as a dorsal end face. The outer shroud 70 has a gas passage face 78 facing radially inward and facing the high-temperature gas flow path. The front end face and the rear end face are substantially parallel to each other, and the ventral end face and the dorsal end face are substantially parallel to each other. Therefore, when viewed from the radial direction, as shown in FIG. Figure 3 As shown, the outer shroud 70 substantially has a parallelogram shape.

[0039] The shroud end portion 74 is a flange-shaped or edge-shaped structure protruding from the shroud body 72. The shroud end portion 74 includes a front shroud end portion 74 disposed on the upstream side of the outer shroud 70. L The rear shroud end portion 74 disposed on the downstream side of the outer shroud 70 T A back shield end portion 74 disposed on the back side of the outer shield 70 N , and a ventral shroud end portion 74 disposed on the ventral side of the outer shroud 70 P For example, Figure 3 As shown, the front shield end 74 L , rear side shield end 74 T , back shield end 74 N and the ventral shield end 74 P The shield body 72 is disposed on the outer periphery of the shield body 72 to surround the entire shield body 72 .

[0040] Front shield end 74 L The front shield end flow path 75 is included in the interior thereof. L . Rear side shield end 74 T The rear shield end flow path 75 is included in the interior thereof. T . Back shield end 74 N The back shield end flow path 75 is included in the interior thereof. N . Ventral shield end 74 P The ventral shield end flow path 75 is included in the interior P .

[0041] In this embodiment, the front shield end flow path 75L At one end thereof, the back shield end flow passage 75 N The other end of the channel is connected to the ventral shield end flow path 75. P Rear shield end flow path 75 T At one end thereof, the back shield end flow passage 75 N The other end of the channel is connected to the ventral shield end flow path 75. P Connectivity. Figure 2 , Figure 3 and Figure 4 As shown, the front shield end flow path 75 L The shield end flow path inlet 171 is provided. The rear shield end flow path 75 T The shield end flow path outlet 172 is provided. The liquid flows into the front shield end flow path 75 through the shield end flow path inlet 171. L A portion of the cooling air passes through the back shroud end flow path 75 N and the ventral shield end flow path 75 P , then flows through the rear shield end flow path 75 T , flows out from the flow path outlet 172 at the end of the shield. Figure 3 As shown, the shield end flow path 75 L , 75 T , 75 P , 75 N The turbulator 175 is provided. The turbulator 175 may also be a rib disposed on the inner surface of the flow path at the end of the shroud. In order to enhance the cooling of the end of the shroud, the turbulator 175 may also be disposed on the bottom surface of the flow path on the radial inner side surface of the specified flow path. Here, the bottom surface of the flow path may also extend substantially parallel to the radial inner wall 81. In addition, the turbulator 175 may also be disposed on the side surface of the flow path on the circumferential side wall or axial wall of the specified flow path.

[0042] In this embodiment, the shield end flow path inlet 171 is provided in the front shield end flow path 75. L The shield end flow path outlet 172 is provided at the rear shield end flow path 75 T However, the structure of the stationary blade is not limited to this embodiment. The shroud end flow path inlet 171 may also be provided at the back shroud end flow path 75. N , Ventral shroud end flow path 75 P Or rear side shield end flow path 75 T The shield end flow path outlet 172 may also be provided at the back shield end flow path 75 N , Ventral shroud end flow path 75 P Or the front side shield end flow path 75 LAs another embodiment, a plurality of shield end flow path inlets 171 may be provided in one or more shield end flow paths 75. L , 75 T , 75 N , 75 P In addition, a plurality of shield end flow path outlets 172 may be provided in one or more shield end flow paths 75. L , 75 T , 75 N , 75 P .

[0043] The shroud body 72 includes a radial inner wall 81 and a radial outer wall 82 located on the opposite side thereof. The shroud body 72 includes a hollow space S between the radial inner wall 81 and the radial outer wall 82. The radial inner surface of the inner wall 81 constitutes the gas passage surface 78 of the outer shroud 70. The radial inner wall 81 constitutes a part of the shroud body 72. The radial inner wall 81 may extend continuously in the circumferential direction or axial direction of the gas turbine in a manner constituting a part of the shroud end 74. Figure 2 As an example, the radial inner wall 81 is continuously extended in the axial direction of the gas turbine to form the rear shroud end 74. T The shield body 72 includes an impact plate 73 that divides the space S of the outer shield 70 into an outer region on the radial outside and an inner region (cavity) on the radial inside. The outer region is cooled by a portion of the cooling air from the rear shield end flow path 75. T The flow into the outer region is connected to the shroud end flow path outlet 172. The inner region is defined between the radial inner wall 81 of the outer shroud 70 and the impact plate 73.

[0044] A plurality of impingement cooling holes 79 are provided on the impingement plate 73 so as to penetrate the impingement plate 73 in the radial direction. A part of the cooling air existing in the outer region flows into the inner region through the impingement cooling holes 79 of the impingement plate 73. The cooling air is ejected toward the radial outer side surface of the radial inner wall 81, impinges and cools the radial outer side surface of the radial inner wall 81, and then is discharged to the outside through the outer wall 82. For example, the cooling air ejected from the impingement cooling holes 79 toward the radial outer side surface of the radial inner wall 81 in order to impinge and cool the radial outer side surface of the radial inner wall 81 is discharged through a passage connecting the inner region of the hollow space (S) with the outer space located on the side (outside) opposite to the hollow space (S) of the outer wall 82. Such a passage may also be isolated from the outer region of the hollow space S. More specifically, in the present embodiment, the cooling air is discharged through the hole of the discharge pipe 83. The discharge pipe 83 is provided so as to penetrate the radial outer wall 82 and the impingement plate 73 in a manner connecting the inner region with the outer space.

[0045] (airfoil)

[0046] The stationary blade body 51 includes a plurality of air passages 141, 142, 143. More specifically, the interior of the stationary blade body 51 is surrounded by partition walls 51 extending in the radial direction. P The plurality of air passages 141, 142, 143 are divided into a plurality of air passages 141, 142, 143. A plurality of inserts 151, 152, 153 are inserted into each of the air passages 141, 142, 143. The plurality of inserts 151, 152, 153 respectively include inner air passages 161, 162, 163 extending in the radial direction, extending from the outer shroud 70 through the vane body 51 toward the inner shroud 60 in the radial direction. Each of the inserts 151, 152, 153 is continuously formed from the outer shroud 70 through the vane body 51 to the inner shroud 60. Each of the inner air passages 161, 162, 163 has an air intake port 58 opening on the inner side of the intake manifold 56.

[0047] Each of the inserts 151, 152, 153 has a plurality of holes (through holes) 59 communicating with the inner air passages 161, 162, 163. A portion of the cooling air supplied to the inner air passages 161, 162, 163 of the inserts 151, 152, 153 is ejected from the plurality of holes 59 toward the inner surface of the vane body 51 to perform impact cooling on the inner surface of the airfoil 51. The plurality of air passages 141, 142, 143 have outer air passages defined between the inserts 151, 152, 153 and the inner surface of the vane body 51, respectively. A portion of the cooling air ejected through the holes 59 is guided by the outer air passages and flows through the outer air passages toward the radial outer side, the radial inner side, or the radial outer side and the inner side. As an example, Figure 3 An outer air passage 57 provided between the side surface of the insert 151 and the inner surface of the front end of the vane body 51 is shown.

[0048] The intake manifold 56 and the exhaust pipe 83 are connected to a forced air cooling system in which the cooling air extracted from the interior of the combustor shell is cooled by an external cooler (not shown) and then compressed by an external compressor (not shown). The compressed air is used for cooling and then returns to the interior of the combustor shell. In the above description, an example of an air cooling system being applied to the present embodiment is described. However, the present stator is not limited to such an embodiment. The present disclosure can also be applied to other types of cooling systems. For example, the intake manifold 56 and the exhaust pipe 83 can also be connected to a closed-loop steam cooling system or a closed-loop air cooling system. The compressed air for cooling is supplied to the intake manifold and is initially directly supplied to the air intake 58 without passing through the shroud body 72 and the shroud end 74. That is, the cooling air is initially used for cooling the airfoil 51 before being used for cooling the shroud body 72 and the shroud end 74.

[0049] In this embodiment, the air passage 141 is a front end air passage located at the upstream end of the stationary blade body 51. For example, in the insert 151 as the front end insert, part of the cooling air supplied to the inner air passage 161 through the air intake 58 is ejected toward the inner surface of the front end portion of the airfoil 51 through the hole portion 59, and then flows radially outward through the outer air passage 57. The space between the inner surface of the front end portion of the stationary blade body 51 and the insert 151, that is, the outer air passage 57 and the front shroud end flow path 75 L A portion of the cooling air ejected toward the inner surface of the front end of the airfoil 51 flows into the front shroud end flow path 75 through the outer air passage 57 connected to the shroud end flow path inlet 171. L The shield end flow path inlet 171.

[0050] Figure 5 1 is a partial perspective view of a stationary blade in the first embodiment. In this embodiment, the air passage 142 is an intermediate air passage located downstream of the front air passage 141 and located between the front air passage 141 and the rear air passage 143 (described in detail below). For example, in the insert 152 as the intermediate insert, a part of the cooling air supplied to the inner air passage 162 through the air intake 58 is ejected toward the inner surface of the central part of the airfoil 51 through the hole 59, then flows radially inward toward the inner shroud 60 through the outer air passage, and then, as shown in FIG. Figure 5 As shown, the cooling air flows into the shroud end flow path inlet 181 (arranged on the rear shroud end) of the inner shroud 60. Then, the cooling air passes through the shroud end flow path 65 of the inner shroud 60, cools the shroud end 64 of the inner shroud 60, and then flows into the shroud body 62 of the shroud 60 through the shroud end flow path outlet 182 (arranged on the front shroud end flow path) of the inner shroud 60. Similar to the outer shroud 70, the cooling air is ejected from the impact cooling holes of the impact plate 63 to cool the radial outer wall of the inner shroud 60 having a gas passage surface facing the radial outer side and facing the high-temperature gas passage.

[0051] In the present embodiment, a portion of the cooling air ejected from the front inner air passage 161 toward the inner surface of the front end portion of the airfoil 51 flows radially outward toward the outer shroud 70 through the outer air passage 57. In addition, a portion of the cooling air ejected from the intermediate inner air passage 162 toward the inner surface of the central portion of the airfoil 51 flows radially inward toward the inner shroud 60 through the outer air passage 57. However, the structure of the stationary blade is not limited to this embodiment. It may also be configured so that a portion of the cooling air ejected from the front inner air passage 161 toward the inner surface of the front end portion of the airfoil 51 flows radially inward toward the inner shroud 60 through the outer air passage 57. In addition, it may also be configured so that a portion of the cooling air ejected from the intermediate inner air passage 162 toward the inner surface of the central portion of the airfoil 51 flows radially outward toward the outer shroud 70 through the outer air passage 57. Such a change is described in detail below as another embodiment.

[0052] In several embodiments of the present disclosure, Figure 2 As shown, the air passage 143 is a rear end air passage located at the downstream end of the stationary blade body 51. The rear end air passage 143 is provided with an airfoil cooling structure 154 on the downstream side of the insert 153. The airfoil cooling structure 154 includes a passage in which a plurality of pin fins 164 are arranged inside. For example, in the insert 153 as the rear end insert, a part of the cooling air supplied to the inner air passage (rear end inner air passage) 163 via the air intake 58 is sprayed toward the inner surface of the rear end portion of the airfoil 51 through the hole portion 59, and then guided to the airfoil cooling structure 154. The cooling air passes through the passage provided with the pin fins 164, and then is discharged to the high temperature gas flow path at the trailing edge portion 53 of the airfoil 51.

[0053] Figure 6 FIG. 2 is a partial stereogram of a stationary blade according to another embodiment. Figure 6 As shown, in this embodiment, the shield end flow path inlet 181 of the inner shield 60 is arranged at the front shield end 64 L In addition, the shield end flow path outlet 182 of the inner shield 60 is arranged at the rear shield end 64 T In addition, in this embodiment, the shroud end flow path inlet 171 of the outer shroud 70 is arranged at the rear shroud end 74 T In addition, the shroud end flow path outlet 172 of the outer shroud 70 is arranged at the front shroud end 74 L In this embodiment, in the insert 151 as the front end insert, part of the cooling air supplied to the inner air passage 161 through the air intake 58 is ejected toward the inner surface of the front end of the airfoil 51 through the hole 59, and then guided radially inward toward the inner shroud 60 through the outer air passage 57, and then, as shown in FIG. Figure 6 As shown, the flow into the inner shroud 60 is inlet 181 of the shroud end flow passage (arranged at the front shroud end 64 L Next, the cooling air passes through the shroud end flow path 65 of the inner shroud 60 to cool the shroud end 64 of the inner shroud 60, and then passes through the shroud end flow path outlet 182 of the inner shroud 60 (arranged at the rear shroud end 64). T ) flows into the shroud body 62 of the inner shroud 60. In addition, in the embodiment, in the insert 152 as the intermediate insert, a part of the cooling air supplied to the inner air passage 162 through the air intake port 58 is ejected toward the inner surface of the central portion of the airfoil 51 through the hole portion 59, and then is guided radially outward toward the outer shroud 70 through the outer air passage 57, and then flows into the shroud end flow path inlet 171 (arranged at the rear shroud end 74) of the outer shroud 70. T Next, the cooling air passes through the shroud end flow path 75 of the outer shroud 70 to cool the shroud end 74 of the outer shroud 70, and then passes through the shroud end flow path outlet 172 of the outer shroud 70 (arranged at the front shroud end 74). L ) flows into the shield body 72 of the outer shield 70.

[0054] (Cooling method)

[0055] Next, the method for cooling the vane according to the first embodiment will be described. Figure 7 FIG. 2 is a flow chart illustrating a cooling method of a stationary blade according to a first embodiment. Figure 7 As shown, in step S102, a part of the cooling air flows into the front air passage 141 to cool the front air passage 141. The cooling air passes through the hole 59 of the insert 151, is ejected from the front inner air passage 161 toward the inner surface of the front end portion of the airfoil 51, and then passes through the outer air passage 57 toward either the outer shroud 70 or the inner shroud 60, and is guided radially outward or radially inward to cool the outer shroud 70 or the inner shroud 60.

[0056] In step S104, a part of the cooling air flows into the intermediate air passage 142 to cool the intermediate air passage 142. The cooling air passes through the hole 59 of the insert 151, is ejected from the intermediate inner air passage 162 toward the inner surface of the center portion of the airfoil 51, and then passes through the outer air passage 57 toward the other of the outer shroud 70 and the inner shroud 60, and is guided radially outward or radially inward to cool the other of the outer shroud 70 and the inner shroud 60.

[0057] Next, a cooling method of a stationary blade according to a second embodiment will be described. Figure 81 is a flowchart for explaining a cooling method for a stationary blade according to the second embodiment. This method will be explained using the air passage 141 and the outer shroud 70 as an example. Fig. 9 The cooling process of the second embodiment is schematically illustrated. Figure 8 and Fig. 9 As shown in (a), in step S202, part of the cooling air flows into the inner air passage 161 of the insert 151 through the air intake port 58. Then, the cooling air is ejected toward the inner surface of the front end of the airfoil 51 through the hole 59 to cool the airfoil 51, and flows radially outward through the outer air passage 57. In a certain embodiment, the cooling air flowing into the inner air passage may be introduced from a forced air cooling system.

[0058] like Fig. 9 As shown in (b) of FIG. 2 , in step S204 , cooling air flows into the shroud end flow path 75 through the shroud end flow path inlet 171 . The cooling air flows along the shroud end flow path 75 to cool the shroud end 74 .

[0059] like Fig. 9 As shown in (c), in step S206 , cooling air flows into the outer region of the shroud body 72 and is ejected toward the radial outer surface of the radial inner wall 81 through the impingement cooling holes 79 , impinging on the radial outer surface of the radial inner wall 81 to cool the shroud body 72 .

[0060] Next, a method for cooling a stationary blade according to a third embodiment will be described. Fig.10 FIG. 2 is a flow chart illustrating a cooling method of a stationary blade according to a third embodiment. Fig.10 As shown, in step S302, in at least one air channel, a portion of the cooling air flows into the inner air channel of the insert through the air intake port. Then, the cooling air is sprayed toward the inner surface of the front end of the airfoil through the hole portion to cool the airfoil, and flows radially outward through the outer air channel. In a certain embodiment, the cooling air flowing into the inner air channel can also be introduced from a forced air cooling system.

[0061] In step S304, cooling air flows into the outer region of the shroud body, and is ejected toward the radially outer surface of the radially inner wall through the impact cooling holes, thereby cooling the radially outer surface of the radially inner wall and cooling the shroud body.

[0062] In step S306, cooling air flows into the shroud end flow path through the shroud end flow path inlet. The cooling air flows along the shroud end flow path to cool the shroud end. In one embodiment, the cooling air returns to the forced air cooling system through the shroud end flow path outlet.

[0063] Next, a fourth embodiment of the present application will be described below. Fig.11FIG. 2 is a schematic cross-sectional view of a stationary blade according to a fourth embodiment. Fig.11 As shown, in the fourth embodiment, a plurality of airfoils 51 (two in this embodiment) are connected to the shroud end flow passage 75. L , 75 T , 75 N , 75 P Surrounded. Compared with the first embodiment ( Figure 3 ) are different, the two shield end flow path inlets 171 are provided at the front shield end flow path 75 L .

[0064] The space between the inner surface of the front end of the two airfoils 51 and each insert 151, that is, each outer air passage, is connected to the front shroud end flow path 75 via an air passage provided at the outer end of the outer air passage of each airfoil 51. L The cooling air flows into the front shroud end flow path 75 through each shroud end flow path inlet 171. L , through the back shield end flow path 75 N Or ventral shield end flow path 75 P The flow passes through the shroud end flow path outlet 172 and flows into the outer area of ​​the shroud body 72 .

[0065] In the above-mentioned embodiment, the stationary blade body (airfoil) includes three air passages 141, 142, 143. However, the number of air passages included in the stationary blade body (airfoil) is not limited to three. The stationary blade body (airfoil) may also include a different number of air passages such as two, four, five, or more than five. In such a modified embodiment, each air passage may also be connected to the outer shroud or the inner shroud.

[0066] Next, a fifth embodiment of the present application will be described below. Fig. 12A and 12B Each of them is a schematic cross-sectional view of a stationary blade according to the fifth embodiment. Fig.13 It is a partially enlarged view of a stationary blade according to the fifth embodiment. Fig. 12A and 12B The embodiment in which the shield end surrounds the shield body and the shield end flow path is divided into three sub-flow paths is shown. In this embodiment, the outer shield 70 has two shield end flow path inlets (front shield end flow path inlet 171 L and the flow path inlet 171 at the end of the rear shield T ) and two shield end flow path outlets (ventral shield end flow path outlet 172 P and the flow path outlet 172 at the end of the rear shield T ). The front shield end flow path inlet 171 L Set at the front shield end 74 L. Rear side shield end flow path inlet 171 T Set at the rear shield end 74 T Ventral shield end flow path outlet 172 P Set at the ventral shield end 74 p . Rear side shield end flow path outlet 172 T Set at the rear shield end 74 T In addition, in this embodiment, the stationary blade body (airfoil) includes air passages 191, 192, 193, 194, and 195 arranged in sequence from the upstream end to the downstream end of the flow of high-temperature gas in the turbine. The air passages 191, 192, 193, 194, and 195 each include an insert and an inner air passage (not shown).

[0067] In this embodiment, the inner shroud 60 has two shroud end flow path inlets (front shroud end flow path inlet 181 and front shroud end flow path inlet 182). L and the flow path inlet 181 at the end of the rear shield T ) and two shield end flow path outlets (rear shield end flow path outlet 182 T and the flow path outlet 182 at the end of the back shield N ). The flow path inlet 181 at the end of the front shield L Set at the front shield end 64 L . Rear side shield end flow path inlet 181 T Set at the rear shield end 64 T . Rear side shield end flow path outlet 182 T Set at the rear shield end 64 T . Back shield end flow path outlet 182 N Set at the back shield end 64 N .

[0068] like Fig. 12A As shown, the first air passage 191 is connected to the front shield end 74. L The shield end flow path inlet 171 of the outer shield 70 L In addition, the fourth air passage 194 is connected to the rear side shield end 74 T The shield end flow path inlet 171 of the outer shield 70 T Connectivity.

[0069] like Fig. 12A As shown, the first secondary flow path 201 is at the flow path inlet 171 at the end of the front shield. L The rear shield end flow path outlet 172 T The second secondary flow path 202 is located at the flow path inlet 171 at the front shield end. L The ventral shield end flow path outlet 172 PThe third auxiliary flow path 203 is located at the flow path inlet 171 at the rear shield end. T The ventral shield end flow path outlet 172 P For example, the first to third sub-flow paths each have a cooling air inlet at one end thereof, a cooling air outlet at the other end thereof, and an airtight flow path from the one end to the other end.

[0070] In this embodiment, for example, a portion of the cooling air supplied to the first air passage 191 is ejected from the first inner air passage toward the inner surface of the front end portion of the airfoil 51 through the hole portion 59 of the first insert, and then guided in a manner of flowing radially outward through the outer air passage of the outer shroud 70. Then, as Fig. 12A As shown, the flow into the front shield end flow path inlet 171 L The cooling air then flows along the front shroud end flow path 75L. The cooling air then flows along the ventral shroud end flow path 75P and then exits from the ventral shroud end flow path outlet 172. P In addition, the cooling air flows along the back shroud end flow path 75 N Flow along the rear shield end flow path 75 T Flow, and then from the rear side shield end flow path outlet 172 T In this embodiment, for example, a portion of the cooling air supplied to the fourth air passage 194 is ejected from the fourth inner air passage through the hole 59 of the fourth insert toward the inner surface of the center portion of the airfoil 51, and then guided toward the outer shroud 70 through its own outer air passage to flow radially outward. Then, as Fig. 12A As shown, the flow into the rear shield end flow path inlet 171 T The cooling air then flows along the rear shroud end flow path 75 T Next, the cooling air flows along the ventral shroud end flow path 75 P Flow, then from the ventral shield end flow path outlet 172 P outflow.

[0071] like Fig.13 As shown, the ventral shield end flow path outlet 172 P The cooling air flows into the outer area of ​​the space S of the shield body 72 and is ejected toward the radial outer side of the radial inner wall 81 through the cooling holes 79, thereby performing impact cooling on the radial outer side of the radial inner wall 81 and cooling the shield body 72. The cooling air is then discharged through the hole of the discharge pipe 83. Similarly, the cooling air is discharged from the flow path outlet 172 at the rear end of the shield. T The outer region of the space S flowing into the shield body 72 .

[0072] like Fig. 12B As shown, the second air passage 192 is connected to the front shield end 64. L The shield end flow path inlet 181 of the inner shield 60 L In addition, the third air passage 193 is connected to the rear shield end 64 T The shield end flow path inlet 181 of the inner shield 60 T Connected. Fig. 12B In the middle, the flow path outlet 182 at the end of the back shield N Set at the end flow path 65 of the back shield N In addition, at the rear shield end 64 T The shroud end flow path outlet 182 of the inner shroud 60 is provided T .like Fig. 12B As shown, the first secondary flow path 201 is at the flow path inlet 181 at the end of the front shield. L The rear shield end flow path outlet 182 T The second secondary flow path 202 is located at the flow path inlet 181 at the end of the front shield. L The back shield end flow path outlet 182 N The third auxiliary flow path 203 is located at the flow path inlet 181 at the rear shield end. T The back shield end flow path outlet 182 N Extend between.

[0073] In this embodiment, for example, a portion of the cooling air supplied to the second air passage 192 is ejected from the second inner air passage toward the inner surface of the middle portion of the airfoil 51 through the hole portion 59 of the second insert, and then guided in such a manner that it flows radially inward through the outer air passage of the inner shroud 60. Then, as Fig. 12B As shown, the flow into the front shield end flow path inlet 181 L The cooling air then flows along the front shroud end flow path 65 L Then, the cooling air flows along the back shroud end flow path 75 N Flow, and then from the back shield end flow path outlet 182 N In addition, the cooling air flows along the ventral shroud end flow path 65 P Flow along the rear shield end flow path 65 T Flow, and then from the rear side shield end flow path outlet 182 TThe cooling air flows out to the shroud body 62, for example, to the inner region of the space S of the shroud body 62. As with the outer shroud 70, the cooling air is ejected through the cooling holes of the impact plate to cool the radial outer wall of the inner shroud 60 having a gas passage surface facing radially outward and opposite to the high-temperature gas flow path. In this embodiment, for example, a portion of the cooling air supplied to the third air passage 193 is ejected from the third inner air passage through the hole portion 59 of the third insert toward the inner surface of the middle portion of the airfoil 51, and then is guided to flow radially inward through its own outer air passage toward the inner shroud 60, and then, as shown in FIG. Fig. 12B As shown, the flow into the rear shield end flow path inlet 181 T The cooling air then flows along the rear shroud end flow path 65 T Then, the cooling air flows along the back shroud end flow path 75 N Flow, and then from the back shield end flow path outlet 182 N The liquid flows out into the shield body 62 , for example, into the inner region of the space S of the shield body 62 .

[0074] The fifth air passage 195 is a rear end air passage located at the downstream end of the stationary blade body 51. As described above, in the fifth air passage 195, part of the cooling air supplied to the fifth inner air passage through the air intake port 58 is injected toward the inner surface of the rear end portion of the airfoil 51 through the hole portion 59, and then guided to flow toward the airfoil cooling structure 154. Part of the cooling air flows in the passage provided with the pin fins 164, and then is discharged to the high temperature gas flow path at the trailing edge portion 53 of the airfoil 51.

[0075] The structure of the stationary blade is not limited to this embodiment. Fig. 12A In the embodiment, the cooling air may flow in the first secondary flow path 201 in the opposite direction. T As the flow path outlet 172 at the end of the front shield L To the front side shield end flow path 75 L The cooling air moves in the first secondary flow path 201 from the flow path inlet 171 at the rear shroud end. T Towards the front shield end flow path outlet 172 L flow.

[0076] Next, a sixth embodiment of the present application will be described below. Fig.14A and 14B Each of them is a schematic cross-sectional view of a stationary blade according to the sixth embodiment. Fig.14A and 14BThe embodiment in which the shield end surrounds the shield body and the shield end flow path is divided into four sub-flow paths is described separately. In this embodiment, the outer shield 70 has two shield end flow path inlets (front shield end flow path inlet 171 L and the flow path inlet 171 at the end of the rear shield T ) and two shield end flow path outlets (ventral shield end flow path outlet 172 P and the flow path outlet 172 at the end of the back shield N The front shield end flow path inlet 171 L Set at the front shield end 74 L . Rear side shield end flow path inlet 171 T Set at the rear shield end 74 T Ventral shield end flow path outlet 172 P Set at the ventral shield end 74 P . Back shield end flow path outlet 172 N Set at the back shield end 74 N .

[0077] like Fig.14A As shown, the first secondary flow path 201 is at the flow path inlet 171 at the end of the front shield. L The back shield end flow path outlet 172 N The second secondary flow path 202 is located at the flow path inlet 171 at the front shield end. L The ventral shield end flow path outlet 172 P The third auxiliary flow path 203 is located at the flow path inlet 171 at the rear shield end. T The ventral shield end flow path outlet 172 P The fourth auxiliary flow path 204 is located at the flow path inlet 171 at the rear shield end. T The back shield end flow path outlet 172 N For example, the first to fourth sub-flow paths each have a cooling air inlet at one end thereof, a cooling air outlet at the other end thereof, and an airtight flow path from the one end to the other end.

[0078] In this embodiment, the inner shroud 60 has two shroud end flow path inlets (front shroud end flow path inlet 181 and front shroud end flow path inlet 182). L and the flow path inlet 181 at the end of the rear shield T ) and two shield end flow path outlets (ventral shield end flow path outlet 182 P and the flow path outlet 182 at the end of the back shield N ). The front shield end flow path inlet 181 L Set at the front shield end 64 L . Rear side shield end flow path inlet 181T Set at the rear shield end 64 T . Ventral shield end flow path outlet 182 P Set at the ventral shield end 64 P . Back shield end flow path outlet 182 N Set at the back shield end 64 N .

[0079] like Fig. 14B As shown, the first secondary flow path 201 is at the flow path inlet 181 at the end of the front shield. L The ventral shield end flow path outlet 182 P The second secondary flow path 202 is located at the flow path inlet 181 at the end of the front shield. L The back shield end flow path outlet 182 N The third auxiliary flow path 203 is located at the flow path inlet 181 at the rear shield end. T The back shield end flow path outlet 182 N The fourth auxiliary flow path 204 is located at the flow path inlet 181 at the rear shield end. T The ventral shield end flow path outlet 182 P For example, the first to fourth sub-flow paths each have a cooling air inlet at one end thereof, a cooling air outlet at the other end thereof, and an airtight flow path from the one end to the other end.

[0080] like Fig.14A As shown, the first air passage 191 is connected to the front shield end 74. L The shield end flow path inlet 171 of the outer shield 70 L In addition, the fourth air passage 194 is connected to the rear side shield end 74 T The shield end flow path inlet 171 of the outer shield 70 T Connectivity.

[0081] In this embodiment, for example, a portion of the cooling air supplied to the first air passage 191 is ejected from the first inner air passage toward the inner surface of the front end portion of the airfoil 51 through the hole portion 59 of the first insert, and then guided to flow radially outward through the outer air passage 57 of the outer shroud 70. Then, as Fig.14A As shown, the flow into the front shield end flow path inlet 171 L The cooling air then flows along the front shroud end flow path 75 L Next, the cooling air flows along the ventral shroud end flow path 75 P Flow, then from the ventral shield end flow path outlet 172 PThe shield body 72 flows out, for example, into the outer region of the space S of the shield body 72. Alternatively, the shield body 72 flows along the back shield end flow path 75. N Flow, and then from the back shield end flow path outlet 172 N Flows out and flows into the outer region of the shroud body 72, for example, the space S of the shroud body 72. In this embodiment, for example, a portion of the cooling air supplied to the fourth air passage 194 is ejected from the fourth inner air passage through the hole portion 59 of the fourth insert toward the inner surface of the central portion of the airfoil 51, and then is guided to flow radially outward through the outer air passage 57 of the outer shroud 70. Then, as Fig.14A As shown, the flow into the rear shield end flow path inlet 171 T The cooling air then flows along the rear shroud end flow path 75 T Next, the cooling air flows along the ventral shroud end flow path 75 P Flow, then from the ventral shield end flow path outlet 172 P The shield body 72 flows out, for example, into the outer region of the space S of the shield body 72. Alternatively, the shield body 72 flows along the back shield end flow path 75. N Flow, and then from the back shield end flow path outlet 172 N The liquid flows out and flows into the shield body 72 , for example, into the outer region of the space S of the shield body 72 .

[0082] like Fig. 14B As shown, the second air passage 192 is connected to the front shield end 64. L The shield end flow path inlet 181 of the inner shield 60 L The third air flow path 193 is connected to the rear shroud end 64 T The shield end flow path inlet 181 of the inner shield 60 T Connectivity.

[0083] In this embodiment, for example, a portion of the cooling air supplied to the second air passage 192 is ejected from the second inner air passage toward the inner surface of the center portion of the airfoil 51 through the hole portion 59 of the second insert, and then guided in a manner of flowing radially inward through the outer air passage 57 of the inner shroud 60. Then, as Fig. 14B As shown, the flow into the front shield end flow path inlet 181 L The cooling air then flows along the front shroud end flow path 65 L Next, the cooling air flows along the ventral shroud end flow path 65 P Flow, then from the ventral shield end flow path outlet 182 PThe shield body 62 flows out, for example, into the inner region of the space S of the shield body 62. Alternatively, the shield body 62 flows along the back shield end flow path 65. N Flow, and then from the back shield end flow path outlet 182 N Flows out and flows into the shroud body 62, for example, into the inner region of the space S of the shroud body 62. In this embodiment, for example, a portion of the cooling air supplied to the third air passage 193 is ejected from the third inner air passage through the hole 59 of the third insert toward the inner surface of the central portion of the airfoil 51, and then is guided in a manner of flowing radially inward through the outer air passage 57 of the inner shroud 60. Then, as Fig. 14B As shown, the flow into the rear shield end flow path inlet 181 T The cooling air then flows along the rear shroud end flow path 65 T Next, the cooling air flows along the ventral shroud end flow path 65 P Flow, then from the ventral shield end flow path outlet 182 P The shield body 62 flows out, for example, into the inner region of the space S of the shield body 62. Alternatively, the shield body 62 flows along the back shield end flow path 65. N Flow, and then from the back shield end flow path outlet 182 N The liquid flows out and flows into the shield body 62 , for example, into the inner region of the space S of the shield body 62 .

[0084] The structure of the stationary blade is not limited to this embodiment. As an alternative embodiment, the first air passage 191 may be connected to the front shroud end 64. L The shield end flow path inlet 181 of the inner shield 60 L In addition, the fourth air passage 194 may also be connected to the rear side shield end 64 T The shield end flow path inlet 181 of the inner shield 60 T In addition, the second air passage 192 may also be connected to the front side shield end 74 L The shield end flow path inlet 171 of the outer shield 70 L In addition, the third air flow path 193 may also be connected to the rear shroud end 74 T The shield end flow path inlet 171 of the outer shield 70 T Connectivity.

[0085] Next, a seventh embodiment will be described. Fig.15 This is a partial schematic diagram of a stator blade according to the seventh embodiment. In this embodiment, the ventral shroud end flow path outlet 172 P It has two adjacent outlets (a first outlet located at the front and a second outlet located at the rear).P The partition wall 220 is divided into two flow paths. The partition wall is provided between the two outlets. In this embodiment, the flow path inlet 171 at the end of the front shield is L The incoming cooling air is blocked by the partition wall 220 and flows out from the first outlet, and then flows out from the rear shroud end flow path inlet 171. T The incoming cooling air is blocked by the partition wall 220 and flows out from the second outlet.

[0086] According to this structure, the flow path inlet 171 at the front shield end can be L The air flow from the rear shield end flow path inlet 171 T The air flow from the front shield end flow path inlet 171 L The temperature of the cooling air is related to the temperature of the cooling air from the rear shroud end flow path inlet 171 T In this embodiment, the temperature of the cooling air is different. In this embodiment, it is possible to prevent the two air flows with different temperatures from mixing and to easily perform temperature control of the cooling system.

[0087] The structure of the stationary blade is not limited to this embodiment. The structure having two outlets and a partition wall between the two outlets may also be applied to other shroud end flow paths. For example, the structure having two outlets and a partition wall between the two outlets may also be applied to the back shroud end flow path 75. N and the back shield end flow path outlet 172 N .

[0088] The present disclosure is not limited to the above-mentioned embodiments and can be implemented in various embodiments. For better understanding, specific embodiments are described with reference to the accompanying drawings, but the above description is provided as an example and does not limit the scope of the invention defined by the accompanying technical solutions. The scope of the present invention should be determined by the accompanying technical solutions. Those skilled in the art can make various changes without departing from the scope of the invention, and the accompanying technical solutions cover such changes.

[0089] Description of reference numerals:

[0090] 10 Gas Turbine

[0091] 20 Turbine

[0092] 22 Turbine housing

[0093] 24 Rotor shaft

[0094] 26 Turbine rotor

[0095] Ar axis

[0096] 30 Burner

[0097] 50 Stationary blades

[0098] 51 Stationary blade body (airfoil)

[0099] 51 P next door

[0100] 52 Front edge

[0101] 53 trailing edge

[0102] 54 dorsal side

[0103] 55 Ventral side

[0104] 56 Intake manifold

[0105] 57 Outer air channel

[0106] 58 Air intake

[0107] 59 hole

[0108] 141, 142, 143 Air channels

[0109] 151, 152, 153 Inserts

[0110] 161, 162, 163 Inner air channels

[0111] 191, 192, 193, 194, 195 Air channels

[0112] 154 Airfoil cooling structure

[0113] 164 Pin fin

[0114] 60 Inner shroud

[0115] 70 Outer shroud

[0116] 62, 72 Shield body

[0117] 63, 73 Impact plate

[0118] 64, 74 Shield end

[0119] 65, 75 shroud end flow path

[0120] S Hollow Space

[0121] 171 Flow path inlet at the end of the guard

[0122] 172 Flow path outlet at the end of the guard

[0123] 175 Turbulator

[0124] 76 Wall

[0125] 78 Gas passage surface

[0126] 79 Impingement cooling holes

[0127] 81 Radial inner wall

[0128] 82 radial outer wall

[0129] 83 discharge pipe

[0130] 181 Flow path inlet at the end of the guard

[0131] 182 Flow path outlet at the end of the guard

[0132] 201, 202, 203, 204 Auxiliary flow path

[0133] 220 Next door.

Claims

1. A shroud, which is a shroud of a turbine stator blade, wherein: The shield includes a shield body and a shield end portion, wherein the shield end portion is disposed around the shield body and surrounds the shield body, and the shield end portion includes a shield end flow path inside, and the shield end flow path is disposed along the periphery of the shield body. The shroud end portion includes: a plurality of cooling air inlets configured to introduce cooling air from the outside of the shroud end portion into the shroud end portion flow path; and a plurality of cooling air outlets configured to allow cooling air to flow out from the shroud end portion flow path to the outside of the shroud end portion. The shroud end flow path is divided into three or more sub-flow paths by the plurality of cooling air inlets and the plurality of cooling air outlets.

2. The shield according to claim 1, wherein: The shroud end flow path is divided into four sub-flow paths by the plurality of cooling air inlets and the plurality of cooling air outlets.

3. The shield according to claim 1, wherein: Each of the secondary flow paths includes one of the plurality of cooling air inlets at one end thereof and one of the plurality of cooling air outlets at the other end thereof, and includes an airtight flow path from the one end to the other end.

4. The shield according to claim 1, wherein: At least one of the plurality of cooling air inlets is disposed at a downstream end portion of the shroud end portion with respect to a flow direction of high temperature gas of the turbine.

5. The shield according to claim 1, wherein: The shroud end portion includes a front shroud end portion and a rear shroud end portion, the front shroud end portion is arranged at an upstream end portion of the shroud end portion relative to a flow direction of the high-temperature gas of the turbine, and the rear shroud end portion is arranged at a downstream end portion of the shroud end portion relative to a flow direction of the high-temperature gas of the turbine, The plurality of cooling air inlets include a first cooling air inlet and a second cooling air inlet. The first cooling air inlet is provided at the end of the front shroud, and the second cooling air inlet is provided at the end of the rear shroud.

6. The shield according to claim 2, wherein: The shroud end portion includes: a front shroud end portion, which is arranged at an upstream end portion of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; a rear shroud end portion, which is arranged at a downstream end portion of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; a dorsal shroud end portion, which is arranged at a dorsal side of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; and a ventral shroud end portion, which is arranged at a ventral side of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine. The plurality of cooling air inlets include a first cooling air inlet and a second cooling air inlet, wherein the first cooling air inlet is disposed at a middle portion of the end portion of the front shield, and the second cooling air inlet is disposed at a middle portion of the end portion of the rear shield, The plurality of cooling air outlets include a first cooling air outlet and a second cooling air outlet, wherein the first cooling air outlet is disposed at a middle portion of the end portion of the dorsal shield, and the second cooling air outlet is disposed at a middle portion of the end portion of the ventral shield. The secondary flow path includes: a first secondary flow path defined by the first cooling air inlet and the first cooling air outlet; and a second secondary flow path defined by the first cooling air inlet and the second cooling air outlet. a third secondary flow path defined by the second cooling air inlet and the first cooling air outlet; and a fourth sub-flow path defined by the second cooling air inlet and the second cooling air outlet.

7. The shield according to claim 1, wherein: The plurality of cooling air outlets are connected to the shroud main body in such a manner that the cooling air flows from the shroud end flow path into the shroud main body.

8. The shield according to claim 7, wherein: The shield body contains a space inside, The cooling air flows into the internal space from the shroud end flow path.

9. The shield according to claim 1, wherein: The shield end portion surrounds the entire circumference of the shield body.

10. The shield according to claim 1, wherein: The shroud end portion includes: a front shroud end portion, which is arranged at an upstream end portion of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; a rear shroud end portion, which is arranged at a downstream end portion of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; a dorsal shroud end portion, which is arranged at a dorsal side of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine; and a ventral shroud end portion, which is arranged at a ventral side of the shroud end portion relative to the flow direction of the high-temperature gas of the turbine. The dorsal shroud end portion includes a dorsal shroud end flow path inside, and the ventral shroud end portion includes a ventral shroud end flow path inside, The dorsal shroud end flow path or the ventral shroud end flow path is divided by a partition wall.

11. The shield according to claim 6, wherein: The first cooling air outlet is divided by a partition wall into a front first cooling air outlet defining the first secondary flow path and a rear first cooling air outlet defining the third secondary flow path. The second cooling air outlet is divided by a partition wall into a front second cooling air outlet defining the second sub-flow path and a rear second cooling air outlet defining the fourth sub-flow path.

12. The shield according to claim 1, wherein: The shield body contains a space inside, The space is connected to the shroud end flow path via the cooling air outlet, and the cooling air flows from the shroud end flow path into the internal space via the cooling air outlet.

13. The shield according to claim 12, wherein: The shield body includes an impact plate disposed in the space. The impact plate divides the space into a radially outer region and a radially inner region of the turbine. The radially outer region is connected to the shroud end flow path via the cooling air outlet, The impact plate includes a plurality of cooling holes penetrating in the radial direction.

14. A cooling method for cooling a stationary blade of a turbine having a shroud, wherein: The shroud includes a shroud body and a shroud end portion, the shroud end portion being arranged around the shroud body and surrounding the shroud body, the shroud end portion including a shroud end flow path inside, the shroud end flow path being arranged along the shroud body, the shroud end portion including: a front shroud end portion, which is arranged at an upstream end portion of the shroud end portion relative to a flow direction of high-temperature gas of the turbine; a rear shroud end portion, which is arranged at a downstream end portion of the shroud end portion relative to a flow direction of high-temperature gas of the turbine; a dorsal shroud end portion, which is arranged at a dorsal side of the shroud end portion relative to a flow direction of high-temperature gas of the turbine; and a ventral shroud end portion, which is arranged at a ventral side of the shroud end portion relative to a flow direction of high-temperature gas of the turbine, the dorsal shroud end portion including a dorsal shroud end flow path inside, and the ventral shroud end portion including a ventral shroud end flow path inside. The cooling method is carried out as follows: Allowing cooling air to flow from an upstream side to a downstream side within the dorsal shroud end flow path relative to a flow direction of high-temperature gas of the turbine; Allowing cooling air to flow from a downstream side to an upstream side within the dorsal shroud end flow path relative to a flow direction of high temperature gas of the turbine; as well as The cooling air is caused to flow out from a cooling air outlet provided in a middle portion of the back shroud end flow path.

15. The cooling method according to claim 14, wherein: The cooling air outlet comprises a first outlet and a second outlet adjacent to each other, The cooling method is carried out as follows: causing the cooling air flowing from the upstream side to the downstream side to flow out from the first outlet; and causing the cooling air flowing from the downstream side to the upstream side to flow out from the second outlet, The first outlet and the second outlet are separated by a partition wall disposed therebetween.

16. The cooling method according to claim 14, wherein: The cooling air is caused to flow into the shroud body from the back shroud end flow path through the cooling air outlet.

17. The cooling method according to claim 16, wherein: The shield body contains a space inside, The cooling air flows into the internal space from the shroud end flow path.

18. The cooling method according to claim 17, wherein: The shield body includes an impact plate disposed in the space. The impact plate divides the space into a radially outer region and a radially inner region of the turbine, the radially outer region is connected to the shroud end flow path via the cooling air outlet, and the impact plate has a plurality of cooling holes penetrating along the radial direction. The cooling air is caused to flow from the back shroud end flow path toward the outer region of the shroud body through the cooling air outlet, and is ejected through the cooling holes of the impingement plate.

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