WO2013089139A1 - タービン - Google Patents
タービン Download PDFInfo
- Publication number
- WO2013089139A1 WO2013089139A1 PCT/JP2012/082206 JP2012082206W WO2013089139A1 WO 2013089139 A1 WO2013089139 A1 WO 2013089139A1 JP 2012082206 W JP2012082206 W JP 2012082206W WO 2013089139 A1 WO2013089139 A1 WO 2013089139A1
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- WIPO (PCT)
- Prior art keywords
- blade
- seal fin
- steam
- tip
- wall surface
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/02—Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/14—Form or construction
- F01D5/141—Shape, i.e. outer, aerodynamic form
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/001—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between stator blade and rotor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
- F01D11/12—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part
- F01D11/122—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part with erodable or abradable material
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/22—Blade-to-blade connections, e.g. for damping vibrations
- F01D5/225—Blade-to-blade connections, e.g. for damping vibrations by shrouding
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2220/00—Application
- F05D2220/30—Application in turbines
- F05D2220/31—Application in turbines in steam turbines
Definitions
- the present invention relates to a turbine used in, for example, a power plant, a chemical plant, a gas plant, a steel mill, a ship, and the like.
- a turbine used in, for example, a power plant, a chemical plant, a gas plant, a steel mill, a ship, and the like.
- This steam turbine is roughly classified into an impulse turbine and a reaction turbine depending on the operation method.
- An impulse turbine is one in which a moving blade rotates only by an impact force received from steam.
- the stationary blade has a nozzle shape, and the steam that has passed through the stationary blade is injected to the moving blade, and the moving blade rotates only by the impact force received from the steam.
- the reaction turbine has the same shape as the moving blade, and the moving blade is affected by the impact force received from the steam that has passed through the stationary blade and the reaction force against the expansion of the steam that occurs when passing through the moving blade. Is what rotates.
- a gap having a predetermined width is formed in the radial direction between the tip portion of the rotor blade and the casing, and also between the tip portion of the stationary blade and the shaft body.
- a gap having a predetermined width is formed in the direction.
- a part of the steam flowing in the axial direction of the shaft body leaks to the downstream side through the clearance between the tip portions of the rotor blades and the stationary blades.
- the steam leaking downstream from the gap between the moving blade and the casing does not give impact force or reaction force to the moving blade, so that the driving blade is rotated regardless of whether it is an impulse turbine or a reaction turbine. Little contribution as power.
- the steam leaking downstream from the gap between the stationary blade and the shaft body does not change its speed and does not expand even if it exceeds the stationary blade, so regardless of whether it is an impulse turbine or a reaction turbine, It hardly contributes as a driving force for rotating the moving blade on the downstream side. Therefore, in order to improve the performance of the steam turbine, it is important to reduce the amount of steam leakage in the gap between the tip portions of the moving blades and the stationary blades.
- seal fins are conventionally used as a means for preventing steam from leaking from the gaps at the tips of the rotor blades and stationary blades.
- this seal fin is used at the tip of a moving blade, it is provided so as to protrude from one of the moving blade and the casing and to form a minute gap between the other.
- JP 2006-291967 A Japanese Patent Laid-Open No. 02-030903
- FIG. 8 is a schematic cross-sectional view showing the periphery of the tip portion of the rotor blade 80 for a conventional steam turbine.
- the separation vortex HU reduces the amount of leakage by compressing the steam S leaking downstream through the minute gap 85 between the tip of the seal fin 82 and the casing 84 in the radial direction. Small effect. As a result, in the configuration in which the seal fin 82 protrudes from the moving blade 80, the sealing performance cannot be obtained satisfactorily.
- the present invention has been made in view of such circumstances, and an object of the present invention is to provide a tip of a fin and a wing body in a turbine in which the seal fin extends from one of the wing body and the structure toward the other. Another object of the present invention is to provide means for reducing the amount of steam leakage in the gap between the structures.
- a turbine according to the present invention includes a blade and a structure that is provided at a radial front end side of the blade via a gap and that rotates relative to the blade, and in which a fluid flows in the gap.
- a step portion having a step in the radial direction provided at any one of a radial tip portion of the blade and a portion of the structure facing the radial tip portion, and a radial tip portion of the blade
- a seal fin that extends from the other part of the structure facing the tip end in the radial direction toward the step part and forms a micro gap between the part and the step in the fluid flow direction.
- a flow collision surface on which the fluid collides, a convex portion protruding from the flow collision surface toward the upstream side, and the flow collision surface Comprising a facing surface that direction, the.
- the fluid that has collided with the flow collision surface forms a main vortex in the space between the flow collision surface and the opposing surface and on the blade proximal side from the convex portion. Then, part of the main vortex is peeled off at the convex portion, so that a peeling vortex is generated in the space between the flow collision surface and the opposing surface and on the blade tip side from the convex portion. Furthermore, when a part of the peeling vortex peels off at the corner of the step part, a peeling vortex is generated inside the widened portion formed on the upstream side of the seal fin.
- the separation vortex generated in the widened portion flows from the seal fin toward the structure at the position of the minute gap formed between the tip of the seal fin and the structure. As a result, this separation vortex exhibits a so-called contraction effect that reduces the amount of fluid leakage in the minute gap.
- the thermal elongation generated in the blade is larger than the thermal elongation generated in the structure, and further, when the blade is a moving blade, centrifugal elongation occurs. Cutting free-cutting material.
- the turbine shifts to rated operation, and the thermal expansion of the blades is as large as the thermal expansion of the structure or smaller than the thermal expansion of the structure, so that the seal fin is separated from the free-cutting material.
- the radial width between the seal fin and the free-cutting material is narrower than the radial width between the seal fin and the step portion when there is no free-cutting material. Thereby, the amount of fluid leakage at the tip of the seal fin can be reduced.
- step portion is provided in the structure and the seal fin is provided in the blade.
- the structure body is a casing that houses a shaft body that is rotationally driven, and the blade is a moving blade that is fixed to the shaft body and extends toward the casing.
- the structure is a shaft body that is rotationally driven, and the blade is a stationary blade that is fixed to a casing that houses the shaft body and extends toward the shaft body.
- the amount of steam leakage in the gap between the tip of the seal fin and the blade or the structure is reduced.
- FIG. 1 is a schematic cross-sectional view showing a steam turbine according to a first embodiment of the present invention.
- FIG. 2 is a partial enlarged cross-sectional view in which the vicinity of a tip portion of a moving blade in FIG. It is a figure explaining the contraction flow effect of a peeling vortex, Comprising: It is the elements on larger scale which expanded the front-end
- FIG. 1 is a schematic cross-sectional view showing a steam turbine 1 according to the first embodiment.
- the steam turbine 1 is provided in a hollow casing 10, a regulating valve 20 that adjusts the amount and pressure of steam S (fluid) flowing into the casing 10, and a casing 10 that is rotatably provided.
- a bearing portion 60 that is rotatably supported around the CL.
- Casing 10 has an internal space hermetically sealed and a flow path for steam S.
- This casing 10 has a ring-shaped partition plate outer ring 11 (structure) fixed to its inner wall surface.
- the shaft body 30 is inserted through the partition plate outer ring 11.
- a plurality of regulating valves 20 are attached to the inside of the casing 10, and each includes a regulating valve chamber 21 into which steam S flows from a boiler (not shown), a valve body 22, and a valve seat 23.
- a regulating valve chamber 21 into which steam S flows from a boiler (not shown), a valve body 22, and a valve seat 23.
- the shaft body 30 includes a shaft main body 31 and a plurality of disks 32 extending radially from the outer periphery of the shaft main body 31.
- the shaft body 30 transmits rotational energy to a machine such as a generator (not shown).
- the annular stationary blade group 40 includes a plurality of stationary blades 41 provided on the inner surface of the casing 10 along the circumferential direction of the shaft body 30.
- the stationary blade 41 includes a blade main body 42 having a base end portion held by the partition plate outer ring 11 and a ring-shaped hub shroud 43 that connects a radial tip portion of the blade main body 42 in the circumferential direction. Yes.
- the shaft 30 is inserted through the hub shroud 43 with a gap having a predetermined width in the radial direction.
- the six annular stator blade groups 40 configured in this way are provided at predetermined intervals in the axial direction of the shaft body 30, and convert the pressure energy of the steam S into velocity energy, and are adjacent to the downstream side. It guides to the moving blade 51 side.
- the bearing portion 60 includes a journal bearing device 61 that receives the shaft body 30 in the radial direction and a thrust bearing device 62 that receives the shaft body 30 in the axial direction, and supports the shaft body 30 in a rotatable manner.
- the annular blade group 50 includes a plurality of blades 51 provided along the circumferential direction of the shaft body 30.
- the blade 51 includes a blade body 511 having a base end fixed to the disk 32, and a ring-shaped tip shroud 512 (not shown in FIG. 1) that connects the radial tip ends of the blade body 511 in the circumferential direction. ).
- the six annular blade groups 50 configured as described above are provided so as to be adjacent to the downstream side of the six annular stationary blade groups 40. As a result, the annular stator blade group 40 and the annular rotor blade group 50 that are made into one set and one stage are configured in a total of six stages along the axial direction.
- FIG. 2 is a partially enlarged cross-sectional view in which the periphery of the tip portion of the rotor blade 51 in FIG. 1 is enlarged.
- An annular groove 12 is formed along the circumferential direction on the inner peripheral surface of the partition plate outer ring 11 shown in FIG.
- the annular groove 12 is formed by an upstream side wall surface 13 (opposing surface), a bottom surface 14, and a downstream side wall surface 15.
- a stepped step portion 141 is provided at a position facing the chip shroud 512 on the bottom surface 14.
- the step portion 141 is composed of three steps protruding toward the moving blade 51 toward the downstream side, and includes three axial wall surfaces (inner circumferential surfaces) 141a, 141b, 141c along the axial direction, and along the radial direction. It has three radial wall surfaces 141d, 141e, 141f.
- the step portion 141 only needs to have at least the axial wall surface 141a and the radial wall surface 141d, and the number of steps is not limited to three and can be arbitrarily changed.
- the tip 51 of the rotor blade 51 is provided with the ring-shaped tip shroud 512 as described above.
- the tip shroud 512 has a substantially rectangular cross section, and a steam collision surface 53 (flow collision surface) on which the steam S collides is provided at a position facing the upstream side wall surface 13 of the partition plate outer ring 11.
- the convex part 54 which protrudes toward an upstream is provided in the radial direction front-end
- the convex portion 54 has a substantially rectangular shape on the step surface, and is provided at the tip end in the radial direction of the tip shroud 512.
- the cross-sectional shape of the convex part 54 is not limited to the rectangle of this embodiment, A design change is possible arbitrarily, for example, it can also be made into a triangle and a semicircle.
- the cross-sectional shape of the tip shroud 512 is not limited to this embodiment, and may be a stepped shape in which the thickness in the radial direction becomes thinner toward the downstream side, for example.
- the position where the convex portion 54 is formed is not limited to the radial front end portion of the steam collision surface 53 of the tip shroud 512, and may be, for example, a radial central portion or a radial base end portion.
- the convex portion 54 serves as a so-called axial seal fin. May be configured.
- the first seal fin 55A located on the most upstream side has its base end fixed at a position slightly downstream of the radial wall surface 141d, and its distal end close to the axial wall surface 141a of the step portion 141. The position has been reached. Thereby, a minute gap 56A is formed between the first seal fin 55A and the axial wall surface 141a.
- the second seal fin 55B located on the second upstream side has its base end fixed at a position slightly downstream of the radial wall surface 141e, and its tip close to the axial wall surface 141b of the step portion 141. The position has been reached. Thereby, a minute gap 56B is formed between the second seal fin 55B and the axial wall surface 141b.
- the third seal fin 55C located on the most downstream side has a base end portion fixed slightly downstream from the radial wall surface 141f, and a tip portion thereof reached a position close to the axial wall surface 141c of the step portion 141. ing. Thereby, a minute gap 56C is formed between the third seal fin 55C and the axial wall surface 141c. And the length of the seal fin 55 comprised in this way becomes short gradually in order of the 1st seal fin 55A, the 2nd seal fin 55B, and the 3rd seal fin 55C.
- the length, shape, installation position, number, and the like of the seal fins 55 are not limited to this embodiment, and the design can be appropriately changed according to the cross-sectional shape of the tip shroud 512 and / or the partition plate outer ring 11.
- the dimensions of the minute gaps 56A, 56B, and 56C are such that the seal fin 55 and the partition plate outer ring 11 are in contact with each other in consideration of the thermal elongation amount of the casing 10 and the moving blade 51, the centrifugal elongation amount of the moving blade, and the like. It is preferable to set the minimum value within a safe range where there is no problem.
- the three minute gaps 56A, 56B, and 56C are all set to the same size, but if necessary, the minute gaps 56A, 56B, and 56C may be set to different dimensions for each seal fin 55. Good.
- the first cavity C1 located on the most upstream side is the upstream side wall surface 13 of the partition plate outer ring 11, the bottom surface 14 of the partition plate outer ring 11, the first seal fin 55A, and the steam collision surface of the chip shroud 512. 53.
- the second cavity C2 located on the second upstream side is formed by the first seal fin 55A, the bottom surface 14 of the partition plate outer ring 11, the second seal fin 55B, and the outer peripheral surface 512a of the chip shroud 512.
- the third cavity C3 located on the most downstream side is formed by the second seal fin 55B, the bottom surface 14 of the partition plate outer ring 11, the third seal fin 55C, and the outer peripheral surface 512a of the tip shroud 512. .
- the first cavity C1 has a substantially rectangular shape in a cross section along the axial direction.
- the first seal fin 55A is fixed at a position slightly downstream of the radial wall surface 141d. Accordingly, a widened portion 57 that is slightly widened in the axial direction is formed in the downstream portion of the first cavity C1 in the axial direction.
- the second cavity C2 also has a substantially rectangular shape in a cross section along the axial direction.
- the second seal fin 55B is fixed at a position slightly downstream of the radial wall surface 141e. Therefore, a widened portion 58 that is slightly widened in the axial direction is also formed in the downstream portion of the second cavity C2 in the axial direction.
- the third cavity C3 also has a substantially rectangular shape in a cross section along the axial direction.
- the third seal fin 55C is fixed at a position slightly downstream of the radial wall surface 141f. Therefore, a widened portion 59 that is slightly widened in the axial direction is formed also in the axially downstream portion of the third cavity C3.
- FIG.1 and FIG.2 the effect of the steam turbine 1 which concerns on 1st embodiment is demonstrated using FIG.1 and FIG.2.
- the regulating valve 20 shown in FIG. 1 When the regulating valve 20 shown in FIG. 1 is opened, the steam S flows into the casing 10 from a boiler (not shown). The steam S is guided to the annular moving blade group 50 by the annular stationary blade group 40 of each stage, and the annular moving blade group 50 starts rotating. Thereby, the energy of the steam S is converted into rotational energy by the annular blade group 50, and this rotational energy is transmitted from the shaft body 30 that rotates integrally with the annular blade group 50 to a generator (not shown) or the like. Is done.
- a separation vortex HU2 is generated in the widened portion 57 of the first cavity C1.
- the direction of rotation of the separation vortex HU2 is opposite to that of the separation vortex HU1, that is, counterclockwise in FIG.
- the separation vortex HU2 exhibits a so-called contraction effect that reduces the leak amount of the steam S in the minute gap 56A between the first seal fin 55A and the partition plate outer ring 11.
- FIG. 3 is a diagram for explaining the contraction effect of the separation vortex HU2, and is a partially enlarged cross-sectional view in which the periphery of the front end portion of the first seal fin 55A in FIG. 2 is enlarged.
- the counterclockwise separation vortex HU2 flows from the first seal fin 55A toward the partition plate outer ring 11 at the position of the minute gap 56A. Accordingly, the separation vortex HU2 has a radially outward inertial force.
- the steam S leaking downstream through the minute gap 56A is pressed to the axial wall surface 141a side by the inertial force of the separation vortex HU2, so that the width in the radial direction as shown by the one-dot chain line in FIG.
- the separation vortex HU2 has an effect of reducing the leak amount by compressing the steam S in the radial direction, that is, a contraction effect.
- the effect of the contraction flow increases as the inertial force of the separation vortex HU2 increases, that is, as the flow velocity of the separation vortex HU2 increases.
- the vapor S leaking from the minute gap 56A flows into the second cavity C2.
- the steam S collides with the radial wall surface 141e of the partition plate outer ring 11 to form a clockwise main vortex SU2.
- a counterclockwise peeling vortex HU3 is generated in the widened portion 58 of the third cavity C3.
- the separation vortex HU3 flows from the second seal fin 55B toward the partition plate outer ring 11 at the position of the minute gap 56B. Accordingly, the separation vortex HU3 also exhibits a contraction effect that reduces the leak amount of the steam S in the minute gap 56B, similarly to the separation vortex HU2.
- the vapor S leaking from the minute gap 56B flows into the third cavity C3.
- the steam S collides with the radial wall surface 141f of the partition plate outer ring 11, thereby forming a clockwise main vortex SU3.
- a counterclockwise peeling vortex HU4 is generated in the widened portion 59 of the third cavity C3.
- the separation vortex HU4 flows from the third seal fin 55C toward the partition plate outer ring 11 at the position of the minute gap 56C. Accordingly, the separation vortex HU4 also exhibits a contraction effect that reduces the leak amount of the steam S in the minute gap 56C, similarly to the separation vortex HU2.
- the number of cavities C along the axial direction is not limited to three, and an arbitrary number can be provided.
- the steam turbine according to the second embodiment differs from the steam turbine 1 according to the first embodiment only in the configuration of the partition plate outer ring 11 fixed to the inner wall surface of the casing 10 shown in FIG. Since the other configuration is the same as that of the first embodiment, the same reference numerals are used and description thereof is omitted here.
- FIG. 4 is a schematic cross-sectional view showing the periphery of the tip of the rotor blade 51 according to the second embodiment.
- the free cutting material 16 is applied with a uniform thickness so as to cover the bottom surface 14 of the annular groove 12 formed in the partition plate outer ring 11.
- the free-cutting material 16 is made of a material that has less sliding frictional heat and is more machinable than the seal fin 55. Examples of the free-cutting material 16 include cobalt, nickel, chromium, aluminum, and yttrium materials (CoNiCrAlY materials), nickel, chromium, aluminum materials (NiCrAl materials), nickel, chromium, and iron.
- Abradable materials made of various known free-cutting materials such as aluminum, boron, and nitrogen-based materials (NiCrFeAlBN-based materials) are used.
- a honeycomb layer made of metal or ceramic can be used in addition to the abradable material.
- the free cutting material 16 is applied to the entire bottom surface 14 of the annular groove 12, but it is sufficient that the free cutting material 16 is applied at least at a position facing the three seal fins 55 in the step portion 141. Specifically, if it is applied to the axial wall surface 141a facing the first seal fin 55A, the axial wall surface 141b facing the second seal fin 55B, and the axial wall surface 141c facing the third seal fin 55C. Good. Moreover, the free-cutting material 16 does not need to have a uniform thickness over the entire bottom surface 14, and the thickness may be appropriately changed depending on the position.
- FIG. 5A and FIG. 5B are diagrams illustrating the operational effects of the steam turbine according to the second embodiment.
- heat enters the annular blade group 50 at the start-up, and the thermal elongation of the annular blade group 50 due to the heat becomes larger than the thermal elongation of the casing 10.
- the seal fin 55 may come into contact with the partition plate outer ring 11. Therefore, a sufficiently large radial width W1 (shown in FIG. 5B) is set between the seal fin 55 and the partition plate outer ring 11 so that they do not contact each other even at the time of activation.
- the thermal elongation generated in the annular blade group 50 becomes larger than the thermal elongation generated in the casing 10, and thus the centrifugal blade group 50 is further centrifuged. Due to the elongation, the free-cutting material 16 is cut by the tip of the seal fin 55 as shown in FIG. 5A. Thereafter, when a predetermined time elapses, the steam turbine 1 shifts to a rated operation. As a result, the thermal expansion of the annular blade group 50 is equal to the thermal expansion of the casing 10 or smaller than the thermal expansion of the casing 10, so that the seal fin 55 has its tip as shown in FIG. 5B.
- the radial width W2 between the tip end portion of the seal fin 55 and the free-cutting material 16 is very narrow compared to the radial width W1. Thereby, the leak amount of the vapor
- the steam turbine according to the third embodiment differs from the steam turbine 1 according to the first embodiment in the configuration of the partition plate outer ring 11 and the moving blade 51 shown in FIG. Since the other configuration is the same as that of the first embodiment, the same reference numerals are used and description thereof is omitted here.
- FIG. 6 is a schematic cross-sectional view showing the periphery of the tip of the rotor blade 51 according to the third embodiment.
- the annular groove 12 is formed in the inner peripheral surface of the partition plate outer ring
- the annular groove 12 is formed by the upstream side wall surface 13, the bottom surface 14, and the downstream side wall surface 15.
- a step-like step portion 145 is provided at a position facing the chip shroud 512 on the bottom surface 14.
- the step portion 145 includes four steps, four axial wall surfaces (inner peripheral surfaces) 145a, 145b, 145c, and 145d along the axial direction, and four radial wall surfaces 145e, 145f, 145g along the radial direction, 145h. And the convex part 70 which protrudes toward an upstream is provided in the radial direction wall surface 145f (flow collision surface) where the vapor
- the tip shroud 512 disposed at the tip of the rotor blade 51 is different from the first embodiment in that a stepped step portion 71 is formed on the outer peripheral surface 512a. Yes. Since the rest of the configuration of the chip shroud 512 is the same as that of the first embodiment, the same reference numerals are given and description thereof is omitted here.
- the step portion 71 includes three steps, and has three axial wall surfaces (inner peripheral surfaces) 71a, 71b, 71c along the axial direction, and three radial wall surfaces 71d, 71e, 71f along the radial direction. is doing. And the convex part 72 which protrudes toward an upstream is provided in the radial direction wall surface 71f (flow collision surface) where the vapor
- three seal fins 73 extending in the radial direction are provided at predetermined intervals in the axial direction.
- the first seal fin 73A located on the most upstream side has a base end portion which is the outer peripheral surface 512a of the tip shroud 512 and is fixed at a position slightly downstream of the radial wall surface 145e.
- tip part of 73 A of 1st seal fins has reached the position close to the axial direction wall surface 145a of the partition plate outer ring
- a minute gap 74A is formed between the first seal fin 73A and the axial wall surface 145a.
- the second seal fin 73B located on the second upstream side has a base end portion that is the axial wall surface 145b of the partition plate outer ring 11 and is fixed at a position slightly downstream of the radial wall surface 71e. .
- the tip end of the second seal fin 73B reaches a position close to the axial wall surface 71b of the tip shroud 512. Thereby, a minute gap 74B is formed between the second seal fin 73B and the axial wall surface 71b.
- the third seal fin 73C located on the most downstream side has a base end portion that is the axial wall surface 71c of the tip shroud 512 and is fixed at a position slightly downstream of the radial wall surface 145h.
- the tip end of the third seal fin 73C reaches a position close to the axial wall surface 145d of the partition plate outer ring 11. Thereby, a minute gap 74C is formed between the third seal fin 73C and the axial wall surface 145d.
- seal fins 73 are not limited to the present embodiment, and the design can be appropriately changed according to the cross-sectional shape of the tip shroud 512 and / or the partition plate outer ring 11.
- the 1st cavity C1 located in the most upstream is the structure similar to 1st embodiment.
- the fourth cavity C4 located on the second upstream side is formed by the first seal fin 73A, the bottom surface 14 of the partition plate outer ring 11, the second seal fin 73B, and the outer peripheral surface 512a of the chip shroud 512.
- the fifth cavity C5 located on the most downstream side is formed by the second seal fin 73B, the bottom surface 14 of the partition plate outer ring 11, the third seal fin 73C, and the outer peripheral surface 512a of the tip shroud 512. .
- the radial wall surface 145f that forms the fourth cavity C4 corresponds to the flow collision surface according to the present invention
- the downstream side surface of the first seal fin 73A that also forms the fourth cavity C4 is the main surface. This corresponds to the facing surface according to the invention.
- the radial wall surface 71f that forms the fifth cavity C5 corresponds to the flow collision surface according to the present invention
- the downstream side surface of the second seal fin 73B that also forms the fifth cavity C5 is the opposing surface according to the present invention. It corresponds to.
- the effects of the steam turbine 1 according to the third embodiment will be described with a focus on differences from the first embodiment.
- the main vortex SU1, the separation vortex HU1, and the separation vortex HU2 are placed inside the first cavity C1, as in the first embodiment. Occurs.
- the separation vortex HU2 exhibits a so-called contraction effect that reduces the leakage amount of the steam S in the minute gap 74A.
- the separation vortex HU6 flows from the second seal fin 73B toward the tip shroud 512 at the position of the minute gap 74B. Therefore, this separation vortex HU6 also exhibits a contraction effect that reduces the leakage amount of the steam S in the minute gap 74B.
- the steam S collides with the radial wall surface 71f of the tip shroud 512, thereby forming a counterclockwise main vortex SU5.
- a clockwise peeling vortex HU7 is generated.
- a counterclockwise separation vortex HU8 is generated in the widened portion 77 of the fifth cavity C5.
- the separation vortex HU8 flows from the third seal fin 73C toward the partition plate outer ring 11 at the position of the minute gap 74C. Therefore, this separation vortex HU8 also exhibits a contraction effect that reduces the leakage amount of the steam S in the minute gap 74C.
- the leakage amount of the steam S is reduced by the contraction effect of the separation vortex HU2, separation vortex HU6, separation vortex HU8 in the first cavity C1, the fourth cavity C4, and the fifth cavity C5, respectively. Can be reduced.
- steam S can be suppressed further to the minimum from 1st embodiment.
- the number of cavities C along the axial direction is not limited to three, and an arbitrary number can be provided.
- the steam turbine according to the fourth embodiment is different from the first embodiment in that the annular stator blade group 40 shown in FIG. 1 corresponds to the blade according to the present invention and the shaft body 30 corresponds to the structure according to the present invention. Is different. Since the other configuration is the same as that of the first embodiment, the same reference numerals are used and description thereof is omitted here.
- FIG. 7 is a schematic cross-sectional view showing the periphery of the tip portion of the stationary blade 41 according to the fourth embodiment.
- An annular groove 33 is formed on the outer peripheral surface of the shaft body 30 along the circumferential direction.
- the annular groove 33 is formed by an upstream side wall surface 34 (opposing surface), a bottom surface 35, and a downstream side wall surface 36.
- a stepped step portion 351 is provided at a position facing the stationary blade 41 on the bottom surface 35.
- the step portion 351 includes three steps protruding toward the stationary blade 41 toward the downstream side, and includes three axial wall surfaces (outer peripheral surfaces) 351a, 351b, and 351c along the axial direction, and three along the radial direction.
- the step portion 351 only needs to have at least an axial wall surface 351a and a radial wall surface 351d, and the number of steps is not limited to three and can be arbitrarily changed.
- the ring-shaped hub shroud 43 is disposed at the tip of the stationary blade 41 as described above.
- the hub shroud 43 has a substantially rectangular cross section, and a steam collision surface 44 (flow collision surface) on which the steam S collides is provided at a position facing the upstream side wall surface 34 of the shaft body 30.
- the convex part 45 which protrudes toward an upstream is provided in the radial direction front-end
- the convex portion 45 has a substantially rectangular shape on the step surface, and is provided at the distal end portion in the radial direction of the hub shroud 43.
- the cross-sectional shape of the convex part 45 is not limited to the rectangle of this embodiment, A design change is possible arbitrarily, for example, it can also be made into a triangle and a semicircle.
- the cross-sectional shape of the hub shroud 43 is not limited to this embodiment, and may be a stepped shape in which the thickness in the radial direction becomes thinner toward the downstream side, for example.
- the position where the convex portion 45 is formed is not limited to the radial front end portion on the steam collision surface 44 of the hub shroud 43, and may be, for example, a radial central portion or a radial base end portion.
- the convex portion 45 as a so-called axial seal fin. May be configured.
- three seal fins 46 are provided on the inner peripheral surface 43 a of the hub shroud 43 so as to protrude in the radial direction at predetermined intervals in the axial direction.
- the first seal fin 46A located on the most upstream side has its proximal end fixed at a position slightly downstream of the radial wall surface 351d, and its distal end reaches a position close to the axial wall surface 351a. Yes. Thereby, a minute gap 47A is formed between the first seal fin 46A and the axial wall surface 351a.
- the second seal fin 46B located on the second upstream side has its base end fixed at a position slightly downstream of the radial wall surface 351e, and its tip reaches a position close to the axial wall surface 351b. ing. Thereby, a minute gap 47B is formed between the second seal fin 46B and the axial wall surface 351b.
- the third seal fin 46C located on the most downstream side has a proximal end portion fixed slightly downstream from the radial wall surface 351f, and a distal end portion reaching a position close to the axial wall surface 351c. Thereby, a minute gap 47C is formed between the third seal fin 46C and the axial wall surface 351c. And the length of the seal fin 46 comprised in this way becomes short gradually in order of 46A of 1st seal fins, 46B of 2nd seal fins, and 46C of 3rd seal fins.
- seal fins 46 are not limited to the present embodiment, and the design can be appropriately changed according to the cross-sectional shape of the hub shroud 43 and / or the shaft body 30.
- the three cavities C are formed by the shaft body 30, the three seal fins 46, and the hub shroud 43.
- the sixth cavity C6 located on the most upstream side includes the upstream side wall surface 34 of the shaft body 30, the bottom surface 35 of the shaft body 30, the first seal fin 46A, and the steam collision surface 44 of the hub shroud 43. Is formed by.
- the seventh cavity C7 located on the second upstream side is formed by the first seal fin 46A, the bottom surface 35 of the shaft body 30, the second seal fin 46B, and the inner peripheral surface 43a of the hub shroud 43.
- the eighth cavity C8 located on the most downstream side is formed by the second seal fin 46B, the bottom surface 35 of the shaft body 30, the third seal fin 46C, and the inner peripheral surface 43a of the hub shroud 43. .
- the sixth cavity C6 has a substantially rectangular shape in a cross section along the axial direction.
- the first seal fin 46A is fixed at a position slightly downstream of the radial wall surface 351d. Accordingly, a widened portion 48A that is slightly widened in the axial direction is formed at the downstream side in the axial direction of the sixth cavity C6.
- the seventh cavity C7 also has a substantially rectangular shape in a cross section along the axial direction.
- the second seal fin 46B is fixed at a position slightly downstream of the radial wall surface 351e. Accordingly, a widened portion 48B that is slightly widened in the axial direction is also formed in the axially downstream portion of the seventh cavity C7.
- the eighth cavity C8 also has a substantially rectangular shape in a cross section along the axial direction.
- the third seal fin 46C is fixed at a position slightly downstream of the radial wall surface 351f. Accordingly, a widened portion 48C that is slightly widened in the axial direction is also formed in the axially downstream portion of the eighth cavity C8.
- FIG. 1 Part of the steam S flowing in the axial direction collides with the steam collision surface 44 of the hub shroud 43.
- a clockwise main vortex SU6 is generated, for example, in the clockwise direction in FIG.
- a separation vortex HU9 is generated in a region inside the sixth cavity C6 and on the blade tip side from the convex portion 45.
- the direction of rotation of the separation vortex HU9 is opposite to that of the main vortex SU6, that is, counterclockwise in FIG.
- a separation vortex HU10 is generated in the widened portion 48A of the sixth cavity C6.
- the direction of rotation of the separation vortex HU10 is opposite to that of the separation vortex HU9, that is, clockwise in FIG. 7, and flows from the first seal fin 46A toward the shaft body 30 at the position of the minute gap 47A. Therefore, the separation vortex HU10 exhibits a so-called contraction effect that reduces the amount of leakage of the steam S in the minute gap 47A.
- the vapor S leaking from the minute gap 47A flows into the seventh cavity C7.
- the steam S collides with the radial wall surface 351e of the shaft body 30 to form a counterclockwise main vortex SU7.
- a clockwise peeling vortex HU11 is generated in the widened portion 48B of the seventh cavity C7.
- the separation vortex HU11 flows from the second seal fin 46B toward the shaft body 30 at the position of the minute gap 47B. Therefore, this separation vortex HU11 also exhibits a contraction effect that reduces the leakage amount of the steam S in the minute gap 47B.
- the vapor S leaking from the minute gap 47B flows into the eighth cavity C8.
- the steam S collides with the radial wall surface 351f of the shaft body 30 to form a counterclockwise main vortex SU8.
- a clockwise peeling vortex HU12 is generated in the widened portion 48C of the eighth cavity C8.
- the separation vortex HU12 flows from the third seal fin 46C toward the shaft body 30 at the position of the minute gap 47C. Therefore, this separation vortex HU12 also exhibits a contraction effect that reduces the amount of leakage of the steam S in the minute gap 47C.
- the number of cavities C along the axial direction is not limited to three, and an arbitrary number can be provided.
- the annular groove 12 and the step portions 141 and 145 are formed in the partition plate outer ring 11.
- the partition plate outer ring 11 is not an essential component of the present invention, and the annular groove 12 and the step portions 141 and 145 may be formed in the casing 10 without providing the partition plate outer ring 11.
- the present invention is applied to a condensing steam turbine.
- the present invention can also be applied to other types of steam turbines such as a two-stage extraction turbine, an extraction turbine, and an air-mixing turbine.
- this invention was applied to the steam turbine, it can be applied also to a gas turbine, Furthermore, this invention is applicable to all the apparatuses which have a rotary blade.
- the present invention includes a blade and a structure that is provided on the radial front end side of the blade via a gap and that rotates relative to the blade, and in the turbine in which fluid flows in the gap, the diameter of the blade
- a step portion having a step in the radial direction, the step portion having a step in the radial direction, the radial tip portion of the blade, and the structure in the structure body.
- a seal fin that extends from the other part of the portion facing the distal end in the radial direction toward the step part and forms a minute gap with the step part, and upstream of the seal fin in the fluid flow direction.
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Abstract
Description
本願は、2011年12月13日に日本に出願された特願2011-272355号について優先権を主張し、その内容をここに援用する。
しかし、これら特許文献1及び特許文献2には、シュラウドにこの凸部を設ける意義に関しては記載されていない。
動翼80を構成するシュラウド81からシールフィン82が突出する場合、動翼80にぶつかった蒸気Sは、動翼80の上流側に形成されたキャビティCの内部に主渦SUを形成する。そして、この主渦SUがシュラウド81の角部83にぶつかってその一部が剥離することにより、剥離渦HUが形成される。しかし、この剥離渦HUは、シールフィン82の先端部においてケーシング84からシールフィン82の側へ向かって流れている。
従って、この剥離渦HUは、縮流効果すなわちシールフィン82の先端とケーシング84との間の微小間隙85を通って下流側へリークする蒸気Sを径方向に押し縮めることでリーク量を低減させる効果が小さい。これにより、動翼80からシールフィン82が突出する構成では、シール性能が良好に得られなかった。
これにより、この剥離渦は、微小間隙における流体のリーク量を低減させる、いわゆる縮流効果を発揮する。
これにより、シールフィンの先端部における流体のリーク量を低減させることができる。
以下、図面を参照して本発明の実施の形態について説明する。まず、本発明の第一実施形態に係る蒸気タービンの構成について説明する。図1は、第一実施形態に係る蒸気タービン1を示す概略断面図である。
そして、このように構成される6個の環状静翼群40が、軸体30の軸方向に所定間隔で設けられており、蒸気Sの圧力エネルギーを速度エネルギーに変換して、下流側に隣接する動翼51側に案内するようになっている。
これにより、一組一段とされる環状静翼群40及び環状動翼群50が、軸方向に沿って合計六段に亘って構成されている。
図2に示す仕切板外輪11の内周面には、周方向に沿って環状溝12が形成されている。この環状溝12は、上流側壁面13(対向面)と、底面14と、下流側壁面15とにより形成されている。そして、底面14におけるチップシュラウド512に対向する位置には、階段状のステップ部141が設けられている。このステップ部141は、下流側に行くに従って動翼51の側へ突出する3つの段差からなり、軸方向に沿う3つの軸方向壁面(内周面)141a,141b,141cと、径方向に沿う3つの径方向壁面141d,141e,141fとを有している。
尚、ステップ部141は、少なくとも軸方向壁面141aと径方向壁面141dを有していれば足り、その段差の数は3段に限定されず任意に変更が可能である。
また、チップシュラウド512の断面形状も本実施形態に限定されず、例えば下流側に行くに従って径方向への厚みが薄くなるような階段形状であってもよい。
また、凸部54を形成する位置は、チップシュラウド512の蒸気衝突面53における径方向先端部に限定されず、例えば径方向中央部や径方向基端部であってもよい。
また、凸部54の先端を上流側壁面13に近接した位置まで突出させ、凸部54と上流側壁面13との間に微小な隙間を形成することにより、いわゆる軸方向シールフィンとして凸部54を構成してもよい。
これにより、第一シールフィン55Aと軸方向壁面141aとの間には、微小間隙56Aが形成されている。
これにより、第二シールフィン55Bと軸方向壁面141bとの間には、微小間隙56Bが形成されている。
これにより、第三シールフィン55Cと軸方向壁面141cとの間には、微小間隙56Cが形成されている。
そして、このように構成されるシールフィン55は、第一シールフィン55A、第二シールフィン55B、及び第三シールフィン55Cの順にその長さが徐々に短くなっている。
また、微小間隙56A,56B,56Cの寸法は、ケーシング10や動翼51の熱伸び量、動翼の遠心伸び量等を考慮した上で、シールフィン55と仕切板外輪11とが接触することがない安全な範囲内で、最小の値に設定することが好適である。
本実施形態では、3つの微小間隙56A,56B,56Cを全て同じ寸法に設定しているが、必要に応じて、シールフィン55ごとに微小間隙56A,56B,56Cを異なる寸法に設定してもよい。
このうち、最も上流側に位置する第一キャビティC1は、仕切板外輪11の上流側壁面13と、同じく仕切板外輪11の底面14と、第一シールフィン55Aと、チップシュラウド512の蒸気衝突面53とによって形成されている。
また、2番目に上流側に位置する第二キャビティC2は、第一シールフィン55Aと、仕切板外輪11の底面14と、第二シールフィン55Bと、チップシュラウド512の外周面512aとによって形成されている。
また、最も下流側に位置する第三キャビティC3は、第二シールフィン55Bと、仕切板外輪11の底面14と、第三シールフィン55Cと、チップシュラウド512の外周面512aとによって形成されている。
更に、第三キャビティC3も、軸方向に沿った断面で略矩形形状を有している。但し、前述のように第三シールフィン55Cは、径方向壁面141fより若干下流側の位置に固定されている。従って、第三キャビティC3の軸方向下流部にも、軸方向に若干拡幅された拡幅部59が形成されている。
図1に示す調整弁20を開状態にすると、不図示のボイラからケーシング10の内部に蒸気Sが流入する。この蒸気Sは、各段の環状静翼群40によって環状動翼群50へと案内され、環状動翼群50が回転を開始する。これにより、環状動翼群50によって蒸気Sのエネルギーが回転エネルギーに変換され、この回転エネルギーが、環状動翼群50と一体的に回転する軸体30から不図示の発電機等に対して伝達される。
図2に示すように、環状静翼群40を通過して軸方向に流れる蒸気Sは、その一部がチップシュラウド512の蒸気衝突面53に衝突する。そうすると、第一キャビティC1の内部であって凸部54よりブレード基端側の領域には、例えば図2では反時計回りの主渦SU1が発生する。
そして、この主渦SU1の一部が凸部54にて剥離することによって、第一キャビティC1の内部であって凸部54よりブレード先端側の領域には、剥離渦HU1が発生する。この剥離渦HU1の回転方向は、主渦SU1と逆回りすなわち図2では時計回りである。
そして、ステップ部141の角部142にて剥離渦HU1の一部が更に剥離することによって、第一キャビティC1の拡幅部57には、剥離渦HU2が発生する。この剥離渦HU2の回転方向は、剥離渦HU1と逆回りすなわち図2では反時計回りである。そして、この剥離渦HU2は、第一シールフィン55Aと仕切板外輪11との間の微小間隙56Aにおける蒸気Sのリーク量を低減させる、いわゆる縮流効果を発揮する。
反時計回りの剥離渦HU2は、微小間隙56Aの位置で、第一シールフィン55Aから仕切板外輪11の側へ向かって流れている。従って、この剥離渦HU2は、径方向外向きの慣性力を有している。これにより、微小間隙56Aを通って下流側へリークする蒸気Sは、剥離渦HU2の慣性力で軸方向壁面141a側に押さえ込まれることにより、図3に一点鎖線で示すように径方向への幅が縮められる。
このように、剥離渦HU2は、蒸気Sを径方向に押し縮めることでそのリーク量を低減させる効果、すなわち縮流効果を有している。また、この縮流効果は、剥離渦HU2の慣性力が大きいほど、すなわち剥離渦HU2の流速が速いほど、その効果が大きくなる。
従って、この剥離渦HU3も、前記剥離渦HU2と同様に、微小間隙56Bにおける蒸気Sのリーク量を低減させる縮流効果を発揮する。
従って、この剥離渦HU4も、前記剥離渦HU2と同様に、微小間隙56Cにおける蒸気Sのリーク量を低減させる縮流効果を発揮する。
次に、本発明の第二実施形態に係る蒸気タービンの構成について説明する。
第二実施形態に係る蒸気タービンは、第一実施形態の蒸気タービン1と比較すると、図1に示すケーシング10の内壁面に固定された仕切板外輪11の構成だけが異なっている。それ以外の構成については第一実施形態と同じであるため、同じ符号を用い、ここでは説明を省略する。
本実施形態では、仕切板外輪11に形成された環状溝12の底面14を覆って、快削材16が均一の厚みで施工されている。この快削材16は、摺動摩擦熱が少なく、シールフィン55より被削性に優れた材質で構成されている。
この快削材16としては、例えば、コバルト、ニッケル、クロム、アルミニウム、及びイットリウム系の材料(CoNiCrAlY系材料)や、ニッケル、クロム、アルミニウム系の材料(NiCrAl系材料)や、ニッケル、クロム、鉄、アルミニウム、ホウ素、及び窒素系の材料(NiCrFeAlBN系材料)等、公知の快削性材料各種からなるアブレイダブル材が用いられる。
尚、快削材16としては、上記アブレイダブル材のほか、金属またはセラミック等からなるハニカム層を用いることができる。
具体的には、第一シールフィン55Aに対向する軸方向壁面141aや、第二シールフィン55Bに対向する軸方向壁面141bや、及び第三シールフィン55Cに対向する軸方向壁面141cに施工すればよい。
また、快削材16は、底面14の全体に亘って均一の厚みである必要はなく、位置により厚みを適宜変更しても構わない。
蒸気タービン1では、その起動時に環状動翼群50に熱が入り、その熱による環状動翼群50の熱伸びが、ケーシング10の熱伸びより大きくなることにより、更には環状動翼群50に遠心伸びが生じることにより、シールフィン55が仕切板外輪11に接触する場合がある。
従って、シールフィン55と仕切板外輪11との間には、起動時にも両者が接触しないような十分な大きさの径方向幅W1(図5Bに示す)が設定される。
そうすると、環状動翼群50の熱伸びが、ケーシング10の熱伸びと同等の大きさ、または、ケーシング10の熱伸びより小さくなることにより、図5Bに示すように、シールフィン55はその先端部が快削材16から離れた状態となる。そしてこの時、シールフィン55の先端部と快削材16との間の径方向幅W2は、径方向幅W1と比較して非常に狭いものである。
これにより、シールフィン55の先端部における蒸気Sのリーク量を低減させることができる。
次に、本発明の第三実施形態に係る蒸気タービンの構成について説明する。
第三実施形態に係る蒸気タービンは、第一実施形態の蒸気タービン1と比較すると、図1に示す仕切板外輪11及び動翼51の構成がそれぞれ異なっている。それ以外の構成については第一実施形態と同じであるため、同じ符号を用い、ここでは説明を省略する。
本実施形態でも、第一実施形態と同様に、仕切板外輪11の内周面には周方向に沿って環状溝12が形成されている。この環状溝12は、上流側壁面13と、底面14と、下流側壁面15とにより形成されている。そして、底面14におけるチップシュラウド512に対向する位置には、階段状のステップ部145が設けられている。
このステップ部145は、4つの段差からなり、軸方向に沿う4つの軸方向壁面(内周面)145a,145b,145c,145dと、径方向に沿う4つの径方向壁面145e,145f,145g,145hとを有している。そして、蒸気Sが衝突する径方向壁面145f(流れ衝突面)には、上流側に向かって突出する凸部70が設けられている。
チップシュラウド512について、それ以外の構成は第一実施形態と同じであるため、同じ符号を付し、ここでは説明を省略する。
このうち、最も上流側に位置する第一シールフィン73Aは、その基端部が、チップシュラウド512の外周面512aであって径方向壁面145eより若干下流側の位置に固定されている。そして、第一シールフィン73Aの先端部は、仕切板外輪11の軸方向壁面145aに近接した位置に達している。
これにより、第一シールフィン73Aと軸方向壁面145aとの間には、微小間隙74Aが形成されている。
これにより、第二シールフィン73Bと軸方向壁面71bとの間には、微小間隙74Bが形成されている。
これにより、第三シールフィン73Cと軸方向壁面145dとの間には、微小間隙74Cが形成されている。
このうち、最も上流側に位置する第一キャビティC1は、第一実施形態と同様の構成である。
また、2番目に上流側に位置する第四キャビティC4は、第一シールフィン73Aと、仕切板外輪11の底面14と、第二シールフィン73Bと、チップシュラウド512の外周面512aとによって形成されている。
また、最も下流側に位置する第五キャビティC5は、第二シールフィン73Bと、仕切板外輪11の底面14と、第三シールフィン73Cと、チップシュラウド512の外周面512aとによって形成されている。
また、第五キャビティC5を形成する径方向壁面71fが、本発明に係る流れ衝突面に相当し、同じく第五キャビティC5を形成する第二シールフィン73Bの下流側面が、本発明に係る対向面に相当する。
図6に示すように、軸方向に流れる蒸気Sが蒸気衝突面53に衝突すると、第一実施形態と同様にして、第一キャビティC1の内部には主渦SU1と剥離渦HU1と剥離渦HU2とが発生する。そして、剥離渦HU2は、微小間隙74Aにおける蒸気Sのリーク量を低減させる、いわゆる縮流効果を発揮する。
この剥離渦HU6は、微小間隙74Bの位置で、第二シールフィン73Bからチップシュラウド512の側へ向かって流れている。従って、この剥離渦HU6も、微小間隙74Bにおける蒸気Sのリーク量を低減させる縮流効果を発揮する。
この剥離渦HU8は、微小間隙74Cの位置で、第三シールフィン73Cから仕切板外輪11の側へ向かって流れている。従って、この剥離渦HU8も、微小間隙74Cにおける蒸気Sのリーク量を低減させる縮流効果を発揮する。
これにより、本実施形態によれば、蒸気Sのリーク量を第一実施形態より更に最小限に抑えることができる。尚、軸方向に沿ったキャビティCの数は3つに限られず、任意の数だけ設けることができる。
次に、本発明の第四実施形態に係る蒸気タービンの構成について説明する。
第四実施形態に係る蒸気タービンは、図1に示す環状静翼群40が本発明に係るブレードに相当するとともに、軸体30が本発明に係る構造体に相当する点で第一実施形態とは異なっている。それ以外の構成については第一実施形態と同じであるため、同じ符号を用い、ここでは説明を省略する。
軸体30の外周面には、周方向に沿って環状溝33が形成されている。この環状溝33は、上流側壁面34(対向面)と、底面35と、下流側壁面36とにより形成されている。そして、底面35における静翼41に対向する位置には、階段状のステップ部351が設けられている。
このステップ部351は、下流側に行くに従って静翼41の側へ突出する3つの段差からなり、軸方向に沿う3つの軸方向壁面(外周面)351a,351b,351cと、径方向に沿う3つの径方向壁面351d,351e,351fとを有している。
尚、ステップ部351は、少なくとも軸方向壁面351aと径方向壁面351dを有していれば足り、その段差の数は3段に限定されず任意に変更が可能である。
そして、この蒸気衝突面44における径方向先端部には、上流側に向かって突出する凸部45が設けられている。この凸部45は、段面略矩形形状を有し、ハブシュラウド43の径方向先端部に設けられている。
また、凸部45を形成する位置は、ハブシュラウド43の蒸気衝突面44における径方向先端部に限定されず、例えば径方向中央部や径方向基端部であってもよい。
また、凸部45の先端を上流側壁面34に近接した位置まで突出させ、凸部45と上流側壁面34との間に微小な隙間を形成することにより、いわゆる軸方向シールフィンとして凸部45を構成してもよい。
このうち、最も上流側に位置する第一シールフィン46Aは、その基端部が径方向壁面351dより若干下流側の位置に固定され、その先端部が軸方向壁面351aに近接した位置に達している。これにより、第一シールフィン46Aと軸方向壁面351aとの間には、微小間隙47Aが形成されている。
そして、このように構成されるシールフィン46は、第一シールフィン46A、第二シールフィン46B、及び第三シールフィン46Cの順にその長さが徐々に短くなっている。
このうち、最も上流側に位置する第六キャビティC6は、軸体30の上流側壁面34と、同じく軸体30の底面35と、第一シールフィン46Aと、ハブシュラウド43の蒸気衝突面44とによって形成されている。
また、2番目に上流側に位置する第七キャビティC7は、第一シールフィン46Aと、軸体30の底面35と、第二シールフィン46Bと、ハブシュラウド43の内周面43aとによって形成されている。
また、最も下流側に位置する第八キャビティC8は、第二シールフィン46Bと、軸体30の底面35と、第三シールフィン46Cと、ハブシュラウド43の内周面43aとによって形成されている。
更に、第八キャビティC8も、軸方向に沿った断面で略矩形形状を有している。但し、前述のように第三シールフィン46Cは、径方向壁面351fより若干下流側の位置に固定されている。従って、第八キャビティC8の軸方向下流部にも、軸方向に若干拡幅された拡幅部48Cが形成されている。
軸方向に流れる蒸気Sは、その一部がハブシュラウド43の蒸気衝突面44に衝突する。そうすると、第六キャビティC6の内部であって凸部45よりブレード基端側の領域には、例えば図7では時計回りの主渦SU6が発生する。そして、この主渦SU6の一部が凸部45にて剥離することによって、第六キャビティC6の内部であって凸部45よりブレード先端側の領域には、剥離渦HU9が発生する。この剥離渦HU9の回転方向は、主渦SU6と逆回りすなわち図7では反時計回りである。
そして、軸体30の角部49Aにて剥離渦HU9の一部が更に剥離することによって、第六キャビティC6の拡幅部48Aには、剥離渦HU10が発生する。この剥離渦HU10の回転方向は、剥離渦HU9と逆回りすなわち図7では時計回りであり、微小隙間47Aの位置で、第一シールフィン46Aから軸体30の側へ向かって流れている。
従って、この剥離渦HU10は、微小間隙47Aにおける蒸気Sのリーク量を低減させる、いわゆる縮流効果を発揮する。
そして、軸体30の角部49Bにて主渦SU7の一部が剥離することによって、第七キャビティC7の拡幅部48Bにおいて、時計回りの剥離渦HU11が発生する。この剥離渦HU11は、微小間隙47Bの位置で、第二シールフィン46Bから軸体30の側へ向かって流れている。
従って、この剥離渦HU11も、微小間隙47Bにおける蒸気Sのリーク量を低減させる縮流効果を発揮する。
そして、軸体30の角部49Cにて主渦SU8の一部が剥離することによって、第八キャビティC8の拡幅部48Cにおいて、時計回りの剥離渦HU12が発生する。この剥離渦HU12は、微小間隙47Cの位置で、第三シールフィン46Cから軸体30の側へ向かって流れている。
従って、この剥離渦HU12も、微小間隙47Cにおける蒸気Sのリーク量を低減させる縮流効果を発揮する。
尚、軸方向に沿ったキャビティCの数は3つに限られず、任意の数だけ設けることができる。
また、上記実施形態では、本発明を復水式の蒸気タービンに適用したが、他の型式の蒸気タービン、例えば、二段抽気タービン、抽気タービン、混気タービン等に適用することもできる。
更に、上記実施形態では、本発明を蒸気タービンに適用したが、ガスタービンにも適用することができ、更には、回転翼を有する全ての機器に本発明を適用することができる。
10 ケーシング
11 仕切板外輪
12 環状溝
13 上流側壁面
14 底面
141 ステップ部
141a,141b,141c 軸方向壁面
141d,141e,141f 径方向壁面
142~144、146 角部
145 ステップ部
145a,145b,145c,145d 軸方向壁面
145e,145f,145g,145h 径方向壁面
15 下流側壁面
16 快削材
20 調整弁
21 調整弁室
22 弁体
23 弁座
24 蒸気室
30 軸体
31 軸本体
32 ディスク
33 環状溝
34 上流側壁面
35 底面
351 ステップ部
351a,351b,351c 軸方向壁面
351d,351e,351f 径方向壁面
36 下流側壁面
40 環状静翼群
41 静翼
42 翼本体
43 ハブシュラウド
43a 内周面
44 蒸気衝突面
45 凸部
46 シールフィン
46A 第一シールフィン
46B 第二シールフィン
46C 第三シールフィン
47A~47C 微小間隙
48A~48C 拡幅部
49A~49C角部
50 環状動翼群
51 動翼
511 翼本体
512 チップシュラウド
512a 外周面
53 蒸気衝突面
54 凸部
55 シールフィン
55A 第一シールフィン
55B 第二シールフィン
55C 第三シールフィン
56A~56C 微小間隙
57~59 拡幅部
60 軸受部
61 ジャーナル軸受装置
62 スラスト軸受装置
70 凸部
71 ステップ部
71a,71b,71c 軸方向壁面
71d,71e,71f 径方向壁面
72 凸部
73 シールフィン
73A 第一シールフィン
73B 第二シールフィン
73C 第三シールフィン
74A~74C 微小間隙
75~77 角部
C キャビティ
C1 第一キャビティ
C2 第二キャビティ
C3 第三キャビティ
C4 第四キャビティ
C5 第五キャビティ
C6 第六キャビティ
C7 第七キャビティ
C8 第八キャビティ
HU1~HU12 剥離渦
S 蒸気
SU1~SU8 主渦
W1 径方向幅
W2 径方向幅
Claims (5)
- ブレードと、該ブレードの径方向先端側に隙間を介して設けられるとともに前記ブレードに対して相対回転する構造体とを備え、前記隙間に流体が流通するタービンにおいて、
前記ブレードの径方向先端部及び前記構造体における前記径方向先端部に対向する部位のうちいずれか一方に設けられ、径方向への段差を有するステップ部と、
前記ブレードの径方向先端部及び前記構造体における前記径方向先端部に対向する部位のうち他方から前記ステップ部に向かって延出し、該ステップ部との間に微小間隙を形成するシールフィンと、
前記流体の流通方向で前記シールフィンより上流側に設けられ、前記流体が衝突する流れ衝突面と、
該流れ衝突面から上流側に向かって突出する凸部と、
前記流れ衝突面に対向する対向面と、
を備えるタービン。 - 前記ステップ部の表面に、前記シールフィンより被削性に優れた快削材が設けられている、請求項1に記載のタービン。
- 前記ステップ部が前記構造体に設けられ、
前記シールフィンが前記ブレードに設けられている、請求項1又は2に記載のタービン。 - 前記構造体が、回転駆動される軸体を収容するケーシングであり、
前記ブレードが、前記軸体に固定されて前記ケーシングの側へ延びる動翼である、請求項1から3のいずれか一項に記載のタービン。 - 前記構造体が、回転駆動される軸体であり、
前記ブレードが、前記軸体を収容するケーシングに固定されて前記軸体の側へ延びる静翼である、請求項1から3のいずれか一項に記載のタービン。
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JP5518032B2 (ja) | 2014-06-11 |
JP2013124554A (ja) | 2013-06-24 |
EP2792852A1 (en) | 2014-10-22 |
EP2792852A4 (en) | 2015-07-22 |
CN104024581A (zh) | 2014-09-03 |
KR101716010B1 (ko) | 2017-03-13 |
KR20140088572A (ko) | 2014-07-10 |
IN2014MN00923A (ja) | 2015-04-17 |
CN104024581B (zh) | 2016-04-13 |
US10006292B2 (en) | 2018-06-26 |
US20140314579A1 (en) | 2014-10-23 |
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