JP2012137006A - Turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine of high performance by efficiently reducing steam leakage.SOLUTION: A stepped part 52 having at least one stepped surface 53 facing the upstream side and projected to a partition plate outer ring 11 side is provided to a chip shroud 51. A seal fin 12 extending toward the stepped part 52 and forming a very small clearance H between the stepped part 52 and itself is provided to the partition plate outer ring 11. A plurality of grooves 71 guiding main eddies Y1 flowing in the direction including the circumferential component toward the axial direction are formed in the stepped surface 53A located on the uppermost upstream side of the stepped part 52.

Description

  The present invention relates to a turbine used in, for example, a power plant, a chemical plant, a gas plant, a steel mill, a ship, and the like.

  Conventionally, as a kind of steam turbine, a casing, a shaft body (rotor) rotatably provided inside the casing, a stationary blade fixedly disposed on an inner peripheral portion of the casing, and a downstream side of the stationary blade One having a plurality of stages of moving blades radially provided on a shaft body is known. This steam turbine is roughly classified into an impulse turbine and a reaction turbine depending on the operation method.

An impulse turbine is one in which a moving blade rotates only by an impact force received from steam. In the impulse turbine, the stationary blade has a nozzle shape, and the steam that has passed through the stationary blade is injected to the moving blade, and the moving blade rotates only by the impact force received from the steam.
On the other hand, the reaction turbine has the same shape as the moving blade, and the moving blade is affected by the impact force received from the steam passing through the stationary blade and the reaction force against the expansion of the steam generated when passing through the moving blade. Is what rotates.

  By the way, in such a steam turbine, a gap having a predetermined width is formed in the radial direction between the tip portion of the rotor blade and the casing, and also between the tip portion of the stationary blade and the shaft body. A gap having a predetermined width is formed in the direction. A part of the steam flowing in the axial direction of the shaft body leaks to the downstream side through the clearance between the tip portions of the rotor blades and the stationary blades.

Here, the steam leaking downstream from the gap between the moving blade and the casing does not give impact force or reaction force to the moving blade, so that the driving blade is rotated regardless of whether it is an impulse turbine or a reaction turbine. Little contribution as power. In addition, the steam leaking downstream from the gap between the stationary blade and the shaft body does not change its speed and does not expand even if it exceeds the stationary blade, so regardless of whether it is an impulse turbine or a reaction turbine, It hardly contributes as a driving force for rotating the moving blade on the downstream side. Therefore, in order to improve the performance of the steam turbine, it is important to reduce the amount of steam leakage in the gap between the tip portions of the moving blades and the stationary blades.
For this reason, seal fins are conventionally used as a means for preventing steam from leaking from the gaps at the tips of the rotor blades and stationary blades. Hereinafter, for example, a case where a seal fin is used at the tip of the moving blade will be described in detail.

FIG. 14 is an enlarged view of a main part of a conventional steam turbine.
As shown in the figure, the casing 801 of the steam turbine 800 is provided with seal fins 804 so as to form a minute gap H100 toward the shroud cover 803 which is the tip of the moving blade 802. By configuring in this way, the gap between the moving blade and the casing is minimized, and an attempt is made to suppress steam leakage.

  In addition, for example, a technique is disclosed in which a protrusion 805 that forms a concavo-convex portion that is cut off in a triangle along the circumference is provided on the upstream side of the shroud cover 803. A plurality of protrusions 805 are provided between adjacent blades (not shown), and generate vortex loss of the steam S100 that collides with the shroud cover 803. Accordingly, an action of pushing back the steam S flowing into the minute gap H100 formed at the tip of the seal fin 804 is caused to reduce steam leakage (for example, refer to Patent Document 1).

JP 2000-73702 A

  By the way, as shown in FIG. 14, the steam that collides with the shroud cover 803 forms a main vortex Y100 so as to return to the upstream side, and a part of the main vortex Y100 at the edge (edge) of the shroud cover 803. The flow is separated, and a separation vortex Y200 that rotates in the opposite direction to the main vortex Y100 is formed. Since this separation vortex Y200 causes a downflow from the tip of the seal fin 804 toward the shroud cover 803, it is possible to further reduce steam leakage by efficiently using the separation vortex Y200.

  However, in the above-described prior art, since the projection 805 that forms the uneven portion that is cut into a triangle along the circumference is provided on the upstream side of the shroud cover 803, the end of the shroud cover 803 is provided. The distance from the edge to the seal fin 804 is not uniform, and it is difficult to stabilize the vortex shape of the separation vortex Y200. For this reason, there is a problem that it is difficult to effectively reduce steam leakage.

  Therefore, the present invention has been made in view of the above-described circumstances, and provides a high-performance turbine that reduces steam leakage more efficiently.

  In order to solve the above-described problems, a turbine according to the present invention is a turbine including a blade and a structure that is provided on the tip end side of the blade via a gap and that rotates relative to the blade. The tip of the blade is provided with a step portion that has at least one step surface facing the upstream side and protrudes toward the structure body, and the structure body extends toward the step portion. A seal fin that forms a minute gap is provided between the step portion and a main vortex that guides the main vortex flowing in the direction including the circumferential component in the axial direction on the upstream side of the seal fin. Guide means are provided.

  Here, in order to efficiently rotate the blade and the structure relative to each other, the flow direction of the steam passing through the blade includes a strong circumferential component. For this reason, the flow direction of the main vortex formed by the steam colliding with the stepped surface of the step portion includes a strong circumferential component. In such a case, the flow direction of the separation vortex formed by separating a part of the flow from the main vortex also includes a strong circumferential component, and the downflow is efficiently generated from the seal fin tip toward the step portion. I can't.

  However, since the present invention is provided with main vortex guiding means for guiding the main vortex flowing in the direction including the circumferential component in the axial direction on the upstream side of the seal fin, the shaft in the flow direction of the main vortex is provided. The direction component can be set large. For this reason, the axial component in the flow direction of the separation vortex can also be set large, and it becomes possible to efficiently generate a downflow due to the separation vortex. Therefore, it is possible to efficiently reduce the steam leakage through the minute gap and provide a high-performance turbine.

  In the turbine according to the present invention, the main vortex guide means is provided on a step surface located at least on the most upstream side of the step surfaces, and a plurality of grooves arranged in parallel along the circumferential direction, and a plurality of blades The plurality of grooves and the plurality of blades are formed along the radial direction, and the groove depth of the plurality of grooves and the blade height of the plurality of blades are Is set so as to gradually decrease toward the outside in the direction, and at the radially outermost side, the groove depth of the plurality of grooves and the blade height of the plurality of blades are set to be zero. It is characterized by being.

With this configuration, the circumferential component in the flow direction of the main vortex can be directed in the axial direction with a simple structure.
Moreover, since the groove depth of the plurality of grooves and the blade height of the plurality of blades are set to be zero on the radially outermost side, the distance from the edge of the step surface to the seal fin Can be made constant. For this reason, the vortex shape of the separation vortex can be stabilized, and the downflow can be generated more efficiently.
Further, the circumferential component of the steam is converted into a rotational force by colliding with a plurality of grooves and a plurality of blades, and the blade and the structure can be relatively rotated relative to each other.
Therefore, it becomes possible to provide a higher performance turbine.

  The turbine according to the present invention is characterized in that the main vortex guide means is a plurality of guide plates arranged in parallel along the circumferential direction at least on the most upstream side of the gap.

By comprising in this way, the circumferential direction component in the flow direction of the main vortex can be turned to an axial direction using a guide plate. Further, when the main vortex collides with the guide plate, a vortex or a turbulent flow is generated, and the pressure loss of the main vortex increases and the total pressure can be reduced.
Here, the flow rate of the leaked steam is represented by the flow rate of the leaked steam = coefficient × the cross-sectional area of the channel in the gap × (upstream steam pressure−downstream steam pressure). That is, the flow rate of the leaked steam can be reduced by reducing the total pressure of the steam. For this reason, a higher performance turbine can be provided.

  In the turbine according to the present invention, an annular groove that secures the gap is formed in the structure at a position corresponding to the tip of the blade, and the main vortex guide means is located upstream of the annular groove. One of a plurality of grooves and a plurality of blades provided on the inner surface of the side and arranged in parallel along the circumferential direction, wherein the plurality of grooves and the plurality of blades are along the radial direction The groove depths of the plurality of grooves and the blade heights of the plurality of blades are set so as to gradually decrease toward the radially outer side, and at the radially outermost side, The groove depth of the plurality of blades and the blade heights of the plurality of blades are set to be zero.

  With this configuration, the circumferential component in the flow direction of the main vortex can be directed in the axial direction with a simple structure, so that it is possible to provide an inexpensive and high-performance turbine.

  The turbine according to the present invention is characterized in that the plurality of grooves and the plurality of blades are inclined to a side opposite to a direction of a circumferential component of the main vortex toward a radially outer side.

  By comprising in this way, the axial direction component in the flow direction of the main vortex can be set larger. For this reason, it becomes possible to generate | occur | produce the downflow by peeling vortex more efficiently, and a high performance turbine can be provided.

  According to the present invention, the axial component in the flow direction of the main vortex can be set large. For this reason, the axial component in the flow direction of the separation vortex can also be set large, and it becomes possible to efficiently generate a downflow due to the separation vortex. Therefore, it is possible to efficiently reduce the steam leakage through the minute gap and provide a high-performance turbine.

It is a schematic structure figure of a steam turbine in an embodiment of the present invention. It is an expanded sectional view which shows the principal part I in FIG. FIG. 3 is a view as seen from an arrow A in FIG. 2. It is behavior explanatory drawing of the steam between the stationary blade and moving blade in 1st Embodiment of this invention. It is explanatory drawing about the contraction flow effect of the peeling vortex in 1st Embodiment of this invention. It is a top view of the chip shroud in 2nd Embodiment of this invention. It is a schematic block diagram of the upstream of the chip | tip shroud in 3rd Embodiment of this invention. It is a B arrow line view of FIG. It is a schematic block diagram which shows the chip | tip shroud periphery in 4th Embodiment of this invention. It is a schematic block diagram of the upstream of the chip | tip shroud in 5th Embodiment of this invention. It is C arrow line view of FIG. It is a schematic block diagram of the upstream of the chip | tip shroud in 6th Embodiment of this invention. It is D arrow line view of FIG. It is a principal part enlarged view of the conventional steam turbine.

(First embodiment)
(Steam turbine)
Next, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram illustrating a steam turbine according to a first embodiment of the present invention.
The steam turbine 1 is provided in a casing 10, a regulating valve 20 that adjusts the amount and pressure of the steam S flowing into the casing 10, and an inward rotation of the casing 10. The main structure includes a shaft body 30 to be transmitted, a stationary blade 40 held in the casing 10, a moving blade 50 provided on the shaft body 30, and a bearing portion 60 that rotatably supports the shaft body 30 about its axis. Yes.
The bearing portion 60 includes a journal bearing device 61 and a thrust bearing device 62, and supports the shaft body 30 in a rotatable manner.

  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 through which the shaft body 30 is inserted is firmly fixed to the inner wall surface of the casing 10.

  A plurality of regulating valves 20 are attached to the inside of the casing 10, and each includes a regulating valve chamber 21 into which steam S flows from a boiler (not shown), a valve body 22, and a valve seat 23. When the valve seat 23 is separated from the valve seat 23, the steam flow path is opened, and the steam S flows into the internal space of the casing 10 through the steam chamber 24.

  The shaft body 30 includes a shaft main body 31 and a plurality of disks 32 extending from the outer periphery of the shaft main body 31 in the rotational axis radial direction (hereinafter simply referred to as the radial direction). The shaft body 30 transmits rotational energy to a machine such as a generator (not shown).

A large number of the stationary blades 40 are arranged radially so as to surround the shaft body 30 to form an annular stationary blade group, and are respectively held by the partition plate outer ring 11. The radially inner sides of these stationary blades 40 are connected by a ring-shaped hub shroud 41 through which the shaft body 30 is inserted, and the tip portions thereof are arranged with a radial gap with respect to the shaft body 30.
The annular stator blade group composed of the plurality of stator blades 40 is formed with six intervals in the rotation axis direction (hereinafter simply referred to as the axial direction), and converts the pressure energy of the steam S into velocity energy, Guide to the moving blade 50 side adjacent to the downstream side.

  The rotor blade 50 is firmly attached to the outer peripheral portion of the disk 32 included in the shaft body 30. A large number of the moving blades 50 are arranged radially on the downstream side of each annular stationary blade group to constitute the annular moving blade group.

These annular stator blade groups and annular rotor blade groups are grouped into one stage. That is, the steam turbine 1 is configured in six stages. The tip portions of the rotor blades 50 are tip shrouds 51 extending in the circumferential direction.
Here, in this embodiment, the shaft body 30 and the partition plate outer ring 11 are “structures” in the present invention. Further, the stationary blade 40, the hub shroud 41, the tip shroud 51, and the moving blade 50 are “blades” in the present invention. When the stationary blade 40 and the hub shroud 41 are “blades”, the shaft body 30 is a “structure”. On the other hand, when the rotor blade 50 and the tip shroud 51 are “blades”, the partition plate outer ring 11 is “ Structure ”. In the following description, the partition plate outer ring 11 is described as a “structure”, and the moving blade 50 is described as a “blade”.

2 is an enlarged cross-sectional view showing a main part I in FIG. 1, and FIG.
As shown in FIGS. 2 and 3, the tip shroud 51, which is the tip of the moving blade 50, is arranged to face the partition plate outer ring 11 with a gap K in the radial direction of the casing 10. The tip shroud 51 has a stepped portion 52 (52A to 52C) that has a step surface 53 (53A to 53C) and protrudes toward the partition plate outer ring 11 side.

  In the present embodiment, the chip shroud 51 forms three step portions 52 (52A to 52C). In these three step portions 52A to 52C, the projecting height of the upper surface 152 (152A to 152C) from the moving blade 50 is such that the axially upstream side (left side in FIG. 2) of the shaft body 30 is downstream (FIG. 2). It is arranged so as to become gradually higher toward the right side). That is, in the step portions 52A to 52C, the step surfaces 53 (53A to 53C) forming the steps are formed facing forward in the axial direction.

  Here, among the step surfaces 53 (53A to 53C), a plurality of grooves 71 are arranged in parallel along the circumferential direction on the step surface 53A located on the most upstream side. Each groove 71 is formed in a slit shape so as to be along the radial direction in an axial plan view. Moreover, each groove | channel 71 is formed in the axial direction cross-section substantially triangle shape, and is set so that it may become shallow gradually as the groove depth D1 goes to radial direction outer side. And each groove | channel 71 is set so that this groove depth D1 may become zero near the upper surface 152A of the step part 52A of the 1st step.

On the other hand, the annular groove 111 is formed in the part corresponding to the chip shroud 51 in the partition plate outer ring 11. Then, on the bottom surface 111a of the annular groove, three seal fins 12 (12A to 12C) project in the radial direction so as to correspond to the respective step portions 52 (52A to 52C) 1: 1.
Each of the seal fins 12 (12A to 12C) has a small gap H (H1 to H3) between the corresponding step portions 52 (52A to 52C) in the radial direction so as to go downstream. The length is formed to be short.

  Here, each dimension of the minute gap H (H1 to H3) is safe so that they do not come into contact with each other in consideration of the thermal elongation amount of the casing 10 and the moving blade 50, the centrifugal elongation amount of the moving blade 50, and the like. Within the range, it is set to the smallest one. In the present embodiment, H1 to H3 all have the same dimensions. However, it goes without saying that these can be changed as appropriate.

  Further, each seal fin 12 (12A to 12C) is provided slightly downstream from the step surface 53 (53A to 53C) of the corresponding step portion 52 (52A to 52C). That is, spaces SP (SP1 to SP3) are formed between the edge portions 55 (55A to 55C) of the step surfaces 53 (53A to 53C) and the corresponding seal fins 12 (12A to 12C), respectively. .

  Here, each groove 71 formed on the step surface 53A located on the most upstream side is set so that the groove depth D1 becomes zero in the vicinity of the upper surface 152A of the first step portion 52A. The distance L between the edge portion 55A of the step surface 53A and the seal fin 12A is the same over the entire circumference of the tip shroud 51. That is, the space SP1 formed between the step surface 53A and the seal fin 12A is formed uniformly over the entire circumferential direction.

Under such a configuration, the partition plate outer ring 11, the seal fins 12 (12A to 12C), and the chip shroud 51 form three cavities C (C1 to C3).
That is, among the three cavities C (C1 to C3), the first cavity C1 located on the most upstream side includes the bottom surface 111a of the annular groove 111, the upstream inner surface 111b, and the first seal fin 12A. The first step portion 52A of the chip shroud 51 is surrounded and formed.

The second cavity C2 on the downstream side of the first cavity C1 includes a bottom surface 111a of the annular groove 111, the first seal fin 12A, the second seal fin 12B, and the tip shroud 51. It is surrounded by the step part 52A of the eye and the step part 52B of the second stage.
Further, the third cavity C3 on the downstream side of the second cavity C2 includes a bottom surface 111a of the annular groove 111, a second seal fin 12B, a third seal fin 12C, and a tip shroud 51. It is surrounded by the step part 52B of the eye and the step part 52C of the third stage.

(Operation of steam turbine)
Next, the operation of the steam turbine 1 will be described based on FIG. 1, FIG. 2, FIG. 4, and FIG.
FIG. 4 is an explanatory view of the behavior of steam between the stationary blade and the moving blade.
As shown in FIGS. 1, 2, and 4, when the regulating valve 20 (see FIG. 1) is opened, the steam S flows from the boiler (not shown) into the internal space of the casing 10. The steam S flowing into the internal space of the casing 10 sequentially passes through the annular stator blade group and the annular rotor blade group in each stage. At this time, pressure energy is converted into velocity energy by the stationary blade 40, and most of the steam S passing through the stationary blade 40 flows between the moving blades 50 constituting the same stage. The speed / pressure energy of S is converted into rotational energy, and rotation is applied to the shaft body 30.

That is, as detailed in FIG. 4, the absolute flow velocity Cz of the steam S flowing out from the stationary blade 40 includes a strong circumferential component. That is, when the rotational speed of the moving blade 50 is V, the relative flow velocity of the steam S viewed from the moving blade 50 is W, and the inclination of the relative flow velocity W with respect to the circumferential direction is φ, the inclination φ is generally φ <90. °
It becomes. For this reason, the relative flow velocity W also includes a circumferential component.

A part (for example, several percent) of the steam S having such a flow becomes so-called leaked steam that flows out from the stationary blade 40 and then flows into the annular groove 111. The steam S flowing into the annular groove 111 first flows into the first cavity C1, collides with the step surface 53A of the first step portion 52A, and returns to the upstream side, for example, on the paper surface of FIG. Produces a main vortex Y1 that rotates counterclockwise.
At this time, since the plurality of grooves 71 are formed on the step surface 53A along the radial direction in the plan view in the axial direction, the flow direction of the main vortex Y1 formed by colliding with the step surface 53A is steam. It is guided axially from the relative flow velocity W of S. As a result, the relative flow velocity W ′ of the steam S is inclined in the axial direction relative to the relative flow velocity W (see the broken line in FIG. 4).

  As described above, the main vortex Y1 including a strong axial component is separated from the main vortex Y1 at the edge 55A of the step surface 53A, and the main vortex Y1 is opposite to the main vortex Y1. Then, a separation vortex Y2 is generated so as to rotate clockwise on the paper surface of FIG. The separation vortex Y2 exhibits a so-called contraction effect that reduces the leakage flow of the steam S in the minute gap H1 between the first seal fin 12A and the tip shroud 51.

More specifically, the contraction effect by the separation vortex Y2 will be described based on FIG.
FIG. 5 is a view for explaining the contraction effect of the separation vortex, and is a partially enlarged cross-sectional view in which the periphery of the tip end portion of the first seal fin in FIG. 2 is enlarged.
As shown in the figure, the separation vortex Y2 has a radially inward inertial force immediately before the minute gap H1 between the first seal fin 12A and the tip shroud 51. Therefore, the steam S leaking downstream through the minute gap H1 is pressed down by the inertial force of the separation vortex Y2, so that the radial width is reduced as shown by the one-dot chain line in FIG. Thus, the separation vortex Y2 has an effect of reducing the leakage flow by compressing the steam S radially inward, that is, a contraction effect.

  In addition, this contraction effect becomes more effective as the inertial force of the separation vortex Y2 increases, that is, as the flow of the axial component of the separation vortex Y2 increases. Here, the main vortex Y1 that generates the separation vortex Y2 is inclined in the axial direction with respect to the relative flow velocity W of the steam S by the plurality of grooves 71 formed in the step surface 53A in the flow direction. As a result, the axial component of the flow direction of the separation vortex Y2 also becomes strong. For this reason, the contraction effect by the separation vortex Y2 is greater than that in the case where the plurality of grooves 71 are not formed on the step surface 53A.

  Further, each groove 71 is formed to have a substantially triangular cross section in the axial direction, and the groove depth D1 is set to be zero near the upper surface 152A of the first step portion 52A. The space SP1 formed between the seal fin 12A and the seal fin 12A is uniformly formed over the entire circumferential direction. For this reason, the shape of the peeling vortex Y2 can be formed uniformly and stably over the entire circumferential direction.

Here, the distance L between the edge portion 55A of the step surface 53A and the seal fin 12A is:
L / H1≈2 (1)
It is desirable to set so as to satisfy. By setting in this way, the maximum position of the velocity component facing radially inward in the downflow of the separation vortex Y2 can easily coincide with the tip (inner edge) of the seal fin 12A. In such a case, since the downflow passes through the minute gap H1 more favorably, it is considered that the contraction effect on the leakage flow is maximized.

  Subsequently, the vapor S passes through the minute gap H1 and flows into the second cavity C2, collides with the step surface 53B of the second step portion 52B, and returns to the upstream side, for example, as shown in FIG. This produces a main vortex Y1 that rotates counterclockwise above. Then, a part of the flow is separated from the main vortex Y1 at the end edge portion 55B of the second step portion 52B, so that the watch rotates in the direction opposite to the main vortex Y1, in this example on the paper surface of FIG. A peeling vortex Y2 is generated so as to turn around. The separation vortex Y2 also reduces the leakage flow of the steam S in the minute gap H2 between the second seal fin 12B and the tip shroud 51, similarly to the separation vortex Y2 formed in the first step portion 52A. Demonstrate the effect of contraction.

  Further, the steam S passes through the minute gap H2 and flows into the third cavity C3, collides with the step surface 53C of the step portion 52C of the third step, and returns to the upstream side, for example, on the paper surface of FIG. Produces a main vortex Y1 that rotates counterclockwise. Then, a part of the flow is separated from the main vortex Y1 at the end edge portion 55C of the step portion 52C at the third stage, so that the watch rotates in the direction opposite to the main vortex Y1, in this example on the paper surface of FIG. A peeling vortex Y2 is generated so as to turn around. The separation vortex Y2 also reduces the leakage flow of the steam S in the minute gap H3 between the third seal fin 12C and the tip shroud 51, similarly to the separation vortex Y2 formed in the first step portion 52A. Demonstrate the effect of contraction.

(effect)
Therefore, according to the first embodiment described above, among the step surfaces 53 (53A to 53C) formed in the step portion 52 of the chip shroud 51, the plurality of grooves 71 are formed on the step surface 53A located on the most upstream side. The main vortex Y1 that is formed and flows in the direction including the circumferential component can be guided in the axial direction by these grooves 71, and the axial component in the flow direction of the main vortex Y1 can be set large. For this reason, the axial component in the flow direction of the separation vortex Y2 can also be set large, and it is possible to efficiently generate a downflow due to the separation vortex Y2. Therefore, the leakage flow of the steam S passing through the minute gap H1 with a simple structure can be efficiently reduced, and the high-performance steam turbine 1 can be provided.

Each groove 71 is formed in a substantially triangular cross section in the axial direction, and the groove depth D1 is set to be zero near the upper surface 152A of the first step portion 52A. For this reason, the shape of the separation vortex Y2 can be formed uniformly and stably over the entire circumferential direction, and the effect of contraction of the steam S by the separation vortex Y2 can be further increased.
Furthermore, the circumferential component of the steam S is converted into a rotational force by colliding with the plurality of grooves 71, and the shaft body 30 can be rotated more efficiently.

(Second Embodiment)
Next, 2nd Embodiment of this invention is described based on FIG. 6, using FIG.1, FIG.4, FIG.5. The same aspects as those in the first embodiment will be described with the same reference numerals (the same applies to the following embodiments).
FIG. 6 is an explanatory diagram for explaining the second embodiment and corresponds to FIG. 3 (a view taken in the direction of arrow A in FIG. 2).

  In the second embodiment, the steam turbine 1 is provided in a casing 10, a regulating valve 20 that adjusts the amount and pressure of the steam S flowing into the casing 10, and an inward rotation of the casing 10. A shaft body (rotor) 30 that transmits to a machine such as the generator shown in the figure, a stationary blade 40 held in the casing 10, a moving blade 50 provided on the shaft body 30, and the shaft body 30 can be rotated about its axis. The main part is the bearing part 60 that is supported by the rotor. The stator blades 40 are arranged radially so as to surround the shaft body 30 to form an annular stator blade group. The points that are held, the radially inner sides of these stationary blades 40 are connected by a ring-shaped hub shroud 41 through which the shaft body 30 is inserted, and the moving blades 50 are located downstream of each annular stationary blade group. A large number of radially arranged rings The blade group is configured, the tip of which is a tip shroud 51 extending in the circumferential direction, the annular stationary blade group and the annular moving blade group are one-stage, and the tip shroud 51 Is a step portion 52 (52A to 52C) which has a step surface 53 (53A to 53C) and protrudes toward the partition plate outer ring 11, and the partition plate outer ring 11 has a tip shroud 51 attached to it. An annular groove 111 is formed in a corresponding portion, and three seal fins 12 (12A to 12C) correspond to each step portion 52 (52A to 52C) 1: 1 on the bottom surface 111a of the annular groove. The basic configuration such as a point projecting in the radial direction is the same as that of the first embodiment described above (the same applies to the following embodiments).

Here, the difference between the second embodiment and the first embodiment is that the shape of the plurality of grooves 171 formed in the step surface 53A of the step part 52 of the first step of the second embodiment is different from that of the first embodiment. This is different from the groove 71 formed on the step surface 53A.
More specifically, each groove 171 is formed to have a substantially triangular cross section in the axial direction, and the first embodiment described above in that the groove depth is set so as to become gradually shallower toward the outer side in the radial direction. The grooves 71 are the same as the grooves 71 of the first embodiment except that the grooves 171 are formed so as to intersect the radial direction in plan view in the axial direction. That is, each groove 171 is inclined toward the side opposite to the direction of the circumferential component of the steam S flowing out from the stationary blade 40 as it goes radially outward.

The inclination angle with respect to the radial direction of each groove 171 is obtained as follows.
That is, of the absolute velocity Cz steam S flowing out from the stationary blade 40 (see FIG. 4), a circumferential component and C _theta, steam S to form a Shuuzu Y1 collides with the step surface 53A of the tip shroud 51 ' in the flow rate W _{L (see} FIG. 5), when the circumferential component of flow direction and W _Erushita, the rotational speed of the blades 50 was set to V (see FIG. 4), the inclination angle of each groove 171,
C _θ = V + W _Lθ = 0 (2)
It is set to satisfy.

  By setting the inclination angle of each groove 171 so as to satisfy the formula (2), in addition to the same effects as those of the first embodiment described above, the axial component in the flow direction of the main vortex Y1 is set to be more reliably set larger. be able to. For this reason, it becomes possible to generate the downflow due to the separation vortex Y2 more efficiently, and it is possible to provide the steam turbine 1 with higher performance.

In the first embodiment described above, among the step surfaces 53 (53A to 53C) formed on the three step portions 52 (52A to 52C) of the chip shroud 51, the step surface 53A located on the most upstream side is used. The case where the plurality of grooves 71 are formed has been described. Furthermore, in the second embodiment, the case where the plurality of grooves 171 are formed in the step surface 53A has been described.
However, the present invention is not limited to this, and a plurality of grooves 71 and 171 may also be formed on the step surface 53B of the second step portion 52B and the step surface 53C of the third step portion 52C.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a schematic configuration diagram of the upstream side of the chip shroud in the third embodiment, and FIG. 8 is a view as seen from the direction of arrow B in FIG.
As shown in FIGS. 7 and 8, the difference between the third embodiment and the first embodiment is that in the first embodiment, a plurality of grooves 71 are formed on the step surface 53A of the first step portion 52A. On the other hand, in the third embodiment, a plurality of blades 271 are arranged in parallel along the circumferential direction on the step surface 253A of the first step portion 52A.

  The blade | wing 271 is provided so that it may protrude toward an axial direction upstream side so that a radial direction may be followed by an axial plan view. Further, the blade 271 is formed such that the shape of the circumferential cross section gradually becomes thinner from the radially inner side to the radially outer side, and the direction of the circumferential component of the steam S flowing out from the stationary blade 40 is It is formed so as to be gradually inclined toward the opposite side. An arcuate surface 271a is formed at the radially inner end of the blade 271 so that the static pressure applied to the steam S passing therethrough is reduced.

  Further, the blades 271 are formed in a substantially triangular shape in the axial direction cross section, and are set so as to gradually decrease as the blade height T1 goes outward in the radial direction. The blade 271 is set such that the blade height T1 becomes zero in the vicinity of the upper surface 152A of the stepped portion 52A of the first stage. That is, the step surface 253A of the first step portion 52A is gradually inclined toward the upstream side in the axial direction toward the radially outer side.

  Therefore, according to the above-described third embodiment, the same effects as those of the above-described first embodiment can be obtained. Further, it is possible to select whether the groove 71 is formed on the step surface 53A or the blade 271 is provided on the step surface 253A according to the specifications of the steam turbine 1, and the variations of the chip shroud 51 can be expanded.

  In the third embodiment described above, among the step surfaces 53 (53A to 53C) formed on the three step portions 52 (52A to 52C) of the chip shroud 51, the step surface 53A located on the most upstream side is used. The case where the plurality of blades 271 are arranged in parallel along the circumferential direction has been described. However, the present invention is not limited to this, and a plurality of blades 271 may be formed also on the step surface 53B of the second step portion 52B and the step surface 53C of the third step portion 52C.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 9 is a schematic configuration diagram showing the periphery of the tip shroud in the fourth embodiment.
As shown in FIG. 9, the difference between the fourth embodiment and the first embodiment is the shape of a plurality of grooves 371 formed in the step surface 53A of the step portion 52 at the first step.

More specifically, the groove depth D2 of each groove 371 is set so as to become gradually shallower toward the outer side in the radial direction, and this groove depth D2 becomes zero near the upper surface 152A of the first step portion 52A. However, each groove 371 does not have a substantially triangular cross section in the axial direction.
That is, in each groove 371, the first arc-shaped portion 371a is formed so that the groove depth D2 becomes shallower toward the radially outer side. Further, a second arc-shaped portion 371b is formed at the tip of the first arc-shaped portion 371a of each groove 371 so as to bulge toward the upstream side.

Thus, by forming each groove | channel 371, the tangent direction in the radial direction outer side of each groove | channel 371 substantially corresponds with the surface direction of the level | step difference surface 53A. For this reason, in the steam S ′ that collides with the stepped surface 53A of the chip shroud 51 to form the main vortex Y1, the velocity vector at the end edge portion 55A is directed substantially in the radial direction, and the inertial force of the separation vortex Y2 increases.
Therefore, according to the above-described fourth embodiment, in addition to the same effects as those of the above-described first embodiment, it is possible to increase the downflow due to the separation vortex Y2. For this reason, the leakage flow of the steam S passing through the minute gap H1 can be reduced more efficiently, and the steam turbine 1 with higher performance can be provided.

  In the above-described fourth embodiment, among the step surfaces 53 (53A to 53C) formed on the three step portions 52 (52A to 52C) of the chip shroud 51, the step surface 53A located on the most upstream side is used. The case where the plurality of grooves 371 are formed has been described. However, the present invention is not limited to this, and a plurality of grooves 371 may also be formed on the step surface 53B of the second step portion 52B and the step surface 53C of the third step portion 52C.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIGS.
FIG. 10 is a schematic configuration diagram of the upstream side of the chip shroud in the fifth embodiment, and FIG. 11 is a view taken in the direction of arrow C in FIG.
As shown in FIGS. 10 and 11, the difference between the fifth embodiment and the first embodiment is that the chip shroud 51 of the first embodiment has a plurality of grooves 71 on the step surface 53A. On the other hand, in the fifth embodiment, the groove 71 is not formed in the chip shroud 51, and the turning vane is provided in the first cavity C1 located on the most upstream side among the three cavities C (C1 to C3). 471 is provided.

  The turning vane 471 includes a plurality of guide plates 472 arranged in parallel along the circumferential direction. Each guide plate 472 is formed long in the axial direction on the bottom surface 111a side of the first cavity C1. More specifically, it is formed so as to extend obliquely toward the upstream side from the first seal fin 12A toward the side opposite to the direction of the circumferential component in the flow direction of the main vortex Y1 (FIG. 11). Each guide plate 472 extends to the upstream inner surface 111b of the annular groove 111, and is joined to the inner surface 111b, the bottom surface 111a of the annular groove 111, and the first seal fin 12A. .

  Under such a configuration, a space between the guide plates 472 adjacent in the circumferential direction is set as a flow path 473 through which the main vortex Y1 flows. The flow path 473 guides the main vortex Y1 so as to cancel out this circumferential component. For this reason, compared with the case where the turning vane 471 is not provided, the axial component of the main vortex Y1 becomes large, and the same effect as in the first embodiment described above can be achieved.

In the above-described fifth embodiment, the case has been described in which the plurality of guide plates 472 constituting the turning vane 471 are formed long in the axial direction on the bottom surface 111a side of the first cavity C1. However, the present invention is not limited to this, and a tongue piece 474 is formed to extend radially inward on the inner surface 111b side on the upstream side of the annular groove 111 in each guide plate 472 (two-dot chain line in FIG. 10). Reference), each guide plate 472 may be formed in a substantially L shape in plan view in the circumferential direction.
In this case, the tongue piece 474 is formed so that the tongue piece 474 and the moving blade 50 do not come into contact with each other in consideration of thermal expansion of the turning vane 471 and the tip shroud 51.

  In the fifth embodiment described above, the case where the turning vane 471 is provided in the first cavity C1 located on the most upstream side among the three cavities C (C1 to C3) has been described. However, the present invention is not limited to this, and the turning vanes 471 may be provided also in the second cavity C2 and the third cavity C3.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS.
FIG. 12 is a schematic configuration diagram of the upstream side of the chip shroud in the sixth embodiment, and FIG. 13 is a view taken in the direction of arrow D in FIG.
As shown in FIGS. 12 and 13, the difference between the sixth embodiment and the first embodiment is that the chip shroud 51 of the first embodiment has a plurality of grooves 71 in the step surface 53A. On the other hand, in the sixth embodiment, a plurality of blades 571 are provided on the inner side surface 111 b on the upstream side of the annular groove 111 instead of the tip shroud 51.

The blades 571 are provided so as to extend along the radial direction in a plan view in the axial direction and to protrude toward the downstream side in the axial direction. Further, the blades 571 are formed so as to gradually incline toward the side opposite to the direction of the circumferential component of the main vortex Y1 that collides with the stepped surface 53A and returns to the upstream side as it goes radially outward. .
Further, the blade 571 is formed in a substantially triangular shape in the axial cross section, and is set so that the blade height T2 gradually decreases toward the radially outer side, and the blade height T2 becomes zero at the outermost side. It is formed as follows. That is, the inner surface 111b on the upstream side of the annular groove 111 is formed so that the portion corresponding to the blade 571 gradually goes downstream as it goes radially outward.

Even in such a case, the main vortex Y1 flowing in the direction including the circumferential component can be guided in the axial direction by the blades 571. Therefore, the same as in the first embodiment described above. There is an effect.
In the sixth embodiment described above, the case where the plurality of blades 571 are provided on the inner surface 111b on the upstream side of the annular groove 111 has been described. However, the present invention is not limited to this, and a plurality of grooves may be formed instead of the blades 571. In this case, it is desirable to form the plurality of grooves so as to have a substantially triangular cross section in the axial direction.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.
For example, in the above-described embodiment, the partition plate outer ring 11 provided in the casing 10 is the structure. However, the present invention is not limited to this, and the casing 10 itself may be directly configured as the structure of the present invention without providing the partition plate outer ring 11. That is, this structure may be any member as long as it surrounds the moving blade 50 and defines a flow path so that fluid passes between the moving blades.

Furthermore, in the above-described embodiment, a case has been described in which a plurality of step portions 52 are provided in the chip shroud 51 and a plurality of cavities C are thereby formed. However, the present invention is not limited to this, and the number of step portions 52 and the number of cavities C corresponding thereto is arbitrary, and may be one, three, or four or more.
The seal fin 12 and the step part 52 do not necessarily have to correspond to each other at 1: 1, and these numbers can be arbitrarily designed.
In the above-described embodiment, the present invention is applied to the moving blade 50 and the stationary blade 40 in the final stage. However, the present invention may be applied to the moving blade 50 and the stationary blade 40 in other stages.

  Furthermore, in the above-described embodiments and modifications, the “blade” according to the present invention is used as the moving blade 50, and the step portion 52 (52 </ b> A to 52 </ b> C) is formed in the tip shroud 51 as the tip portion, and the present invention is also related. The case where the “structure” is the partition plate outer ring 11 and the seal fins 12 (12A to 12C) are provided here has been described. However, the present invention is not limited to this, and the “blade” according to the present invention is used as the stationary blade 40, the step portion 52 is formed at the tip thereof, and the “structure” according to the present invention is the shaft body (rotor) 30. As an alternative, the seal fins 12 may be provided here. Also in this case, the above-described embodiment can be adopted for the step unit 52.

In the above-described embodiment, the present invention is applied to a condensing steam turbine. However, the present invention is applied to other types of steam turbines, for example, turbine types such as a two-stage extraction turbine, an extraction turbine, and an air-mixing turbine. It can also be applied.
Furthermore, in the above-described embodiment, the present invention is applied to the steam turbine 1, but the present invention can also be applied to a gas turbine, and furthermore, the present invention can be applied to all the rotor blades. it can.

1 Steam turbine (turbine)
10 Casing 11 Partition outer ring (structure)
12 (12A-12C) Seal fin 30 Shaft body (structure)
40 Static blade (blade)
41 Hub Shroud 50 Blade (Blade)
51 Chip shroud 52 (52A to 52C) Step portion 53 (53A to 53C) Stepped surface 71, 171, 371 Groove 111 Annular groove 111b Inner side 271, 571 Blade 471 Turning vane 472 Guide plate D1, D2 Groove depth H, H1 ~ H3 Minute gap K Gap T1, T2 Blade height Y1 Main vortex Y2 Separation vortex

Claims (5)

The blade,
In a turbine provided with a structure that is provided on the tip side of the blade via a gap and that rotates relative to the blade,
The tip portion of the blade is provided with a step portion having at least one step surface facing the upstream side and projecting to the structure side,
The structure body is provided with seal fins extending toward the step portion and forming a minute gap between the step portion,
A turbine having a main vortex guide means for guiding a main vortex flowing in a direction including a circumferential component in an axial direction on an upstream side of the seal fin. The main vortex guide means is any one of a plurality of grooves and a plurality of blades provided on a step surface located at least on the most upstream side of the step surfaces and arranged in parallel along the circumferential direction. ,
The plurality of grooves and the plurality of blades are formed along the radial direction,
The groove depths of the plurality of grooves and the blade heights of the plurality of blades are set to gradually decrease toward the radially outer side,
The turbine according to claim 1, wherein a groove depth of the plurality of grooves and a blade height of the plurality of blades are set to be zero at a radially outermost side.   The turbine according to claim 1, wherein the main vortex guide means is a plurality of guide plates arranged in parallel along the circumferential direction at least on the most upstream side of the gap. In the structure, an annular groove that secures the gap is formed at a position corresponding to the tip of the blade,
The main vortex guide means is provided on the upstream inner surface of the annular groove, and is one of a plurality of grooves arranged in parallel along the circumferential direction, and a plurality of blades,
The plurality of grooves and the plurality of blades are formed along the radial direction,
The groove depths of the plurality of grooves and the blade heights of the plurality of blades are set to gradually decrease toward the radially outer side,
The turbine according to claim 1, wherein a groove depth of the plurality of grooves and a blade height of the plurality of blades are set to be zero at a radially outermost side.   5. The plurality of grooves and the plurality of blades are inclined to a side opposite to a direction of a circumferential component of the main vortex as going outward in the radial direction. Turbine.

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