TURBINE GUIDE SHAFTS AND STEAM TURNINE

Abstract

A turbine guide vane (21) with: a pressure side (21P) extending in a radial direction that intersects a flow direction of steam and faces upstream in the flow direction, wherein a slot (5) extending in the radial direction and capturing / trapping a liquefied component of the vapor is formed on a downstream side of the pressure side (21P), wherein a hydrophilic uneven region (6) which has a greater liquid film capacity than that of the pressure side (21P) by being excavated in a depth direction intersecting the pressure side (21P) is formed at a position further upstream than the slot (5), characterized in that the hydrophilic uneven area (6) has a depth in the depth direction that increases stepwise from upstream to downstream in the direction of flow, and has a flow resistance that decreases downstream and towards the slot (5), the hydrophilic uneven region (6) comprises a plurality of protruding sections (T) arranged at intervals or spaces in the direction of flow and in the radial direction, a length between the preceding sections (T) in the flow direction is designated as La, a length from each of the preceding sections (T) in the flow direction is designated as Lb, and a value of La / Lb decreases downstream and towards the slot (5), and the value of La / Lb decreases gradually.

Description

[Technical field]

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

[0002] A steam turbine is equipped with a rotating shaft that can be turned about an axis, a plurality of turbine rotor blade stages arranged at intervals in an axial direction on an outer circumferential surface of the rotating shaft, a casing that covers the rotating shaft and the turbine rotor blade stages on an outer circumferential side, and a plurality of turbine guide vane or stator blade stages arranged alternately with the turbine rotor blade stages on an inner circumferential surface of the casing. An intake port is formed on an upstream side of the casing, which draws in steam from the outside, and an exhaust port is formed on a downstream side of the casing.The high-temperature and high-pressure steam drawn in through the intake opening is converted into a rotational force of the rotating shaft at the turbine guide vane stage, after a flow direction and speed have been set at the turbine guide vane stage.

[0003] As the steam flows through the turbine from upstream to downstream, it loses energy, and the temperature (and pressure) decreases. Therefore, in the turbine guide vane stage, on the downstream side, some of the steam liquefies and exists in the airflow as fine water droplets, some of which adhere to a surface of the guide vane. The droplets quickly grow into a liquid film on the blade surface. This liquid film is constantly exposed to a high-velocity steam flow around it. However, as the liquid film continues to grow and thicken, some of it is carried away by the steam flow and dispersed into very large droplets. These dispersed droplets flow downstream, progressively accelerated by the steam flow. The larger the droplets, the greater the inertial force.In this way, the large droplets in the main steam flow cannot pass between the turbine blades and therefore collide with them. Since the peripheral speed of the turbine blades can exceed the speed of sound, the surfaces of the turbine blades can erode when the dispersed droplets collide with them, and erosion can occur. Furthermore, the collision of the droplets can impede the rotation of the turbine blades, and a loss of braking power can result.

[0004] Several techniques have been proposed to prevent the adhesion and growth of such droplets. For example, in the device described below in JP 2017-106 451 A, an extraction port is formed for drawing in a liquid film from the surface of the turbine guide vane, and a hydrophilic removal surface is formed extending from one side of the leading edge of the turbine guide vane to the extraction port. After the liquid film has moved along the removal surface, it can be drawn off through the extraction port.

[0005] Furthermore, US Patent 2007 / 0031639A1 discloses a component with low wettability comprising 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 chosen such that the surface section exhibits wettability sufficient to generate a contact angle of at least approximately 100 degrees with a reference fluid. The elements have a height dimension (h) and a width dimension (a) and are spaced (b) apart from one another. The ratio of b / a and the ratio of h / a are chosen such that droplets exhibit metastable non-Wenzel behavior. [Summary of the invention][Technical problem]

[0006] Furthermore, droplets can adhere to the surface of the turbine guide vane to form a fluid film, not only at a terminal edge on the upstream side (a leading edge), but also in the middle between the leading and trailing edges. The flow rate of the fluid film thus increases from upstream to downstream. However, since the hydrophilicity of the extraction surface in the device described in JP 2017-106 451 A is uniform across its entire area, this increase in the fluid film flow rate cannot be accommodated. Consequently, the fluid film on the upstream side can extend beyond the extraction opening, forming the aforementioned very large droplets and dispersing. Therefore, the device described in JP 2017-106 451 A requires further improvement.

[0007] The present invention was made to solve the aforementioned problems, and one object of the present invention is to provide a turbine guide vane and a steam turbine that can further reduce the growth of a liquid film. [Solution to the problem]

[0008] The characteristics of independent claims are proposed.

[0009] A turbine guide vane according to one aspect of the present invention comprises a pressure side extending in a radial direction that intersects a flow direction of steam and faces upstream in the flow direction, wherein a slot extending in the radial direction and capturing or trapping a liquefied component of the steam is formed on a downstream side of the pressure side, a hydrophilic uneven region with a liquid film capacity greater than that of the pressure side by being formed at a position further upstream than the slot in a depth direction intersecting the pressure side, and wherein the hydrophilic uneven region has a depth in the depth direction that increases and a flow resistance that decreases downstream and towards the slot.

[0010] According to the aforementioned configuration, the depth of the hydrophilic uneven region increases downstream and towards the slot. Consequently, more droplets can be retained downstream in this hydrophilic uneven region. Here, the droplets can adhere to the surface of the turbine guide vane not only at a leading edge on the upstream side, but also in the midway between the leading and trailing edges to form a fluid film. The droplet flow rate thus increases from upstream to downstream. According to the aforementioned configuration, the potential for dispersal downstream of the turbine guide vane can be reduced, even if more droplets adhere to the midway from upstream to downstream, because the droplets can be retained by the hydrophilic uneven region.

[0011] In the turbine guide vane, the hydrophilic uneven region can comprise a plurality of protruding sections spaced at intervals in the flow direction and the radial direction, and a length between the protruding sections in the flow direction can be denoted as La and a length of the protruding sections in the flow direction can be denoted as Lb, with a value of La / Lb being able to decrease downstream and towards the slot.

[0012] The flow resistance against the liquid film arises not only from an interaction between the liquid film and the wall surface, but also from an interaction between the liquid films themselves. This interaction is particularly significant when the liquid film is water. Since, in this case, the droplets and the vapor are attracted to each other, a flow resistance occurs between the droplets flowing in the direction of flow between the aforementioned sections and the vapor flowing radially between them. If the length between the aforementioned sections in the direction of flow is denoted as La, and the length of each of the aforementioned sections in the direction of flow is denoted as Lb, the flow resistance decreases as the value of La / Lb becomes smaller.According to the aforementioned configuration, the flow resistance of the steam towards the slot can be reduced, as the La / Lb value decreases downstream. Consequently, the loss on the pressure side due to the formation of the hydrophilic uneven region can be reduced.

[0013] In the case of the turbine guide vane, the protruding sections can have rectangular shapes when viewed in a direction orthogonal to the pressure side, and can have rectangular cross-sections when viewed in the radial direction.

[0014] According to the aforementioned configuration, the leading edge section has a rectangular shape when viewed orthogonally to the pressure side and a rectangular cross-section when viewed radially. Therefore, for example, the leading edge section can be formed more simply and cost-effectively than if it had a polygonal shape other than a rectangular or columnar shape. Consequently, the cost and time required to manufacture the turbine guide vane can be reduced.

[0015] In the case of the turbine guide vane, the hydrophilic uneven area can exhibit a stepwise increasing depth in the direction of flow from upstream to downstream.

[0016] According to the aforementioned configuration, the depth increases stepwise from upstream to downstream. Therefore, for example, the hydrophilic uneven zone can be formed more simply and cost-effectively than in a configuration where the depth increases continuously. This reduces the cost and time required to manufacture the turbine guide vane.

[0017] The turbine guide vane can further include a water-repellent area which is positioned further upstream than the hydrophilic uneven area in the direction of flow and has a higher water-repellent effect than that of the pressure side.

[0018] According to the aforementioned configuration, since the water-repellent region exhibits a higher water-repellent effect than the pressure side, the droplets adhering to the water-repellent region flow downstream with the vapor flow before they aggregate into a larger liquid film. The droplets can thus be induced to flow downstream in a state of fine droplets. This further reduces the formation of a liquid film due to the downstream flow of droplets with a large particle size.

[0019] 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 preceding 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.

[0020] According to the aforementioned configuration, a steam turbine can be obtained in which the growth of the liquid film is further reduced and losses are minimized. [Advantageous effects of the invention]

[0021] According to the present invention, a turbine guide vane and a steam turbine can be provided which can further reduce the growth of a liquid film. [Brief description of the drawings] Fig. Figure 1 is a schematic view showing a configuration of a steam turbine according to an embodiment of the present invention. Fig. Figure 2 is a perspective view showing a configuration of a turbine guide vane according to a first embodiment of the present invention. Fig. Figure 3 is an enlarged view showing a configuration of a pressure side of a turbine guide vane according to a first embodiment of the present invention. Fig. 4 is a view of a cross-section along a line AA of Fig. 3. Fig. Figure 5 is an enlarged cross-sectional view of a hydrophilic uneven area according to the first embodiment of the present invention. Fig. Figure 6 is an explanatory diagram showing the behavior of droplets in the hydrophilic uneven region according to the first embodiment of the present invention. Fig. Figure 7 is a perspective view showing a configuration of a turbine guide vane according to a second embodiment of the present invention. [Description of the embodiments][First embodiment]

[0022] A first embodiment of the present invention is described with reference to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 described. A steam turbine 100 according to the present embodiment is equipped with 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 sliding bearing 4A and an axial bearing 4B rotatably supporting a shaft end 11 of the steam turbine rotor 3 about the axis O.

[0023] 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 at regular intervals in the circumferential direction of the rotating shaft 1. A plurality of rows of rotor blades 30 are also arranged at regular intervals in the direction of the axes O. Each of the rotor blades 30 has a rotor blade body 31 (a turbine rotor blade) and a rotor blade cover 34. The rotor blade body 31 projects radially outward from the outer circumferential surface of the steam turbine rotor 3. The rotor blade body 31 has a flow-profiled cross-section when viewed in the radial direction. A rotor blade cover 34 is provided at an outer end section (an end section on the radially outer side) of the rotor blade body 31.

[0024] 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, a steam inlet pipe 12 is provided in the direction of axis O, which draws in steam S. On the other side of the steam turbine casing 2, in the direction of axis O, a steam outlet pipe 13 is provided, which discharges the steam S. The steam flows within the steam turbine casing 2 from one side to the other in the direction of axis O. In the following description, a direction in which the steam flows is simply referred to as the "flow direction".Furthermore, the side on which the steam supply pipe 12 is located, viewed from the steam outlet pipe 13, is referred to as the upstream side in the direction of flow, and the side on which the steam outlet pipe 13 is located, viewed from the steam supply pipe 12, is referred to as the downstream side in the direction of flow.

[0025] A plurality of rows of guide vanes or stator blades 20 are provided on the inner circumferential surface of the steam turbine casing 2. Each of the guide vanes 20 has a guide vane body 21 (a turbine guide vane), a guide vane cover 22, and a guide vane base 24. The guide vane body 21 is a flow-profile-shaped element that is connected to the inner circumferential surface of the steam turbine casing 2 via the guide vane base 24. Furthermore, a guide vane cover 22 is provided at an outer end section (an end section on the radial inner surface) of the guide vane body 21. Similar to the rotor blades 30, the plurality of guide vanes 20 are arranged on the inner circumferential surface in the circumferential direction and along the axis O. The rotor blades 30 are arranged to enter a region between the plurality of adjacent guide vanes 20.The guide vanes 20 and the rotor vanes 30 therefore extend in a direction (a radial direction with respect to the axis O) that intersects with the flow direction of the steam.

[0026] The steam S is supplied to the interior of the steam turbine casing 2, which is configured as described above, via the steam supply pipe 12 on the upstream side. As it flows 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 vane 20 aligns the steam flow S, and the aligned mass of the steam S presses on the rotor blade 30 to exert a rotational force on the steam turbine rotor 3. The rotational force of the steam turbine rotor 3 is derived from the shaft end 11 and used to drive an external device (a generator or the like). While the steam turbine rotor 3 rotates, the steam S is discharged through the steam outlet 13 on the downstream side to a downstream device (a condenser or the like).

[0027] The plain bearings 4A carry a radial load with respect to axis O. A plain bearing 4A is provided at each end of the steam turbine rotor 3. The axial bearing 4B carries a load in the direction of axis O. The axial bearing 4B is only provided at the end section on the upstream side of the steam turbine rotor 3.

[0028] The configuration of the guide vane main body 21 is described below with reference to Fig. 2 described. The guide vane body 21 extends in the radial direction (radial direction with respect to axis O), which is a direction that intersects the flow direction. The cross-section of the guide vane body 21, viewed in the radial direction, has a flow-profile shape. In particular, the 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 tapered shape, with a progressively decreasing length in the circumferential direction when viewed in the radial direction. 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.

[0029] One surface of the guide vane body 21 on one side in the circumferential direction is a suction side 21Q, which faces downstream in the flow direction. The suction side 21Q has a curved surface shape that is convex on one side in the circumferential direction. On the other side of the guide vane body 21, a surface facing the flow direction is a pressure side 21P. The pressure side 21P has a curved surface shape that is concave on one side in the circumferential direction. When the steam is flowing, the pressure on the pressure side 21P is higher than the pressure on the suction side 21Q.

[0030] An end surface facing radially inwards towards the guide vane main body 21 is the inner circumferential end surface 21A, and an end surface facing radially outwards is the outer circumferential end surface 21B. The in Fig. The guide vane cover 22 and the guide vane base 24 shown in Figure 1 are in Fig. 2 omitted.

[0031] A slot 5 and a hydrophilic uneven region 6 are formed on a section on the pressure side 21P that is offset from 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 radially along the pressure side 21P. One long side of the slot 5 extends radially, and one short side extends in the flow direction mentioned above. As will be described in detail later, the slot 5 is designed to capture or trap the liquefied components (droplets) of the vapor flowing from the front edge 21F to the rear edge 21R along the pressure side 21P.The slot 5 is connected to a flow path (not shown) formed inside the guide vane main body 21, and the captured or trapped droplets are guided or directed outwards from the guide vane main body 21 through this flow path.

[0032] The hydrophilic uneven region 6 is adjacent to the slot 5 and extends further upstream (towards the front rim 21F) than the slot 5 in the flow direction. The hydrophilic uneven region 6 has a higher hydrophilicity than the pressure side 21P and is designed to cause droplets flowing from the front rim 21F along the pressure side 21P to enter the slot 5 at the rear rim 21R without repelling them. The hydrophilic uneven region 6 is subdivided into three areas in the flow direction from the front rim 21F to the rear rim 21R. An area closest to the front edge 21F is a first area 61, and an area closest to the rear edge 21R is a third area 63. An area between the first area 61 and the third area 63 is a second area 62.

[0033] The liquid film capacity is higher in the second region (62) than in the first region (61). The liquid film capacity is higher in the third region (63) than in the second region (62). The term "liquid film capacity" used here refers to the extent of permeation and retention of the liquid film in this region. Furthermore, the amount of permeation and retention is determined by the porosity in this region. Additionally, the flow resistance to the droplets is lower in the second region (62) than in the first region (61). The flow resistance to the droplets is lower in the third region (63) than in the second region (62).

[0034] More precisely, as in Fig. As shown in Figure 3, microscopic examination of the hydrophilic uneven region 6 reveals a plurality of projecting sections T in the first region 61, the second region 62, and the third region 63. The projecting sections T have a rectangular shape when viewed in a direction orthogonal to the pressure side 21P and have substantially rectangular cross-sections when viewed in the radial direction. In the present embodiment, the projecting sections T of the first region 61 (first projecting sections 61T) form, for example, squares when viewed in the orthogonal direction to the pressure side 21P. The first projecting sections 61T are arranged at intervals in a grid pattern in the flow direction and in the radial direction.Furthermore, the shapes of the cross-sections of the preceding sections T also allow for a processing error, as long as the shapes of the cross-sections of the preceding sections T are essentially rectangular shapes.

[0035] A forward section T (a second forward section 62T) of the second region 62 has a rectangular shape when viewed in the direction orthogonal to the pressure side 21P. In particular, a length in the flow direction of the second forward section 62T is slightly longer than that of the first forward section 61T. Like the first forward section 61T, the second forward section 62T is also arranged at intervals in the flow direction and in the radial direction in a grid pattern. A forward section T (a third forward section 63T) of the third region 63 has a rectangular shape, with a length in the flow direction of the third forward section 63T being longer than that of the second forward section 62T. Like the second forward section 62T, the third forward section 63T is also arranged at intervals in the flow direction and in the radial direction in a grid pattern.

[0036] Among the spaces formed between the preceding sections T, one space formed in the radial direction (i.e., the direction orthogonal to the flow direction of the vapor) is called the flow path P. The flow path P is formed by making a space formed between a pair of preceding sections T that are adjacent to each other in the radial direction continuous in the flow direction. As described in detail below, some of the droplets and vapor can flow through the flow path P in the flow direction.

[0037] Furthermore, as in Fig. As shown in Figure 4, in the hydrophilic uneven region 6, the height of a lower surface B in the direction orthogonal to the pressure side 21P increases stepwise from the first region 61 to the third region 63. In particular, the distance (a depth in a depth direction) from the pressure side 21P to the lower surface B increases stepwise towards the slot 5. The lower surface B (a second lower surface 62B) of the second region 62 is formed at a lower position than the lower surface B (a first lower surface 61B) of the first region 61. The lower surface B (a third lower surface 63B) of the third region 63 is formed at a lower position than the second lower surface 62B. The first lower surface 61B, the second lower surface 62B, and the third lower surface 63B each have a shape along the pressure side 21P. Although in Fig. 4. While the first lower surface 61B, the second lower surface 62B, and the third lower surface 63B are each shown as having a planar shape for the sake of simplicity, they are in fact curved in conformity with the curved surface shape of the printed side 21P. The third lower surface 63B is connected to the end edge of the slot 5 on the upstream side.

[0038] As in Fig. As shown in Figure 5, the value of the length ratio La / Lb of the protruding section T decreases stepwise from the first region 61 to the third region 63, where a length between the sections projecting in the flow direction is denoted as La and a length of the protruding section T in the flow direction is denoted as Lb. Specifically, the distance between the first end surface T1 of a protruding section T, facing upstream in the flow direction, and the second end surface T2 of another protruding section T, adjacent to the protruding section T facing downstream in the flow direction, is denoted as La. Furthermore, a length from the first end surface T1 to the second end surface T2 of a protruding section T (i.e., a length of an upper surface T3 of the protruding section T in the flow direction) is denoted as Lb.Preferably, in the first region 61, the value of the length ratio La / Lb is set to a value less than 1, particularly preferably La / Lb<0.8 and most preferably La / Lb<0.5.

[0039] Since, as described above, the length of the long side of the rectangle formed by the aforementioned section T increases stepwise from the first region 61 to the third region 63, the value of the length ratio La / Lb decreases stepwise from the first region 61 to the third region 63. The value of La (i.e., an intermediate distance of the aforementioned section T) is less than 1 µm or 100 µm or more. The aforementioned section T is preferably manufactured using short pulse machining and laser machining, including surface interference wave machining, as described above.

[0040] It is known that when the preceding section T is configured as described above, the hydrophilic uneven region 6 exhibits high hydrophilicity. A state of “high hydrophilicity,” as used here, refers to the state in which a contact angle formed by the droplets adhering to the hydrophilic uneven region with respect to the surface of the hydrophilic uneven region is less than 90°. In particular, the state in which the contact angle is less than 5° is termed superhydrophilicity.

[0041] Since the value of La / Lb decreases stepwise from the first section 61 to the third section 63, the flow resistance to the steam flowing through the flow path P can also be reduced stepwise. In particular, as shown in Fig. As shown in Figure 6, when the droplets Wd remain in the space between the first preceding sections 61T, which are adjacent to each other in the flow direction, a tensile force is generated by the droplets Wd with respect to the steam flow Fs flowing through the flow path P. This force becomes a flow resistance with respect to the steam flow Fs. Thus, if the value of the length ratio La / Lb mentioned above is reduced, the tensile force of the droplets Wd decreases per unit length of the flow path P. Therefore, as shown in Fig. As shown in Figure 6, in the second region 62, the tensile force Wd, which is captured or trapped between the second preceding sections 62T, is smaller than the tensile force in the first region 61. Similarly, in the third region 63, the tensile force induced by the droplets, which are captured or trapped between the third preceding sections 63T, is smaller than the tensile force in the second region 62. Thus, in the hydrophilic uneven region 6, the flow resistance with respect to the steam flow Fs downstream and towards the slot 5 is reduced.

[0042] The behavior of the steam in the guide vane main body 21 according to the present embodiment is described below. The temperature of the steam flowing through the steam turbine casing 2 decreases as the steam moves from upstream to downstream. Therefore, in the turbine guide vane stage, a portion of the steam liquefies on the downstream side and is deposited on the surface of the guide vane main body 21 in the form of droplets (water droplets). The droplets progressively grow into a liquid film. As the liquid film continues to grow, a portion of it is carried away and dispersed as very large droplets.The scattered droplets attempt to enter the main steam flow and flow downstream, but the very large droplets, due to the large inertial force acting upon them, cannot sufficiently enter the main flow and collide with the turbine blade (the main blade body 31). Since the peripheral speed of the turbine blade can exceed the speed of sound, the surface of the turbine blade can be eroded by the collision of the scattered droplets, resulting in erosion. Furthermore, the rotation of the turbine blades can be impeded by the collision of the droplets, leading to a loss of braking power.

[0043] In the guide vane main body 21 according to the present embodiment, the slot 5 and the hydrophilic uneven area 6 are formed on the pressure side 21P. Therefore, most droplets can be captured or trapped by the slot 5, and the possibility of downstream dispersion can be reduced. Since the hydrophilic uneven area 6, which has a larger liquid film capacity than the pressure side 21P, is formed in a more upstream position than the slot 5, the droplets adhering to the hydrophilic uneven area 6 diffuse and are immediately accustomed to the hydrophilic uneven area 6 after adhering. This reduces the possibility of the droplets aggregating and growing.

[0044] The droplets on the surface of the guide vane main body 21 can adhere not only to the end edge (the leading edge 21F) on the upstream side, but also in the midway between the leading edge 21F and the trailing edge 21R to form a liquid film. The flow rate of the liquid film increases from upstream to downstream on the pressure side 21P. Therefore, if the hydrophilicity is uniform across the entire area in the flow direction, the increasing flow rate of the liquid film cannot be accommodated. Consequently, there is a probability that the liquid film will continue to grow upstream of the slot 5, becoming very large droplets and dispersing.

[0045] In the aforementioned configuration, however, the depth of the hydrophilic uneven region 6 increases downstream and towards the slot 5. Consequently, more droplets can be retained downstream in the hydrophilic uneven region 6. The apparent fluid film capacity thus increases downstream. Even if more droplets accumulate at the center from upstream to downstream, the possibility of dispersion towards the downstream side of the guide vane main body 21 can therefore be reduced, since the droplets can be retained by the second region 62 or the third region 63 of the hydrophilic uneven region 6.

[0046] Between the droplets Wd, which flow between the aforementioned sections T in the direction of flow, and the flow Fs of steam, which flows between the aforementioned sections T in the radial direction, the droplets Wd and the steam are attracted to each other, and a flow resistance is created relative to the steam flow Fs. If the length between the aforementioned sections T in the direction of flow is denoted as La and the length of each of the aforementioned sections in the direction of flow is denoted as Lb, the flow resistance decreases as the value of La / Lb becomes smaller. According to the configuration described above, the flow resistance with respect to the steam flow Fs towards the slot 5 can be reduced because the value of the length ratio La / Lb becomes smaller downstream. This can reduce the loss on the pressure side 21P caused by the formation of the hydrophilic uneven region 6.

[0047] Furthermore, according to the aforementioned configuration, the preceding section T has a rectangular shape when viewed from the direction orthogonal to the pressure side 21P, and has a rectangular cross-section when viewed in the radial direction. Therefore, for example, the preceding section T can be formed more simply and cost-effectively than if the preceding section T had a polygonal shape other than a rectangular or columnar shape. Consequently, the cost and time required to manufacture the guide vane main body 21 can be reduced.

[0048] Furthermore, according to the aforementioned configuration, the length of the hydrophilic uneven region 6 increases stepwise from upstream to downstream in the depth direction. Therefore, for example, the hydrophilic uneven region 6 can be designed more simply and cost-effectively than in a configuration where the depth increases continuously in the depth direction. This reduces the cost and time required for manufacturing the guide vane main body 21.

[0049] The first embodiment of the present invention has been described above. Various changes and modifications to the aforementioned configuration can be made within the scope of the present invention. For example, the first embodiment describes an example in which the hydrophilic uneven region 6 is subdivided into three regions: the first region 61, the second region 62, and the third region 63. However, the aspect of the hydrophilic uneven region 6 is not limited to the aforementioned example, and a configuration can also be adopted in which the hydrophilic uneven region 6 is subdivided into four or more regions with different hydrophilicities. [Second embodiment]

[0050] Next, a second embodiment of the present invention will be described with reference to Fig. 7 described. The same components as in the first embodiment are designated by the same reference numerals, and a detailed description of them is not provided. As in Fig.Figure 7 shows that in the present embodiment, a water-repellent region 7, which has a water-repellent property, is provided in a position further upstream than the hydrophilic uneven region 6. The term "water-repellent property," as used here, indicates the condition in which a contact angle formed by the droplets adhering to the water-repellent region 7 is 90° or greater. Thus, after reaching the water-repellent region 7, the droplets are repelled without adhering to it for long and reach the hydrophilic uneven region 6 on the downstream side. In the water-repellent region 7, the droplets therefore enter the vapor flow and flow downstream before aggregating into a larger liquid film. The droplets can thus be induced to flow downstream in their fine droplet state.This further suppresses the formation of a liquid film by the downstream flow of droplets with large particle sizes.

[0051] The aforementioned condition, in which the contact angle is 150° or more, is referred to as the super water-repellent condition, and since a stronger water-repellent function can be exerted, the formation of a liquid film can be suppressed more effectively.

[0052] The second embodiment of the present invention has been described above. Various changes and modifications to the aforementioned configuration can be made within the scope of the present invention. [Industrial applicability]

[0053] According to the present invention, a turbine guide vane and a steam turbine can be provided which can further reduce the growth of a liquid film. [List of reference symbols] 100 steam turbine 1 rotating shaft 2 steam turbine housings 3 steam turbine rotor 4A Plain bearing 4B Axial bearing 5 slots 6 hydrophilic uneven area 7 water-repellent areas 11 Wave end 12 Steam supply pipe 13 Steam discharge 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 Intake side 21R rear edge 22 Guide vane cover 30 Running shovel 31 Main rotor blade body 34 Blade cover 51 slotted main body 52 enlarged section 61 first area 61B first lower surface 61T first preceding section 62 second area 62B second lower surface 62T second preceding section 63 third area 63B third lower surface 63T third preceding section B lower surface Fs steam flow O axis P Flow path S steam T preceding section T1 first final surface T2 second end surface T3 upper surface Wd droplets.

Claims

[1] A turbine guide vane (21) with: a pressure side (21P) extending in a radial direction that intersects a flow direction of steam and faces upstream in the flow direction, wherein a slot (5) extending in the radial direction and capturing / trapping a liquefied component of the vapor is formed on a downstream side of the pressure side (21P), wherein a hydrophilic uneven region (6) which has a greater liquid film capacity than that of the pressure side (21P) by being excavated in a depth direction intersecting the pressure side (21P) is formed at a position further upstream than the slot (5), characterized by , that the hydrophilic uneven area (6) has a depth in the depth direction that increases stepwise from upstream to downstream in the direction of flow, and has a flow resistance that decreases downstream and towards the slot (5), the hydrophilic uneven region (6) comprises a plurality of protruding sections (T) arranged at intervals or spaces in the direction of flow and in the radial direction, a length between the preceding sections (T) in the flow direction is designated as La, a length from each of the preceding sections (T) in the flow direction is designated as Lb, and a value of La / Lb decreases downstream and towards the slot (5), and the value of La / Lb decreases gradually. [2] The turbine guide vane (21) according to claim 1, wherein the foreground sections (T) have rectangular shapes when viewed in a direction orthogonal to the pressure side (21P) and have rectangular cross-sections when viewed in the radial direction. [3] The turbine guide vane (21) according to one of claims 1 to 2, which further comprises a water-repellent area (7) which is provided at a more upstream position than the hydrophilic uneven area (6) in the flow direction and which has a higher water-repellent effect than that of the pressure side (21P). [4] A steam turbine (100) with: a rotating shaft (1) which is rotatable about an axis (O), a plurality of turbine rotor blades (31) 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 (31) from an outer circumferential side, and a plurality of turbine guide vanes (21) according to one of claims 1 to 3, which are arranged in the circumferential direction around the axis (O) on an inner circumferential surface of the housing (2) and are provided adjacent to the turbine rotor blades (31) in the axial direction.

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