Turbine stator vane and steam turbine

Abstract

The turbine vane has: a vane main body extending in a radial direction intersecting a flow direction of steam; a hydrophilic region formed on a surface of the vane main body, having a relatively high hydrophilicity than other portions, and gradually increasing in radial dimension as it approaches a downstream side in the flow direction; and a recovery portion provided on a downstream side of the hydrophilic region and recovering a liquid film flowing along the hydrophilic region.

Description

Technical Field

[0001] This invention relates to a turbine stator blade and a steam turbine. This application claims priority to Japanese Patent Application No. 2020-136246, filed on August 12, 2020, the contents of which are incorporated herein by reference. Background Technology

[0002] The steam turbine comprises: a rotating shaft rotatable about an axis; a plurality of turbine moving blades arranged at intervals along the axial direction on the outer circumferential surface of the rotating shaft; a casing covering the rotating shaft and the turbine moving blades from the outer circumferential side; and a plurality of turbine stationary blades radially supported by inner and outer rings on the inner circumferential side of the casing. Each turbine moving blade has a plurality of moving blades arranged circumferentially along the rotating shaft, and each turbine stationary blade has a plurality of stationary blades arranged circumferentially along the rotating shaft. The turbine moving blades form a stage by being adjacent to the turbine stationary blades on the downstream side in the axial direction. An inlet is formed on the upstream side of the casing, connected to an inlet pipe for drawing steam from the outside, and an exhaust chamber is formed on the downstream side. The steam generated in the boiler is regulated in pressure and temperature by several regulating valves, its flow rate is regulated by a turbine inlet valve, and it flows into the turbine. The high-temperature, high-pressure steam drawn in from the inlet pipe is regulated in flow direction and velocity in the turbine stationary blades, and then converted into rotational force of the rotating shaft in the turbine moving blades.

[0003] As steam travels through the turbine, it loses energy and its temperature (and pressure) decreases as it moves from upstream to downstream. In particular, steam turbines for thermal power generation typically consist of a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine. The two stages from the downstream side of the low-pressure turbine (a pair of turbine stationary blades and a pair of turbine moving blades) create a two-phase flow environment. Thus, in the downstream stage, a portion of the steam liquefies and exists as tiny droplets (water droplets) in the airflow, some of which adhere to the surface of the turbine stationary blades. These droplets exist on the surface of the turbine stationary blades from upstream to downstream, growing and forming a liquid film by accumulating on the blade surface. This liquid film is constantly exposed to the high-speed steam flow. If the liquid film grows further and its thickness increases, a portion of it is torn apart by the steam flow, or the liquid film adhering to the stationary blades disperses downstream from the trailing edge of the stationary blades as larger droplets. The dispersed droplets are gradually accelerated downstream by the steam flow. Larger droplets have greater inertial forces, preventing them from flowing smoothly through the turbine blades and causing them to collide with them. The circumferential velocity of the turbine blades increases towards the tip, sometimes exceeding the speed of sound. Therefore, collisions between the scattered droplets and the turbine blades can cause erosion on their surface. Furthermore, the droplet collisions can impede the rotation of the turbine blades, resulting in braking losses.

[0004] To prevent the adhesion and growth of such droplets, various technologies have been proposed to date. For example, in the device described in Patent Document 1 below, a suction port for drawing in a liquid film is formed on the surface of the turbine stationary blade, and a hydrophilic removal surface is formed extending from the leading edge of the turbine stationary blade toward the suction port. The removal surface is configured such that its width (radial dimension) gradually narrows from the upstream side to the downstream side. In other words, the area of ​​the hydrophilic removal surface decreases as the width narrows. After the liquid film moves along the removal surface, it can be drawn out through the suction port.

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2017-106451 Summary of the Invention

[0008] The technical problem to be solved by the invention

[0009] However, as in Patent Document 1, when the width of the removal surface narrows towards the downstream side, the liquid film becomes more concentrated in the narrower area towards the downstream side of the removal surface, leading to an increase in its thickness. Furthermore, when multiple droplet flows (liquid veins) are formed within the removal surface, these multiple liquid veins combine with each other as they concentrate towards the downstream side, resulting in an increase in the thickness of the liquid film. If the thickness of the liquid film upstream of the suction port increases in this way, it is more easily torn apart by the vapor flow, and the droplets may scatter again downstream. Moreover, if the liquid film becomes thicker, it is difficult to be drawn in by the suction port, and the thickness of the liquid film that is not drawn in by the suction port increases as it reaches and remains at the trailing edge of the stationary blade further downstream of the suction port. As a result, the diameter of the droplets scattering downstream increases, and the number of droplets may also increase. Therefore, there is still room for improvement in the device described in Patent Document 1.

[0010] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a turbine stationary blade and steam turbine that can further reduce the growth of liquid film so as to more effectively and easily recover the liquid film.

[0011] means for solving technical problems

[0012] To address the aforementioned issues, the turbine stator blade of the present invention comprises: a blade body extending radially in a direction intersecting the flow direction of steam; a hydrophilic region formed on the surface of the blade body, having a relatively higher hydrophilicity than other parts, and whose radial dimension gradually increases as it moves downstream of the flow direction; and a recovery section disposed downstream of the hydrophilic region, which recovers the liquid film flowing along the hydrophilic region.

[0013] Invention Effects

[0014] According to the present invention, it is possible to provide a turbine stator blade and a steam turbine that can further reduce the growth of liquid film so that the liquid film can be recovered more effectively and easily. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram showing the structure of the steam turbine according to the first embodiment of the present invention.

[0016] Figure 2 This is an enlarged cross-sectional view showing the main part of the steam turbine according to the first embodiment of the present invention.

[0017] Figure 3 This is an enlarged cross-sectional view of the main part of a modified example of a steam turbine according to the first embodiment of the present invention.

[0018] Figure 4 This is an enlarged cross-sectional view showing the main part of the steam turbine according to the second embodiment of the present invention.

[0019] Figure 5 This is an enlarged cross-sectional view showing the main part of the steam turbine according to the third embodiment of the present invention.

[0020] Figure 6 This is an enlarged cross-sectional view showing the main part of the steam turbine according to the fourth embodiment of the present invention. Detailed Implementation

[0021] <First Implementation>

[0022] (Structure of a steam turbine)

[0023] The following is for reference. Figure 1 and Figure 2 The steam turbine 1 (especially a low-pressure steam turbine) and the stationary blade 10 (turbine stationary blade) according to the first embodiment of the present invention will be described. Figure 1 As shown, the steam turbine 1 has a rotor 2 and a casing 3.

[0024] The rotor 2 has a rotating shaft 6 with a circular cross-section extending along axis Ac, and a plurality of moving blade cascades 7 disposed on the outer circumferential surface of the rotating shaft 6. The rotating shaft 6 is rotatable about axis Ac. The plurality of moving blade cascades 7 are arranged at intervals along axis Ac. Each moving blade cascade 7 has a plurality of moving blades 8 arranged circumferentially along axis Ac. The moving blades 8 extend radially outward from the outer circumferential surface of the rotating shaft 6. The detailed structure of the moving blades 8 will be described later.

[0025] The housing 3 has a housing body 3H that covers the rotor 2 from the outer periphery, and a plurality of stationary blade cascades 9 supported from the outer and inner periphery by an outer ring 21 (described later) and an inner ring 23 (described later) disposed on the inner periphery of the housing body 3H. The housing body 3H is cylindrical about an axis Ac. The plurality of stationary blade cascades 9 are arranged at intervals along the axis Ac. The steam turbine 1 has the same number of moving blade cascades 7 as the stationary blade cascades 9, with one moving blade cascade 7 located between a pair of adjacent stationary blade cascades 9 in the axis Ac direction. That is, the moving blade cascades 7 and the stationary blade cascades 9 are arranged alternately in the axis Ac direction. One stationary blade cascade 9 and one moving blade cascade 7 form a "stage". Each stationary blade cascade 9 has a plurality of stationary blades 10 arranged circumferentially along the axis Ac. The stationary blades 10 extend radially relative to the axis Ac.

[0026] A steam flow path 11 is formed on one side of the housing body 3H along the Ac direction. This steam flow path 11 is used to draw high-temperature, high-pressure steam introduced from the inlet pipe into the stage of the housing body 3H. An exhaust chamber 12 is provided on the other side of the housing body 3H along the Ac direction to handle steam pressure recovery.

[0027] The steam flowing into the steam flow path 11 passes through the stage within the shell body 3H, then through the exhaust chamber 12 and is delivered to the condenser (not shown). In the following description, when viewed from the exhaust chamber 12, the side where the steam flow path 11 is located is referred to as the upstream side in the direction of steam flow. When viewed from the steam flow path 11, the side where the exhaust chamber 12 is located is referred to as the downstream side.

[0028] (Structure of the moving blade)

[0029] like Figure 2 As shown, the moving blade 8 has a platform 81, a moving blade body 82, and a shroud 83. The platform 81 is disposed on the outer peripheral surface of the rotating shaft 6 (outer peripheral surface 6A of the rotating shaft). The moving blade body 82 is disposed on the outer peripheral side of the platform 81. The moving blade body 82 extends radially and has a blade-shaped cross-section when viewed radially. As an example, the moving blade body 82 is formed such that its dimension in the axial direction Ac gradually decreases as it moves from the radially inner side to the outer side. A shroud 83 is disposed at the radially outer end of the moving blade body 82. The shroud 83 has a generally rectangular cross-section with the axial direction Ac as its length direction. The outer peripheral surface of the shroud 83 is radially spaced from the inner peripheral surface of the housing body 3H (inner peripheral surface 3A of the housing).

[0030] (Structure of the stationary blade)

[0031] The stationary blade 10 has an outer ring 21, a stationary blade body 22, and an inner ring 23. The stationary blade body 22 has a hydrophobic region 30, a hydrophilic region 40, and a slit S. The outer ring 21 is annular about the axis Ac. The outer ring 21 is supported on the housing body 3H by a support member (not shown). The stationary blade body 22 is fixedly disposed between the outer ring 21 and the inner ring 23. The stationary blade body 22 extends radially inward from the inner circumferential surface 21A of the outer ring and has a blade-shaped cross-section when viewed radially. That is, the stationary blade body 22 extends in a direction intersecting the flow direction of the steam. As an example, the dimension of the stationary blade body 22 in the direction of the axis Ac gradually decreases as it moves from the radially outer side towards the inner side. The inner ring 23 is provided at the radially inner end of the stationary blade body 22. The inner ring 23 has a generally rectangular cross-section with the axis Ac as its length direction. The inner circumferential surface of the inner ring 23 is radially spaced from the outer circumferential surface 6A of the rotating shaft.

[0032] A hydrophobic region 30, a hydrophilic region 40, and a slit S are formed on the surface of the stationary blade body 22 (more specifically, on the surface facing upstream in the thickness direction of the two sides of the stationary blade body 22: the ventral side). As an example, the hydrophobic region 30 is preferably formed from the end of the outer peripheral side of the stationary blade body 22 to a region of about 1 / 2 to 2 / 3 radially. The hydrophobic region 30 is formed throughout the entire region from the upstream end edge (leading edge Le) to the downstream end edge (trailing edge Te) of the stationary blade body 22.

[0033] The hydrophobic region 30 has a higher hydrophobicity than the hydrophilic region 40 (described later) on the surface of the stator blade body 22. For example, the hydrophobic region 30 can be formed by performing micro-processing to improve the hydrophobicity on the surface of the stator blade body 22 or by attaching a hydrophobic sheet. If the hydrophobic region 30 is formed in this way, the contact angle of the attached droplets can be 90° or more. In addition, it is sufficient for the hydrophobic region 30 to have at least a difference in hydrophilicity with the hydrophilic region 40. Therefore, a structure can be adopted in which only the hydrophilic region 40 is formed on the surface of the stator blade body 22 without forming the hydrophobic region 30.

[0034] A slit S is formed on the trailing edge Te side of the hydrophobic region 30, which serves as a recovery section C for collecting the liquid film flowing along the hydrophilic region 40 (described later). The slit S extends along the trailing edge Te. The slit S is one or more elongated holes communicating with the interior of the stationary blade body 22. That is, the stationary blade body 22 is hollow. The interior space of the stationary blade body 22 is preferably set to a negative pressure state by means of a device not shown.

[0035] Multiple (four in one example) hydrophilic regions 40 are formed from the leading edge Le of the stationary blade body 22 to the slit S. The hydrophilic regions 40 have a relatively higher hydrophilicity than the aforementioned hydrophobic regions 30 or regions other than the hydrophobic regions 30. That is, in the hydrophilic regions, the contact angle of the attached droplets is smaller than that of the droplets attached to the hydrophobic regions. Thus, the droplets expand in a manner adapted to the surface of the hydrophilic regions 40 and are retained as a thin liquid film.

[0036] In this embodiment, a plurality of hydrophilic regions 40 are arranged radially. Furthermore, the width (i.e., radial dimension) of each hydrophilic region 40 gradually increases from the upstream side (leading edge Le side) to the downstream side (slit S side). Additionally, in Figure 2 In the example, the expansion rate of the width of the hydrophilic region 40 is constant. That is, Figure 2 An example is shown where both the radially outer and inner edges of the hydrophilic region 40 extend in a straight line. However, depending on the design and specifications, a structure may also be adopted in which the expansion rate of the width of the hydrophilic region 40 gradually increases or decreases towards the downstream side.

[0037] At the upstream edge of the slit S, multiple hydrophilic regions 40 are continuous with each other. In other words, the upstream edge of the slit S extends across the entire region and is connected to the hydrophilic regions 40. In other words, the upstream edge of the slit S does not contact the hydrophobic regions 30.

[0038] (Effects)

[0039] Next, the operation of the steam turbine 1 and the movement of the droplets in the stationary blades 10 according to this embodiment will be described. When the steam turbine 1 is operated, high-temperature and high-pressure steam is first introduced into the interior of the casing body 3H through the steam flow path 11. The steam flows alternately through the stationary blade cascade 9 and the moving blade cascade 7 as it flows downstream inside the casing body 3H. The stationary blade cascade 9 rectifies the steam flow so that it flows into the moving blade cascade 7 adjacent to the downstream side. Since the steam acts on the moving blade cascade 7, it imparts torque to the rotating shaft 6 through the moving blade cascade 7. With this torque, the rotor 2 rotates around the axis Ac. The rotational energy of the rotor 2 is extracted from the shaft end and used for driving a generator (not shown), etc.

[0040] Here, as the steam in the stage passes through the main flow path of the turbine, its energy is converted into rotational energy, and its temperature (and pressure) decreases each time it passes through the stage from the upstream side to the downstream side. Consequently, in the downstream stator blade cascade 9, a portion of the steam liquefies and exists as tiny droplets in the airflow, some of which adhere to the surface of the stator blade 10 (stator blade body 22). These droplets grow to form a liquid film. Furthermore, as the droplets continue to increase in number, if the liquid film thickens as it flows downstream, a portion of it is torn apart by the steam flow, or the liquid film adhering to the stator blade cascade 9 is dispersed from the trailing edge of the stator blade as large droplets. The dispersed droplets are gradually accelerated by the steam flow as they flow downstream. If these large droplets collide with the downstream moving blade 8, erosion may occur on the surface of the moving blade 8. Furthermore, the collision of droplets may also impede the rotation of the moving blade 8 (rotor 2), resulting in braking losses.

[0041] Therefore, in this embodiment, as described above, a hydrophilic region 40 is formed on the surface of the stationary blade body 22. Droplets adhering to the stationary blade body 22 spread thinly in a manner adapted to the hydrophilic region 40, forming a liquid film. Due to the difference in hydrophilicity at the boundary between the hydrophilic region 40 and other portions, the liquid film remains inside the hydrophilic region 40. This liquid film flows downstream along the vapor flow within the hydrophilic region 40.

[0042] Here, the radial dimension of the hydrophilic region 40 gradually increases as it moves downstream. Therefore, as the liquid film flows downstream, its area within the hydrophilic region 40 expands, becoming a thinner liquid film. Consequently, the liquid film surface becomes more stable compared to a thicker liquid film. Therefore, waves are less likely to form on the liquid film surface, reducing the possibility of the liquid film being torn apart by the vapor flow. As a result, the liquid film flows downstream along the hydrophilic region 40 and is easily collected by the slit S, which serves as the recovery section C. This suppresses the generation of large droplets torn apart by the vapor flow upstream of the slit S, as well as large droplets that fly across the slit S and scatter from the trailing edge of the stationary blade body 22. Therefore, the possibility of droplets scattering to the moving blade 8 located downstream of the low stationary blade 10 can be reduced. On the other hand, due to the thickness of the liquid film, if the liquid film is torn apart by vapor, it will scatter downstream as large droplets, or the liquid film adhering to the stationary blade cascade 9 will scatter from the trailing edge of the stationary blade as large droplets, and may cause erosion by colliding with the moving blade 8. According to the above structure, the occurrence of such erosion can be suppressed.

[0043] Furthermore, according to the above structure, multiple hydrophilic regions 40 are arranged radially. This allows droplets to be guided to the hydrophilic regions 40 over a wider radial range. Also, since the steam turbine 1 typically continues to operate under rated conditions, the area and path of the liquid film forming on the surface of the stationary blade body 22 are generally stable, and the liquid film tends to form further outward than the radially inner side (mainly from the outer peripheral end of the stationary blade body 22 to approximately 1 / 2 to 2 / 3 of the radial direction). For example, by pre-determining such an area or path, if multiple hydrophilic regions 40 are formed along this path, the area of ​​the hydrophilic regions 40 can be minimized. That is, although the hydrophobicity of the inner peripheral surface of the stationary blade body 22 can be higher than that of the hydrophobic regions 30, due to excessive processing costs, the hydrophobic regions 30 are preferably formed only on the outer peripheral side where the hydrophilic regions 40 are formed, as described above. Thus, compared to the case where the hydrophilic regions 40 are formed on the entire stationary blade body 22, manufacturing or maintenance costs can be reduced.

[0044] Furthermore, according to the above structure, the hydrophilic region 40 extends from the leading edge Le of the stationary blade body 22 to the slit S that serves as the recovery section C. Thus, the hydrophilic region 40 can stably guide and recover the liquid film throughout the entire area from the leading edge Le of the stationary blade body 22 to the recovery section C.

[0045] Furthermore, according to the above structure, the slit S, which serves as the recovery section C, is formed on the trailing edge Te side of the stationary blade body 22. This slit S allows for more stable capture and recovery of the liquid film.

[0046] Furthermore, according to the above structure, at the upstream edge of the slit S, multiple hydrophilic regions 40 are continuous with each other. In other words, the edge is connected to the hydrophilic regions 40 throughout the entire region. Thus, for example, compared to a case where a portion of the edge is not connected to the hydrophilic regions 40, the amount of liquid film guided to the recovery section C can be increased, and the liquid film can be captured and recovered more effectively and stably.

[0047] Furthermore, according to the above structure, the portion radially connected to the hydrophilic region 40 is designated as the hydrophobic region 30. This increases the difference in hydrophilicity at the boundary between the hydrophilic region 40 and the hydrophobic region 30. As a result, the likelihood of the liquid film adhering to the hydrophilic region 40 moving across the boundary towards the hydrophobic region 30 is reduced. That is, the liquid film is more easily retained inside the hydrophilic region 40. Consequently, the likelihood of the liquid film detaching from the hydrophilic region 40 is further reduced, allowing the liquid film to be guided more smoothly to the slit S, which serves as the recovery section C.

[0048] The first embodiment of the present invention has been described above. Furthermore, various modifications or improvements can be made to the above structure without departing from the spirit of the invention. For example, in the first embodiment, a structure in which a plurality (four) of hydrophilic regions 40 are arranged radially has been described. However, the structure of the hydrophilic regions 40 is not limited to this; as another example, other structures may also be used. Figure 3 The structure shown. In Figure 3 In the example, only one hydrophilic region 40b is formed from the leading edge Le to the slit S. Furthermore, the width (radial dimension) of this hydrophilic region 40b gradually increases as it moves from the upstream side to the downstream side. With this structure, the same effect as described above can be achieved.

[0049] <Second Implementation>

[0050] Next, refer to Figure 4 The second embodiment of the present invention will now be described. Furthermore, structures identical to those in the first embodiment and its variations will be labeled with the same reference numerals, and detailed descriptions will be omitted. Figure 4 As shown, in this embodiment, a separation zone 50 is formed within each hydrophilic region 40.

[0051] The separation zone 50 has the same hydrophobicity as the hydrophobic region 30 described above. The separation zone 50 extends in a triangular pattern downstream from the leading edge Le side of the hydrophilic region 40. More specifically, the radial dimension of the separation zone 50 gradually increases as it approaches the slit S side from the leading edge Le side. Thus, the hydrophilic region 40 is radially divided into multiple (two) regions, forming a pair of regions extending in a band-like pattern from the upstream side to the downstream side. These pairs of regions extend radially apart from each other as they move from the upstream side to the downstream side.

[0052] According to the above structure, a separation zone 50 is formed within the hydrophilic region 40. By appropriately adjusting the shape or size of this separation zone 50 according to the actual movement of the liquid film in the steam turbine 1, the direction of travel of the liquid film within the hydrophilic region 40 can be controlled more precisely. In other words, by forming the separation zone 50, the width (radial dimension) of the hydrophilic region 40 is relatively smaller, and its length in the upstream and downstream directions is relatively larger. As a result, when the liquid film is guided from the upstream side to the downstream side, the possibility of the liquid film flow detaching radially is reduced, and the droplets can be guided more stably to the downstream recovery section C. This further reduces the possibility of the liquid film growing and scattering towards the downstream moving blades 8.

[0053] The second embodiment of the present invention has been described above. Furthermore, various modifications or improvements can be made to the above structure without departing from the spirit of the invention. For example, in the second embodiment described above, an example of forming only one separation zone 50 within a hydrophilic region 40 was described. However, the manner in which the separation zone 50 is formed is not limited to this; as another example, two or more separation zones 50 may be formed in each hydrophilic region 40.

[0054] <Third Implementation Method>

[0055] Next, refer to Figure 5 The third embodiment of the present invention will now be described. Furthermore, structures identical to those in the above embodiments will be labeled with the same reference numerals, and detailed descriptions will be omitted. For example... Figure 5 As shown, in this embodiment, the shape of the hydrophilic region 40c differs from that in the embodiments described above. Furthermore, in this embodiment, no slit S is formed on the stationary blade body 22.

[0056] The hydrophilic region 40c extends from the leading edge Le of the stationary blade body 22 toward the inner circumferential surface (inner circumferential surface 21A) of the outer ring 21. That is, the hydrophilic region 40c extends radially outward from the upstream side toward the downstream side. The inner circumferential surface 21A of the outer ring forms a recovery section C for recovering the liquid film flowing along the hydrophilic region 40c. In the hydrophilic region 40c, the width (radial dimension) gradually increases toward the downstream side (the side of the inner circumferential surface 21A of the outer ring). Multiple such hydrophilic regions 40c are formed radially spaced apart (three, for example).

[0057] According to the above structure, the inner circumferential surface 21A of the outer ring functions as the recovery section C. That is, after the droplets adhering to the stationary blade body 22 form a liquid film in the hydrophilic region 40c, they flow towards the outer circumferential side towards the inner circumferential surface 21A. As a result, the flow of the liquid film downstream in the direction of vapor flow (mainstream direction) is reduced, and the possibility of droplets scattering to the downstream moving blade 8 is further reduced. Thus, the generation of erosion in the moving blade 8 can be suppressed.

[0058] The third embodiment of the present invention has been described above. Furthermore, various modifications or improvements can be made to the above structure without departing from the spirit of the present invention.

[0059] <Fourth Implementation Method>

[0060] Next, refer to Figure 6 The fourth embodiment of the present invention will now be described. Furthermore, structures identical to those in the above embodiments will be labeled with the same reference numerals, and detailed descriptions will be omitted. For example... Figure 6As shown, in this embodiment, the hydrophilic region 40d has: a first region A1 having the same structure as the hydrophilic region 40c described in the third embodiment above; and a second region A2 formed on the inner periphery of the first region A1.

[0061] The first region A1 extends from the leading edge Le toward the inner circumferential surface 21A of the outer ring. On the other hand, the second region A2 extends radially inward as it moves from the upstream side to the downstream side. Multiple second regions A2 are arranged radially at intervals (three in one example). Furthermore, the upstream end of the second region A2 is located midway along the extending direction of the first region A1 (including the direction of the axial direction Ac). The downstream end of the second region A2 is located at the trailing edge Te.

[0062] According to the above structure, most of the liquid film can be guided towards the outer ring 21 through the first region A1, and components of droplets that cannot be captured by the first region A1 or components that detach from the first region A1 can be captured through the second region A2. The second region A2 extends radially inward towards the downstream side. As a result, the possibility of droplets or liquid films remaining in the radial center of the stationary blade body 22 is reduced. Furthermore, for example, even if the liquid film in the second region A2 is torn and generates large droplets, they can be dispersed towards the inner circumferential portion of the downstream moving blade 8. Since the circumferential velocity on the inner circumferential side of the moving blade 8 is lower than the circumferential velocity at the end of the outer circumferential side, the relative velocity with the large droplets is suppressed to a low level. As a result, even in the case of collision with large droplets, the possibility of erosion can be minimized.

[0063] The fourth embodiment of the present invention has been described above. Furthermore, various modifications or improvements can be made to the above structure without departing from the spirit of the present invention.

[0064] <Postscript>

[0065] For example, the turbine stationary blade (stationary blade 10) and steam turbine 1 described in each embodiment are as follows.

[0066] (1) The turbine stationary blade (stationary blade 10) according to the first embodiment includes: a stationary blade body 22 extending radially in a direction intersecting the flow direction of steam; hydrophilic regions 40, 40b, 40c, 40d formed on the surface of the stationary blade body 22, having relatively higher hydrophilicity than other parts, and gradually increasing in radial dimension as it moves downstream of the flow direction; and a recovery section C provided downstream of the hydrophilic regions 40, 40b, 40c, 40d, and recovering the liquid film flowing along the hydrophilic regions 40, 40b, 40c, 40d.

[0067] According to the above structure, hydrophilic regions 40, 40b, 40c, and 40d are formed on the surface of the stationary blade body 22. As a result, droplets adhering to the stationary blade body 22 expand thinly in a manner adapted to the hydrophilic regions 40, 40b, 40c, and 40d, forming a liquid film. Due to the difference in hydrophilicity at the boundaries between the hydrophilic regions 40, 40b, 40c, and 40d and other parts, the liquid film remains inside the hydrophilic region 40. This liquid film flows downstream along the vapor flow within the hydrophilic regions 40, 40b, 40c, and 40d. Here, the radial dimensions of the hydrophilic regions 40, 40b, 40c, and 40d gradually increase as they move downstream. Therefore, as the liquid film flows downstream, its area expands within the hydrophilic regions 40, 40b, 40c, and 40d, becoming an even thinner liquid film. Therefore, compared to the case where the liquid film is maintained at a thicker thickness, the likelihood of the liquid film being torn apart by the vapor flow is reduced. As a result, the liquid film can be recovered more effectively to the recovery section C, reducing the possibility of droplets scattering onto the turbine moving blades (moving blades 8) located downstream of the turbine stationary blades.

[0068] (2) The turbine stationary blades involved in the second method have a plurality of the hydrophilic regions 40, 40c, 40d arranged along the radial direction.

[0069] According to the above structure, multiple hydrophilic regions 40, 40c, and 40d are arranged radially. This allows droplets to be guided to the hydrophilic regions 40, 40c, and 40d over a wider radial range. Furthermore, since the steam turbine 1 typically continues to operate under rated conditions, the area and path of the liquid film forming on the surface of the stationary blade body 22 remain relatively stable. For example, by pre-determining such an area or path, if multiple hydrophilic regions 40, 40c, and 40d are formed along this path, the area of ​​the hydrophilic regions 40, 40c, and 40d can be minimized. Therefore, compared to the case where hydrophilic regions 40, 40c, and 40d are formed on the entire stationary blade body 22, manufacturing or maintenance costs can be reduced.

[0070] (3) In the turbine stator blade involved in the third method, the hydrophilic regions 40, 40b, 40c (or the first region A1 of the hydrophilic region 40d) extend from the leading edge Le of the stator blade body 22 to the recovery section C.

[0071] According to the above structure, the hydrophilic regions 40, 40b, and 40c (or the first region A1 of the hydrophilic region 40d) extend from the leading edge Le of the stationary blade body 22 to the recovery section C. Thus, the liquid film is stably guided by the hydrophilic regions 40, 40b, and 40c (or the first region A1 of the hydrophilic region 40d) throughout the entire area from the leading edge Le of the stationary blade body 22 to the recovery section C, enabling more efficient recovery of the liquid film.

[0072] (4) The turbine stator blade involved in the fourth method also has a separation zone 50, which divides the hydrophilic region 40 into multiple parts by extending from a position further downstream than the leading edge Le side in the hydrophilic region 40.

[0073] According to the above structure, a separation zone 50 is formed within the hydrophilic region 40. By appropriately changing the shape or size of this separation zone 50, the direction of travel of the liquid film within the hydrophilic region 40 can be controlled more precisely. In other words, by forming the separation zone 50, the width (radial dimension) of the hydrophilic region 40 is relatively smaller, and its length in the upstream and downstream directions is relatively larger. As a result, when the liquid film is guided from the upstream side to the downstream side, the possibility of radial detachment is reduced, and the droplets can be guided more stably to the downstream recovery section C.

[0074] (5) In the turbine stator blade involved in the fifth method, the recovery part C is a slit S, which is formed on the trailing edge Te side of the stator blade body 22, extends along the trailing edge Te and communicates with the interior of the stator blade body 22.

[0075] According to the above structure, the slit S, which serves as the recovery section C, is formed on the trailing edge Te side of the stationary blade body 22. The liquid film can be captured and recovered more stably by this slit S.

[0076] (6) The turbine stator blade involved in the sixth method has a plurality of hydrophilic regions 40 arranged along the radial direction, and the plurality of hydrophilic regions 40 are continuous with each other on the end edge of the upstream side of the slit S.

[0077] According to the above structure, at the upstream end of the slit S, multiple hydrophilic regions 40 are continuous with each other. In other words, the end edge is connected to the hydrophilic region 40 throughout the entire area. Thus, for example, compared to the case where a portion of the end edge is not connected to the hydrophilic region 40, the amount of liquid film that does not reach the recovery section C is reduced, enabling more efficient and stable capture and recovery of the liquid film.

[0078] (7) The turbine stationary blade involved in the seventh method also includes an outer ring 21 disposed on the outer peripheral side of the stationary blade body 22, and the recovery part C is the inner peripheral surface of the outer ring 21 (outer ring inner peripheral surface 21A).

[0079] According to the above structure, the inner circumferential surface of the outer ring 21 functions as the recovery section C. That is, after the droplets attached to the stationary blade body 22 form a liquid film in the hydrophilic region 40c (or the first region A1 of the hydrophilic region 40d), they flow towards the inner circumferential surface of the outer ring 21. As a result, the flow of the liquid film downstream in the direction of vapor flow (mainstream direction) is reduced, and the possibility of droplets scattering to the downstream turbine blades is further reduced.

[0080] (8) In the turbine stator blade involved in the eighth method, the hydrophilic region 40c (or the first region A1 of the hydrophilic region 40d) extends radially outward from the upstream side to the downstream side, thereby connecting to the inner circumferential surface of the outer ring 21.

[0081] According to the above structure, the liquid film can be stably and smoothly guided along the hydrophilic region 40c (or the first region A1 of the hydrophilic region 40d) to the inner circumferential surface of the outer ring 21.

[0082] (9) In the turbine stator blade of the ninth method, the hydrophilic region 40d has: a first region A1 extending toward the inner circumferential surface of the outer ring 21; and a second region A2 formed on the inner circumferential side of the first region A1, extending radially inward as it moves from the upstream side toward the downstream side.

[0083] According to the above structure, most of the liquid film can be guided towards the outer ring 21 through the first region A1, and components of the droplets that cannot be captured by the first region A1 can be captured through the second region A2. The second region A2 extends radially inward towards the downstream side. As a result, the possibility of liquid film retention in the radial center of the stationary blade body 22 is reduced. Furthermore, for example, even if a large droplet is generated on the trailing edge side of the liquid film originating from the second region A2, it can be dispersed towards the inner circumferential side of the downstream turbine blade. Since the circumferential velocity on the inner circumferential side of the turbine blade is lower than the circumferential velocity at the end of the outer circumferential side, the relative velocity with the large droplet is suppressed to a low level. As a result, even in the case of collision with a large droplet, the possibility of erosion can be minimized.

[0084] (10) In the turbine stator blade involved in the 10th method, at least the portion of the surface of the stator blade body 22 that is connected to the hydrophilic regions 40, 40b, 40c, 40d is a hydrophobic region 30 having a relatively higher hydrophobicity than the hydrophilic regions 40, 40b, 40c, 40d.

[0085] According to the above structure, the portions connected to the hydrophilic regions 40, 40b, 40c, and 40d are designated as the hydrophobic region 30. Consequently, the difference in hydrophilicity at the boundaries between the hydrophilic regions 40, 40b, 40c, and 40d and the hydrophobic region 30 becomes greater. As a result, the liquid film is more easily retained inside the hydrophilic regions 40, 40b, 40c, and 40d, further reducing the likelihood of the liquid film detaching from these regions.

[0086] (11) The steam turbine 1 according to the 11th aspect includes: a rotating shaft 6 rotatable about an axis Ac; a plurality of turbine moving blades (moving blades 8) arranged circumferentially on the outer peripheral surface (outer peripheral surface 6A of the rotating shaft 6) in a direction relative to the axis Ac; a housing body 3H covering the rotating shaft 6 and the turbine moving blades from the outer peripheral side; and a plurality of turbine stationary blades (stationary blades 10) arranged circumferentially on the inner peripheral surface of the housing body 3H in a direction relative to the axis Ac, and disposed adjacent to the turbine moving blades in the direction of the axis Ac.

[0087] Based on the above structure, by suppressing the growth of the liquid film, the performance degradation or erosion caused by coarse droplets can be reduced, thus providing a more efficient and highly reliable steam turbine 1.

[0088] Industrial availability

[0089] This invention relates to a turbine stator blade and a steam turbine. According to the invention, a turbine stator blade and a steam turbine can be provided that can further reduce liquid film growth, thereby enabling more efficient and easier recovery of the liquid film.

[0090] Symbol Explanation

[0091] 1-Steam turbine, 2-Rotor, 3-Casing, 3A-Inner circumferential surface of casing, 3H-Main body of casing, 6-Rotating shaft, 6A-Outer circumferential surface of rotating shaft, 7-Moving blade cascade, 8-Moving blade (turbine moving blade), 9-Stationary blade cascade, 10-Stationary blade (turbine stationary blade), 11-Steam flow path, 12-Exhaust chamber, 21-Outer ring, 21A-Inner circumferential surface of outer ring, 22-Main body of stationary blade, 23-Inner ring, 30-Hydrophobic region, 40, 40b, 40c, 40d-Hydrophilic region, 50-Separation zone, 81-Platform, 82-Main body of moving blade, 83-Shield, A1-First region, A2-Second region, Ac-Axis, C-Recovery section, Le-Leading edge, S-Slit, Te-Left edge.

Claims

1. A turbine stator blade, comprising: The stationary blade body extends radially, intersecting the direction of steam flow; The hydrophilic region, formed on the surface of the stationary blade body, has a relatively higher hydrophilicity than other parts, and its radial dimension gradually increases as it moves downstream in the flow direction; A hydrophobic region, formed on the surface of the stator blade body, radially connected to the hydrophilic region, and having a relatively higher hydrophobicity than the hydrophilic region; and The recovery unit is located downstream of the hydrophilic region and recovers the liquid film flowing along the hydrophilic region.

2. The turbine stationary blade according to claim 1, having a plurality of said hydrophilic regions arranged along the said radial direction.

3. The turbine stationary blade according to claim 1 or 2, wherein, The hydrophilic region extends from the leading edge of the stationary blade body to the recovery section.

4. The turbine stator blade according to claim 1 or 2, further comprising a separation zone, the separation zone dividing the hydrophilic region into a plurality of sections by extending downstream from a position in the hydrophilic region further downstream than the leading edge side.

5. The turbine stationary blade according to claim 1 or 2, wherein, The recovery section is a slit formed on the trailing edge side of the stationary blade body, extending along the trailing edge of the stationary blade body and communicating with the interior of the stationary blade body.

6. The turbine stator blade according to claim 5, having a plurality of said hydrophilic regions arranged along said radial direction, On the upstream edge of the slit, the plurality of hydrophilic regions are continuous with each other.

7. The turbine stationary blade according to claim 1 or 2, further comprising an outer ring disposed on the outer periphery of the stationary blade body. The recovery section is the inner circumferential surface of the outer ring.

8. The turbine stationary blade according to claim 7, wherein, The hydrophilic region extends radially outward from the upstream side to the downstream side, thereby connecting to the inner circumferential surface of the outer ring.

9. The turbine stationary blade according to claim 8, wherein, The hydrophilic region has: The first region extends toward the inner circumferential surface of the outer ring; and The second region is formed on the inner periphery of the first region and extends radially inward as it moves from the upstream side to the downstream side.

10. A steam turbine comprising: A rotation axis that can rotate around an axis; Multiple turbine blades are arranged circumferentially on the outer circumferential surface of the rotating shaft, relative to the axis direction. The housing body covers the rotating shaft and the turbine blades from the outer periphery; and The turbine stationary blades of any one of claims 1 to 9 are arranged circumferentially relative to the axis on the inner circumferential surface of the housing body and are disposed adjacent to the turbine moving blades in the axial direction.

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