Stationary blade and steam turbine provided with same

Abstract

The present invention comprises a blade body that is disposed in a steam flow path in which steam flows, that has an airfoil shape cross-section, and that extends in a blade height direction perpendicular to said cross-section. The blade body has: a blade internal space that is formed between a positive pressure surface and a negative pressure surface of the blade body; a recess that is recessed toward the blade internal space from the positive pressure surface; and a communication path that communicates between the recess and the blade internal space. The recess is defined by: a front side surface that is positioned toward the front edge of the blade body; a rear side surface that is positioned more to the rear edge of the blade body than the front side surface, and that is opposite from the front side surface; and a bottom surface that connects the front side surface and the rear side surface. The rear side surface is inclined at an acute angle with respect to the positive pressure surface so as to increasingly approach the rear edge further toward the blade internal space in a direction perpendicular to the positive pressure surface, from the positive pressure surface. The communication path opens at the bottom surface.

Description

Stationary blade, and steam turbine including the same

[0001] The present disclosure relates to a stationary blade and a steam turbine including the same. This application claims priority based on Japanese Patent Application No. 2024-172960 filed in Japan on October 2, 2024, the content of which is incorporated herein by reference.

[0002] When drain of steam exists in the steam flow path within the steam turbine, wet loss due to this drain occurs, resulting in a decrease in the efficiency of the steam turbine. Further, when this drain exists, the drain collides with the blades in the steam flow path, eroding the blades. Therefore, many steam turbines have a structure for discharging this drain. For example, in Patent Document 1 below, a structure for discharging drain is formed in the stationary blade of a steam turbine.

[0003] The stationary blade described in this Patent Document 1 includes a blade body disposed within a steam flow path through which steam flows. This blade body has a cross-section forming an airfoil shape and extends in the blade height direction perpendicular to this cross-section. The blade body has a leading edge, a trailing edge, a pressure surface connecting the leading edge and the trailing edge, and a suction surface connecting the leading edge and the trailing edge and having a relationship opposite to the pressure surface. Further, as a structure for discharging drain, the blade body has an internal blade space formed between the pressure surface and the suction surface, a recess recessed from the pressure surface toward the side of the internal blade space, and a communication passage connecting the recess and the internal blade space.

[0004] The internal blade space has an opening communicating to the outside. The recess extends in the blade height direction along the pressure surface. This recess is defined by a front side surface located on the leading edge side, a rear side surface located on the trailing edge side relative to the front side surface and facing the front side surface, and a bottom surface. The front side surface extends in a direction perpendicular to the pressure surface and in the blade height direction. The rear side surface also extends in a direction perpendicular to the pressure surface and in the blade height direction. The bottom surface extends in a direction substantially parallel to the pressure surface. The edge on the leading edge side of this bottom surface is connected to the edge on the internal blade space side of the front side surface. The edge on the trailing edge side of this bottom surface is connected to the edge on the internal blade space side of the rear side surface. The communication passage opens at the bottom surface of the recess. The position of the opening of the communication passage is a position closer to the rear side surface within the bottom surface.

[0005] In this stator vane, condensate flowing along the positive pressure surface is collected in a recess, and then discharged into the vane's internal space via a connecting passage. Therefore, this stator vane can discharge condensate outside the steam flow path while suppressing the discharge of steam within the steam flow path.

[0006] Patent No. 6227653

[0007] As mentioned above, in steam turbines, it is desirable to efficiently discharge condensate outside the steam flow path while suppressing the discharge of steam within the steam flow path.

[0008] Therefore, the purpose of this disclosure is to provide a technology that can efficiently discharge condensate outside the steam flow path while suppressing the discharge of steam within the steam flow path.

[0009] A stator vane according to one embodiment of the disclosure for achieving the above objective comprises a vane body disposed in a steam channel through which steam flows, having an airfoil cross-section and extending in a vane height direction perpendicular to the cross-section. The vane body has a leading edge, a trailing edge, a positive pressure surface connecting the leading edge and the trailing edge, a negative pressure surface connecting the leading edge and the trailing edge and facing the positive pressure surface, a vane internal space formed between the positive pressure surface and the negative pressure surface, a recess recessing from the positive pressure surface toward the vane internal space, and a communication passage connecting the recess and the vane internal space. The vane internal space has an opening that leads to the outside. The recess extends in a recess extension direction having a component in the vane height direction along the positive pressure surface. The recess is defined by a front surface located toward the leading edge, a rear surface located toward the trailing edge and facing the front surface, and a bottom surface connecting the front surface and the rear surface. The rear side surface is inclined at an acute angle with respect to the positive pressure surface, such that it approaches the trailing edge side as it moves toward the inside of the recess, which is the side of the wing's internal space, with respect to the positive pressure surface. The communication passage opens at the bottom surface.

[0010] When condensate contained in the steam flowing through the steam channel collides with the positive pressure surface, this condensate flows along the positive pressure surface toward the trailing edge. A portion of the condensate flowing along the positive pressure surface is collected in the recess. The condensate in the recess flows into the wing space through the connecting passage. In other words, in this embodiment, the condensate flowing along the positive pressure surface is collected in the recess, and then discharged into the wing space through the connecting passage. Therefore, in this embodiment, it is possible to discharge condensate outside the steam channel while suppressing the discharge of steam within the steam channel.

[0011] Incidentally, some of the drain that flows along the positive pressure surface toward the trailing edge does not flow into the recess even when it reaches the front surface of the recess, but instead collides with the rear surface of the recess due to the inertial force of the drain flow. The rear surface of this embodiment is inclined at an acute angle with respect to the positive pressure surface so that it approaches the trailing edge as it moves toward the inside of the recess. In other words, the rear surface of this embodiment is inclined at an acute angle with respect to the positive pressure surface so that it gradually moves toward the inside of the recess as it moves toward the direction in which the drain flows due to the inertial force. Therefore, in this embodiment, most of the drain that collides with the rear surface flows toward the inside of the recess along the rear surface, and hardly flows toward the outside of the recess on the opposite side of the inside of the recess. Thus, in this embodiment, the drain that collides with the rear surface can be efficiently collected in the recess.

[0012] In the recess of this embodiment, a vortex flow of steam and condensate is generated. This vortex flow flows inward along the rear surface towards the inside of the recess, then towards the front edge along the bottom surface, and further towards the outside of the recess along the front surface. As described above, the rear surface of this embodiment is inclined at an acute angle with respect to the positive pressure surface, so that it approaches the rear edge as it moves inward towards the inside of the recess. Therefore, the vortex flow is inhibited and weakened compared to the case where the rear surface extends only inward towards the inside of the recess perpendicular to the positive pressure surface. As a result, the flow that flows outward along the front surface within the vortex flow is weakened, and this flow can reduce the possibility that condensate that has flowed into the recess will be discharged outside the recess.

[0013] As described above, in this embodiment, drain can be efficiently collected in the recess.

[0014] A steam turbine according to one embodiment of the disclosure for achieving the above objective comprises a stator blade in the above embodiment, a rotor rotatable about an axis, and a casing covering the rotor. The stator blade is fixed to the casing within the casing.

[0015] According to one aspect of this disclosure, it is possible to efficiently discharge condensate outside the steam flow path while suppressing the discharge of steam within the steam flow path.

[0016] This is an overall cross-sectional view of a steam turbine in one embodiment of the present disclosure. This is a cross-sectional view of the main part of a steam turbine around a stator blade in the first embodiment of the present disclosure. This is a cross-sectional view taken along line III-III in Figure 2. This is a cross-sectional view taken along line IV-IV in Figure 2. This is a cross-sectional view taken along line V-V in Figure 2. This is an explanatory diagram showing the flow of drain in a recess in the first embodiment of the present disclosure. This is a cross-sectional view of the main part of a stator blade around a recess in a comparative example. This is an explanatory diagram (1) showing the flow of drain in a recess in a comparative example. This is an explanatory diagram (2) showing the flow of drain in a recess in a comparative example. This is a cross-sectional view of the main part of a stator blade around a recess in the second embodiment of the present disclosure. This is an explanatory diagram showing the flow of drain in a recess in the second embodiment of the present disclosure. This is a cross-sectional view of the main part of a steam turbine around a stator blade in the third embodiment of the present disclosure. This is a cross-sectional view of the main part of a steam turbine around a stator blade in the fourth embodiment of the present disclosure. This is a cross-sectional view of the main part of a stator blade in the part around a recess where a communication passage exists in the fifth embodiment of the present disclosure. This is a cross-sectional view of the main part of a stator blade in the part around a recess where a communication passage does not exist in the fifth embodiment of the present disclosure. This is a cross-sectional view of the main part of the stationary vane in the area around the recess where a communication passage exists, according to the sixth embodiment of the present disclosure. This is a cross-sectional view of the main part of the stationary vane in the area around the recess where a communication passage does not exist, according to the fifth embodiment of the present disclosure.

[0017] The embodiments and various modifications described herein will be explained below with reference to the drawings.

[0018] "Embodiment of a Steam Turbine" An embodiment of the steam turbine according to this disclosure will be described in detail with reference to Figure 1.

[0019] The steam turbine in this embodiment is a two-flow type steam turbine, as shown in Figure 1. This steam turbine comprises a first steam turbine section ST1 and a second steam turbine section ST2. Both the first steam turbine section ST1 and the second steam turbine section ST2 include a rotor 10 that rotates about an axis Ar, a casing 20 that covers the rotor 10, a plurality of blade rings 30 arranged inside the casing 20, one or more stator blade rows 50 held by each blade ring 30, a bearing 15, and a steam inlet pipe 16. The rotor 10 of the first steam turbine section ST1 and the rotor 10 of the second steam turbine section ST2 are located on the same axis Ar and are connected so as to be able to rotate as a single unit. For the purposes of the following explanation, the direction in which the axis Ar extends will be referred to as the axial direction Da. Of the two sides in the axial direction Da, one side will be referred to as the first side Da1 and the other side as the second side Da2.

[0020] The first steam turbine section ST1 and the second steam turbine section ST2 share a steam inlet pipe 16. In the first steam turbine section ST1, all components except the steam inlet pipe 16 are arranged on the first side Da1 in the axial direction Da with respect to the steam inlet pipe 16. In the first steam turbine section ST1, the second side Da2 forms the upstream side Dau, and the first side Da1 forms the downstream side Dad. Similarly, in the second steam turbine section ST2, all components except the steam inlet pipe 16 are arranged on the second side Da2 with respect to the steam inlet pipe 16. In the second steam turbine section ST2, the first side Da1 forms the upstream side Dau, and the second side Da2 forms the downstream side Dad. The first steam turbine section ST1 and the second steam turbine section ST2 are identical in shape and structure. However, the upstream axis Da in the second steam turbine section ST2 is on the opposite side in the axial direction Da from the upstream axis Da in the first steam turbine section ST1.

[0021] Each rotor 10 in the first steam turbine section ST1 and the second steam turbine section ST2 has a rotor shaft 11 extending in the axial direction Da with respect to the axis Ar, and a plurality of rotor blade rows 12 fixed to the outer circumference of the rotor shaft 11 and arranged in the axial direction Da. A bearing 15 is provided at the portion of the rotor shaft 11 downstream of the axis Da to rotatably support the rotor shaft 11. Each rotor blade row 12 has a plurality of rotor blades arranged in the circumferential direction Dc with respect to the axis Ar. The rotor blades have an airfoil shape with a cross-sectional shape perpendicular to the radial direction Dr with respect to the axis Ar, and have a blade body extending in the radial direction Dr. A plurality of stator blade rows 50 are arranged in the axial direction Da. At the position upstream of the axis Da of each rotor blade row 12, one of the plurality of stator blade rows 50 is positioned. Therefore, the number of plurality of stator blade rows 50 is equal to the number of plurality of rotor blade rows. Each row of stator vanes 50 has multiple stator vanes arranged in the circumferential direction Dc.

[0022] Each of the multiple blade rings 30 is cylindrical with respect to the axis Ar. Furthermore, the multiple blade rings 30 are aligned in the axial direction Da. As described above, one or more stator blade rows 50 are held by the multiple blade rings 30. The annular space between the inner circumference of the multiple blade rings 30 and the outer circumference of the rotor shaft 11 forms a steam flow path 17.

[0023] Each casing 20 in the first steam turbine section ST1 and the second steam turbine section ST2 includes an inner casing 21, an exhaust casing 22, and a diffuser 23.

[0024] The inner casing 21 is cylindrical with the axis Ar as its center. Multiple wing rings 30 are attached to the inner circumference of this inner casing 21.

[0025] The diffuser 23 is annular with respect to the axis Ar, and forms a diffuser space 23s that gradually widens radially outward towards Da, the downstream side of the axis. Steam S that has passed through the last stage of the multiple rotor blade rows 12 flows into the diffuser space 23s.

[0026] The exhaust casing 22 has an exhaust port 27. This exhaust port 27 opens radially outward from the inside and vertically downward. A condenser C that returns steam S back to water is connected to this exhaust port 27. The exhaust casing 22 forms an exhaust space 22s through which the steam S that has passed through the diffuser space 23s flows. This exhaust space 22s extends circumferentially Dc with respect to the axis Ar around the outer circumference of the diffuser 23, guiding the steam S that flows in from the diffuser space 23s to the exhaust port 27.

[0027] The exhaust casing 22 of the first steam turbine section ST1 and the exhaust casing 22 of the second steam turbine section ST2 are connected to each other and integrated into one unit.

[0028] The steam inlet pipe 16 is cylindrical with its axis Ap as the center. The axis Ap extends vertically, passing through a position midway between the first stage stator blade row 50 of the first steam turbine section ST1 and the first stage stator blade row 50 of the second steam turbine section ST2 in the axial direction Da. The steam inlet pipe 16 is positioned above the axis Ar. This steam inlet pipe 16 guides steam S from the outside into the steam flow path 17 of the first steam turbine section ST1 and the steam flow path 17 of the second steam turbine section ST2.

[0029] The steam S that flows into the steam passage 17 collides with multiple rotor blades, causing the rotor 10 to rotate. The steam S that has rotated the rotor 10 passes through the diffuser space 23s and the exhaust space 22s, and is exhausted from the exhaust port 27 of the exhaust casing 22. The steam S exhausted from the exhaust port 27 flows into the condenser C, where it returns to water.

[0030] "First Embodiment of Stationary Vanes" The embodiment of the stationary vanes of the stationary vane array 50 described above will be explained with reference to Figures 2 to 9. Figure 2 shows the stationary vane 51 of the final stage stationary vane array 50 among the multiple stationary vane arrays 50.

[0031] As shown in Figure 2, the stator vane 51 comprises a blade body 52, an inner shroud 61, and an outer shroud 62. The blade body 52 has an airfoil cross-section and extends in the blade height direction Dh perpendicular to this cross-section. When the stator vane 51 is attached to the blade ring 30, the blade height direction Dh becomes the radial direction Dr with respect to the axis Ar. Therefore, in the following, the blade height direction Dh may also be referred to as the radial direction Dr. The inner shroud 61 is provided at one end of the blade body 52 in the blade height direction Dh, in other words, at the radially inner end Dri of the blade body 52. ​​The outer shroud 62 is provided at the other end of the blade body 52 in the blade height direction Dh, in other words, at the radially outer end Dro of the blade body 52. ​​This outer shroud 62 is held by the blade ring 30. The space between the inner shroud 61 and the outer shroud 62 forms part of the steam passage 17 through which steam S flows. Therefore, the wing body 52 is positioned within this steam passage 17.

[0032] As shown in Figures 2 and 3, the airfoil 52 has a leading edge 52s located furthest upstream on the axis (Dau), a trailing edge 52r located furthest downstream on the axis (Dad), and a positive pressure surface 52p and a negative pressure surface 52n connecting the leading edge 52s and the trailing edge 52r. The positive pressure surface 52p is a concave surface facing one side of the circumferential direction Dc and recessed on the other side of the circumferential direction Dc. The negative pressure surface 52n is a convex surface facing the other side of the circumferential direction Dc and protruding on the other side of the circumferential direction Dc. This negative pressure surface 52n is back-to-back with the positive pressure surface 52p.

[0033] The blade body 52 of this embodiment further includes, as a structure for discharging drain DN formed from condensed steam S, a blade internal space 53 formed between a positive pressure surface 52p and a negative pressure surface 52n, a recess 55 that is recessed from the positive pressure surface 52p toward the blade internal space 53, and two communication passages 54 that connect the recess 55 and the blade internal space 53.

[0034] The outer shroud 62 has a drain transfer channel 63 that penetrates the outer shroud 62 radially in the direction Dr. The blade ring 30 that holds the outer shroud 62 has a drain discharge channel 31 that penetrates the blade ring 30 radially in the direction Dr. The drain transfer channel 63 of the outer shroud 62 and the drain discharge channel 31 of the blade ring 30 are in communication with each other. The internal space 53 of the blade body 52 has an opening 53o that communicates with the drain transfer channel 63 of the outer shroud 62.

[0035] The outer shrouds 62 of each of the multiple stator vanes 51 constituting the stator vane row 50 may be joined together to form an outer ring. In addition, the inner shrouds 61 of each of the multiple stator vanes 51 constituting the stator vane row 50 may be joined together to form an inner ring.

[0036] The recess 55 extends along the positive pressure surface 52p in the recess extension direction De, which has a component in the blade height direction Dh. In this embodiment, the recess extension direction De is substantially the same direction as the blade height direction Dh.

[0037] As shown in Figures 4 and 5, the recess 55 is defined by a front surface 56 located on the side Df of the leading edge 52s, a rear surface 57 located on the side Db of the trailing edge 52r and facing the front surface 56, and a bottom surface 58 connecting the front surface 56 and the rear surface 57. Here, for the sake of the following explanation, the side of the wing internal space 53 that is perpendicular to the positive pressure surface 52p and is based on the positive pressure surface 52p will be called the inner side Dsi of the recess. Also, the side of the recess that is perpendicular to the positive pressure surface 52p and is opposite to the inner side Dsi will be called the outer side Dso of the recess.

[0038] The front surface 56 faces the side Db of the rear edge 52r and extends in the direction of the recess extension De, as well as extending from the edge of the positive pressure surface 52p towards the inside of the recess Dsi. The rear surface 57 faces the side Df of the front edge 52s and extends in the direction of the recess extension De, as well as extending in a direction that approaches the side Db of the rear edge 52r as it moves from the edge of the positive pressure surface 52p towards the inside of the recess Dsi. Therefore, this rear surface 57 is inclined to form an acute angle with respect to the positive pressure surface 52p. The bottom surface 58 connects the edge of the inside of the recess Dsi of the front surface 56 and the edge of the inside of the recess Dsi of the rear surface 57. This bottom surface 58 faces the outside of the recess Dso and extends in the direction of the recess extension De, as well as extending from the edge of the inside of the recess Dsi of the rear surface 57 towards the front surface 56, and is inclined with respect to the positive pressure surface 52p so that it gradually moves towards the inside of the recess Dsi as it moves towards the front surface 56.

[0039] Both connecting passages 54 open at the bottom surface 58 of the recess 55. The position of the opening 54o of one of the two connecting passages 54 is spaced apart in the recess extension direction De from the position of the opening 54o of the other connecting passage 54. Also, the positions of the openings 54o of both connecting passages 54 are both located on the bottom surface 58, closer to the front surface 56. Parts of the edges of the openings 54o of both connecting passages 54 are part of the front surface 56.

[0040] As the steam S in the steam channel 17 flows downstream of the axis to Da, its pressure gradually decreases and its moisture content increases. Therefore, in the region of Da downstream of the axis within the steam channel 17, the steam S may contain condensed drain DN.

[0041] As shown in FIG. 3, the drain DN in the steam S collides with the blade body 52 together with this steam S. A part of the drain DN in the steam S collides with substantially the entire positive pressure surface 52p of the blade body 52. The drain DN that has collided with the positive pressure surface 52p of the blade body 52 is liquefied into a liquid film and flows along the positive pressure surface 52p toward the side Db of the trailing edge 52r. Also, another part of the drain DN in the steam S collides with the portion on the side Df of the leading edge 52s in the negative pressure surface 52n of the blade body 52. The drain DN that has collided with the portion on the side Df of the leading edge 52s in the negative pressure surface 52n of the blade body 52 peels off from this negative pressure surface 52n in the process of flowing along the negative pressure surface 52n toward the side Db of the trailing edge 52r. A part of the drain DN peeled off from the negative pressure surface 52n adheres to the positive pressure surface 52p of another blade body 52 adjacent to this blade body 52 in the circumferential direction Dc. Therefore, it is important to remove the drain DN adhering to the positive pressure surface 52p for removing the drain DN in the steam flow path 17.

[0042] In the present embodiment, a part of the drain DN flowing along the positive pressure surface 52p is collected in the recess 55. The drain DN in the recess 55 flows into the intra-blade space 53 via the communication passage 54. The drain DN that has flowed into the intra-blade space 53 flows into the exhaust space 22s of the exhaust casing 22 shown in FIG. 1 via the drain transfer flow path 63 of the outer shroud 62 and the drain discharge flow path 31 of the blade ring 30. The drain DN that has flowed into the exhaust space 22s flows into the condenser C together with the steam S existing in the exhaust space 22s.

[0043] The pressure in the exhaust space 22s is lower than the pressure in the steam flow path 17. Therefore, the drain DN flowing into the recess 55 is sucked into the intra-blade space 53.

[0044] Here, referring to FIGS. 7 to 9, a blade body 52x of a stationary blade having a structure for discharging the drain DN, which is a comparative example, will be described. The blade body 52x of this comparative example is one of the blade bodies exemplified in Patent Document 1 described in the "Background Art" section.

[0045] As shown in FIG. 7, the blade body 52x of the comparative example has, similar to the blade body 52 of the stationary blade in the present embodiment, an intra-blade space 53, a recess 55x recessed from the positive pressure surface 52p to the inside Dsi of the recess, and a communication passage 54x that connects the recess 55x and the intra-blade space 53.

[0046] The recess 55x extends in the recess extending direction De having a component in the blade height direction Dh along the positive pressure surface 52p. This recess 55x is defined by a front side surface 56 located on the side Df of the leading edge 52s, a rear side surface 57x located on the side Db of the trailing edge 52r and facing the front side surface 56, and a bottom surface 58x connecting the front side surface 56 and the rear side surface 57x.

[0047] The front side surface 56 faces the side Db of the trailing edge 52r, extends in the recess extending direction De, and extends from the edge of the positive pressure surface 52p to the inner side Dsi of the recess. The rear side surface 57x faces the side Df of the leading edge 52s, extends in the recess extending direction De, and extends from the edge of the positive pressure surface 52p to the inner side Dsi of the recess. Thus, this rear side surface 57x is parallel to the front side surface 56. The bottom surface 58x connects the edge of the inner side Dsi of the front side surface 56 and the edge of the inner side Dsi of the rear side surface 57x. This bottom surface 58x faces the outer side Dso of the recess, extends in the recess extending direction De, and is substantially parallel to the positive pressure surface 52p.

[0048] The communication passage 54x opens at the bottom surface 58x of the recess 55x. The position of the opening 54xo of the communication passage 54x is a position closer to the side Db of the rear side surface 57x in the bottom surface 58x. A part of the edge of the opening 54xo of this communication passage 54x is a part of the rear side surface 57x.

[0049] As shown in FIG. 8, a part of the drain DN flowing along the positive pressure surface 52p toward the side Db of the trailing edge 52r flows along the front side surface 56 of the recess 55x. Also, another part of the drain DN flowing along the positive pressure surface 52p toward the side Db of the trailing edge 52r, even when reaching the position of the front side surface 56, does not flow into the recess 55x along this front side surface 56, but collides with the rear side surface 57x of the recess 55x due to the inertial force of the drain flow. A part of the drain DN that has collided with the rear side surface 57x flows along the rear side surface 57x into the inner side Dsi of the recess, and then flows into the communication passage 54x. Also, another part of the drain DN that has collided with the rear side surface 57x may flow along the rear side surface 57x to the outer side Dso of the recess and be discharged outside the recess 55x.

[0050] As shown in Figure 9, a vortex flow Vf of steam S and drain DN is generated within the recess 55x. This vortex flow Vf flows along the rear surface 57x toward the inside of the recess Dsi, then along the bottom surface 58x toward the side Df of the front edge 52s, and further toward the outside of the recess Dso along the front surface 56. In the comparative example, within the vortex flow Vf, a portion of the drain DN that has flowed into the recess 55x may be discharged to the outside of the recess Dso due to the flow along the front surface 56 toward the outside of the recess Dso.

[0051] Next, the function of the stator vane body 52 in this embodiment will be explained with reference to Figure 6.

[0052] Due to the pressure difference between the recess 55 and the wing space 53, an attractive force F acts from the wing space 53 into the recess 55 via the connecting passage 54. In this embodiment, the opening 54o of the connecting passage 54 is located on the bottom surface 58, closer to the front surface 56. Moreover, a portion of the edge of the opening 54o of the connecting passage 54 is part of the front surface 56. Therefore, in this embodiment, the attractive force F acts on the inside of the recess Dsi at a position along the front surface 56.

[0053] In this embodiment as well, similar to the comparative example, a portion of the drain DN flowing along the positive pressure surface 52p to the side Db of the trailing edge 52r flows along the front surface 56 of the recess 55. Another portion of the drain DN flowing along the positive pressure surface 52p to the side Db of the trailing edge 52r, even when it reaches the front surface 56, flows along this front surface 56 and does not flow into the recess 55, but collides with the rear surface 57 of the recess 55 due to the inertial force of the drain flow.

[0054] In this embodiment, the rear surface 57 is inclined at an acute angle with respect to the positive pressure surface 52p, so that it approaches the side Db of the trailing edge 52r as it moves toward the inner surface Dsi of the recess. In other words, in this embodiment, the rear surface 57 is inclined at an acute angle with respect to the positive pressure surface 52p, so that as it moves toward the direction in which the drain DN flows due to inertial force, it gradually moves toward the inner surface Dsi of the recess. Therefore, in this embodiment, most of the drain DN that collides with the rear surface 57 flows along the rear surface 57 toward the inner surface Dsi of the recess, and hardly flows toward the outer surface Dso of the recess on the opposite side of the inner surface Dsi.

[0055] In this embodiment, as in the comparative example, a vortex flow Vf of steam S and drain DN is generated within the recess 55. This vortex flow Vf flows along the rear surface 57 toward the inner side Dsi of the recess, then along the bottom surface 58 toward the side Df of the leading edge 52s, and further toward the outer side Dso of the recess along the front surface 56. As described above, the rear surface 57 in this embodiment is inclined at an acute angle with respect to the positive pressure surface 52p so that it approaches the side Db of the trailing edge 52r as it approaches the inner side Dsi of the recess. The bottom surface 58 in this embodiment extends from the edge of the inner side Dsi of the recess of the rear surface 57 toward the side of the front surface 56, and is inclined with respect to the positive pressure surface 52p so that it gradually moves toward the inner side Dsi of the recess as it approaches the side of the front surface 56. Therefore, the vortex flow Vf is inhibited and weakened compared to the comparative example, where the rear side surface 57x extends only to the inner recess Dsi perpendicular to the positive pressure surface 52p, and the bottom surface 58x is substantially parallel to the positive pressure surface 52p. As a result, the flow along the front side surface 56 toward the outer recess Dso in the vortex flow Vf is weakened, and this flow can reduce the possibility that some of the drain DN that has flowed into the recess 55 will be discharged to the outer recess Dso.

[0056] Furthermore, in this embodiment, due to the inertial force of the drain flow, as the drain DN flows from the edge of the front surface 56 of the recess 55 toward the rear surface 57 of the recess 55, the aforementioned suction force F acts on the drain DN at a position closer to the front surface 56. Therefore, the position where the drain DN collides in the rear surface 57 is closer to the inside of the recess Dsi, that is, the bottom surface 58. From this viewpoint as well, in this embodiment, the drain DN that collides with the rear surface 57 hardly flows toward the outside of the recess Dso. Also, in this embodiment, in the vortex flow Vf of steam S and drain DN within the recess 55, the flow along the front surface 56 toward the outside of the recess Dso is weakened by the suction force F from the communication passage 54. From this viewpoint as well, in this embodiment, the possibility of drain DN that flows into the recess 55 being discharged toward the outside of the recess Dso can be reduced.

[0057] As described above, the bottom surface 58 in this embodiment extends from the edge of the inner recess Dsi of the rear surface 57 towards the front surface 56, and is inclined with respect to the positive pressure surface 52p so that it gradually moves toward the inner recess Dsi as it approaches the front surface 56. Therefore, in this embodiment, the drain DN that collides with the rear surface 57 and travels from the rear surface 57 to the bottom surface 58 flows along this bottom surface 58 toward the front surface 56. As this drain DN flows toward the front surface 56, it flows into the communication passage 54. Thus, in this embodiment, the drain DN does not remain on the bottom surface 58 but flows efficiently into the communication passage 54.

[0058] In this embodiment, as described above, since a part of the edge of the opening 54o of the communication passage 54 is part of the front surface 56, the drain DN that has flowed along the front surface 56 can be smoothly guided into the communication passage 54.

[0059] Furthermore, the blade body 52 of this embodiment has two connecting passages 54. These two connecting passages 54 are spaced apart from each other in the direction De extending from the recess and open at the bottom surface 58. Therefore, the opening area of ​​the two connecting passages 54 at the bottom surface 58 is smaller than the opening area of ​​the recess 55. Thus, in this embodiment, the flow rate of steam flowing out into the blade internal space 53 through the two connecting passages 54 can be suppressed. As described above, in this embodiment, the flow rate of steam flowing out into the blade internal space 53 can be suppressed, and thus the decrease in the efficiency of the steam turbine can be suppressed.

[0060] As described above, in this embodiment, the possibility of drain DN flowing into the recess 55 being discharged outside the recess 55 can be reduced compared to the comparative example, and drain DN can be efficiently collected in the recess 55. As a result, in this embodiment, while suppressing the discharge of steam S in the steam flow path 17, drain DN adhering to the positive pressure surface 52p can be efficiently discharged outside the steam flow path 17.

[0061] In this embodiment, there is one recess 55, but there may be two or more recesses 55. When two or more recesses 55 are provided, it is preferable that they are spaced apart from each other in the recess extension direction De and arranged in the recess extension direction De.

[0062] "Second Embodiment of the Stationary Wings" Next, a second embodiment of the stationary wings will be described with reference to Figures 10 and 11.

[0063] The stator vane in this embodiment differs from the stator vane in the first embodiment only in its structure for discharging drain DN from the wing body 52a. The wing body 52a in this embodiment has, as a structure for discharging drain DN, a wing internal space 53, a recess 55a that recesses from the positive pressure surface 52p into the inner surface Dsi of the recess, and two communication passages 54 that connect the recess 55a and the wing internal space 53, similar to the wing body 52 in the first embodiment. The recess 55a in this embodiment is defined by having a front surface 56, a rear surface 57, and a bottom surface 58, similar to the recess 55 in the first embodiment. The recess 55a in this embodiment is further defined by an introduction surface 59. This introduction surface 59 is connected to the positive pressure surface 52p and the front surface 56, and is inclined with respect to the positive pressure surface 52p and the front surface 56 so as it approaches the side Db of the trailing edge 52r, it gradually moves towards the inner surface Dsi of the recess. The introduction surface 59 may be a flat surface or a curved surface.

[0064] Water flowing along a surface experiences an adsorption force from that surface. Therefore, as shown in Figure 11, when the drain DN flowing along the positive pressure surface 52p reaches the inlet surface 59, it receives an adsorption force from this inlet surface 59 and flows along the inlet surface 59. A portion of the drain DN flowing along the inlet surface 59 reaches the front surface 56 of the recess 55a, where it receives an adsorption force from this front surface 56 and flows along the front surface 56. Therefore, in this embodiment, the amount of drain DN flowing along the front surface 56 can be increased compared to when there is no inlet surface 59.

[0065] Furthermore, even when the remaining portion of the drain DN flowing along the introduction surface 59 reaches the front surface 56 of the recess 55a, it flows along this front surface 56 and does not flow into the recess 55a, but instead collides with the rear surface 57 of the recess 55a due to the inertial force of the drain flow. In this embodiment, as described above, the amount of drain DN flowing along the front surface 56 is increased, so the amount of drain DN that collides with the rear surface 57 of the recess 55a can be reduced. Moreover, in this embodiment, since the inertial force of the drain flow is in the direction along the introduction surface 59, the position where this drain DN collides in the rear surface 57 is closer to the inside of the recess Dsi, that is, the bottom surface 58. For this reason, in this embodiment, the possibility of drain DN that has flowed into the recess 55a being discharged to the outside of the recess Dso can be reduced.

[0066] "Third Embodiment of the Stationary Wings" Next, a third embodiment of the stationary wings will be described with reference to Figure 12.

[0067] The stator vane in this embodiment differs from the stator vane in the first embodiment only in its structure for discharging drain DN from the wing body 52c. The wing body 52c in this embodiment has an internal wing space 53, similar to the wing body 52 in the first embodiment, as a structure for discharging drain DN. The wing body 52c in this embodiment further has a first recess 55b, a second recess 55c, two connecting passages 54 that connect the first recess 55b and the internal wing space 53, two connecting passages 54 that connect the second recess 55c and the internal wing space 53, a plurality of grooves 60 connected to the first recess 55b, and a plurality of grooves 60 connected to the second recess 55c.

[0068] The configurations of the first recess 55b and the second recess 55c are the same as those of the recess 55 in the first embodiment. The configurations of the first recess 55b and the second recess 55c may also be the same as those of the recess 55a in the second embodiment. In this embodiment, the second recess 55c is spaced apart from the first recess 55b in the recess extending direction De and is aligned in the recess extending direction De. Here, the side where the outer shroud 62 exists in the recess extending direction De is called the outer shroud side Deo, and the side where the inner shroud 61 exists in the recess extending direction De is called the inner shroud side Dei.

[0069] The multiple first grooves 60b, which are multiple grooves 60 connected to the first recess 55b, and the multiple second grooves 60c, which are multiple grooves 60 connected to the second recess 55c, all have a component in the drain flow direction Ddf perpendicular to the blade height direction Dh and toward the side Db of the trailing edge 52r from the leading edge 52s, and a component in the blade height direction Dh on the side where the outer shroud 62 is located, and extend in the groove extension direction Dge intersecting the recess extension direction De. The multiple first grooves 60b and the multiple second grooves 60c are aligned in the recess extension direction De.

[0070] Each groove 60 has a leading edge end 60sf, which is the end of the side Df of the leading edge 52s in the drain flow direction Ddf, and a trailing edge end 60sb, which is the end of the side Db of the trailing edge 52r in the drain flow direction Ddf. Multiple first grooves 60b are formed in the positive pressure surface 52p in the region on the side Df of the leading edge 52s, rather than in the first recess 55b. The trailing edge ends 60sb of the multiple first grooves 60b are connected to the first recess 55b. Multiple second grooves 60c are formed in the positive pressure surface 52p in the region on the side Df of the leading edge 52s, rather than in the second recess 55c. The trailing edge ends 60sb of the multiple second grooves 60c are connected to the second recess 55c.

[0071] Here, among the multiple first grooves 60b, the first groove 60b on the innermost shroud side Dei is designated as the inner shroud side first groove 60b2. The position of the recess extension direction De at the leading edge side end 60sf of this inner shroud side first groove 60b2 is on the inner shroud side Dei than the position of the recess extension direction De at the edge of the outer shroud side Deo of the second recess 55c.

[0072] In this embodiment, a portion of the drain DN flowing along the positive pressure surface 52p is collected in the multiple first grooves 60b and then flows into the first recess 55b. Another portion of the drain DN flowing along the positive pressure surface 52p is collected in the multiple second grooves 60c and then flows into the second recess 55c. Therefore, in this embodiment, a larger amount of drain DN can be collected than in the case without the grooves 60.

[0073] Furthermore, in this embodiment, drain DN in the positive pressure surface 52p, between the first recess 55b and the second recess 55c, and on the side Df that is ahead of the leading edge 52s of these recesses 55, can be collected by the first groove 60b2 on the inner shroud side that is connected to the first recess 55b.

[0074] In this embodiment, the wing body 52c has a plurality of recesses 55b, 55c, but as with the wing body 52 of the first embodiment, the number of recesses may be one. Alternatively, the number of recesses may be three or more. In these cases as well, it is preferable that a plurality of grooves 60 are connected to each recess. In this case, of the two adjacent recesses in the recess extension direction De, the recess on the outer shroud side Deo becomes the first recess, and the recess on the inner shroud side Dei becomes the second recess.

[0075] "Fourth Embodiment of the Stationary Wings" Next, the fourth embodiment of the stationary wings will be described with reference to Figure 13.

[0076] The stator vane in this embodiment is a modified version of the stator vane in the third embodiment. The wing body 52d in this embodiment, like the wing body 52c in the third embodiment, has a first recess 55d, a second recess 55e, two communication passages 54 connecting the first recess 55d and the wing internal space 53, two communication passages 54 connecting the second recess 55e and the wing internal space 53, a plurality of grooves 60 connected to the first recess 55d, and a plurality of grooves 60 connected to the second recess 55e.

[0077] The configurations of the first recess 55d and the second recess 55e are the same as those of the recess 55 in the first embodiment. The configurations of the first recess 55d and the second recess 55c may also be the same as those of the recess 55a in the second embodiment. In this embodiment, the second recess 55e is spaced apart from the first recess 55d in the recess extending direction De and is aligned in the recess extending direction De. However, in this embodiment, the second recess 55e is adjacent to the outer shroud side Deo relative to the first recess 55d. That is, in this embodiment, the relative position of the second recess 55e with respect to the first recess 55d is different from that of the third embodiment.

[0078] The multiple first grooves 60d, which are multiple grooves 60 connected to the first recess 55d, and the multiple second grooves 60e, which are multiple grooves 60 connected to the second recess 55e, all have a component in the drain flow direction Ddf perpendicular to the blade height direction Dh and toward the side Db of the trailing edge 52r from the leading edge 52s, and a component in the blade height direction Dh toward the side where the inner shroud 61 is located, and extend in the groove extension direction Dge which intersects the recess extension direction De. In other words, in this embodiment, the direction in which the multiple grooves 60 extend is different from that of the third embodiment. The multiple first grooves 60d and the multiple second grooves 60e are aligned in the recess extension direction De.

[0079] Multiple first grooves 60d are formed in the positive pressure surface 52p in a region Df on the leading edge 52s side of the first recess 55d. The trailing edge ends 60sb of the multiple first grooves 60d are connected to the first recess 55d. Also, multiple second grooves 60e are formed in the positive pressure surface 52p in a region Df on the leading edge 52s side of the second recess 55e. The trailing edge ends 60sb of the multiple second grooves 60e are connected to the second recess 55e.

[0080] Here, among the multiple first grooves 60d, the first groove 60d that is furthest to the outer shroud side Deo is designated as the outer shroud side first groove 60d2. The position of the recess extension direction De at the leading edge side end 60sf of this outer shroud side first groove 60d2 is on the outer shroud side Deo than the position of the recess extension direction De at the edge of the inner shroud side Dei of the second recess 55e.

[0081] In this embodiment, a portion of the drain DN flowing along the positive pressure surface 52p is collected in the multiple first grooves 60d and then flows into the first recess 55d. Another portion of the drain DN flowing along the positive pressure surface 52p is collected in the multiple second grooves 60e and then flows into the second recess 55e. Therefore, in this embodiment as well, similar to the third embodiment, the amount of drain DN collected can be increased compared to when there are no grooves 60.

[0082] Furthermore, in this embodiment, drain DN in the positive pressure surface 52p between the first recess 55d and the second recess 55e, and on the side Df that is ahead of the leading edge 52s of these recesses 55, can be collected by the first groove 60d2 on the outer shroud side that is connected to the first recess 55d.

[0083] In this embodiment, the wing body 52d has a plurality of recesses 55d, 55e, but as with the wing body 52 of the first embodiment, the number of recesses may be one. Alternatively, the number of recesses may be three or more. In these cases as well, it is preferable that a plurality of grooves 60 are connected to each recess. In this case, of the two adjacent recesses in the recess extension direction De, the recess on the inner shroud side Dei becomes the first recess, and the recess on the outer shroud side Deo becomes the second recess.

[0084] "Fifth Embodiment of the Stationary Wings" Next, the fifth embodiment of the stationary wings will be described with reference to Figures 14 and 15.

[0085] The stator vane in this embodiment differs from the stator vane in the first embodiment only in its structure for discharging drain from the wing body 52f. The wing body 52f in this embodiment has, as a structure for discharging drain, a wing internal space 53, a recess 55f that is recessed from the positive pressure surface 52p into the inner side Dsi of the recess, and two communication passages 54 that connect the recess 55f and the wing internal space 53, similar to the wing body 52 in the first embodiment. The recess 55f in this embodiment has an outer recess 55fo and an inner recess 55fi. Both the outer recess 55fo and the inner recess 55fi extend in the recess extension direction De having a component in the wing height direction Dh, similar to the recesses 55 and 55a in the above embodiments. In the following, the direction perpendicular to the positive pressure surface 52p, with the side of the wing internal space 53 facing the positive pressure surface 52p being referred to as the inner side Dsi, and the side opposite to this inner side Dsi being referred to as the outer side Dso. Therefore, the inner wing Dsi is the inner recess Dsi in each of the above embodiments, and the outer wing Dso is the outer recess Dso in each of the above embodiments.

[0086] The outer recess 55fo is recessed from the positive pressure surface 52p toward the inner side Dsi of the wing. This outer recess 55fo is defined by an outer front surface 56fo located on the side Df of the leading edge 52s, an outer rear surface 57fo located on the side Db of the trailing edge 52r and facing the outer front surface 56fo, and an outer bottom surface 58fo extending from the inner side Dsi of the outer front surface 56fo toward the side Df of the leading edge 52s. The outer rear surface 57fo extends in the recess extension direction De, similar to the rear side surface 57 in the embodiment described above, and is inclined to form an acute angle with respect to the positive pressure surface 52p, gradually approaching the side Db of the trailing edge 52r as it moves from the edge of the positive pressure surface 52p toward the inner side Dsi of the wing.

[0087] The inner recess 55fi is recessed from the outer bottom surface 58fo toward the inner wing Dsi. This inner recess 55fi is defined by an inner front surface 56fi located on the side Df of the leading edge 52s, an inner rear surface 57fi located on the side Db of the trailing edge 52r and facing the inner front surface 56fi, and an inner bottom surface 58fi connecting the edge of the inner wing Dsi of the inner front surface 56fi and the edge of the inner wing Dsi of the inner rear surface 57fi. The inner front surface 56fi is located slightly on the side Db of the trailing edge 52r than the outer front surface 56fo. The inner rear surface 57fi is located on the side Df of the leading edge 52s than the edge of the inner wing Dsi of the outer rear surface 57fo. The inner bottom surface 58fi is located on the inner wing Dsi than the outer bottom surface 58fo.

[0088] Similar to the bottom surface 58 in the above embodiment, the inner bottom surface 58fi has openings for each of the two connecting passages 54. Of the two connecting passages 54, the position of the opening 54o of one connecting passage 54 is spaced apart in the recess extension direction De from the position of the opening 54o of the other connecting passage 54. Therefore, the inner bottom surface 58fi has a portion where the openings 54o of the connecting passages 54 exist, as shown in Figure 14, and a portion where the openings 54o of the connecting passages 54 do not exist, as shown in Figure 15. The positions of the openings 54o of the two connecting passages 54 are closer to the inner front surface 56fi within the inner bottom surface 58fi. Part of the edges of the openings 54o of the two connecting passages 54 is part of the inner front surface 56fi.

[0089] As described above, the outer rear surface 57fo in this embodiment is inclined at an acute angle with respect to the positive pressure surface 52p, similar to the rear surface 57 in each of the above embodiments, so that it approaches the side Db of the trailing edge 52r as it moves toward the inner side Dsi of the blade. Therefore, in this embodiment as well as in each of the above embodiments, even if the drain flowing along the positive pressure surface 52p toward the side Db of the trailing edge 52r collides with the outer rear surface 57fo, it flows along the outer rear surface 57fo toward the inner side Dsi of the blade and hardly flows toward the outer side Dso of the blade. Furthermore, in this embodiment as well as in the recesses 55 and 55a in each of the above embodiments, the vortex flow Vf of steam and drain in the outer recess 55fo can be weakened compared to the comparative example. Therefore, in this embodiment as well, the possibility that a portion of the drain that has flowed into the outer recess 55fo will be discharged toward the outer side Dso of the blade can be reduced. However, if the flow rate of drain along the positive pressure surface 52p to the side Db of the trailing edge 52r increases, some of the drain that has flowed into the outer recess 55fo may be discharged to the outer side Dso of the blade. Also, for example, if there is no inner recess 55fi and only an outer recess 55fo, that is, in the recess 55 of the above embodiment, drain tends to accumulate in the portion of the bottom surface 58 of the recess 55 where there is no opening 54o of the communication passage 54 in the recess extending direction De. For this reason, some of the drain accumulated in this portion may be discharged to the outer side Dso of the blade.

[0090] In this embodiment, since the inner recess 55fi is located on the inner side Dsi of the outer recess 55fo, the inflow of drain accumulated on the outer bottom surface 58fo of the outer recess 55fo into the inner recess 55fi is promoted. That is, in this embodiment, the amount of drain accumulated on the outer bottom surface 58fo of the outer recess 55fo can be reduced. Furthermore, since the inner recess 55fi is hardly affected by the vortex flow Vf of the drain in the outer recess 55fo, once drain flows into the inner recess 55fi, the possibility of this drain being discharged from the inner recess 55fi to the outer side Dso of the blade is extremely small. Furthermore, in this embodiment, as in the above embodiments, the two connecting passages 54 are located apart from each other in the recess extension direction De and open at the inner bottom surface 58fi. For this reason, in this embodiment as well, the opening area of ​​the two connecting passages 54 at the inner bottom surface 58fi is smaller than the opening area of ​​the outer recess 55fo. Therefore, in this embodiment as well, the flow rate of steam flowing out into the wing cavity 53 via the two communication passages 54 can be suppressed. For this reason, in this embodiment, drain in the wing surface can be collected more efficiently than in the above embodiments. In this embodiment, the drain that flows into the inner recess 55fi is discharged into the wing cavity 53 via the communication passages 54.

[0091] The wing body 52f of this embodiment has one recess, similar to the wing body 52 of the first embodiment. However, similar to the third and fourth embodiments, it may have multiple recesses 55f as described above, as well as multiple grooves connected to each of the multiple recesses 55f. In this case, similar to the third and fourth embodiments, the multiple recesses 55f are spaced apart in the recess extending direction De and arranged in the recess extending direction De.

[0092] "Sixth Embodiment of the Stationary Wings" Next, the sixth embodiment of the stationary wings will be described with reference to Figures 16 and 17.

[0093] The stator vane in this embodiment differs from the stator vane in the fifth embodiment only in its structure for discharging drain from the wing body 52g. The wing body 52g in this embodiment has, as a structure for discharging drain, a wing internal space 53, a recess 55g that is recessed from the positive pressure surface 52p into the inner surface Dsi of the recess, and two communication passages 54 that connect the recess 55g and the wing internal space 53, similar to the wing body 52f in the fifth embodiment. The recess 55g in this embodiment has an outer recess 55go and an inner recess 55gi, similar to the recess 55f in the fifth embodiment. Both the outer recess 55go and the inner recess 55gi extend in the recess extension direction De, which has a component in the wing height direction Dh, similar to the outer recess 55fo and inner recess 55fi in the fifth embodiment.

[0094] The outer recess 55go is recessed from the positive pressure surface 52p toward the inner wing surface Dsi. This outer recess 55go is defined by having an outer front surface 56go located on the side Df of the leading edge 52s, an outer rear surface 57go located on the side Db of the trailing edge 52r and facing the outer front surface 56go, and an outer bottom surface 58go extending from the inner wing surface Dsi of the outer front surface 56go toward the side Df of the leading edge 52s. Furthermore, this outer recess 55go is defined by having an introduction surface 59. This introduction surface 59 is connected to the positive pressure surface 52p and the outer front surface 56go, and is inclined with respect to the positive pressure surface 52p and the outer front surface 56go so that it gradually moves toward the inner wing surface Dsi as it approaches the side Db of the trailing edge 52r. The introduction surface 59 may be a flat surface or a curved surface. The outer rear surface 57go extends in the recess extension direction De, similar to the outer rear surface 57fo in the fifth embodiment, and is inclined to form an acute angle with respect to the positive pressure surface 52p, gradually approaching the side Db of the trailing edge 52r as it moves from the edge of the positive pressure surface 52p toward the inner side Dsi of the wing. The outer bottom surface 58go extends from the edge of the outer rear surface 57go toward the outer front surface 56go, and is inclined with respect to the positive pressure surface 52p, gradually moving toward the inner side Dsi of the wing as it moves toward the outer front surface 56go.

[0095] The inner recess 55gi is recessed from the outer bottom surface 58go toward the inner wing Dsi. This inner recess 55gi is defined by an inner front surface 56gi located on the side Df of the leading edge 52s, an inner rear surface 57gi located on the side Db of the trailing edge 52r and opposite to the inner front surface 56gi, and an inner bottom surface 58gi connecting the edge of the inner wing Dsi of the inner front surface 56gi and the edge of the inner wing Dsi of the inner rear surface 57gi. The inner front surface 56gi is continuous with the outer front surface 56go. That is, the inner front surface 56gi is flush with the outer front surface 56go. The inner rear surface 57gi is located on the side Df of the leading edge 52s toward the edge of the inner wing Dsi of the outer rear surface 57go. The inner bottom surface 58gi is located on the inner wing Dsi toward the outer bottom surface 58go. Similar to the bottom surface 58 in the above embodiments, the inner bottom surface 58gi has openings for each of the two connecting passages 54. In this embodiment as well, the position of the opening 54o of one of the two connecting passages 54 is spaced apart in the direction of the recess extension De from the position of the opening 54o of the other connecting passage 54. Therefore, the inner bottom surface 58gi has a portion where the openings 54o of the connecting passages 54 exist, as shown in Figure 16, and a portion where the openings 54o of the connecting passages 54 do not exist, as shown in Figure 17.

[0096] The opening 54o of each connecting passage 54 is positioned closer to the inner front surface 56gi within the inner bottom surface 58gi. A portion of the edge of the opening 54o of each connecting passage 54 is part of the inner front surface 56gi.

[0097] In this embodiment, the outer recess 55go is defined by having an introduction surface 59. Therefore, in this embodiment, as in the second embodiment, when a portion of the drain flowing along the introduction surface 59 reaches the outer front surface 56go, it receives an adsorption force from this outer front surface 56go and flows along the outer front surface 56go. For this reason, in this embodiment, the amount of drain flowing along the outer front surface 56go can be increased compared to when there is no introduction surface 59. In addition, another portion of the drain flowing along the introduction surface 59, even when it reaches the outer front surface 56go of the outer recess 55go, flows along this outer front surface 56go and does not flow into the outer recess 55go, but collides with the outer rear surface 57go of the outer recess 55go due to the inertial force of the drain flow. In this embodiment, as described above, because the amount of drain flowing along the outer front surface 56go is increased, the amount of drain colliding with the outer rear surface 57go can be reduced. Furthermore, in this embodiment, the inertial force of the drain flow is in the direction along the introduction surface 59, so the position where this drain collides in the outer rear surface 57go is closer to the inner side of the wing Dsi, that is, the outer bottom surface 58go. For this reason, in this embodiment, the possibility of drain flowing into the outer recess 55go being discharged to the outer side of the wing Dso can be reduced.

[0098] In this embodiment, the inner front surface 56gi is connected to the outer front surface 56go, and a portion of the edge of the opening 54o of each communication passage 54 is a portion of the inner front surface 56gi. Therefore, in this embodiment, as in the first embodiment, the drain that has flowed along the outer front surface 56go can be smoothly guided into the communication passage 54. Furthermore, in this embodiment, as in the first embodiment, the position of the suction force F acting from the wing internal space 53 into the recess 55g via the communication passage 54 is located along the outer front surface 56go and the inner front surface 56gi. Therefore, in this embodiment, from the above viewpoint, as in the first embodiment, the possibility of the drain that has flowed into the outer recess 55go being discharged to the outer surface Dso of the wing can be reduced.

[0099] In this embodiment, the outer rear surface 57go, like the rear surface 57 in each of the above embodiments, is inclined at an acute angle with respect to the positive pressure surface 52p, so that it approaches the side Db of the trailing edge 52r as it moves toward the inner side Dsi of the wing. Therefore, in this embodiment as well, from this viewpoint, the possibility that a portion of the drain that has flowed into the outer recess 55go will be discharged to the outer side Dso of the wing can be reduced.

[0100] In this embodiment, an inner recess 55gi is located on the inner side Dsi of the outer recess 55go, and the outer bottom surface 58go is inclined with respect to the positive pressure surface 52p such that it gradually moves toward the inner side Dsi of the wing as it approaches the outer front surface 56go. Therefore, in this embodiment, the inflow of drain accumulated on the outer bottom surface 58go of the outer recess 55go into the inner recess 55gi is promoted. Thus, in this embodiment as well, drain in the wing surface can be efficiently collected.

[0101] The wing body 52g of this embodiment has one recess 55g, similar to the wing body 52 of the first embodiment. However, similar to the third and fourth embodiments, it may have multiple recesses 55g as described above, as well as multiple grooves connected to each of the multiple recesses 55g. In this case, similar to the third and fourth embodiments, the multiple recesses 55g are spaced apart in the recess extending direction De and arranged in the recess extending direction De.

[0102] "Other Modifications" In each of the above embodiments, two connecting passages 54 are connected to the recess. However, depending on the length in the recess extension direction De of the recess, only one connecting passage 54 may be connected to the recess, or three or more connecting passages 54 may be connected to the recess.

[0103] This disclosure is not limited to the embodiments described above. Various additions, modifications, substitutions, partial deletions, etc., are possible without departing from the conceptual idea and spirit of the present invention derived from the claims and their equivalents.

[0104] "Note" The stator vane 51 in the above embodiments and modifications is understood, for example, as follows: (1) The stator vane 51 in the first embodiment is arranged in the steam passage 17 through which steam S flows, and comprises blade bodies 52, 52a, 52c, 52d, 52f, and 52g having an airfoil cross-section and extending in the blade height direction Dh perpendicular to the cross-section. Each of the wing bodies 52, 52a, 52c, 52d, 52f, and 52g has a leading edge 52s, a trailing edge 52r, a positive pressure surface 52p connecting the leading edge 52s and the trailing edge 52r, a negative pressure surface 52n connecting the leading edge 52s and the trailing edge 52r and facing the positive pressure surface 52p, an internal wing space 53 formed between the positive pressure surface 52p and the negative pressure surface 52n, recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g that recess from the positive pressure surface 52p toward the internal wing space 53, and a communication passage 54 that connects the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g with the internal wing space 53. The wing internal space 53 has an opening 53o that communicates with the outside. The recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g extend in the recess extension direction De, which has a component in the wing height direction Dh along the positive pressure surface 52p. The recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g are defined by a front surface 56 located on the side Df of the leading edge 52s, a rear surface 57 located on the side Db of the trailing edge 52r and facing the front surface 56, and a bottom surface 58 connecting the front surface 56 and the rear surface 57. The rear side surface 57 is inclined at an acute angle with respect to the positive pressure surface 52p, such that it approaches the side Db of the trailing edge 52r as it moves toward the inner side Dsi of the recess, which is the side of the wing cavity 53, with respect to the positive pressure surface 52p. The communication passage 54 opens at the bottom surface 58.

[0105] When the drain DN contained in the steam S flowing through the steam passage 17 collides with the positive pressure surface 52p, this drain DN flows along the positive pressure surface 52p to the side Db of the trailing edge 52r. A portion of the drain DN flowing along the positive pressure surface 52p is collected in the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g. The drain DN in the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g flows into the wing cavity 53 via the connecting passage 54. In other words, in this embodiment, the drain DN flowing along the positive pressure surface 52p is collected in the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g, and then the drain DN in these recesses 55, 55a, 55b, and 55c is discharged into the blade space 53 via the communication passage 54. Therefore, in this embodiment, the discharge of steam S from the steam passage 17 is suppressed while the drain DN can be discharged outside the steam passage 17.

[0106] Incidentally, a portion of the drain DN flowing along the positive pressure surface 52p toward the side Db of the trailing edge 52r does not flow into the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, 55g even when it reaches the position of the front surface 56 of the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, 55g, but instead collides with the rear surface 57 of the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, 55g due to the inertial force of the drain flow. In this embodiment, the rear surface 57 is inclined to form an acute angle with respect to the positive pressure surface 52p so that it approaches the side Db of the trailing edge 52r as it moves toward the inside Dsi of the recess. In other words, the rear surface 57 of this embodiment is inclined at an acute angle with respect to the positive pressure surface 52p so that as it moves in the direction in which the drain DN flows due to inertial force, it gradually moves toward the inner surface Dsi of the recess. Therefore, in this embodiment, most of the drain DN that collides with the rear surface 57 flows along the rear surface 57 toward the inner surface Dsi of the recess, and hardly flows toward the outer surface Dso of the recess on the opposite side of the inner surface Dsi. Thus, in this embodiment, the drain DN that collides with the rear surface 57 can be efficiently collected in the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g.

[0107] In this embodiment, a vortex flow Vf of steam S and drain DN is generated within the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g. This vortex flow Vf flows along the rear surface 57 toward the inner surface Dsi of the recess, then along the bottom surface 58 toward the side Df of the leading edge 52s, and further toward the outer surface Dso of the recess along the front surface 56. As described above, the rear surface 57 in this embodiment is inclined at an acute angle with respect to the positive pressure surface 52p so that it approaches the side Db of the trailing edge 52r as it moves toward the inner surface Dsi of the recess. Therefore, the vortex flow Vf is inhibited and weakened compared to the case where the rear surface 57 extends only toward the inner surface Dsi of the recess perpendicular to the positive pressure surface 52p. As a result, in the vortex flow Vf, the flow along the front side surface 56 toward the outer recess Dso is weakened, and this flow reduces the possibility that the drain DN that has flowed into the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g will be discharged to the outer recess Dso.

[0108] As described above, in this embodiment, efficient drain DN can be collected in the recesses 55, 55a, 55b, 55c, 55d, 55e, 55f, and 55g.

[0109] (2) In the second embodiment, the stator vane 51 is such that, in the stator vane 51 of the first embodiment, the position of the opening 54o of the communication passage 54 is located on the bottom surface 58, closer to the front surface 56.

[0110] Due to the pressure difference between the recesses 55, 55a, 55b, 55c, 55d, 55e and the wing space 53, an attractive force F acts from the wing space 53 into the recesses 55, 55a, 55b, 55c, 55d, 55e via the connecting passage 54. In this embodiment, the opening 54o of the connecting passage 54 is located on the bottom surface 58, closer to the front side surface 56. Therefore, due to the inertial force of the drain flow, as the drain DN flows from the edge of the front side surface 56 of the recesses 55, 55a, 55b, 55c, 55d, 55e toward the rear side surface 57, the aforementioned attractive force F acts on the drain DN at a position closer to the front side surface 56. This drain DN then collides with the rear side surface 57. Within the rear surface 57, the position where the drain DN collides is closer to the inner side Dsi of the recess, that is, the side of the bottom surface 58, due to the suction force F acting before it collides with the rear surface 57. Therefore, in this embodiment, the possibility that the drain DN that flows into the recesses 55, 55a, 55b, 55c, 55d, and 55e is discharged to the outer side Dso of the recess can be reduced.

[0111] Furthermore, in the vortex flow Vf of steam S and drain DN within the recesses 55, 55a, 55b, 55c, 55d, and 55e, the flow along the front surface 56 toward the outside of the recess Dso is weakened by the suction force F from the connecting passage 54. Therefore, in this embodiment, from this viewpoint as well, the possibility of drain DN flowing into the recesses 55, 55a, 55b, 55c, 55d, and 55e being discharged to the outside of the recess Dso can be reduced.

[0112] As described above, in this embodiment, the possibility of drain DN flowing into the recesses 55, 55a, 55b, 55c, 55d, and 55e being discharged to the outside of the recess Dso can be reduced, and as a result, drain DN can be efficiently collected in the recesses 55, 55a, 55b, 55c, 55d, and 55e.

[0113] (3) In the third embodiment, the stationary vane 51 is such that, in the stationary vane 51 of the first embodiment, the bottom surface 58 extends from the edge of the inner surface Dsi of the recess of the rear surface 57 toward the front surface 56 and is inclined with respect to the positive pressure surface 52p such that it gradually moves toward the inner surface Dsi of the recess toward the front surface 56.

[0114] In this embodiment, as described above, a vortex flow Vf of steam S and drain DN is generated in the recesses 55, 55a, 55b, 55c, 55d, and 55e. The bottom surface 58 in this embodiment is inclined with respect to the positive pressure surface 52p such that it gradually moves towards the inside of the recess Dsi as it approaches the front surface 56. As a result, the vortex flow Vf is inhibited and weakened compared to when the bottom surface 58 is parallel to the positive pressure surface 52p. Consequently, the flow in the vortex flow Vf that moves along the front surface 56 toward the outside of the recess Dso is weakened, and this flow reduces the possibility that drain DN that has flowed into the recesses 55, 55a, 55b, 55c, 55d, and 55e will be discharged to the outside of the recess Dso.

[0115] (4) In the fourth embodiment, the stator vane 51 is such that, in the stator vane 51 of the third embodiment, the position of the opening 54o of the communication passage 54 is located on the bottom surface 58, closer to the front surface 56.

[0116] Due to the pressure difference between the recesses 55, 55a, 55b, 55c, 55d, 55e and the wing space 53, an attractive force F acts from the wing space 53 into the recesses 55, 55a, 55b, 55c, 55d, 55e via the connecting passage 54. In this embodiment, the opening 54o of the connecting passage 54 is located on the bottom surface 58, closer to the front side surface 56. Therefore, due to the inertial force of the drain flow, as the drain DN flows from the edge of the front side surface 56 of the recesses 55, 55a, 55b, 55c, 55d, 55e toward the rear side surface 57, the aforementioned attractive force F acts at a position closer to the front side surface 56. This drain DN then collides with the rear side surface 57. Within the rear surface 57, the position where the drain DN collides is closer to the inner side Dsi of the recess, that is, the side of the bottom surface 58, due to the suction force F acting before it collides with the rear surface 57. Therefore, in this embodiment, the possibility that the drain DN that flows into the recesses 55, 55a, 55b, 55c, 55d, and 55e is discharged to the outer side Dso of the recess can be reduced.

[0117] Furthermore, in the vortex flow Vf of steam S and drain DN within the recesses 55, 55a, 55b, 55c, 55d, and 55e, the flow along the front surface 56 toward the outside of the recess Dso is weakened by the suction force F from the connecting passage 54. Therefore, in this embodiment, from this viewpoint as well, the possibility of drain DN flowing into the recesses 55, 55a, 55b, 55c, 55d, and 55e being discharged to the outside of the recess Dso can be reduced.

[0118] As described above, in this embodiment, the possibility of drain DN flowing into the recesses 55, 55a, 55b, 55c, 55d, and 55e being discharged to the outside of the recess Dso can be reduced, and as a result, drain DN can be efficiently collected in the recesses 55, 55a, 55b, 55c, 55d, and 55e.

[0119] Furthermore, the bottom surface 58 in this embodiment is inclined with respect to the positive pressure surface 52p such that it gradually moves towards the inner side Dsi of the recess as it approaches the front side surface 56. As a result, the drain DN flows from the rear side surface 57 to the bottom surface 58 and then along this bottom surface 58 towards the front side surface 56. In the process of flowing towards the front side surface 56, this drain DN flows into the communication passage 54. Therefore, in this embodiment, the drain DN does not remain on the bottom surface 58 but flows efficiently into the communication passage 54.

[0120] (5) In the fifth embodiment, the stationary vane 51 is such that, in any one of the second to fourth embodiments, a part of the edge of the opening 54o of the communication passage 54 is a part of the front surface 56.

[0121] A portion of the drain DN flowing along the positive pressure surface 52p to the side Db of the trailing edge 52r flows along the front surface 56 of the recesses 55, 55a, 55b, 55c, 55d, and 55e. In this embodiment, since a portion of the edge of the opening 54o of the communication passage 54 is part of the front surface 56, the drain DN that has flowed along the front surface 56 can be smoothly guided into the communication passage 54. Furthermore, in this embodiment, the position of the suction force F acting from the wing internal space 53 through the communication passage 54 into the recesses 55, 55a, 55b, 55c, 55d, and 55e is located along the front surface 56. Therefore, in this embodiment, due to the inertial force of the drain flow, as the drain DN flows from the edge of the front surface 56 of the recesses 55, 55a, 55b, 55c, 55d, 55e toward the rear surface 57 of the recesses 55, 55a, 55b, 55c, 55d, 55e toward the rear surface 57 of the recesses 55, 55a, 55b, 55c, 55d, 55e toward the rear surface 57, the aforementioned suction force F acts at a position along the front surface 56. This drain DN then collides with the rear surface 57. Within the rear surface 57, the position where the drain DN collides is closer to the inside of the recess Dsi, that is, the bottom surface 58, due to the suction force F acting before it collides with the rear surface 57. Therefore, in this embodiment, the possibility of drain DN that has flowed into the recesses 55, 55a, 55b, 55c, 55d, 55e being discharged to the outside of the recess Dso can be reduced.

[0122] (6) The stator vane 51 in the sixth embodiment is the stator vane 51 in any one of the first to fifth embodiments, wherein the recess 55a is connected to the positive pressure surface 52p and the front surface 56, and has an introduction surface 59 that is inclined with respect to the positive pressure surface 52p and the front surface 56 so as it approaches the side Db of the trailing edge 52r, it gradually moves toward the inside of the recess Dsi.

[0123] Water flowing along a surface experiences an adsorption force from that surface. Therefore, when the drain DN flowing along the positive pressure surface 52p reaches the inlet surface 59, it receives an adsorption force from this inlet surface 59 and flows along the inlet surface 59. A portion of the drain DN flowing along the inlet surface 59 reaches the front surface 56 of the recess 55a, where it receives an adsorption force from this front surface 56 and flows along the front surface 56. For this reason, in this embodiment, the amount of drain DN flowing along the front surface 56 can be increased compared to when there is no inlet surface 59.

[0124] Furthermore, even when a portion of the drain DN flowing along the introduction surface 59 reaches the front surface 56 of the recess 55a, it flows along this front surface 56 and does not flow into the recess 55a, but instead collides with the rear surface 57 of the recess 55a due to the inertial force of the drain flow. In this embodiment, as described above, the amount of drain DN flowing along the front surface 56 is increased, so the amount of drain DN that collides with the rear surface 57 of the recess 55a can be reduced. Moreover, in this embodiment, since the inertial force of the drain flow is in the direction along the introduction surface 59, the position where this drain DN collides in the rear surface 57 is closer to the inside Dsi of the recess, that is, the bottom surface 58. For this reason, in this embodiment, the possibility of drain DN that has flowed into the recess 55a being discharged outside the recess 55a can be reduced.

[0125] (7) In the seventh embodiment, the stator vane 51 in any one of the first to sixth embodiments has a plurality of communication passages 54. The plurality of communication passages 54 are spaced apart from each other in the direction De of the recess extension and open at the bottom surface 58.

[0126] The wing body 52 in this embodiment has a plurality of connecting passages 54. The plurality of connecting passages 54 are spaced apart from each other in the direction De extending from the recess and open at the bottom surface 58. Therefore, the opening area of ​​the plurality of connecting passages 54 at the bottom surface 58 is smaller than the opening area of ​​the recess 55. Thus, in this embodiment, the flow rate of steam flowing out into the wing internal space 53 through the plurality of connecting passages 54 can be suppressed.

[0127] (8) The stator vane 51 in the eighth embodiment is such that, in the stator vane 51 in the first embodiment, the recesses 55f and 55g have outer recesses 55fo and 55go and inner recesses 55fi and 55gi. Both the outer recesses 55fo and 55go and the inner recesses 55fi and 55gi extend in the recess extension direction De having a component in the wing height direction Dh. The outer recesses 55fo and 55go are defined by an outer front surface 56fo and 56go located on the side Df of the leading edge 52s, recessed from the positive pressure surface 52p on the inner side Dsi of the wing, which is on the side of the wing's internal space 53 relative to the positive pressure surface 52p; an outer rear surface 57fo and 57go located on the side Db of the trailing edge 52r, which is further than the outer front surface 56fo and 56go; and an outer bottom surface 58fo and 58go extending from the inner side Dsi of the wing to the side Df of the leading edge 52s on the outer front surface 56fo and 56go. The inner recesses 55fi, 55gi are recessed from the outer bottom surfaces 58fo, 58go toward the inner surface Dsi of the wing and are defined by inner front surfaces 56fi, 56gi located on the side Df of the leading edge 52s, inner rear surfaces 57fi, 57gi located on the side Db of the trailing edge 52r and facing the inner front surfaces 56fi, 56gi, and inner bottom surfaces 58fi, 58gi connecting the edges of the inner surface Dsi of the wing on the inner front surfaces 56fi, 56gi and the edges of the inner surface Dsi of the wing on the inner rear surfaces 57fi, 57gi. The rear side surfaces are the outer rear surfaces 57fo, 57go. The bottom surfaces are the inner bottom surfaces 58fi, 58gi.

[0128] In this embodiment, since the inner recesses 55fi and 55gi are located on the inner surface Dsi of the outer recesses 55fo and 55go, the inflow of drain accumulated on the outer bottom surfaces 58fo and 58go of the outer recesses 55fo and 55go into the inner recesses 55fi and 55gi is promoted. In other words, in this embodiment, the amount of drain accumulated on the outer bottom surfaces 58fo and 58go of the outer recesses 55fo and 55go can be reduced. Furthermore, since the inner recesses 55fi and 55gi are hardly affected by the vortex flow Vf of the drain in the outer recesses 55fo and 55go, once drain flows into the inner recesses 55fi and 55gi, the possibility of this drain being discharged from the inner recesses 55fi and 55gi to the outer surface Dso (opposite side of the inner surface Dsi) is extremely small. For this reason, drain in the wing surface can be efficiently collected.

[0129] (9) In the ninth embodiment, the stationary vane 51 is such that, in the stationary vane 51 of the eighth embodiment, the position of the opening 54o of the communication passage 54 is located on the side of the inner front surfaces 56fi, 56gi within the inner bottom surfaces 58fi, 58gi.

[0130] In this embodiment, as in the second embodiment, due to the inertial force of the drain flow, as the drain flows from the edges of the outer front surfaces 56fo and 56go toward the outer rear surfaces 57fo and 57go, a suction force F from the wing internal space 53 acts on the drain at a position closer to the inner front surfaces 56fi and 56gi. Therefore, in this embodiment, as in the second embodiment, the possibility of the drain that has flowed into the outer recesses 55fo and 55go being discharged to the outer surface Dso of the wing can be reduced.

[0131] (10) In the tenth embodiment, the stator vane 51 is such that, in the stator vane 51 of the eighth embodiment, the outer bottom surfaces 58fo, 58go extend from the edge of the inner surface Dsi of the outer rear surface 57fo, 57go toward the outer front surface 56fo, 56go, and are inclined with respect to the positive pressure surface 52p such that they gradually move toward the inner surface Dsi of the outer front surface 56fo, 56go toward the outer front surface 56fo, 56go.

[0132] In this embodiment, the inflow of drain accumulated on the outer bottom surfaces 58fo and 58go into the inner recesses 55fi and 55gi is promoted. Furthermore, in this embodiment as well as in the third embodiment, the vortex flow Vf within the outer recesses 55fo and 55go is inhibited and weakened compared to the case where the outer bottom surfaces 58fo and 58go are parallel to the positive pressure surface 52p. Therefore, in this embodiment, the possibility of drain that has flowed into the outer recesses 55fo and 55go being discharged to the outer surface Dso of the blade can be reduced.

[0133] (11) In the eleventh embodiment, the stator vane 51 is positioned such that the opening 54o of the communication passage 54 is located on the side of the inner front surfaces 56fi, 56gi within the inner bottom surfaces 58fi, 58gi.

[0134] In this embodiment, as in the second and ninth embodiments, due to the inertial force of the drain flow, as the drain flows from the edges of the outer front surfaces 56fo and 56go toward the outer rear surfaces 57fo and 57go, a suction force F from the wing internal space 53 acts on the drain at a position closer to the inner front surfaces 56fi and 56gi. Therefore, in this embodiment, as in the second and ninth embodiments, the possibility of the drain that has flowed into the outer recesses 55fo and 55go being discharged to the outer surface Dso of the wing can be reduced.

[0135] (12) In the twelfth embodiment, the stationary vane 51 in any one of the nineth to eleventh embodiments has an inner front surface 56gi connected to the outer front surface 56go. A part of the edge of the opening 54o of the communication passage 54 is a part of the inner front surface 56gi.

[0136] In this embodiment, as in the fifth embodiment, the drain that has flowed along the outer front surface 56go can be smoothly guided into the communication passage 54. Furthermore, in this embodiment, as in the fifth embodiment, the position of the suction force F acting from the wing internal space 53 through the communication passage 54 into the recess 55g is located along the outer front surface 56go and the inner front surface 56gi. Therefore, in this embodiment, from the above viewpoint, as in the fifth embodiment, the possibility of the drain that has flowed into the outer recess 55go being discharged to the outer surface Dso of the wing can be reduced.

[0137] (13) The stator vane 51 in the thirteenth embodiment is the stator vane 51 in any one of the eighth to twelfth embodiments, wherein the outer recess 55go is connected to the positive pressure surface 52p and the outer front surface 56go, and has an introduction surface 59 that is inclined with respect to the positive pressure surface 52p and the outer front surface 56go so that it gradually moves toward the inner side Dsi of the vane as it moves toward the side Db of the trailing edge 52r.

[0138] When the drain that has flowed along the positive pressure surface 52p reaches the inlet surface 59, it receives an adsorption force from this inlet surface 59, and a portion of this drain flows along the inlet surface 59. Therefore, in this embodiment as well, similar to the sixth embodiment, the amount of drain that flows along the outer front surface 56go can be increased compared to when there is no inlet surface 59.

[0139] Furthermore, even when the remaining portion of the drain flowing along the introduction surface 59 reaches the position of the outer front surface 56go, it flows along this outer front surface 56go and does not flow into the outer recess 55go, but instead collides with the outer rear surface 57go due to the inertial force of the drain flow. In this embodiment, as in the sixth embodiment, the possibility that the drain that collides with the outer rear surface 57go will be discharged from the outer recess 55go to the outer surface Dso of the blade can be reduced.

[0140] (14) In the fourteenth embodiment, the stator vane 51 is such that, in any one of the eighth to thirteen embodiments, the wing body 52 has a plurality of communication passages 54. The plurality of communication passages 54 are spaced apart from each other in the direction De of the recess extension and open at the inner bottom surfaces 58fi, 58gi.

[0141] In this embodiment, as in the seventh embodiment, the flow rate of steam flowing out into the wing cavity 53 via multiple connecting passages 54 can be suppressed.

[0142] (15) The stator vane 51 in the fifteenth embodiment is such that, in the stator vane 51 in any one of the first to fourteenth embodiments, the wing bodies 52c, 52d have grooves 60 that are recessed from the positive pressure surface 52p to the inner side Dsi of the wing, which is the side of the wing internal space 53 relative to the positive pressure surface 52p. The grooves 60 are perpendicular to the wing height direction Dh and have a component in the drain flow direction Ddf from the leading edge 52s toward the side Db of the trailing edge 52r, and a component in the wing height direction Dh, and extend in a groove extension direction Dge that intersects the recess extension direction De. The grooves 60 have a leading edge side end 60sf which is the end of the side Df of the leading edge 52s in the drain flow direction Ddf, and a trailing edge side end 60sb which is the end of the side Db of the trailing edge 52r in the drain flow direction Ddf. The groove 60 is formed in the positive pressure surface 52p in a region Df on the side of the leading edge 52s, rather than in the recesses 55b, 55c, 55d, and 55e. The trailing edge side end 60sb of the groove 60 is connected to the recesses 55b, 55c, 55d, and 55e.

[0143] In this embodiment, a portion of the drain DN flowing along the positive pressure surface 52p is collected in the groove 60 and then flows into the recesses 55b and 55c. Therefore, in this embodiment, a larger amount of drain DN can be collected than in the case without the groove 60.

[0144] (16) In the sixteenth aspect, the stator vane 51 is such that the wing body 52c has a plurality of grooves 60. The plurality of grooves 60 are arranged in the direction De of the extension of the recess.

[0145] In this embodiment, the amount of drain DN collected can be increased compared to the case where there is only one groove 60.

[0146] (17) In the seventeenth embodiment, the stator vane 51, in the stator vane 51 of the fifteenth embodiment, the wing body 52c has a plurality of recesses 55b, 55c and a plurality of grooves 60 for each of the plurality of recesses 55b, 55c. The plurality of recesses 55b, 55c are spaced apart in the recess extension direction De and are arranged in the recess extension direction De. Of the plurality of recesses 55b, 55c, the second recess 55c is adjacent to the inner shroud side Dei of the recess extension direction De, between the outer shroud side Deo and the inner shroud side Dei. Of the plurality of grooves 60 connected to the first recess 55b, the groove closest to the inner shroud side Dei is the inner shroud side first groove 60b2. The position of the recess extension direction De at the front edge end 60sf of the first groove 60b2 on the inner shroud side is closer to the inner shroud side Dei than the position of the recess extension direction De at the edge of the first side De1 of the second recess 55c in the extension direction.

[0147] In this embodiment, drain DN in the positive pressure surface 52p between the first recess 55b and the second recess 55c, and on the side Df of the leading edge 52s beyond these recesses 55b and 55c, can be collected by the first groove 60b2 on the inner shroud side which is connected to the first recess 55b.

[0148] (18) In the eighteenth embodiment, the stator vane 51 is such that, in the stator vane 51 of the fifteenth embodiment, the wing body 52d has a plurality of recesses 55d, 55e and a plurality of grooves 60 for each of the plurality of recesses 55d, 55e. The plurality of recesses 55d, 55e are spaced apart in the recess extension direction De and are arranged in the recess extension direction De. Of the plurality of recesses 55d, 55e, the second recess 55e is adjacent to the outer shroud side Deo of the outer shroud side Deo and the inner shroud side Dei in the recess extension direction De. Of the plurality of grooves 60 connected to the first recess 55d, the groove closest to the outer shroud side Deo is the outer shroud side first groove 60d2. The position of the recess extension direction De at the front edge end 60sf of the first groove 60d2 on the outer shroud side is Deo on the outer shroud side, which is greater than the position of the recess extension direction De at the edge of the inner shroud side Dei of the second recess 55e.

[0149] In this embodiment, drain DN in the positive pressure surface 52p, between the first recess 55d and the second recess 55e, and on the side Df of the leading edge 52s beyond these recesses 55d and 55e, can be collected by the first groove 60d2 on the outer shroud side, which is connected to the first recess 55d.

[0150] The steam turbines in the above embodiments and modifications can be understood, for example, as follows.

[0151] (19) The steam turbine in the nineteenth embodiment comprises a stator blade 51 in any one of the first to eighteen embodiments, a rotor 10 rotatable about an axis Ar, and a casing 20 covering the rotor 10. The stator blade 51 is fixed to the casing 20 within the casing 20.

[0152] According to one aspect of this disclosure, it is possible to efficiently discharge condensate outside the steam flow path while suppressing the discharge of steam within the steam flow path.

[0153] 10: Rotor 11: Rotor shaft 12: Blade row 15: Bearing 16: Steam inlet pipe 17: Steam passage 20: Casing 21: Inner casing 22: Exhaust casing 22s: Exhaust space 23: Diffuser 23s: Diffuser space 27: Exhaust port 30: Blade ring 31: Drain discharge passage 50: Stator blade row 51: Stator blade 52, 52a, 52c, 52d, 52f, 52g, 52x: Blade body 52s: Leading edge 52r: Trailing edge 52p: Positive pressure surface 52n: Negative pressure surface 53: Blade internal space 53o: Opening 54, 54x: Connecting passage 54o, 54xo: Opening 55, 55a, 55f, 55g, 55x: Recess 55b, 55d: First recess 55c, 55e: second recess 55fo, 55go: outer recess 55fi, 55gi: inner recess 56: front side 56fo, 56go: outer front 56fi, 56gi: inner front 57, 57x: rear side 57fo, 57go: outer rear 57fi, 57gi: inner rear 58, 58x: bottom surface 58fo, 58go: outer bottom surface 58fi, 58gi: inner bottom surface 59: introduction surface 60: groove 60sf: leading edge side end 60sb: trailing edge side end 60b, 60d: first groove 60b2: first groove on inner shroud side 60d2: first groove on outer shroud side 60c, 60e: second groove 61: Inner shroud 62: Outer shroud ST1: First steam turbine section ST2: Second steam turbine section S: Steam DN: Drain Vf: Vortex flow F: Suction force Ar: Axis Ap: Pipe axis Da: Axial direction Da1: First side Da2: Second side Dau: Upstream side of axis Dad: Downstream side of axis Dc: Circumferential direction Dr: Radial direction Dri: Inner radial direction Dro: Outer radial direction Dh: Blade height direction De: Recess extension direction Deo: Outer shroud side Dei: Inner shroud side Ddf: Drain flow direction Dge: Groove extension direction Df: Leading edge side Db: Trailing edge side Dsi: Inner recess (or inner blade side) Dso: Outer recess (or outer blade side)

Claims

1. Displaced within a steam flow path through which steam flows, the wing body has an airfoil cross-section and extends in a wing height direction perpendicular to the cross-section, the wing body having a leading edge, a trailing edge, a positive pressure surface connecting the leading edge and the trailing edge, a negative pressure surface connecting the leading edge and the trailing edge and facing the positive pressure surface, an internal wing space formed between the positive pressure surface and the negative pressure surface, a recess recessing from the positive pressure surface toward the internal wing space, and a communication passage connecting the recess and the internal wing space, the internal wing space having an opening to the outside, the recess extending in a recess extension direction having a component in the wing height direction along the positive pressure surface, the recess being defined by a front surface located toward the leading edge, a rear surface located toward the trailing edge and facing the front surface, and a bottom surface connecting the front surface and the rear surface. The rear side surface is inclined at an acute angle with respect to the positive pressure surface, such that it approaches the trailing edge side as it moves toward the inside of the recess, which is the side of the wing's internal space, with respect to the positive pressure surface, and the communication passage is open at the bottom surface, a stator wing.

2. A stator vane according to claim 1, wherein the position of the opening of the communication passage is located on the bottom surface, closer to the front side surface.

3. A stator vane according to claim 1, wherein the bottom surface is inclined with respect to the positive pressure surface such that it extends from the inner edge of the recess of the rear surface toward the front surface and gradually moves toward the inner side of the recess toward the front surface.

4. A stator vane according to claim 3, wherein the position of the opening of the communication passage is located on the bottom surface, closer to the front side surface.

5. A stator vane according to claim 2, wherein a part of the edge of the opening of the communication passage is a part of the front surface.

6. A stator vane according to claim 1, wherein the recess is connected to the positive pressure surface and the front surface, and has an introduction surface that is inclined with respect to the positive pressure surface and the front surface so as it approaches the trailing edge, it gradually moves inward toward the inside of the recess.

7. A stator vane according to claim 1, wherein the vane body has a plurality of communication passages, the plurality of communication passages are spaced apart from each other in the direction of the extension of the recess and open at the bottom surface.

8. A stator wing according to claim 1, wherein the recess has an outer recess and an inner recess, both the outer recess and the inner recess extend in the recess extension direction having a component in the wing height direction, the outer recess is defined by an outer front surface recessed from the positive pressure surface on the wing side which is the wing internal space side with respect to the positive pressure surface and located on the leading edge side, an outer rear surface located on the trailing edge side of the outer front surface and facing the outer front surface, and an outer bottom surface extending from the wing side of the outer front surface toward the leading edge side, the inner recess is defined by an inner front surface recessed from the outer bottom surface toward the wing side and located on the leading edge side, an inner rear surface located on the trailing edge side of the inner front surface and facing the inner front surface, and an inner bottom surface connecting the wing inner edge of the inner front surface and the wing inner edge of the inner rear surface, the rear side surface is the outer rear surface, and the bottom surface is the inner bottom surface.

9. A stator vane according to claim 8, wherein the position of the opening of the communication passage is located on the inner bottom surface, closer to the inner front surface.

10. A stator vane according to claim 8, wherein the outer bottom surface extends from the inner edge of the outer rear surface toward the outer front surface and is inclined with respect to the positive pressure surface such that it gradually moves toward the inner side of the wing as it approaches the outer front surface.

11. A stator vane according to claim 10, wherein the position of the opening of the communication passage is located on the inner bottom surface, closer to the inner front surface.

12. A stator vane according to claim 9, wherein the inner front surface is connected to the outer front surface, and a part of the edge of the opening of the communication passage is a part of the inner front surface.

13. A stator vane according to claim 8, wherein the outer recess is connected to the positive pressure surface and the outer front surface, and has an introduction surface that is inclined with respect to the positive pressure surface and the outer front surface so as it approaches the trailing edge, it gradually moves inward toward the inside of the vane.

14. A stator vane according to claim 8, wherein the vane body has a plurality of communication passages, the plurality of communication passages are spaced apart from each other in the direction of the extension of the recess and open on the inner bottom surface.

15. A stator vane according to claim 1 or 8, wherein the vane body has a groove recessed inward from the positive pressure surface, on the side of the vane interior space relative to the positive pressure surface, the groove has a component in the drain flow direction perpendicular to the vane height direction and extending from the leading edge toward the trailing edge, and a component in the vane height direction, and extends in a groove extension direction intersecting the recess extension direction, the groove has a leading edge end which is the end on the leading edge side in the drain flow direction, and a trailing edge end which is the end on the trailing edge side in the drain flow direction, the groove is formed in the positive pressure surface in a region on the leading edge side of the recess, and the trailing edge end of the groove is connected to the recess.

16. A stator vane according to claim 15, wherein the vane body has a plurality of grooves, and the plurality of grooves are arranged in the direction of the extension of the recess.

17. A stator vane according to claim 15, wherein the wing body has a plurality of recesses and a plurality of grooves for each of the plurality of recesses, the plurality of recesses are spaced apart in the direction of the extension of the recesses and are arranged in the direction of the extension of the recesses, of the plurality of recesses, the second recess is adjacent to the inner shroud side of the outer shroud side and the inner shroud side of the first recess in the direction of the extension of the recess, of the plurality of grooves connected to the first recess, the groove closest to the inner shroud side is the inner shroud side first groove, and the position of the leading edge end of the inner shroud side first groove in the direction of the extension of the recess is on the inner shroud side than the position of the outer shroud side edge of the second recess in the direction of the extension of the recess.

18. A stator vane according to claim 15, wherein the wing body has a plurality of recesses and a plurality of grooves for each of the plurality of recesses, the plurality of recesses are spaced apart in the direction of the extension of the recesses and are arranged in the direction of the extension of the recesses, of which the second recess is adjacent to the first recess on the outer shroud side of the outer shroud side and the inner shroud side in the direction of the extension of the recesses, of which the plurality of grooves connected to the first recess is the groove furthest to the outer shroud side is the outer shroud side first groove, the position of the leading edge end of the outer shroud side first groove in the direction of the extension of the recess is on the outer shroud side than the position of the outer shroud side edge of the second recess in the direction of the extension of the recess.

19. A steam turbine comprising: a stator vane according to any one of claims 1 to 14; a rotor rotatable about an axis; and a casing covering the rotor, wherein the stator vane is fixed to the casing within the casing.

Images