TURBINE GUIDE SHAFTS AND STEAM TURNINE

Abstract

A turbine guide vane with: a pressure side (21P) extending in a radial direction that intersects a flow direction of steam and is facing upstream in the flow direction, wherein a slot (5) which captures / traps droplets produced by liquefaction of the steam is formed on a downstream side of the pressure side (21P), wherein a finely uneven area (61, 7, 71, 72, 73, 74), which guides or directs the droplets deposited on the pressure side (21P) in the radial direction such that the droplets are moved to the slot (5) and from upstream to downstream, is formed in a position further upstream than the slot (5), and the finely uneven area (61, 7, 71, 72, 73, 74) exhibits a flow resistance to the droplets that increases in the radial direction from the inside out.

Description

[Technical field]

[0001] The present invention relates to a turbine guide vane and a steam turbine. [Technical background]

[0002] A steam turbine comprises a rotating shaft that is rotatable about an axis, a plurality of turbine rotor or runner blade stages arranged in one direction of the axis on an outer circumferential surface of the rotating shaft with a gap between them, a casing that covers the rotating shaft and the turbine rotor blade stages from an outer circumferential side, and a plurality of turbine guide or stator blade stages arranged alternately with the turbine rotor blade stages on an inner circumferential surface of the casing. An inlet opening for receiving steam from the outside is formed on an upstream side of the casing, and an outlet opening is formed on a downstream side of the casing.A flow direction and speed of high-temperature / high-pressure steam, which is drawn in through the inlet opening, are set in the turbine guide vane stages, and then the steam is converted into a rotational force of the rotating shaft in the turbine running blade stages.

[0003] Steam that has flowed through the turbine loses energy from upstream to downstream, and thus its temperature (and pressure) decreases. Therefore, in the turbine guide vane stage, on the downstream side, some of the steam liquefies and exists as fine water droplets in an airflow. Some of these water droplets are deposited on an outer surface of the guide vane. The water droplets immediately grow into a liquid film on the blade surface. This liquid film is constantly exposed to a rapid steam flow around it. However, as this liquid film continues to grow and thicken, some of it is detached by the steam flow and disperses into very large droplets. These dispersed droplets flow downstream in or with a main flow, progressively accelerated by the steam flow.The larger the droplets, the greater the inertial forces acting upon them. This prevents the droplets from flowing through the spaces between the turbine blades into or with the main flow of steam, causing them to collide with the blades. Since the peripheral speed of the turbine blades can exceed the speed of sound, the collision of the droplets with the blades can erode their outer surfaces, leading to erosion. Furthermore, the rotation of the turbine blades can be impeded by these collisions, resulting in braking losses.

[0004] To prevent such adhesion and growth of droplets, various technologies have been proposed. In the device described in the following patent reference 1, for example, an extraction opening for drawing in a liquid film is formed on an outer surface of a turbine guide vane, and a hydrophilic removal surface is formed extending from a leading edge of the turbine guide vane to this extraction opening. After a liquid film has moved along the removal surface, it can be drawn off through the extraction opening.

[0005] Furthermore, patent literature 2 discloses an article with low wettability. The article comprises a body section and a surface section arranged on the body section. The surface section comprises a plurality of elements arranged on the body section, and the elements have a size, shape, and orientation such that the surface section exhibits wettability sufficient to generate a contact angle of at least approximately 100 degrees with a reference liquid. The features include a height dimension and a width dimension and are arranged at a distance from each other characterized by a distance dimension such that a droplet exhibits metastable non-Wenzel behavior.

[0006] Patent literature 3 discloses an erosion-resistant and hydrophobic object comprising a core exhibiting a first hardness and a surface on the core. The surface incorporates a variety of geometric elements exhibiting a second, greater hardness. These geometric elements define a surface porosity (in percent of area) and a corresponding surface strength (in percent of area). The geometric elements and their ratio cause the surface to be hydrophobic, and the second, greater hardness and its ratio result in a surface erosion rate that is equal to or less than the core erosion rate under the same erosion conditions. [Citation list][Patent literature] [Patent literature 1] JP 2017- 106 451 A [Patent literature 2] US 9 827 735 B2 [Patent literature 2] US 2007 / 0 031 639 A1 [Summary of the invention][Technical problem]

[0007] In the device described in the preceding patent reference 1, only a removal surface is uniformly formed towards an extraction opening. This removal surface exhibits constant hydrophilicity. Furthermore, no flow resistance to a liquid film on a processed surface is described, and the control of a liquid film using a difference between flow resistances is not considered. For this reason, a force towards a slot does not necessarily act on droplets that have reached the removal surface. Therefore, it is possible that droplets flow outwards from the removal surface. The device described in the preceding patent reference 1 is thus still capable of improvement.

[0008] The present invention was made to solve the aforementioned problems, and one object of this invention is to provide a turbine guide vane that can capture droplets more efficiently, and a steam turbine that incorporates the same. [Solution to the problem]

[0009] According to the invention, this problem is solved by a turbine guide vane according to claim 1 and by a steam turbine according to claim 9. The dependent claims relate to further advantageous aspects of the invention.

[0010] A turbine guide vane according to one aspect of the present invention comprises a pressure side extending radially across a steam flow direction and facing upstream in the flow direction. A slot, which captures or traps droplets generated by the condensation of the steam, is formed on a downstream side of the pressure side. A finely uneven region, which guides or directs the droplets adhering to the pressure side radially such that the droplets are moved towards the slot and from upstream to downstream, is formed in a position further upstream than the slot. The finely uneven region exhibits a flow resistance to the droplets that increases radially from the inside out.

[0011] According to the above embodiment, the flow resistance to droplets in the finely uneven region increases progressively in the radial direction from the inside to the outside. The higher the flow resistance to droplets, the slower their flow rate. When droplets span two regions with different flow resistances, a velocity component is generated from the region with lower flow resistance to the region with higher flow resistance. If the flow resistance increases radially from the inside to the outside as described above, the droplets flow in such a way that they are guided or directed to the slot based on a vapor flow and the difference between the aforementioned flow resistances.As a result, droplets located radially in a central section on the pressure side are guided to the finely uneven area, causing them to flow radially and then be captured by the slot. According to the slot, the possibility of detached droplets being dispersed downstream of the turbine guide vane and colliding with a turbine rotor blade can be reduced.

[0012] In the aforementioned turbine guide vane, the finely uneven region can comprise a plurality of hydrophilic regions arranged to be adjacent to each other in the radial direction, the flow resistances to the droplets of the plurality of hydrophilic regions being able to differ between the plurality of regions, and the flow resistance of the hydrophilic region being higher the further out the hydrophilic region is positioned in the radial direction.

[0013] According to the foregoing embodiment, the finely uneven region has a plurality of hydrophilic areas arranged radially adjacent to one another. Therefore, droplets or liquid films spread out more thinly based on the hydrophilicity of a wall surface. Accordingly, it is likely that droplets or liquid films will span the aforementioned plurality of areas. Consequently, in droplets or liquid films spanning two areas with different flow resistances, a velocity component is generated from the area with lower flow resistance to the area with higher flow resistance. This guides or directs droplets or liquid films located in a radial position at a central section on the pressure side into the finely uneven region so that they flow towards the slot.Accordingly, the possibility of droplets or liquid films splitting up and dispersing downstream can be further reduced.

[0014] In the turbine guide vane shown above, the finely uneven area can be progressively curved from upstream to downstream in order to change from a state extending in the flow direction to a state extending in the radial direction.

[0015] According to the above embodiment, the finely uneven region is progressively curved from upstream to downstream, transitioning from a state extending in the flow direction to a state extending radially. Therefore, droplets flowing in the direction of flow can be actively guided or directed such that they move radially. Consequently, the possibility of detached droplets dispersing downstream in the flow direction can be further reduced.

[0016] In the aforementioned turbine guide vane, the finely uneven area can include hydrophilic areas and water-repellent areas arranged alternately in the radial direction.

[0017] According to the above configuration, there is a difference between the flow resistances to droplets in the hydrophilic and water-repellent regions. The higher the flow resistance to droplets, the slower their flow rate. When droplets span two regions with different flow resistances, a velocity component is generated from the region with lower resistance to the region with higher resistance. The droplets flow in such a way that they are guided or directed towards the slot. Consequently, droplets located radially in a central section on the pressure side are guided to the finely uneven region, so that they flow radially and are then captured or trapped by the slot.Accordingly, the possibility of split droplets scattering on the downstream side of the turbine guide vane and colliding with the turbine rotor blade can be reduced.

[0018] In the aforementioned turbine guide vane, the finely uneven area can comprise a hydrophilic area and a water-repellent area arranged in the radial direction, as well as an unmachined surface formed between the hydrophilic area and the water-repellent area.

[0019] According to the above configuration, the flow resistances to droplets or liquid films differ between the hydrophilic areas, the areas on the untreated surface, and the water-repellent areas, in that order. Generally, the more hydrophilic a wall surface is, the greater the affinity between water and the wall surface. This is because the mutual attractive forces between water and wall surface become stronger. Consequently, the flow resistance increases. The higher the flow resistance of droplets or liquid films, the slower the flow rate of the droplets. When droplets flow between two areas with different flow resistances, a velocity component is generated from the area with lower flow resistance to the area with higher flow resistance. The droplets flow in such a way that they are guided or directed towards the slot.As a result, droplets located radially at a central section on the pressure side are guided or directed to the finely uneven area, causing them to flow radially and then be captured or trapped by the slot. This reduces the likelihood of detached droplets scattering on the downstream side of the turbine guide vane and colliding with the turbine rotor blade.

[0020] In the aforementioned turbine guide vane, the finely uneven area can comprise a hydrophilic area and a water-repellent area arranged in the radial direction, and an unmachined surface formed between the hydrophilic area and the water-repellent area, and the hydrophilic area, the unmachined surface and the water-repellent area can be arranged in this order and in a repeated form.

[0021] According to the above embodiment, the flow resistance increases from the water-repellent areas to the hydrophilic areas. Generally, a liquid film flows along the flow path of a surrounding airflow. However, if the flow resistances of sections of the wall surface differ, the liquid film will curve towards a section with high flow resistance. This is because a velocity component is generated in a direction where the flow resistance increases. Since a liquid film has a large inertial force due to its liquid composition, the liquid film passes over the area of ​​highest flow resistance on a machined surface, which is repeatedly arranged in the above embodiment, and moves to the location of the next lower flow resistance, and this process is repeated.The droplets flow in such a way that they are guided or directed towards the slot. Consequently, droplets located radially at a central section on the pressure side are guided or directed towards the finely uneven area, so that the droplets flow radially and are then captured or trapped by the slot. This reduces the possibility of detached droplets being dispersed downstream of the turbine guide vane and colliding with the turbine rotor blade.

[0022] In the aforementioned turbine guide vane, the slot can be provided to be spaced from a trailing edge, which is an end edge of the turbine guide vane on the downstream side, with a gap between them in the direction of flow, and a super water-repellent area with a higher water-repellent effect than the pressure side can be formed in the gap.

[0023] According to the above embodiment, a highly water-repellent area is formed in the space between the slot and the rear edge. Accordingly, even if some droplets cannot be sufficiently captured or trapped by the slot and flow away to the downstream side, they are repelled by the highly water-repellent area. Therefore, the possibility of droplets remaining on the downstream side of the slot is reduced. Consequently, a situation in which the remaining droplets accumulate and form a larger liquid film can be prevented.

[0024] The aforementioned turbine guide vane may also have an inner, finely uneven area that guides or directs the droplets adhering to the pressure side radially from upstream to downstream. This area may be formed on an inner side in the radial direction of the finely uneven area on the pressure side. The inner, finely uneven area may exhibit a flow resistance to the droplets that gradually increases radially inwards.

[0025] According to the above configuration, the flow resistance for droplets in the inner, finely uneven region gradually increases radially inwards. The higher the flow resistance for droplets, the slower their flow rate. For droplets spanning two regions with different flow resistance, a velocity component is generated from the region with lower flow resistance to the region with higher flow resistance. Therefore, when the flow resistance increases as described above, the droplets flow radially in such a way that they are guided or directed from the outside inwards. Consequently, droplets located at a central position on the pressure side are guided or directed into the inner, finely uneven region, causing them to flow radially inwards.Since the circumferential velocity of the turbine rotor blade positioned on the downstream side of the turbine guide vane is reduced in the radial direction inwards, compared to a case in which droplets collide with a part positioned on the outside of the turbine rotor blade in the radial direction where the circumferential velocity is relatively high, the possibility of erosion or braking losses occurring can be reduced.

[0026] A steam turbine according to a further aspect of the present invention comprises a rotating shaft rotatable about an axis, a plurality of turbine rotor blades arranged in a circumferential direction with respect to an axial direction on an outer circumferential surface of the rotating shaft, a casing covering the rotating shaft and the turbine rotor blades from an outer circumferential side, and a plurality of turbine guide vanes according to one of the present aspects, arranged in the circumferential direction around the axis on an inner circumferential surface of the casing and provided adjacent to the turbine rotor blades in the axial direction.

[0027] According to the above design, a steam turbine can be provided which includes a turbine guide vane that can capture droplets more efficiently. [Advantageous effects of the invention]

[0028] According to the present invention, a turbine guide vane can be provided which can capture droplets more efficiently, as well as a steam turbine which includes such a guide vane. [Brief description of the drawings] Fig. Figure 1 is a schematic view representing an embodiment of a steam turbine according to a first embodiment of the present invention. Fig. Figure 2 is a perspective view showing an embodiment of a turbine rotor blade according to a first embodiment of the present invention. Fig. Figure 3 is an enlarged view showing an embodiment of a finely uneven area according to the first embodiment of the present invention. Fig. Figure 4 is an explanatory diagram to illustrate the behavior of droplets in the finely uneven area according to the first embodiment of the present invention. Fig. Figure 5 is a side view showing an embodiment of a turbine guide vane according to a second embodiment of the present invention. Fig. Figure 6 is a side view showing an embodiment of a turbine guide vane according to a third embodiment of the present invention. [Description of the embodiments][First embodiment]

[0029] A first embodiment of the present invention is described with reference to the Fig. 1 to 4 described. A steam turbine 100 according to the present embodiment comprises a steam turbine rotor 3 extending in one direction of an axis O, a steam turbine casing 2 covering the steam turbine rotor 3 from an outer circumferential side, and a radial bearing 4A and an axial bearing 4B supporting a shaft end 11 of the steam turbine rotor 3 so that it can rotate about the axis O.

[0030] The steam turbine rotor 3 has a rotating shaft 1 extending along the axis O and a plurality of rotor blades 30 provided on an outer circumferential surface of the rotating shaft 1. The plurality of rotor blades 30 are arranged circumferentially around the rotating shaft 1 with a constant spacing between them. Along the axis O, the plurality of rotor blades 30 are also arranged in a row with a constant spacing between them. Each rotor blade 30 has a rotor blade body 31 (turbine rotor blade) and a rotor blade cover 34. The rotor blade body 31 projects radially outwards from an outer circumferential surface of the steam turbine rotor 3. The rotor blade body 31 has a cross-section that, viewed radially, has a flow-profile shape.The vane cover 34 is provided on a distal end section of the vane main body 31 (an end section on an outer side in the radial direction).

[0031] The steam turbine casing 2 is essentially tubular and covers the steam turbine rotor 3 on its outer circumference. On one side of the steam turbine casing 2, in the direction of axis O, a steam inlet pipe 12 is provided for receiving steam S. On the other side of the steam turbine casing 2, in the direction of axis O, a steam outlet channel 13 is provided for discharging the steam S. The steam flows inside the steam turbine casing 2 in the direction of axis O from one side to the other. In the following description, a flow direction of steam is simply referred to as "a flow direction".Furthermore, the side on which the steam supply pipe 12 is arranged is referred to as the upstream side when viewed from the steam outlet channel 13 in the direction of flow, and the side on which the steam outlet channel 13 is arranged is referred to as the downstream side when viewed from the steam supply pipe 12 in the direction of flow.

[0032] A plurality of turbine guide vanes or stator blades 20 are provided on an inner circumferential surface of the steam turbine casing 2. Each of the guide vanes 20 has a guide vane body 21 (turbine guide vane), a guide vane cover 22, and a guide vane seat 24. The guide vane body 21 is an element connected to the inner circumferential surface of the steam turbine casing 2, with an intermediate guide vane seat 24 in the form of a flow profile. The guide vane cover 22 is also provided at a distal end section of the guide vane body 21 (an end section on an inner surface in the radial direction). Similar to the rotor blades 30, the plurality of guide vanes 20 are arranged circumferentially and along the axis O on the inner circumferential surface.The rotor blades 30 are arranged such that they each enter a region between the regions adjacent to a plurality of guide vanes 20. The guide vanes 20 and the rotor blades 30 extend in a direction that intersects the flow direction of the steam (the radial direction with respect to axis O).

[0033] The steam S is supplied to the interior of the steam turbine casing 2, which is formed as described above, via the steam supply pipe 12 on the upstream side. During the midpoint of a flow through the interior of the steam turbine casing 2, the steam S alternately passes through the guide vanes 20 and the rotor blades 30. The guide vanes 20 straighten the steam flow S, and a lump of steam S, which is a unidirectional fluid, presses against the rotor blades 30 to exert a rotational force on the steam turbine rotor 3. A rotational force from the steam turbine rotor 3 is transmitted from the shaft end 11 and used to drive external equipment (generator, etc.). In accordance with the rotation of the steam turbine rotor 3, the steam S is discharged through the steam outlet channel 13 on the downstream side to a subsequent device (a steam condenser or similar).

[0034] The radial bearing 4A carries a load in the radial direction with respect to axis O. One radial bearing 4A is provided at each of the two ends of the steam turbine rotor 3. The axial bearing 4B carries a load in the axis-O direction. The axial bearing 4B is provided only at the end section of the steam turbine rotor 3 on the upstream side.

[0035] Next, with reference to Fig. Section 2 describes an embodiment of the guide vane body 21. The guide vane body 21 extends in the radial direction (the radial direction with respect to axis O), which is a direction that intersects the flow direction. A cross-section of the guide vane body 21, viewed in the radial direction, has a flow profile shape. In particular, a leading edge 21F, which is a terminal edge on the upstream side in the flow direction, has a curved surface shape. A trailing edge 21R, which is a terminal edge on the downstream side, has a gradually decreasing length in the circumferential direction when viewed in the radial direction, and thus has a tapered shape. From the leading edge 21F to the trailing edge 21R, the guide vane body 21 is slightly curved from side to side in the circumferential direction with respect to axis O.

[0036] A surface of the guide vane body 21 on one side in the circumferential direction serves as a suction or negative pressure side 21Q, facing downstream in the flow direction. The suction side 21Q has a curved surface shape that projects circumferentially to one side. Conversely, a surface of the guide vane body 21 on the opposite side in the circumferential direction serves as a pressure or positive pressure side 21P, facing upstream in the flow direction. The pressure side 21P has a curved surface shape that is recessed circumferentially to one side. When steam is flowing, the pressure at the pressure side 21P is higher than the pressure at the suction side 21Q.

[0037] An end surface of the guide vane main body 21, facing radially inwards, serves as the inner circumferential end surface 21A, and an end surface facing radially outwards serves as the outer circumferential end surface 21B. The inner circumferential end surface 21A extends along the axis O described above. Conversely, the outer circumferential end surface 21B is inclined with respect to the axis O. In particular, in a cross-sectional view containing the axis O, the outer circumferential end surface 21B extends radially outwards from upstream to downstream along the axis O.

[0038] A slot 5, an outer fine uneven region 61 (fine uneven region 6), and an inner fine uneven region 62 are formed on a section at the pressure side 21P near the outer circumferential end surface 21B (i.e., a section that is closer to the outer circumferential end surface 21B than to the inner circumferential end surface 21A). The slot 5 is a rectangular hole extending in a direction that includes a radial component at the pressure side 21P. In particular, the slot 5 extends along the trailing edge 21R. The slot 5 is designed to capture or trap liquefied components (droplets) of the vapor flowing from the front edge 21F to the trailing edge 21R along the pressure side 21P.The slot 5 is connected to a flow channel (not shown) formed within the guide vane main body 21, and the captured or trapped droplets are guided or directed through this flow channel to the outside of the guide vane main body 21.

[0039] The outer, finely uneven area 61 is designed such that droplets adhering to the pressure side 21P are guided or directed radially towards the slot 5. The outer, finely uneven area 61 is located on an outer side in the radial direction of the pressure side 21P. In particular, the outer, finely uneven area 61 is positioned near the outer circumferential end surface 21B. The outer, finely uneven area 61 guides or directs droplets adhering to the pressure side 21P such that the droplets moving in the flow direction are progressively moved outwards in the radial direction.

[0040] The outer, finely uneven area 61 is subdivided radially into a plurality of (four) areas (outer areas 7). The outer area 7 on the innermost side in the radial direction serves as a first outer area 71. A second outer area 72 is adjacent to the first outer area 71 on an outer side in the radial direction, with a second outer boundary line L12 between them. A third outer area 73 is adjacent to the second outer area 72 on an outer side in the radial direction, with a third outer boundary line L13 between them. A fourth outer area 74 is adjacent to the third outer area 73 on an outer side in the radial direction, with a fourth outer boundary line L14 between them. An end edge of the first outer area 71 on its inner side in the radial direction serves as a first outer boundary line L11.A central area Ac extends further inwards in the radial direction than the first outer boundary line L11.

[0041] The end edges on the downstream side of the first outer region 71, the second outer region 72, the third outer region 73, and the fourth outer region 74 are adjacent to the slot 5. The radial length of the slot 5 is less than that of the outer, finely uneven region 61. Therefore, the first outer region 71, the second outer region 72, the third outer region 73, and the fourth outer region 74 are progressively curved from upstream to downstream in the flow direction, transforming into a state where they extend outward in the radial direction, thus connecting with the slot 5. The second outer region 72 is more strongly curved than the first outer region 71. The third outer region 73 is more strongly curved than the second outer region 72. The fourth outer region 74 is more strongly curved than the third outer region 73.The degree of curvature of the curved outer regions 7 therefore increases in the radial direction towards the inside.

[0042] The inner, finely uneven region 62 is positioned further inward in the radial direction than the outer, finely uneven region 61, with a central section (central region Ac) inserted between them on the pressure side 21P. The inner, finely uneven region 62 guides or directs droplets adhering to the pressure side 21P such that the droplets moving in the flow direction are progressively moved inward in the radial direction. The inner, finely uneven region 62 is subdivided in the radial direction into a plurality of (four) regions (inner regions 8). The inner region 8 at the outermost side in the radial direction serves as a first inner region 81. A second inner region 82 is adjacent in the radial direction to an outer side of the first inner region 81, with a second inner boundary line L22 positioned between them.A third inner region 83 is adjacent to the second inner region 82 on an inner side in the radial direction, with a third inner boundary line L23 arranged between them. A fourth inner region 84 is adjacent to the third inner region 83 in the radial direction, with a fourth inner boundary line L24 arranged between them. An end edge of the first inner region 81 on an inner side in the radial direction serves as the first inner boundary line L21. The central region Ac described above is located further outwards in the radial direction than the first inner boundary line L21.

[0043] The end edges on the most downstream side of the first inner region 81, the second inner region 82, the third inner region 83, and the fourth inner region 84 are adjacent to the trailing edge 21R with a gap V between them in the flow direction. The first inner region 81, the second inner region 82, the third inner region 83, and the fourth inner region 84 are all progressively curved from upstream to downstream in the flow direction, transitioning to a radially inward curvature. The second inner region 82 is more curved than the first inner region 81. The third inner region 83 is more curved than the second inner region 82. The fourth inner region 84 is more curved than the third inner region 83. Thus, the degree of curvature of the curved inner regions 8 increases outward in the radial direction.

[0044] Both the outer, finely uneven region 61 and the inner, finely uneven region 62 are hydrophilic. The aforementioned state "hydrophilic" indicates a condition in which the contact angle of droplets with respect to a surface is less than 90°, with a state in which the contact angle becomes less than 5° being referred to as superhydrophilicity. Furthermore, the flow resistances to droplets differ between the outer regions 7 and between the inner regions 8. In particular, the flow resistance to droplets increases progressively from the first outer region 71 to the fourth outer region 74. Similarly, the flow resistance to droplets increases progressively from the first inner region 81 to the fourth inner region 84.For identical materials, the flow resistance of a wall surface against a liquid film is determined by the shape, size, and arrangement of the surface irregularities. Generally, the larger the area in contact with the liquid surface and the more the arrangement directly blocks the flow direction, the higher the flow resistance (with the same arrangement of fine structures, the closer the fine structures are generally arranged, the higher the hydrophilicity, the larger the contact area with the liquid, and the higher the flow resistance). Such a difference between the flow resistances is described by the in . Fig. The design shown in sections 3 and 4 is implemented. Fig. 3 and Fig. Figure 4 shows the first outer region 71 and the second outer region 72. However, a relationship between the second outer region 72 and the third outer region 73, and a relationship between the third outer region 73 and the fourth outer region 74, also resemble the example in Fig. 3 or Fig. 4. In addition, the inner, finely uneven area 62 also has a similar design.

[0045] Fig. Figure 3 shows a representative enlarged section near a boundary line (second outer boundary line L12) between the first outer region 71 and the second outer region 72 in the outer, finely uneven region 61. As shown in the same figure, a plurality of projecting sections T, each projecting individually in the circumferential direction from the printed side 21P, are arranged in the first outer region 71 and the second outer region 72 with equal spacing between them. Each of the projecting sections T has a circular cross-section when viewed in the circumferential direction. The spacing of the projecting sections T formed in the second outer region 72 (second projecting sections T2) is greater than the spacing of the projecting sections T formed in the first outer region 71 (first projecting sections T1).Furthermore, the diameters of the second protruding sections T2 are larger than the diameters of the first protruding sections. Since the protruding sections T (first protruding sections T1) are arranged in a relatively "narrow" manner in the first outer region 71, the flow resistance to droplets in the first outer region 71 is higher than the flow resistance to droplets in the second outer region 72.

[0046] Here, as in Fig. Figure 4 illustrates a case in which a droplet Wd is attached to the outer, finely uneven region 61 in such a way that it spans the second outer boundary line L12. In this case, the drag in a part of the droplet Wd on the side of the second outer region 72 is relatively large compared to the part on the side of the first outer region 71. Accordingly, the velocity V2 of the part of the droplet Wd on the side of the second outer region 72 is lower compared to the velocity V1 of the part of the droplet Wd on the side of the first outer region 71. As a result, the droplet Wd moves as indicated by the two dotted, dashed lines and the arrow R in Figure 4. Fig. 4 is indicated, during the rotation from an original position to the side of the second outer region 72. This movement of the droplets is caused solely by a difference between the flow resistances of the two regions, without depending on an external force such as a fluid force of the steam.

[0047] A driving force based on such a difference in flow resistances guides or directs droplets attached to the outer, finely uneven region 61 progressively outwards in the radial direction and from upstream to downstream in the flow direction. The droplets then flow over the end edge on the downstream side into the slot 5. Similarly, droplets attached to the inner, finely uneven region 62 are guided or directed progressively inwards in the radial direction and from upstream to downstream in the flow direction. The droplets then flow off via the gap V to the downstream side of the guide vane main body 21.

[0048] As described above, according to the aforementioned design, the flow resistance for droplets in the outer, finely uneven region 61 increases progressively towards the slot 5. The higher the flow resistance for droplets, the slower the flow rate of the droplets. For droplets spanning two regions with different flow resistances, a velocity component is generated from the region with the lower flow resistance to the region with the higher flow resistance. Therefore, droplets flow in such a way that they are guided or directed towards the slot 5 when the flow resistance increases towards the slot 5 as described above.As a result, droplets positioned radially at a central section on the pressure side 21P are guided or directed to the outer, finely uneven area 61, so that the droplets flow radially and are then captured or trapped by the slot 5. Accordingly, the possibility of split droplets being dispersed downstream of the guide vane main body 21 can be reduced.

[0049] Furthermore, according to the above embodiment, the outer, finely uneven region 61 has a plurality of hydrophilic outer regions 7 arranged to be radially adjacent to one another. Therefore, the droplets spread out more thinly based on the hydrophilicity of the hydrophilic outer region 7. Accordingly, it is likely that droplets will span between the aforementioned plurality of outer regions 7. Therefore, for droplets flowing between two outer regions 7 with different flow resistances, a velocity component is generated from the region with the lower flow resistance to the region with the higher flow resistance. As a result, droplets located radially in a central section (central region Ac) on the pressure side 21P are guided or directed into the outer, finely uneven region 61 so that they flow towards the slot 5.Accordingly, the possibility of droplets splitting up or separating and dispersing downstream can be further reduced.

[0050] Furthermore, according to the above embodiment, the outer, finely uneven region 61 is progressively curved from upstream to downstream in order to change from a state extending in the flow direction to a state extending radially. Therefore, droplets flowing in the direction of flow can be actively guided or directed such that they are moved radially. Accordingly, the possibility of split or detached droplets being dispersed downstream in the flow direction can be further reduced.

[0051] Furthermore, according to the above embodiment, the drag on droplets in the inner, finely uneven region 62 increases progressively in the radial direction towards the inside. The higher the drag on droplets, the slower the flow rate of the droplets. For droplets spanning two regions with different drag, a velocity component is generated from the region with the lower drag to the region with the higher drag. Therefore, the droplets flow in such a way that they are guided or directed radially from the outside to the inside when the drag increases in the radial direction as described above.As a result, droplets located radially in a central section (central area Ac) on the pressure side 21P are directed or steered towards the inner, finely uneven area 62, causing them to flow inwards radially. Since the circumferential velocity of the impeller 30 is reduced inwards radially, compared to a case where droplets collide with a part positioned on the outside of the impeller 30 radially, where the circumferential velocity is relatively high, the possibility of erosion or braking losses is reduced.

[0052] The first embodiment of the present invention has been described above. The above embodiments can be subjected to various changes and modifications within the scope of the present invention. For example, in the above first embodiment, an example was described in which each of the outer, finely uneven regions 61 and the inner, finely uneven region 62 is subdivided into four regions (the outer regions 7 and the inner regions 8) with different flow resistances. However, the outer, finely uneven region 61 and the inner, finely uneven region 62 can be subdivided into three or fewer regions or into five or more regions based on a difference between the flow resistances.

[0053] Furthermore, a multitude of subdivided areas can be arranged as a group in a repeating pattern. According to this configuration, the flow resistances to droplets or liquid films differ between the hydrophilic areas, the areas on the untreated surface, and the water-repellent areas, in that order. Generally, the more hydrophilic a wall surface is, the greater the affinity between water and the wall surface. This is because the mutual attractive forces between water and the wall surface become stronger. Consequently, the flow resistance increases. The higher the flow resistance to droplets or liquid films, the slower the flow rate of the droplets.When droplets span between two areas with different flow resistance, a velocity component is generated from the area with lower resistance to the area with higher resistance. The droplets flow in such a way that they are guided or directed towards the slot. Consequently, droplets located radially at a central position on the pressure side are guided or directed towards the finely uneven area, so that they flow radially and are then captured or trapped by the slot. This reduces the likelihood of split droplets being dispersed on the downstream side of the turbine guide vane and colliding with the turbine rotor blade.

[0054] Furthermore, an untreated surface can exist between the areas. The term "untreated surface" here refers to a surface in a state where the fine irregularities described above are not present. According to this configuration, the flow resistance increases from the water-repellent areas to the hydrophilic areas. Generally, a liquid film flows along a flow pattern of a surrounding airflow. However, if the flow resistances of sections of the wall surface differ, the liquid film will curve towards a section where the flow resistance is high. This is because a velocity component is generated in a direction in which the flow resistance increases.Since a fluid film has a large inertial force due to its fluid composition, the fluid film passes over the area of ​​highest flow resistance on a machined surface, which is repeatedly arranged in the aforementioned configuration, and moves to the location of the next lower flow resistance, and this process is repeated. The droplets flow in such a way that they are guided or directed towards the slot. This directs or steers droplets located radially at a central section on the pressure side to the finely uneven area, so that the droplets flow radially and are then captured or trapped by the slot. According to the slot, the possibility of split droplets being dispersed downstream of the turbine guide vane and colliding with the turbine rotor blade can be reduced.

[0055] Furthermore, the preceding first embodiment described an example in which only the outer, finely uneven area 61 is adjacent to the slot 5. However, an embodiment can also be used in which the inner, finely uneven area 62 is adjacent to the slot 5 in addition to the outer, finely uneven area 61. In particular, an embodiment can be used in which the slot 5 is arranged on the downstream side of the central area Ac on the pressure side 21P, and the outer, finely uneven area 61 and the inner, finely uneven area 62 are individually curved and extend towards the slot 5.In a configuration where the flow resistances to droplets are greater the closer the areas (the outer areas 7 and the inner areas 8) are to the slot 5, droplets can be guided or directed into the slot 5 not only from the outer, finely uneven area 61, but also from the inner, finely uneven area 62. [Second embodiment]

[0056] A second embodiment of the present invention is described below with reference to Fig. 5 described. The same reference numerals are used for embodiments similar to those of the preceding first embodiment, and a detailed description is omitted. As in Fig. In the present embodiment, the configurations of an outer, finely uneven area 61' and an inner, finely uneven area 62' differ from those of the first embodiment, as shown in Figure 5.

[0057] In the outer, finely uneven region 61', the first outer region 71 and the third outer region 73 are hydrophilic, similar to the first embodiment. Conversely, a second outer region 72' and a fourth outer region 74' serve as water-repellent regions 9 with a water-repellent effect. In the inner, finely uneven region 62', the first inner region 81 and the third inner region 83 are hydrophilic, similar to the first embodiment. Conversely, a second inner region 82' and a fourth inner region 84' serve as water-repellent regions 9 with a water-repellent effect. The aforementioned state of being "water-repellent" here refers to a state in which the contact angle of droplets adhering to the water-repellent regions 9 is 90° or greater. In particular, a case in which the contact angle is 150° or greater is referred to as a super-water-repellent state.In the outer, finely uneven area 61' and the inner, finely uneven area 62', hydrophilic areas and water-repellent areas are arranged alternately in the radial direction.

[0058] As described above, there is a difference in flow resistance between droplets in the hydrophilic and water-repellent regions. The greater the flow resistance, the slower the droplet flow rate. When droplets span two regions with different flow resistances, a velocity component is generated from the region with lower resistance to the region with higher resistance. The droplets flow in such a way that they are guided or directed towards the slot 5 or the space V described above. Consequently, droplets located at a central position (central region Ac) on the pressure side 21P in the radial direction are guided or directed towards the outer, finely uneven region 61' and the inner, finely uneven region 62', so that they flow in the radial direction.Accordingly, the possibility of droplets being scattered on the downstream side of the guide vane main body 21 can be reduced.

[0059] The second embodiment of the present invention has been described above. The above embodiments can be subjected to various changes and modifications within the scope of the present invention. For example, an embodiment described as a modification example of the present first embodiment can also be applied to the present embodiment. [Third embodiment]

[0060] A third embodiment of the present invention is described below with reference to Fig. 6 described. The same reference numerals are used for embodiments similar to those described above, and a detailed description is omitted. As in Fig.As shown in Figure 6, in the present embodiment, a super-water-repellent area 10 with a higher water-repellent effect (super-water-repellent effect) than the printed side 21P is formed in the space V between the slot 5 and the rear edge 21R. The aforementioned state "with super-water-repellent effect" here indicates a state in which the contact angle of droplets adhering to the super-water-repellent area 10 is 150° or greater. The super-water-repellent area 10 extends on the downstream side (towards the side of the rear edge 21R) adjacent to the end edge of the slot 5 on its downstream side.

[0061] According to the above embodiment, the super-water-repellent area 10 is formed in the space V between the slot 5 and the rear edge 21R. Accordingly, even if some droplets cannot be sufficiently captured or trapped by the slot 5 and flow downstream, they are repelled by the super-water-repellent area 10. Therefore, the possibility of droplets remaining on the downstream side of the slot 5 (space V) can be reduced. This prevents a situation in which the remaining droplets accumulate and a larger liquid film is formed.

[0062] The third embodiment of the present invention has been described above. The above embodiments can be subjected to various changes and modifications within the scope of the present invention. For example, the arrangement and design of the protruding sections T in the finely uneven region 6 can be modified as follows, while maintaining the commonalities with each of the embodiments described above. In the finely uneven region 6, the flow resistance can be varied by varying the sizes of the protruding sections T themselves radially from the inside to the outside, while keeping the spacing (interval) between the protruding sections T constant. Furthermore, the flow resistance can be varied by arranging the protruding sections T in a grid pattern in one region and in a zigzag pattern in another region.Furthermore, the drag can be varied by creating a linear depression in one region extending in a predetermined direction, and in another region creating a linear depression extending in a direction orthogonal to the predetermined direction. Additionally, the drag can be differentiated by varying the density T of the aforementioned sections between one region and another. [Industrial applicability]

[0063] The present invention can be applied to a turbine guide vane and a steam turbine. [List of reference symbols] 100 steam turbine 1 rotating shaft 2 steam turbine housings 3 steam turbine rotor 4A Radial bearing 4B Axial bearing 5 slots 6 fine uneven area 7 outer area 8 inner area 9 water-repellent areas 10 super water-repellent areas 11 Wave end 12 Steam supply pipe 13 Steam outlet channel 20 guide vanes 21 Guide vane main body 21A inner circumferential end surface 21B outer peripheral end surface 21F front edge 21P Print page 21Q Suction side 21R rear edge 22 Guide vane cover 30 Running shovel 31 Rotor blade main body 34 Blade cover 61 outer, finely uneven area 62 inner, finely uneven area 71 first outer area 72, 72' second outer area 73 third outer area 74, 74' fourth outer area 81 first inner area 82, 82' second inner area 83 third inner area 84, 84' fourth inner area L11 first outer boundary line L12 second outer boundary line L13 third outer boundary line L14 fourth outer boundary line L21 first inner boundary line L22 second inner boundary line L23 third inner boundary line L24 fourth inner boundary line O axis S steam T preceding section T1 first preceding section T2 second preceding section Wd droplets

Claims

[1] A turbine guide vane with: a pressure side (21P) extending in a radial direction that intersects a flow direction of steam and is facing upstream in the flow direction, wherein a slot (5) which captures / traps droplets produced by liquefaction of the steam is formed on a downstream side of the pressure side (21P), wherein a finely uneven area (61, 7, 71, 72, 73, 74), which guides or directs the droplets deposited on the pressure side (21P) in the radial direction such that the droplets are moved to the slot (5) and from upstream to downstream, is formed in a position further upstream than the slot (5), and the finely uneven area (61, 7, 71, 72, 73, 74) exhibits a flow resistance to the droplets that increases in the radial direction from the inside out. [2] The turbine guide vane according to claim 1, wherein the finely uneven region (61, 7, 71, 72, 73, 74) comprises a plurality of hydrophilic regions arranged such that they are adjacent to each other in the radial direction, wherein the flow resistances to the droplets of the plurality of hydrophilic regions are different between the plurality of regions, and the flow resistance of the hydrophilic region is higher the further out the hydrophilic region is positioned in the radial direction. [3] The turbine guide vane according to claim 1 or 2, wherein the finely uneven area (61, 7, 71, 72, 73, 74) is progressively curved from upstream to downstream in order to change from a state extending in the flow direction to a state extending in the radial direction. [4] The turbine guide vane according to any one of claims 1 to 3, wherein the finely uneven area (61, 7, 71, 72, 73, 74) comprises hydrophilic areas and water-repellent areas arranged alternately in the radial direction. [5] The turbine guide vane according to one of claims 1 to 4, wherein the slot (5) is provided to be spaced apart in the flow direction from a rear edge, which is an end edge of the turbine guide vane (21) on the downstream side, with an intermediate space between them, and a super water-repellent area (10) with a higher water-repellent effect than the pressure side (21P) is formed in the intermediate space. [6] The turbine guide vane according to any one of claims 1 to 5, wherein an inner, finely uneven area (8, 62, 81, 82, 83, 84), which directs or guides the droplets deposited on the pressure side (21P) in the radial direction from upstream to downstream, is further formed on an inner side in the radial direction of the finely uneven area (61, 7, 71, 72, 73, 74) of the pressure side (21P), and wherein the inner, finely uneven area (8, 62, 81, 82, 83, 84) exhibits a flow resistance to the droplets that gradually increases in the radial direction inwards. [7] The turbine guide vane according to any one of claims 1 to 6, wherein the finely uneven region (61, 7, 71, 72, 73, 74) comprises a hydrophilic region and a water-repellent region arranged in the radial direction, and an unmachined surface formed between the hydrophilic region and the water-repellent region. [8] The turbine guide vane according to any one of claims 1 to 7, wherein the finely uneven region (61, 7, 71, 72, 73, 74) comprises a hydrophilic region and a water-repellent region arranged in the radial direction, and an unmachined surface formed between the hydrophilic region and the water-repellent region, and the hydrophilic region, the unmachined surface and the water-repellent region are arranged in this order and in a repeated form. [9] A steam turbine (100) with: a rotating shaft (1) which is rotatable about an axis, a plurality of turbine rotor blades (30) arranged in a circumferential direction with respect to an axial direction on an outer circumferential surface of the rotating shaft (1), a housing (2) that covers the rotating shaft (1) and the turbine blades (30) from an outer circumferential side, and a plurality of turbine guide vanes (21) according to one of claims 1 to 8, which are arranged in the circumferential direction around the axis on an inner circumferential surface of the housing (2) and are provided adjacent to the turbine rotor blades (30) in the axial direction.

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