JP2017155626A - Seal structure and turbomachine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure and a turbomachine capable of effectively restricting the unstable oscillation.SOLUTION: A seal structure comprises: a rotation structure 4 rotating about a shaft center line CL in a prescribed direction; a stationary structure 10 facing in a radial direction R with a gap Gd on the outer peripheral side of the rotation structure 4, and the seal structure restricts the flow of leak flow SL of working fluid from the gap Gd. The seal structure includes: a seal fin 6 extending from the stationary structure 10 toward on the shaft center line CL side; and a guide plate 7 that is attached to the tip side of a surface 6a on the upstream side of the seal fin 6 of the flow component in the axial direction A of the leak flow SL, and that guides the leak flow SL so as to restrict the rotation in a prescribed direction C centered on the shaft center line CL.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a seal structure that suppresses leakage of working fluid from between two relatively rotating structures that are suitable for suppressing unstable vibrations, and a turbomachine using the seal structure.

  In a turbo machine such as a steam turbine, a gas turbine, and a turbo compressor, when a working fluid such as steam leaks (leaks) from a gap formed between the stationary structure and the rotating structure, the leakage of the working fluid is caused in the turbine. It causes a loss of efficiency (leakage loss). For this reason, in the turbo machine, in order to prevent leakage of the working fluid, a sealing fin is formed in the gap to form a sealing structure (see, for example, Patent Document 1).

By the way, in a turbo machine, low frequency vibration considered to be unstable vibration may occur. If unstable vibration occurs, it may lead to malfunction, so the turbomachine must be stopped. One of the major factors that cause unstable vibration is the seal excitation force. The seal excitation force acts on the rotating structure so as to promote the swinging of the rotating structure against minute vibrations of the rotating structure generated for some reason, and thus causes unstable vibration.
The seal excitation force will be further described. The working fluid flowing in the seal portion (portion provided with the seal fin) flows not only in the axial (flow direction) velocity component but also in the circumferential velocity component. Hereinafter, the flow in the circumferential direction is referred to as “swirl flow”), and the seal excitation force is caused by this swirl flow.
That is, when the rotating structure is slightly displaced (eccentric) in the radial direction, the flow path between the rotating structure and the sealing fin is narrowed and the static pressure is increased, and the flow path is expanded and the static pressure is increased. Due to the swirling flow of the leaked working fluid, and there is a phase difference in the static pressure distribution between the upstream side and the downstream side of the sealing fin. The resulting force acts on the rotating body to generate a seal excitation force.

  As techniques for suppressing such unstable turbine vibrations, various techniques have been proposed in which a plurality of shielding plates are arranged in the circumferential direction in the vicinity of the sealing fins to block the swirling flow of the leaked working fluid. (For example, Patent Documents 2 and 3).

JP 2011-208602 A US Patent No. 7,004475 JP 2014-066134 A

By the way, the flow of the leaked working fluid (hereinafter referred to as “leak flow”) not only swirls in the same direction as the rotating structure, but also swivels in the meridian plane (in the cross section including the rotation axis of the rotating structure). It also has a component, and depending on the shape of the space around the seal fin, it also turns toward the gap between the seal fin and the rotating structure. The flow swirling toward the gap has a contraction effect of suppressing the leak flow by suppressing the leak flow that attempts to pass through the gap.
In the techniques exemplified in Patent Documents 2 and 3, turning in the same direction as the rotating structure can be suppressed against leakage flow, but at the same time, turning toward the gap between the seal fin and the rotating structure is also suppressed. Therefore, the contraction effect is reduced, and the amount of leakage of the working fluid and thus the leakage loss of the turbo machine is increased.

  The present invention was devised in view of the above-described problems, and an object thereof is to provide a seal structure and a turbo machine that can suppress unstable vibration while suppressing the amount of leakage of working fluid. And

  (1) In order to achieve the above-described object, the seal structure of the present invention has a rotating structure that rotates in a predetermined direction around an axial center line, and is opposed in the radial direction with a gap formed on the outer peripheral side of the rotating structure. A seal structure that suppresses a flow of a leakage flow of a working fluid from the gap between the stationary structure and the seal fin that extends from the stationary structure toward the axial center line, and the leakage flow The flow component in the axial direction of the seal fin is attached to the tip side near the axial center line on the upstream surface of the seal fin, and is inclined so that at least the inner peripheral portion of the surface facing the predetermined direction faces the outer peripheral side. As a posture, a guide plate for guiding the leak flow is provided.

  (2) The stationary structure is a turbine casing, and a plurality of the rotating structures are installed along the axial direction and are tip shrouds attached to the tip of a moving blade, and the seal fin and the guide plate are The tip shroud is preferably disposed so as to face the radial direction.

  (3) The axial dimension of the guide plate is a surface that faces the upstream side of the seal fin and the axial direction of the tip shroud, and is located on the upstream side of the seal fin. Is preferably set to be smaller than half of the distance between

  (4) It is preferable that the guide plate is a flat plate and has an inclined posture in which a surface facing a side opposite to the predetermined direction is directed to the outer peripheral side.

  (5) It is preferable that the guide plate is inclined by a predetermined angle with respect to the radial direction, and the predetermined angle is set in a range of 5 ° to 30 °.

  (6) The guide plate is a plate having a curved shape, and is attached to the seal fin with an inner surface of the curved shape facing toward a side opposite to the predetermined direction which is a rotation direction of the rotating structure. preferable.

  (7) The seal fin has a ring shape centered on the axial center line, and a plurality of the guide plates are provided in the seal fin along a circumferential direction, and a distance between the guide plates is set to an inner circumference. It is preferable that the end portion on the side is set to be narrower than the outer peripheral side.

  (8) In the guide plate, at least an end portion on the outer peripheral side is inclined by a predetermined angle with respect to a tangent of a circle centering on the axial center line, and the predetermined angle is 5 ° to 30 °. It is preferable that the range is set.

  (9) It is preferable to provide a closing plate that closes the upstream side of the guide plate.

  (10) In order to achieve the above object, a turbo machine according to the present invention is configured so that a rotating structure that rotates in a predetermined direction around an axial center line and a radial direction facing the outer peripheral side of the rotating structure with a gap. And a sealing structure according to any one of (1) to (9).

  (11) The rotary structure includes a plurality of chip shrouds provided along the axis, and the stationary structure includes a turbine casing that surrounds the plurality of chip shrouds, It is preferable that the turbine is provided with the sealing structure with respect to at least one tip shroud.

  (12) Preferably, the at least one tip shroud is a tip shroud disposed closest to the working fluid inlet.

  (13) It is preferable that the at least one tip shroud is a tip shroud disposed in the center in the axial direction.

According to the present invention, the leakage flow of the working fluid has a swirling component in the same direction as the rotation direction (predetermined direction) of the rotating structure, but at least the inner peripheral portion of the surface facing the predetermined direction is the outer periphery. Since the guide plate having the inclined posture toward the side reduces the swirling component in the predetermined direction of the leak flow of the working fluid, it is possible to suppress unstable vibration caused by the swirling of the leak flow.
Further, since the guide plate is provided at the tip of the seal fin, the leak flow can be guided by the guide plate while the leak flow is flowing toward the clearance between the seal fin and the rotating structure. it can. As a result, the leak flow can be guided by the guide plate while leaving the flow component toward the clearance, so that the radial flow toward the clearance suppresses and contracts other leak flows that attempt to pass this clearance. A contracted flow effect is obtained.
Therefore, unstable vibration can be suppressed while suppressing the leakage flow rate of the working fluid due to the contraction effect.

It is a typical longitudinal section showing the whole steam turbine composition concerning each embodiment of the present invention. It is a mimetic diagram showing composition of a seal structure concerning a 1st embodiment of the present invention, and is a sectional view cut along a diameter direction. It is a schematic diagram which shows the structure of the principal part of the seal structure which concerns on 1st Embodiment of this invention, Comprising: (a) is the perspective view, (b) is the front view (a direction arrow view of FIG. 2). is there. It is a schematic diagram which shows the structure of the principal part of the seal structure which concerns on 2nd Embodiment of this invention, Comprising: (a) is the perspective view, (b) is the front view (corresponding to the a direction arrow view of FIG. 2) Figure). It is a schematic diagram which shows the structure of the principal part of the seal structure concerning 3rd Embodiment of this invention, Comprising: (a) is the perspective view, (b) is the front view (corresponding to the a direction arrow view of FIG. 2) Figure). It is a schematic diagram which shows the structure of the principal part of the seal structure which concerns on 4th Embodiment of this invention, Comprising: (a) is the perspective view, (b) is the front view (equivalent to the a direction arrow view of FIG. 2) Figure).

Embodiments of the present invention will be described below with reference to the drawings.
In each embodiment of the present invention, an example in which the seal structure and the turbomachine of the present invention are applied to a steam turbine will be described.
Note that each embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiments. The configurations of the following embodiments can be implemented with various modifications without departing from the spirit of the embodiments, and can be selected or combined as appropriate.

In the following description, the terms “upstream” and “downstream” mean upstream and downstream with respect to the flow component (axial flow component) in the axial direction A of the leaked steam SL unless otherwise specified. That is, the left side in FIGS. 1 and 2 is the upstream side, and the right side is the downstream side.
In addition, the direction toward the rotor axial center line (hereinafter also referred to as “axial center line”) CL of the steam turbine is defined as the inner peripheral side or the inner side, and the opposite side, the direction away from the axial center line CL is described as the outer peripheral side or the outer side. To do.
In the following description, the term “circumferential direction” means the circumferential direction centered on the axial center line CL unless otherwise specified.

[1. First Embodiment]
[1-1. Overall configuration of steam turbine]
A steam turbine 1 of the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the steam turbine 1 of the present embodiment includes a turbine casing (stationary structure, hereinafter also referred to as “casing”) 10 and a generator (not shown) that is rotatably provided inside the casing 10. The rotor shaft 30 is transmitted to a machine, the stationary blade 60 provided on the casing 10, the rotor blade 50 provided on the rotor shaft 30, and the rotor shaft 30 is rotatably supported around the axis line CL. The bearing part 70 is provided. The stationary blade 60 and the moving blade 50 are blades extending in the radial direction R of the rotor shaft 30.
While the casing 10 is stationary, the rotor blade 50 rotates around the axis line CL. That is, the casing 10 and the moving blade 50 (including a chip shroud 4 described later) rotate relative to each other.

  Steam (fluid) S is introduced from a main inlet 21 formed in the casing 10 via a steam supply pipe 20 connected to a steam supply source (not shown), and is connected to a downstream side of the steam turbine 1. 22 is discharged.

The casing 10 has an internal space hermetically sealed and a flow path for the steam S. A ring-shaped partition plate outer ring 11 is firmly fixed to the inner wall surface of the casing 10.
The bearing unit 70 includes a journal bearing device 71 and a thrust bearing device 72, and rotatably supports the rotor shaft 30.

  The stationary blades 60 extend from the casing 10 toward the inner peripheral side, and constitute a group of annular stationary blades arranged radially so as to surround the rotor shaft 30, and are respectively held by the partition plate outer ring 11 described above. ing.

  A plurality of annular stator blade groups composed of a plurality of stator blades 60 are formed at intervals in the axial direction A of the rotor shaft 30 and convert the pressure energy of the steam S into velocity energy and are adjacent to the downstream side. It flows into the moving blade 50.

The rotor blades 50 are firmly attached to the disk 32 formed on the outer peripheral portion of the rotor shaft body 31 of the rotor shaft 30 and are arranged radially in the downstream side of each annular stator blade group to constitute the annular rotor blade group. doing.
These annular stator blade groups and annular rotor blade groups are grouped into one stage. The tip portions of the plurality of blades 50 constituting each blade group are connected by a ring-shaped tip shroud (rotary structure) 4.

[1-2. Seal structure]
The seal structure of the present embodiment will be described with reference to FIGS. 2 and 3 (a) and 3 (b).
As shown in FIG. 2, a cavity 12 that is recessed from the inner peripheral surface of the partition plate outer ring 11 is formed between the plurality of partition plate outer rings 11. The cavity 12 is an annular space centered on the axial center line CL, and has an inner peripheral surface (hereinafter also referred to as “cavity bottom surface 13”) 13 of the casing 10 as a bottom surface.
The chip 12 is housed in the cavity 12, and the bottom surface 13 of the cavity faces the chip shroud 4 in the radial direction R via a gap (hereinafter also referred to as “space”) Gd.

  Most of the steam SM out of the steam S flows into the rotor blade 50, and its energy is converted into rotational energy. As a result, rotation is imparted to the rotor shaft 30. On the other hand, a part of the steam S (for example, about several percent) steam flow (leak flow, hereinafter also referred to as “leak steam”) SL does not flow into the rotor blade 50 but leaks into the gap Gd. Since the energy of the leak steam SL is not converted into rotational energy, the leak steam SL causes a leak loss that reduces the efficiency of the steam turbine 1.

Therefore, each gap Gd between the casing 10 and each chip shroud 4 is provided with a seal structure 2 as the first embodiment of the present invention. In other words, each chip shroud 4 is provided with the seal structure 2 as the first embodiment of the present invention.
Hereinafter, the seal structure 2 will be described.
The tip shroud 4 is ring-shaped as described above. As shown in FIG. 2, the step shroud 4 has a step-like cross-sectional shape (a cross-sectional shape perpendicular to the circumferential direction) protruding from the central portion in the axial direction A. It is constant over the entire circumference. That is, the outer peripheral surface of the shroud 4 has a base surface 41 and a step portion 3 in which a step surface 42 that protrudes more outward than the base surface 41 is formed. Hereinafter, in the base surface 41, the upstream side from the step part 3 is referred to as a base surface 41A, and the downstream side from the step part 3 is referred to as a base surface 41B.

  The cavity bottom surface 13 is provided with seal fins 6A, 6B, 6C extending toward the inner periphery toward the chip shroud 4 (not shown in FIG. 1). Hereinafter, when the seal fins 6A, 6B, and 6C are not distinguished, they are referred to as seal fins 6. The seal fin 6 has an annular shape having a width in the radial direction R around the axis CL, and has the cross-sectional shape shown in FIG.

The upstream seal fin 6A protrudes toward the base surface 41A upstream of the step portion 3, the intermediate seal fin 6B protrudes toward the step surface 42 of the step portion 3, and the downstream seal fin 6C It protrudes toward the base surface 41B on the downstream side of the step part 3. The intermediate seal fin 6B is formed to have a shorter width (length in the radial direction R) than the upstream seal fin 6A and the downstream seal fin 6C.
These seal fins 6 form a minute gap (hereinafter also referred to as a clearance) m in the radial direction R with the shroud 4. Each dimension of these minute gaps m is set within a range in which the seal fin 6 and the moving blade 50 do not contact each other in consideration of the thermal elongation amount of the casing 10 and the moving blade 50, the centrifugal extension amount of the moving blade 50, and the like. Has been.

As a major feature of the present invention, guide plates 7A, 7B, and 7C are installed on the seal fins 6A, 6B, and 6C, respectively. Hereinafter, when the guide plates 7A, 7B, and 7C are not distinguished, they are referred to as guide plates 7.
As shown in FIGS. 2, 3A, and 3B, the guide plate 7 is provided on the tip (end on the axis line CL side) side of the upstream surface 6a of the seal fin 6 (different representation). , It is provided within a predetermined range M from the fin tip 6b). A plurality of guide plates 7 are provided at predetermined intervals along the circumferential direction. In this embodiment, the guide plate 7 has its tip (hereinafter also referred to as “plate tip”) 7 a aligned with the tip (inner peripheral end, hereinafter also referred to as “fin tip”) 6 b of the seal fin 6. Although the plate tip 7a and the fin tip 6b do not necessarily coincide with each other.
Each guide plate 7 is a rectangular flat plate-like body and is disposed so as to extend along the circumferential direction, but is opposite to the rotation direction of the rotor shaft (hereinafter referred to as “rotor rotation direction”) C. The surface 7b facing the side is inclined to face the outer peripheral side.

Here, dimensions of the guide plates 7A, 7B, and 7C in the axial direction A (hereinafter also referred to as “width dimensions”) WA, WB, and WC will be described with reference to FIG.
The width dimension WA of the guide plate 7A is set to be smaller than half of the distance LA described later (WA <LA / 2). Similarly, the width dimension WB of the guide plate 7B is set smaller than a half of a distance LB described later (WB <LB / 2), and the width dimension WC of the guide plate 7C is set smaller than a half of a distance LC described later. (WC <LC / 2).
The distance LA is an axial distance between the upstream surface 6a of the shroud (the surface facing the axial direction A) 43A immediately upstream of the guide plate 7A and the upstream surface 6a of the seal fin 6A to which the guide plate 7A is attached (a distance related to the axial direction A). ). Similarly, the distance LB is the axial distance between the upstream surface of the shroud 43B (the surface facing the axial direction A) 43B immediately upstream of the guide plate 7B and the upstream surface 6a of the seal fin 6B to which the guide plate 7B is attached. The distance LC is a distance between the shroud downstream surface (surface facing the axial direction A) 43C immediately upstream of the guide plate 7C and the upstream surface 6a of the seal fin 6B to which the guide plate 7C is attached.

Hereinafter, the reason why each guide plate 7 is provided, the reason why each guide plate 7 is provided at the fin tip 6b, and the reason why the width dimensions WA, WB, WC of the guide plates 7A, 7B, 7C are set as described above will be described. .
As shown in FIG. 2, the space Gd is partitioned into three small spaces 121, 122, 123 by seal fins 6A, BC, 6C.
As described above, a part of the steam S flowing in the axial direction A through the stationary blade 60 flows into the uppermost stream-side small space 121 as the leaked steam SL without colliding with the moving blade 50. Part of the leaked steam SL that has flowed into the small space 121 collides with the upstream surface 43A of the tip shroud 4, and thus on the upstream side of the upstream surface 43A, in the meridian plane (in the cross section including the rotor axis CL). A main vortex SU1 that turns in one direction (counterclockwise in FIG. 2) is formed. A part of the main vortex SU1 is separated from the main vortex SU1 at the corner portion 44 of the upstream surface 43A, and a space between the upstream surface 43A and the upstream surface 6a of the seal fin 6A (hereinafter referred to as “exfoliation vortex”). 121a, which forms a separation vortex HU1 that rotates in the opposite direction to the main vortex SU1, that is, swirls in the other direction (clockwise in FIG. 2).
When the separation vortex HU1 is considered to be divided into an upstream side (left side in FIG. 2) and a downstream side (right side in FIG. 2), the upstream side flows to the outer peripheral side (upper side in FIG. 2). On the 6A side, it flows to the inner peripheral side (lower side in FIG. 2). Therefore, the separation vortex HU1 exerts a contraction effect on the seal fin 6A side that suppresses the flow of the leaked steam SL that flows toward the clearance m against the shroud base surface 41A.

  The leak steam SL is a flow component (a component perpendicular to the paper surface in FIG. 2) that is swirled in the same direction as the tip shroud 4 (that is, the rotor rotation direction C) by the action of the stationary blade 60 and centered on the axis CL. Also called “swirl component”. For this reason, the main vortex SU1 and the separation vortex HU1 formed by the leak steam SL similarly have a swirl component in the circumferential direction. Therefore, the main vortex SU1 and the separation vortex HU1 become a swirl flow that swirls in the circumferential direction while being swirled as shown by an arrow in FIG. As described in the column “Problems to be Solved by the Invention”, this circumferential swirling flow is one of the factors that cause unstable vibration in the steam turbine 1. Therefore, a guide plate 7A is provided, and the flow of the leaked steam SL is guided by the guide plate 7A so as to suppress the circumferential rotation of the separation vortex HU1.

Here, if the separation vortex HU1 is stopped on the upstream side (left side in FIG. 2) by the guide plate 7A, the swirl flow in the circumferential direction of the leaked steam SL forming the separation vortex HU1 can be stopped, The flow on the downstream side of the separation vortex HU1 having the contraction effect (the flow toward the inner periphery on the right side in FIG. 2) is also lost.
For this reason, the width dimension WA of the guide plate 7A is set so that the flow of the separation vortex HU1 can be reliably suppressed on the downstream side without being suppressed on the upstream side. Specifically, the width dimension WA of the guide plate 7A installed on the upstream surface 6a of the seal fin 6A is set so that the installation range of the guide plate 7A is within the downstream half of the separation vortex formation space 121a. It is set to be smaller than half of the distance LA that is the axial dimension of the space 121a.

  Similarly, the main vortices SU2 and SU3 are generated in the small spaces 122 and 123, and the separation vortices HU2 and HU3 are also generated in the separation vortex forming spaces 122a and 123a constituting the downstream side of the small spaces 122 and 123. For the same reason as the guide plate 7A, the guide plates 7B and 7C are set as described above.

Further, the inclination angle θ of the guide plate 7 with respect to the radial direction R is set in a range of 5 ° to 30 °. Specifically, the inclination angle θ of the guide plate 7 with respect to the reference line L0 (see FIGS. 3A and 3B) is set in the range of 5 ° to 30 °. The reference line L0 is a straight line from the plate tip 7a toward the outer periphery side in the radial direction R. The reason why the inclination angle θ is set in the range of 5 ° to 30 ° is as follows.
Referring to FIG. 2, in the steam turbine 1, a rotating force is applied to the steam SM by the stationary blade 70, and the moving blade 60 and thus the rotor shaft 30 are rotated by the steam SM. The inclination angle of the stationary blade 70 is designed so that the rotor blade 60 and the rotor shaft 30 can be efficiently driven to rotate, and the range thereof is a certain range although it varies depending on various conditions such as the type of steam turbine and operating conditions. Has converged. Since the swirl flow in the circumferential direction of the leak steam SL is also provided by the stationary blade 70, the stream line and speed of the swirl flow converge to a certain range, and the swirl flow of the leak steam SL is effectively suppressed. Therefore, the preferable inclination angle θ is converged within a certain range. As a result of analyzing a certain range (preferable range) of the inclination angle θ by simulation and experiment, it was found to be 5 ° to 30 °.

[1-3. Action / Effect]
The operation and effect of the seal structure 2 as the first embodiment of the present invention will be described with reference to FIGS. 2 and 3A, 3B.
As indicated by a two-dot chain line in FIG. 3B, the leak steam SL turns in the same direction as the rotor rotation direction C while swirling as indicated by arrows F4 and F5 if the guide plate 7 is not provided. In the seal structure 2 of the present embodiment, since the guide plate 7 is provided, the leaked steam SL flowing as shown by arrows F1, F2, and F3 is guided to the guide plate 7 as shown in FIG. Thus, it is guided to flow in the direction opposite to the rotor rotation direction C as indicated by arrows F1 ′, F2 ′, and F3 ′. The guidance by the guide plate 7 only needs to guide (turn) the leaked steam SL in the direction opposite to the rotor rotational direction C (if the swirl component in the rotor rotational direction C is reduced). Good).

  Therefore, a part of the leak steam SL is guided so as to flow in the direction opposite to the rotor rotation direction C, so that the swirl component in the rotor rotation direction C of the flow of the leak steam SL is canceled [the swirl component is completely cancelled. (Including not only canceling) but also partially canceling to reduce the swirl component). Thereby, the unstable vibration of the steam turbine 1 resulting from the turning of the leak steam SL can be suppressed.

Further, the guide plate 7 is provided on the front end side (predetermined range M from the fin front end 6b) of the seal fin 6, and in addition, the width dimensions WA, WB, WC of the guide plates 7A, 7B, 7C are separated from the separation vortex forming space. Since the distances LA, LB, and LC, which are axial dimensions of 121a, 122a, and 123a, are set to be smaller than half, the separation flows HU1, HU2, and HU3 (leakage steam SL) flow toward the clearance m. Inside, the leak steam SL can be guided by the guide plate 7.
Thereby, as indicated by arrows F1 ′, F2 ′, and F3 ′ in FIG. 3A, the leak steam SL can be turned in the rotor rotation direction C while leaving a flow component toward the clearance m of the leak steam SL. . Therefore, the contraction effect by the separated flows HU1, HU2, and HU3 (leak steam SL) is obtained.
Therefore, the unstable vibration of the steam turbine 1 can be suppressed while suppressing the flow rate of the leak steam SL due to the contraction effect.

  Furthermore, the guide plate 7 sets the inclination angle θ with respect to the reference line L0 in a range of 5 ° to 30 °, thereby effectively suppressing the swirling flow of the leak steam SL, and consequently the unstable vibration of the steam turbine 1. it can.

[2. Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the same element as 1st Embodiment, and the description is abbreviate | omitted.

[2-1. Seal structure]
The seal structure 2A according to the second embodiment of the present invention is different from the seal structure 2 according to the first embodiment shown in FIG. 2 and FIGS. A guide plate 17 shown in a) and (b) is used.
A plurality of guide plates 17 are provided on the upstream surface 6a of the seal fin 6 at predetermined intervals along the circumferential direction. In the present embodiment, the guide plate 17 is installed on the seal fin 6 with its tip (hereinafter also referred to as “plate tip”) 17d aligned with the fin tip 6b, but the plate tip 17d and the fin tip 6b You may leave a space between them.
Each guide plate 17 has a curved shape, and is attached to the upstream side surface 6 a of the seal fin 6 with its curved inner side surface 17 c facing away from the rotor rotation direction C. That is, the guide plate 17 is inclined so that the outer peripheral portion [the upper portion in FIGS. 4A and 4B] 17a is closer to the rotor rotation direction C as the inner peripheral side is closer to the inner peripheral portion [ 4 (a) and 4 (b), the lower portion] 17b is inclined so as to be on the opposite side to the rotor rotation direction C as it becomes the inner peripheral side. In other words, the inner peripheral portion 17b of the curved inner surface 17c (that is, the surface facing the direction opposite to the rotor rotation direction C) is inclined to face the outer peripheral side.

The curved shape of the guide plate 17 is preferably a shape that smoothly guides the leak flow SL into the curved inner surface 17c. For example, the inclination angle θ ′ of the outer peripheral end 17e of the guide plate 17 is preferably in the range of 5 ° to 30 °. The inclination angle θ ′ is an angle with respect to the reference line L0 ′, and the reference line L0 ′ is a straight line passing through the outer peripheral end 17e, and is a tangent line of a virtual circle centering on the axial center line CL. The reason why the inclination angle θ ′ is preferably set in the range of 5 ° to 30 ° is that the inclination angle θ of the guide plate 7 in the first embodiment is preferably set in the range of 5 ° to 30 °. The same.
Since other points are the same as the seal structure 2 of the first embodiment, description thereof is omitted.

[2-2. Action / Effect]
As indicated by an arrow F6 in FIG. 4A, the leaked steam SL that flows while facing the rotor rotation direction C is guided by the outer peripheral portion 17a of the guide plate 17 that is inclined in substantially the same direction as the flow direction. The leak steam SL smoothly turns into a curved shape on the guide plate 17 and flows in a direction opposite to the rotor rotation direction C by the guide of the inner peripheral portion 17 b of the guide plate 17.
According to the second embodiment of the present invention, the diversion of the leak steam SL in the direction opposite to the rotor rotation direction C is smoothly performed. Therefore, since the speed of the leak steam SL is reduced when turning, the swirl component of the leak steam SL in the rotor rotation direction C is more effectively canceled than in the first embodiment. As a result, unstable vibration can be suppressed more effectively than in the first embodiment.

[3. Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the same element as 1st Embodiment, and the description is abbreviate | omitted.

[3-1. Seal structure]
The seal structure 2B according to the third embodiment of the present invention is different from the seal structure 2 according to the first embodiment shown in FIG. 2 and FIGS. The guide plates 27 shown in a) and (b) are respectively used.
A plurality of guide plates 27 are provided on the upstream surface 6a of the seal fin 6 at predetermined intervals along the circumferential direction. In the present embodiment, the guide plate 27 is installed on the seal fin 6 with its tip (hereinafter also referred to as “plate tip”) 27a aligned with the fin tip 6b, but the plate tip 27a and the fin tip 6b You may leave a space between them.
Each guide plate 27 has a blade shape that is curved and tapered toward the inner peripheral side, and has a posture in which the curved inner side surface 27b is directed in a direction opposite to the rotor rotation direction C. In addition, the inner peripheral portion 27b 'of the curved inner side surface 27b (that is, the surface facing away from the rotor rotation direction C) is inclined to face the outer peripheral side.
The distance Ln between the surfaces of adjacent guide plates 27 facing each other (that is, the curved inner side surface 27b of one guide plate 27 and the curved outer side surface 27c of the other guide plate 27 is larger than the outer peripheral side at the plate front end 27a. In other words, the leak steam flow path SL defined between the guide plates 27 has a nozzle shape narrowed at the outlet.

The curved shape of the guide plate 27 is preferably a shape that smoothly guides the leak flow SL into the curved inner side surface 27b. Like the guide plate 17 of the second embodiment, the inclination angle θ ′ of the outer peripheral end 27e. Is preferably in the range of 5 ° to 30 °. Here, the outer peripheral end 27e is the outer peripheral end of the guide plate 27 on the center line L1 between the curved inner side surface 27b and the curved outer side surface 27c, and the inclination angle θ ′ of the outer peripheral end 27e is the center at the outer peripheral end 27e. The inclination angle θ ′ of the line L1 with respect to the reference line L0 ′.
Since other points are the same as the seal structure 2 of the first embodiment, description thereof is omitted.

[3-2. Action / Effect]
According to the third embodiment of the present invention, the flow path of the leak steam SL defined as between the guide plates 27 has a nozzle shape constricted at the outlet, so that the guide plate 27 and the rotation direction C The flow of leaked steam guided in the opposite direction becomes faster, and the swirl component of the leaked steam SL in the rotor rotation direction C can be canceled more effectively than in the first embodiment. It can suppress more effectively than embodiment.

[4. Fourth Embodiment]
The fourth embodiment of the present invention will be described below with reference to FIG. In addition, the same code | symbol is attached | subjected about the same element as 1st Embodiment and 3rd Embodiment, and the description is abbreviate | omitted.

[4-1. Seal structure]
In the seal structure 2C of the fourth embodiment of the present invention, a closing plate 28 for closing the upstream side of the guide plate 27 is added to the seal structure 2B of the third embodiment shown in FIGS. 5 (a) and 5 (b). Is. The closing plate 28 is a ring-shaped plate having a width in the radial direction R around the axial center line CL (see FIG. 1), and closes the upstream side of all the guide plates 27. The width dimension in the radial direction R is set so as to cover the entire end face (hereinafter referred to as “upstream end”) 27d on the upstream side of each guide plate 27.
Since other points are the same as the seal structure 27 of the third embodiment, description thereof is omitted.
[4-2. Action / Effect]
In the case where the closing plate 28 is not provided, a part of the leaked steam SL guided by the guide plate 27 is partway along the upstream side as shown by a two-dot chain line arrow F7 in FIG. The left side in a) is warped. The leaked steam SL that has warped from the guide plate 27 is not sufficiently turned in the direction opposite to the rotor rotation direction C, so that the effect of canceling the swirl component is reduced.
According to the fourth embodiment of the present invention, since the upstream side of the guide plate 27 is blocked by the closing plate 28, the leakage steam SL can be prevented from being warped from the guide plate 27, and the leakage steam SL The swirl component in the rotor rotation direction C can be canceled more effectively than in the third embodiment, and thus unstable vibration can be suppressed more effectively than in the third embodiment.

[4-3. Others]
The closing plate 28 preferably closes the upstream side of all the guide plates 27, but may close the upstream side of some of the guide plates 27. Further, the closing plate 28 preferably covers the entire upstream end 27d of each guide plate 27. However, as shown by a two-dot chain line in FIG. 6B, the upstream end 27d of each guide plate 27 is partially covered. You may make it cover.

[5. Others]

(1) In the steam turbine of each of the above embodiments, the seal structure of the present invention is applied to each chip shroud 4, but only the seal structure of the present invention is applied to some (at least one) chip shrouds 4. But you can.
When the seal structure of the present invention is applied to some chip shrouds 4, the non-uniformity of static pressure is maximized, so that it is closest to the main flow inlet 21 that is the inlet of the steam S (in other words, the highest pressure) It is preferable to apply the seal structure of the present invention to the tip shroud 4A (see FIG. 1).
Alternatively, when unstable vibration in the primary mode of the rotor shaft 30 occurs, the amplitude is maximized in the center in the axial direction A, so that the tip shroud 4B (see FIG. 1) in the center in the axial direction A It is preferable to apply a seal structure.
When the steam turbine is supplied with steam from the center in the axial direction A, the tip shroud at the center in the axial direction A becomes the tip shroud closest to the main inlet 21. When the seal structure of the present invention is applied to the tip shroud closest to, a synergistic effect is obtained.

(2) In the steam turbine according to each of the above embodiments, the example in which the guide plates 7, 17, and 27 are installed on each of the plurality of seal fins 6 provided on the single chip shroud 4 has been described. Guide plates 7, 17, 27 may be provided for (at least one) seal fin 6.
When the guide plates 7, 17, 27 are installed on some of the seal fins 6, the non-uniformity of the static pressure is maximized. Therefore, the seal fins 6 on the most upstream side (in other words, the high pressure side) It is preferable to install the guide plates 7, 17, 27.

  (3) If the guide plate has an inclined posture in which at least the inner peripheral portion of the surface facing away from the rotor rotation direction C is directed to the outer peripheral side, the leak steam SL is transferred to the rotor rotation direction C. Therefore, the shape is not limited at all.

  (4) Although the example which applied this invention to the steam turbine was demonstrated in the said embodiment, this invention is applicable also to seals of turbo machines other than steam turbines, such as a gas turbine and a turbo compressor.

1 Steam turbine (turbo machine)
2,2A, 2B Seal structure 4 Tip shroud (rotary structure)
4A Tip shroud arranged at the most upstream side 4B Tip shroud arranged at the center in the flow direction of the leak steam SL 6, 6A, 6B, 6C Seal fin 6a Surface on the upstream side of the seal fin 6b Tip of the seal fin 7, 7A , 7B, 7C Guide plate 7a Tip of guide plate 7, 7A, 7B, 7C 10 Turbine casing (stationary structure)
12 Cavity 13 Cavity bottom (inner circumferential surface)
17 Guide plate 17a Outer peripheral part of guide plate 17 17b Inner peripheral part of guide plate 17c Curved inner surface 17d of guide plate 17 End of guide plate 17 17e Outer end of guide plate 17 20 Steam supply pipe 21 Main inlet 27 Guide plate 27a The front end 27b of the guide plate 27b The curved inner surface 27b 'of the guide plate 27 The inner peripheral portion 27c of the guide plate 27 The curved outer surface 27d of the guide plate 27 The upstream end 27e of the guide plate 27 The outer peripheral end 28 of the guide plate 27 The closing plate 41, 41A, 41B Base surface of the shroud 4 42 Step surface of the shroud 4 43A, 43B, 43C A surface of the shroud 4 facing the axial direction A located immediately upstream of the guide plate 44 A corner 44 of the shroud 4
50 Rotor 60 Stator vane 121, 122, 123 Small space 121a, 122a, 123a Separation vortex formation space A Axial direction C Rotor rotation direction CL Rotor axis (axial axis)
Gd Gap F1-F7, F1'-F3 'Flow of leaked steam SL SU1, SU2, SU3 Main vortex HU1, HU2, HU3 Separation vortex L0, L0' Reference line L1 Center line LA, LB, LC Guide plate 27 And the distance from the surface facing the axial direction A of the shroud 4 immediately upstream thereof Ln Distance between the adjacent guide plates 27 R Radial direction M Predetermined range for installing the guide plate m Minute gap S Steam (working fluid)
SL leak steam (leak flow)
WA, WB, WC Guide plate width dimension Inclination angle θ, θ '

Claims (13)

Leakage flow of the working fluid from the gap between the rotating structure rotating in the predetermined direction around the axis and the stationary structure facing the radial direction with a gap on the outer peripheral side of the rotating structure A seal structure,
Seal fins extending from the stationary structure to the axial center side;
The flow component in the axial direction of the leak flow is attached to the tip side near the axial center line on the upstream surface of the seal fin, and at least the inner peripheral portion of the surface facing the predetermined direction is the outer peripheral side. A seal structure comprising a guide plate for guiding the leak flow as an inclined posture directed toward the head. The stationary structure is a turbine casing;
The rotating structure is a tip shroud that is installed in a plurality along the axial direction and attached to the tip of a moving blade,
The seal structure according to claim 1, wherein the seal fin and the guide plate are disposed to face the tip shroud in the radial direction. The axial dimension of the guide plate is a distance between the upstream surface of the seal fin and the surface of the tip shroud facing the axial direction and located on the upstream side of the seal fin. The seal structure according to claim 2, wherein the seal structure is set to be smaller than a half of the seal structure. The said guide plate is a flat plate, Comprising: It was made into the inclination attitude | position which orient | assigns the surface which turns to the opposite side to the said predetermined direction to the said outer peripheral side, The Claim 1 characterized by the above-mentioned. The seal structure described. The seal structure according to claim 4, wherein the guide plate is inclined by a predetermined angle with respect to the radial direction, and the predetermined angle is set in a range of 5 ° to 30 °. The guide plate is a plate having a curved shape, and is attached to the seal fin with an inner surface of the curved shape facing toward a side opposite to the predetermined direction which is a rotation direction of the rotating structure. The seal structure according to any one of claims 1 to 3. The seal fin has a ring shape centered on the axial center line, and a plurality of the guide plates are provided along the circumferential direction on the seal fin, and the distance between the guide plates is an inner peripheral end. The seal structure according to claim 6, wherein the seal structure is set so as to be narrower than the outer peripheral side. In the guide plate, at least an end portion on the outer peripheral side is inclined by a predetermined angle with respect to a tangent of a circle centering on the axial center line, and the predetermined angle is set in a range of 5 ° to 30 °. The seal structure according to claim 6 or 7, wherein the seal structure is formed. The sealing structure according to claim 7 or claim 8 when quoting claim 7, further comprising a closing plate for closing the upstream side of the guide plate. The rotating structure that rotates in a predetermined direction around an axis line, the stationary structure that faces the radial direction with a gap on the outer peripheral side of the rotating structure, and any one of claims 1 to 9 A turbomachine comprising a seal structure. The rotating structure includes a plurality of chip shrouds provided along the axis, and the stationary structure includes a turbine casing that surrounds the plurality of chip shrouds,
The turbo machine according to claim 10, wherein the turbomachine is provided with the seal structure for at least one tip shroud of the plurality of tip shrouds. The turbomachine according to claim 11, wherein the at least one tip shroud is a tip shroud disposed closest to the inlet of the working fluid. The turbo machine according to claim 11 or 12, wherein the at least one tip shroud is a tip shroud disposed in the center in the axial direction.

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