JP6662661B2 - Seal structure and turbo machinery - Google Patents

Description

  The present invention relates to a seal structure suitable for suppressing unstable vibration and for suppressing leakage of a working fluid from between two relatively rotating structures, and a turbo machine using the same.

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

By the way, in a turbomachine, low-frequency vibration considered as unstable vibration may occur. Turbine must be stopped because unstable vibration may cause malfunction. One of the major factors that cause unstable vibration is the seal excitation force. In response to micro-vibration of the rotating structure caused by any cause, the seal excitation force acts on the rotating structure so as to promote whirling of the rotating structure, thereby causing unstable vibration.
To further explain the seal excitation force, the working fluid flowing through the seal portion (the portion provided with the sealing fins) flows not only with the axial (flow direction) velocity component but also with the circumferential velocity component. Hereinafter, the flow in the circumferential direction is referred to as a “swirl flow”), and the seal excitation force is caused by the 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 to increase the static pressure, and the flow path is expanded to increase the static pressure. And a phase difference occurs in the static pressure distribution between the upstream and downstream of the sealing fin due to the swirling flow of the leaked working fluid. The resulting force acts on the rotating body to generate a seal excitation force.

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

JP 2011-208602 A U.S. Pat. No. 7,004,475 JP 2014-066134 A

By the way, the flow of the leaked working fluid (hereinafter referred to as “leak flow”) not only turns in the same direction as the rotating structure, but also turns in the meridional 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 and leaking the leak flow that is going to pass through the gap.
In the techniques exemplified in Patent Documents 2 and 3, it is possible to suppress the turning in the same direction as the rotating structure with respect to the leak flow, but also suppress the turning toward the gap between the seal fin and the rotating structure at the same time. As a result, the contraction effect is reduced, and the leakage amount of the working fluid and, consequently, the leakage loss of the turbomachine are increased.

  The present invention has been made in view of the above-described problems, and has as its object to provide a seal structure and a turbomachine capable of suppressing unstable vibration while suppressing a leakage amount of a working fluid. And

  (1) In order to achieve the above object, a seal structure according to the present invention radially opposes a rotating structure that rotates in a predetermined direction around an axis with a gap provided on an outer peripheral side of the rotating structure. A seal fin extending from the stationary structure to the axial center line side, wherein the seal fin extends from the gap between the stationary structure and the stationary structure. A slope attached to the tip side of the seal fin near the axis line on the upstream surface of the seal fin with a flow component related to the axial direction, and at least an inner peripheral portion of a surface facing the opposite side to the predetermined direction is directed to 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 the rotating structure is a tip shroud that is installed in a plurality in an axial direction and is attached to a tip of a moving blade, wherein the seal fin and the guide plate are Preferably, the tip shroud is disposed so as to face the radial direction.

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

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

  (5) Preferably, 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 may be a plate having a curved shape, and may be attached to the seal fin such that an inner surface of the curved shape faces a direction opposite to the predetermined direction that is a rotation direction of the rotating structure. preferable.

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

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

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

  (10) In order to achieve the above object, a turbo machine of the present invention radially opposes a rotating structure that rotates in a predetermined direction around an axis with a gap provided on an outer peripheral side of the rotating structure. And a sealing structure according to any one of (1) to (9).

  (11) The rotating structure includes a plurality of chip shrouds provided along the axis, and the stationary structure includes a turbine casing surrounding the plurality of chip shrouds. Preferably, the turbine is provided with the seal structure for at least one of the chip shrouds.

  (12) It is preferable that the at least one tip shroud is a tip shroud arranged closest to an inlet of the working fluid.

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

According to the present invention, the leak flow of the working fluid has a swirl 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 opposite side to the predetermined direction is connected to the outer periphery. Since the swirling component of the leak flow of the working fluid in the predetermined direction is reduced by the guide plate having the inclined posture toward the side, unstable vibration caused by the swirl of the leak flow can be suppressed.
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. Accordingly, the leak flow can be guided by the guide plate while leaving the flow component heading toward the clearance, and the radial flow heading toward the clearance suppresses and reduces other leak flow that is going to pass through the clearance. A flowing contraction effect is obtained.
Therefore, the unstable vibration can be suppressed while suppressing the leak flow rate of the working fluid by the contraction effect.

It is a typical longitudinal section showing the whole steam turbine composition concerning each embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a seal structure according to the first embodiment of the present invention, and is a cross-sectional view cut along a radial direction. FIGS. 2A and 2B are schematic diagrams illustrating a configuration of a main part of the seal structure according to the first embodiment of the present invention, wherein FIG. 2A is a perspective view thereof, and FIG. 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, (a) is the perspective view, (b) is the front view (corresponds to the arrow a direction of FIG. 2). Figure). It is a schematic diagram which shows the structure of the principal part of the seal structure which concerns on 3rd Embodiment of this invention, (a) is its perspective view, (b) is its front view (corresponds to the arrow a direction of FIG. 2 direction). 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, (a) is the perspective view, (b) is the front view (corresponds to the arrow a direction of FIG. 2 arrow). Figure).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In each embodiment of the present invention, an example in which the seal structure and the turbo machine 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 application of technology that are not explicitly described in the following embodiments. Each configuration of the following embodiments can be variously modified and implemented without departing from the spirit thereof, and can be selectively used as needed or can be appropriately combined.

In the following description, the terms “upstream” and “downstream” mean upstream and downstream of the flow component (axial flow component) of the leak steam SL in the axial direction A, 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, a direction toward a rotor axis line CL (hereinafter, also referred to as an “axis line”) CL of the steam turbine will be referred to as an inner side or an inner side, and a direction away from the axis line CL will be referred to as an outer side or an outer side. I do.
In the following description, the term “circumferential direction” means a circumferential direction centered on the axis CL unless otherwise specified.

[1. First Embodiment]
[1-1. Overall configuration of steam turbine]
The 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 is provided rotatably inside a turbine casing (stationary structure, hereinafter also referred to as a “casing”) 10 and a casing 10, and a power generator (not shown) And the like, a stationary blade 60 provided on the casing 10, a moving blade 50 provided on the rotor shaft 30, and rotatably supporting the rotor shaft 30 about an axis CL. The bearing unit 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 blade 50 rotates about the axis CL. That is, the casing 10 and the moving blade 50 (including the tip shroud 4 described later) rotate relative to each other.

  The steam (fluid) S is introduced from a main flow inlet 21 formed in the casing 10 through a steam supply pipe 20 connected to a not-shown steam supply source, and is connected to a steam discharge pipe downstream of the steam turbine 1. Discharged from 22.

The casing 10 has an internal space hermetically sealed and a passage for steam S. A ring-shaped partition plate outer ring 11 is firmly fixed to the inner wall surface of the casing 10.
The bearing portion 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 inward from the casing 10 and constitute a group of annular stationary blades radially arranged so as to surround the rotor shaft 30, and each of the stationary blades is held by the above-described partition plate outer ring 11. ing.

  A plurality of annular stationary blade groups each including the plurality of stationary blades 60 are formed at intervals in the axial direction A of the rotor shaft 30, convert the pressure energy of the steam S into velocity energy, and adjoin the downstream side. It is made to flow into the moving blade 50.

The moving blades 50 are firmly attached to a disk 32 formed on the outer peripheral portion of the rotor shaft main body 31 of the rotor shaft 30, and a large number of moving blades are radially arranged downstream of each of the annular stationary blade groups to constitute an annular moving blade group. are doing.
The group of annular stationary blades and the group of annular moving blades are arranged in one stage. The tips of the plurality of moving blades 50 constituting each moving blade group are connected to each other by a ring-shaped tip shroud (rotary structure) 4.

[1-2. Seal structure]
The seal structure according to the present embodiment will be described with reference to FIGS. 2 and 3A and 3B.
As shown in FIG. 2, a cavity 12 recessed from the inner peripheral surface of the partition plate outer ring 11 is formed between each of the plurality of partition plate outer rings 11. The cavity 12 is an annular space centered on the axis CL and has an inner peripheral surface (hereinafter, also referred to as a “cavity bottom surface 13”) 13 of the casing 10 as a bottom surface.
The chip shroud 4 is accommodated in the cavity 12, and the cavity bottom surface 13 is opposed to 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 bucket 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 steam flow (leak flow, hereinafter also referred to as “leak steam”) SL of a part (for example, about several percent) of the steam S leaks into the gap Gd without flowing into the bucket 50. Since the energy of the leak steam SL is not converted into rotational energy, the leak steam SL causes a leak loss that lowers the efficiency of the steam turbine 1.

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

  Seal fins 6A, 6B and 6C are provided on the cavity bottom surface 13 and extend inward toward the chip shroud 4 (omitted in FIG. 1). Hereinafter, when the seal fins 6A, 6B, and 6C are not distinguished, they are described as seal fins 6. The seal fin 6 has an annular shape having a width in the radial direction R about the axis CL, and has a uniform cross-sectional shape shown in FIG. 2 over the entire circumference.

The upstream seal fin 6A projects toward the base surface 41A on the upstream side of the step portion 3, the intermediate seal fin 6B projects toward the step surface 42 of the step portion 3, and the downstream seal fin 6C It protrudes toward the base surface 41B downstream of the step portion 3. The intermediate seal fin 6B is formed to have a width (length in the radial direction R) shorter 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 between the seal fins 6 and the shroud 4 in the radial direction R. Each dimension of these minute gaps m is set within a range where the seal fin 6 does not come into contact with the moving blade 50 in consideration of the amount of thermal expansion of the casing 10 and the moving blade 50 and the amount of centrifugal elongation of the moving blade 50. Have been.

As a major feature of the present invention, guide plates 7A, 7B, and 7C are provided on the seal fins 6A, 6B, and 6C, respectively. Hereinafter, when the guide plates 7A, 7B, and 7C are not distinguished from each other, they are referred to as guide plates 7.
As shown in FIGS. 2 and 3A and 3B, the guide plate 7 is provided on the tip (end on the axis CL) side of the upstream surface 6a of the seal fin 6 (different expression). Is provided in 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 the present 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. 6, the plate tip 7a and the fin tip 6b do not necessarily have to match.
Each guide plate 7 is a rectangular flat plate-like body, and is arranged so as to extend along the circumferential direction, but opposite to the rotation direction C of the rotor shaft (hereinafter, referred to as “rotor rotation direction”). The surface 7b facing the side is inclined toward the outer peripheral side.

Here, dimensions WA, WB and WC of the guide plates 7A, 7B and 7C in the axial direction A (hereinafter also referred to as "width dimensions") will be described with reference to FIG.
The width dimension WA of the guide plate 7A is set smaller than a half of a distance LA described later (WA <LA / 2). Similarly, the width dimension WB of the guide plate 7B is set smaller than half of a distance LB described later (WB <LB / 2), and the width dimension WC of the guide plate 7C is set smaller than half of a distance LC described later. (WC <LC / 2).
The distance LA is an axial distance (a distance in the axial direction A) between a shroud upstream surface (a surface facing the axial direction A) 43A immediately upstream of the guide plate 7A and an upstream surface 6a of the seal fin 6A to which the guide plate 7A is attached. ). Similarly, the distance LB is an axial distance between a shroud upstream surface (a surface facing the axial direction A) 43B immediately upstream of the guide plate 7B and an upstream surface 6a of the seal fin 6B to which the guide plate 7B is attached. The distance LC is the distance between the shroud downstream surface (the 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 for setting the widths WA, WB, and WC of the guide plates 7A, 7B, and 7C will be described. .
As shown in FIG. 2, the space Gd is divided 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 blades 60 flows into the most upstream small space 121 without colliding with the bucket 50 as the leak steam SL. A part of the leak steam SL that has flowed into the small space 121 collides with the upstream surface 43A of the chip shroud 4, and thereby in the meridional plane (in the cross section including the rotor axis CL) on the upstream side of the upstream surface 43A. A main vortex SU1 that turns in one direction (counterclockwise in FIG. 2) is formed. Then, 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 the space between the upstream surface 43A and the upstream surface 6a of the seal fin 6A (hereinafter, referred to as “separation vortex”). The separation vortex HU1 that rotates in the opposite direction to the main vortex SU1, that is, turns in the other direction (clockwise in FIG. 2) in the meridional plane, is formed at 121a.
When the separation vortex HU1 is divided into an upstream side (left side in FIG. 2) and a downstream side (right side in FIG. 2), the separation vortex HU1 flows to the outer peripheral side (upper side in FIG. 2) on the upstream side, and the downstream side, ie, the seal fins. On the 6A side, it flows toward the inner circumference (lower side in FIG. 2). Therefore, on the seal fin 6A side, the separation vortex HU1 exerts a contraction effect of suppressing the leak steam SL flowing toward the clearance m against the shroud base surface 41A to suppress the flow.

  Due to the action of the stationary blades 60, the leak steam SL is a flow component (a component perpendicular to the paper surface in FIG. 2, hereinafter a component perpendicular to the paper surface in FIG. 2) that turns around the axis CL and in the same direction as the tip shroud 4 (that is, the rotor rotation direction C). (Also called "swirl component"). Therefore, the main vortex SU1 and the separation vortex HU1 formed by the leak steam SL also have a swirl component in the circumferential direction. Accordingly, the main vortex SU1 and the separation vortex HU1 form a swirling flow that also swirls in the circumferential direction while swirling as shown by arrows in FIG. This circumferential swirling flow is one of the factors causing unstable vibration in the steam turbine 1 as described in the section “Problems to be Solved by the Invention”. Therefore, a guide plate 7A is provided, and the guide plate 7A guides the flow of the leak steam SL so as to suppress the rotation of the separation vortex HU1 in the circumferential direction.

Here, if the separation vortex HU1 is stopped on the upstream side (left side in FIG. 2) by the guide plate 7A, the circumferential swirling flow of the leak steam SL forming the separation vortex HU1 can be stopped. The flow on the downstream side of the separation vortex HU1 having the flow contraction effect (the flow toward the inner circumference 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 is not suppressed on the upstream side but can be reliably suppressed on the downstream side. Specifically, the width dimension WA of the guide plate 7A installed on the upstream surface 6a of the seal fin 6A is adjusted so that the installation range of the guide plate 7A is accommodated in the downstream half of the separation vortex formation space 121a. It is set smaller than half the distance LA which 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 separated vortices HU2 and HU3 are also generated in the separated vortex forming spaces 122a and 123a that are located downstream 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 a range of 5 ° to 30 °. The reference line L0 is a straight line extending from the plate front end 7a toward the outer periphery in the radial direction R. The inclination angle θ is set in the range of 5 ° to 30 ° for the following reason.
Referring to FIG. 2, in the steam turbine 1, the swirl 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 rotating blade 60 and the rotor shaft 30 can be efficiently rotated and driven. The range of the inclination angle varies depending on various conditions such as the type of steam turbine and operating conditions, but is within a certain range. Has converged. Since the circumferential swirling flow of the leak steam SL is also provided by the stationary vanes 70, the streamline and speed of the swirling flow converge within a certain range, and the swirling flow of the leak steam SL is effectively suppressed. Is also converged to a certain range. As a result of analyzing a certain range (preferable range) of the inclination angle θ by simulation or experiment, it was found that the range was 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 and 3B.
As shown by the two-dot chain line in FIG. 3B, the leak steam SL swirls in the same direction as the rotor rotation direction C while swirling as indicated by arrows F4 and F5 without the guide plate 7. In the seal structure 2 of the present embodiment, since the guide plate 7 is provided, the leak steam SL flowing as indicated by arrows F1, F2, and F3 is guided by the guide plate 7, as shown in FIG. As shown by arrows F1 ', F2', F3 ', the air is guided to flow in the direction opposite to the rotor rotation direction C. The guide by the guide plate 7 only needs to guide (turn) the leak steam SL relatively in the direction opposite to the rotor rotation direction C (if the swirl component in the rotor rotation direction C is reduced). Good).

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

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

  Further, the guide plate 7 sets the inclination angle θ with respect to the reference line L0 in the range of 5 ° to 30 °, thereby effectively suppressing the swirling flow of the leak steam SL and, thereby, effectively suppressing 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. The same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[2-1. Seal structure]
The seal structure 2A of the second embodiment of the present invention is different from the seal structure 2 of the first embodiment shown in FIGS. This uses the guide plate 17 shown in FIGS.
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 has its tip (hereinafter, also referred to as “plate tip”) 17d set on the seal fin 6 so as to coincide with the fin tip 6b. A space may be left between them.
Each guide plate 17 has a curved shape, and the curved inner surface 17c is attached to the upstream side surface 6a of the seal fin 6 with the curved inner surface 17c facing the direction opposite to the rotor rotation direction C. That is, the guide plate 17 is inclined such that the outer peripheral portion [the upper portion in FIGS. 4A and 4B] 17a is closer to the rotor rotation direction C toward the inner peripheral side, and the inner peripheral portion [ The lower part 17b in FIGS. 4 (a) and 4 (b)] is inclined so as to be on the opposite side to the rotor rotation direction C toward the inner peripheral side. In other words, the inner peripheral portion 17b of the curved inner surface 17c (that is, the surface facing the opposite side to the rotor rotation direction C) is inclined toward the outer peripheral side.

Preferably, the curved shape of the guide plate 17 is such that the leak flow SL is smoothly guided into the curved inner side surface 17c. For example, the inclination angle θ ′ of the outer peripheral end 17 e 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 to a virtual circle centered on the axis CL. The reason why it is preferable to set the inclination angle θ ′ in the range of 5 ° to 30 ° is that it is preferable to set the inclination angle θ of the guide plate 7 in the range of 5 ° to 30 ° in the first embodiment. Is the same.
The other points are the same as those of the seal structure 2 of the first embodiment, and the description is omitted.

[2-2. Action / Effect]
As shown by an arrow F6 in FIG. 4A, the leak steam SL flowing in the rotor rotation direction C is guided by the outer peripheral portion 17a of the guide plate 17 inclined in substantially the same direction as the flow direction. Then, the leak steam SL smoothly turns to the guide plate 17 into a curved shape, and flows in the direction opposite to the rotor rotation direction C by the guide of the inner peripheral portion 17b of the guide plate 17.
According to the second embodiment of the present invention, the leakage steam SL is smoothly turned in the direction opposite to the rotor rotation direction C. Therefore, a decrease in the speed of the leak steam SL during turning is suppressed, so that the swirl component of the leak steam SL in the rotor rotation direction C is more effectively canceled than in the first embodiment. Therefore, unstable vibration can be more effectively suppressed than in the first embodiment.

[3. Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. The same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[3-1. Seal structure]
The seal structure 2B of the third embodiment of the present invention is different from the seal structure 2 of the first embodiment shown in FIGS. A guide plate 27 shown in each of (a) and (b) is 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 has its tip (hereinafter, also referred to as “plate tip”) 27a installed on the seal fin 6 so as to coincide with the fin tip 6b. A space may be left between them.
Each guide plate 27 has a wing shape that is curved and tapered substantially toward the inner peripheral side, and has a posture in which the curved inner surface 27b is directed in a direction opposite to the rotor rotation direction C. Also, the inner peripheral portion 27b 'of the curved inner surface 27b (that is, the surface facing the opposite side to the rotor rotation direction C) is inclined toward the outer peripheral side.
Then, the mutual distance Ln between the opposing surfaces of the adjacent guide plates 27 (that is, the curved inner surface 27b of one guide plate 27 and the curved outer surface 27c of the other guide plate 27 is closer to the plate tip 27a than the outer peripheral side). In other words, the flow path SL of the leaked steam defined between the guide plates 27 has a nozzle shape narrowed at the outlet.

Preferably, the curved shape of the guide plate 27 is such that the leak flow SL is smoothly guided 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 preferred. 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 of the outer peripheral end 27e. The inclination angle θ ′ of the line L1 with respect to the reference line L0 ′.
The other points are the same as those of the seal structure 2 of the first embodiment, and the description is omitted.

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

[4. Fourth embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. The same elements as those in the first and third embodiments are denoted by the same reference numerals, and description thereof will be 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. 5A and 5B. Things. The closing plate 28 is a ring-shaped plate having a width in the radial direction R about the axis CL (see FIG. 1), and covers the upstream side of all the guide plates 27. The width of the guide plate 27 in the radial direction R is set so as to cover the entire upstream end surface 27d (hereinafter, referred to as “upstream end”) 27d.
The other points are the same as those of the seal structure 27 of the third embodiment, and the description is omitted.
[4-2. Action / Effect]
When the blocking plate 28 is not provided, a part of the leak steam SL guided by the guide plate 27 is located on the upstream side as shown by the two-dot chain line arrow F7 in FIG. The left side in a) is warped. The leak steam SL 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 closed by the closing plate 28, it is possible to prevent the leak steam SL from warping from the guide plate 27, and to prevent the leak steam SL from being warped. The swirl component in the rotor rotation direction C can be canceled more effectively than in the third embodiment, and unstable vibration can be more effectively suppressed 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. 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. It may be covered.

[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 shroud 4. May be.
When the seal structure of the present invention is applied to some of the tip shrouds 4, the non-uniformity of the static pressure is maximized, and therefore, the tip shroud 4 is closest to the main flow inlet 21 which is the inlet of the steam S (in other words, the highest pressure is applied). It is preferable to apply the seal structure of the present invention to the tip shroud 4A (see FIG. 1).
Alternatively, when unstable vibration occurs in the primary mode of the rotor shaft 30, the amplitude becomes maximum at the center in the axial direction A, and therefore, the present invention is applied to the chip shroud 4B at the center in the axial direction A (see FIG. 1). Preferably, a sealing structure is applied.
When the steam turbine is supplied with steam from the center in the axial direction A, the chip shroud in the center in the axial direction A becomes the chip shroud closest to the main flow inlet 21. When the seal structure of the present invention is applied to the tip shroud closest to the above, a synergistic effect can be obtained.

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

  (3) If the shape of the guide plate is such that at least the inner peripheral portion of the surface facing the opposite side to the rotor rotation direction C is inclined toward the outer periphery, the leak steam SL is transferred to the rotor rotation direction C. Can be guided in the opposite direction, so that the shape is not limited at all.

  (4) In the above embodiment, an example in which the present invention is applied to a steam turbine has been described. However, the present invention can also be applied to a seal of a turbomachine other than a steam turbine such as a gas turbine or a turbo compressor.

1 steam turbine (turbo machinery)
2, 2A, 2B Seal structure 4 Tip shroud (rotary structure)
4A Chip shroud arranged at the most upstream side 4B Chip shroud arranged at the center in the flow direction of leak steam SL 6, 6A, 6B, 6C Seal fin 6a Surface upstream of seal fin 6b Tip of 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 surface)
Reference Signs List 17 guide plate 17a outer peripheral portion of guide plate 17 17b inner peripheral portion of guide plate 17 17c curved inner surface of guide plate 17 17d tip of guide plate 17e outer peripheral end of guide plate 17 steam supply pipe 21 main inlet 27 guide plate 27a Plate tip 27b of guide plate 27b Inner curved surface of guide plate 27b 'Inner circumferential portion of guide plate 27c Outer curved surface of guide plate 27d Upstream end of guide plate 27e Outer end of guide plate 27 Closing plate 41, 41A, 41B Base surface of shroud 4 42 Step surface of shroud 4 43A, 43B, 43C Surface of shroud 4 located immediately upstream of guide plate facing axial direction A 44 Corner 44 of shroud 4
50 moving blade 60 stationary blade 121, 122, 123 small space 121a, 122a, 123a separation vortex forming space A axis direction C rotor rotation direction CL rotor axis (axis)
Gd Gap F1 to F7, F1 'to F3' Flow of leak steam SL SU1, SU2, SU3 Main vortex HU1, HU2, HU3 Separation vortex L0, L0 'Reference line L1 Center line of guide plate 27 LA, LB, LC Guide plate Distance between the shroud 4 and the surface of the shroud 4 immediately upstream thereof in the axial direction A. Ln Distance between adjacent guide plates 27 R Radial direction M Predetermined range in which guide plates are installed m Micro gap S Steam (working fluid)
SL Leak steam (leak flow)
WA, WB, WC Guide plate width dimensions Tilt angles θ, θ '

Claims (13)

The leak flow of the working fluid flows from the gap between the rotating structure that rotates in a predetermined direction around the axis and the stationary structure that radially opposes the rotating structure with a gap on the outer peripheral side of the rotating structure. A seal structure,
Seal fins extending from the stationary structure toward the axis line;
At least an inner peripheral portion of a surface facing the opposite side to the predetermined direction is attached to the upstream side surface of the seal fin with a flow component in the axial direction of the leak flow, the surface facing the axis direction. A seal plate having a guide plate for guiding the leak flow as an inclined attitude toward the seal. The stationary structure is a turbine casing;
The rotating structure is a plurality of tip shrouds installed along the axial direction, attached to the tip of the moving blade,
2. The seal structure according to claim 1, wherein the seal fin and the guide plate are arranged to face the tip shroud in the radial direction. 3. The axial dimension of the guide plate is the distance between the upstream surface of the seal fin and the surface of the tip shroud that faces the axial direction and is located upstream of the seal fin. 3. The seal structure according to claim 2, wherein the seal structure is set to be smaller than half of the seal structure. The guide plate according to any one of claims 1 to 3, wherein the guide plate is a flat plate, and has a tilted posture in which a surface facing a side opposite to the predetermined direction is directed to the outer peripheral side. The described seal structure. 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 curved plate, and is attached to the seal fin such that an inner surface of the curved shape faces a side opposite to the predetermined direction that is a rotation direction of the rotating structure. The seal structure according to claim 1. The seal fin has a ring shape centered on the axis, and the guide plate is provided in a plurality on the seal fin along a circumferential direction, and a distance between the guide plates is an inner circumferential end. The seal structure according to claim 6, wherein the portion is set to be narrower than the outer peripheral side. In the guide plate, at least an end on the outer peripheral side is inclined by a predetermined angle with respect to a tangent of a circle centered on the axis, and the predetermined angle is set in a range of 5 ° to 30 °. The seal structure according to claim 6, wherein the seal structure is performed. The sealing structure according to claim 7, further comprising a closing plate that closes the upstream side of the guide plate. 9. The rotating structure which rotates in a predetermined direction around an axis, and a stationary structure which radially opposes the rotating structure with a gap provided on the outer peripheral side of the rotating structure, according to 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 surrounding the plurality of chip shrouds,
The turbomachine according to claim 10, wherein the turbine is provided with the seal structure for at least one of the plurality of chip shrouds. The turbomachine according to claim 11, wherein the at least one tip shroud is a tip shroud located closest to an inlet of the working fluid. The turbomachine according to claim 11, wherein the at least one tip shroud is a tip shroud arranged at an axial center.

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