JP2018141453A - Axial flow rotating machine and rotor blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a mixture loss of a main flow of a working fluid and a leak flow of the working fluid, to enhance the efficiency of an axial flow rotating machine.SOLUTION: A steam turbine 100 comprises: a rotating shaft; a casing 2; a stator blade 7; a rotor blade 4 having a rotor-blade side fin 42; and case-side fins 22A, 22B which are arranged at an upstream side and a downstream side with respect to the rotor-blade side fin 42. In the rotor blade 4, since an upstream-side internal peripheral end part 43a at the inside of a radial direction Dr of an upstream face 43 facing an upstream side in the rotor-side fin 42 is located outside the radial direction Dr rather than a downstream-side internal peripheral end part 44a at the inside of the radial direction Dr of a downstream face 44 facing a downstream side of the rotor-blade side fin 42, a thickness dimension of a downstream end 41b of a chip shroud 41 in the radial direction Dr is set smaller than an upstream end 41a of an upstream side of the chip shroud 41.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an axial-flow rotating machine and a moving blade.

In an axial rotating machine such as a steam turbine or a gas turbine, a casing, a rotor rotatably provided in the casing, a stationary blade fixedly disposed on an inner peripheral portion of the casing, and a downstream side of the stationary blade The one provided with the rotor blades provided radially on the rotating shaft is known.
For example, in the case of a steam turbine, steam pressure energy is converted into velocity energy by a stationary blade, and this velocity energy is converted into rotational energy (mechanical energy) by a moving blade. In some cases, pressure energy is converted into velocity energy in the moving blade, and converted into rotational energy (mechanical energy) by reaction force from which steam is ejected.

  For example, as disclosed in Patent Document 1, in this type of rotating machine, a radial gap is formed between the tip of a moving blade and a casing that surrounds the moving blade and forms a steam flow path. Has been. The leakage flow of the working fluid that passes through the gap between the tip of the rotor blade and the casing flows radially inward from the gap between the tip of the rotor blade and the casing on the downstream side of the rotor blade. It joins the main flow of working fluid flowing in the direction.

JP 2007-321721 A

  By the way, the leakage flow of the working fluid flowing out in the radial direction on the downstream side of the moving blade joins the main flow of the working fluid flowing in the central axis direction in the casing so as to intersect. When the main flow of the working fluid and the leakage flow of the working fluid intersect and merge, the main flow of the working fluid and the leakage flow of the working fluid collide and mix, and thus an energy loss called a mixing loss occurs. This increase in the mixing loss may hinder the improvement of the efficiency of the axial-flow rotating machine, and it is desired to reduce the mixing loss.

  The present invention has been made in view of the above circumstances, and reduces the mixing loss between the main flow of the working fluid and the leakage flow of the working fluid, and increases the efficiency of the axial flow rotating machine. The purpose is to provide wings.

The present invention employs the following means in order to solve the above problems.
In the first aspect of the present invention, the axial-flow rotating machine is disposed on the rotating shaft rotating around the central axis and on the radially outer side of the rotating shaft, and the working fluid extends along the central axial direction on the radially inner side A cylindrical casing that flows from the upstream side to the downstream side, a stationary blade having a stationary blade body that extends from the casing toward the radially inner side, and a radially outer side from the rotating shaft. A blade main body, a tip shroud provided on the radially outer side of the blade main body, and a blade that extends radially outward from an outer peripheral surface facing the radially outer side of the tip shroud and faces the inner peripheral surface of the casing A blade provided with fins, and a case side provided on an upstream side and a downstream side with respect to the blade fins, extending radially inward from the casing and facing the outer peripheral surface of the tip shroud It includes a fin, a. In the moving blade fin, the upstream inner peripheral end portion on the radially inner side of the surface facing the upstream side in the moving blade fin is the downstream inner peripheral end on the radially inner side of the surface facing the downstream side of the moving blade fin. By being located radially outside the portion, the downstream downstream end of the tip shroud is formed with a smaller radial thickness than the upstream upstream end of the tip shroud.

According to such a configuration, since the radial thickness dimension of the downstream end of the tip shroud is smaller than the upstream end of the tip shroud, the leakage flow of the working fluid through the clearance between the tip shroud and the inner peripheral surface of the casing However, the separation vortex (the trailing edge wake) generated when peeling from the downstream end of the chip shroud downstream is reduced. Thereby, the loss by the leakage flow of the working fluid in the downstream of a chip shroud is reduced.
Further, since the separation vortex is reduced, the leakage flow of the working fluid separated from the downstream end of the chip shroud is likely to move radially inward in the casing. Thereby, mixing of the main flow of the working fluid and the leakage flow of the working fluid is started at a position near the downstream end of the tip shroud.
Further, the leakage flow of the working fluid separated from the main flow of the working fluid on the upstream side of the tip shroud flows radially outward between the tip shroud and the casing. Since the upstream end of the tip shroud has a larger radial dimension than the downstream end, the leakage flow of the working fluid flowing outward in the radial direction flows longer along the upstream end of the tip shroud. As a result, the separation vortex generated by separation from the leakage flow of the working fluid on the radially outer side of the upstream end of the tip shroud is strengthened. When the separation vortex on the upstream end side of the tip shroud becomes stronger, the leakage flow of the working fluid is less likely to pass through the gap between the tip shroud and the upstream case side fin, and the leakage flow is reduced.

  In a second aspect of the present invention, in the first aspect, the moving blade includes a first outer peripheral surface formed on the upstream side of the moving blade fin on the outer peripheral surface of the tip shroud, and the tip shroud. A second outer peripheral surface formed on the downstream side of the bucket fin on the outer peripheral surface and positioned radially inward of the first outer peripheral surface, and between the first outer peripheral surface and the second outer peripheral surface. And a step surface facing the downstream side in the central axis direction.

  With this configuration, the radial thickness dimension of the downstream end of the tip shroud is smaller than the upstream end of the tip shroud.

  According to a third aspect of the present invention, in the second aspect, the blade fin is formed to extend radially outward from the downstream end of the first outer peripheral surface, and A part on the radially inner side of the surface facing the downstream side may form the step surface.

  With this configuration, a part of the surface facing the downstream side of the rotor blade fin forms a step surface, so that the rotor blade fin does not protrude further downstream than the step surface. Accordingly, it is possible to suppress the downstream case-side fin from interfering with the moving blade fin when the casing and the stationary blade, the rotating shaft, and the moving blade are relatively displaced in the central axis direction due to thermal elongation or the like.

  According to a fourth aspect of the present invention, in the first to third aspects, the outer peripheral surface of the tip shroud may be formed in parallel to the central axis.

  Thereby, the clearance between the case-side fin and the outer peripheral surface of the chip shroud can be easily maintained appropriately.

  According to a fifth aspect of the present invention, in the first to fourth aspects, the inner peripheral surface facing the radially inner side in the tip shroud is inclined radially outward from the upstream side toward the downstream side. You may do it.

  With this configuration, the radial thickness dimension of the downstream end of the chip shroud can be made smaller than the radial thickness dimension of the upstream end of the chip shroud.

  According to a sixth aspect of the present invention, in the first to fifth aspects, the downstream end of the tip shroud has a curved surface or an inclined surface that gradually decreases in radial direction toward the downstream side. You may have.

  According to such a configuration, the separation vortex generated when the leakage flow of the working fluid passing through the gap between the tip shroud and the inner peripheral surface of the casing peels from the downstream end of the tip shroud is further reduced. Thereby, the loss by the leakage flow of the working fluid in the downstream of a chip | tip shroud can be reduced further.

According to a seventh aspect of the present invention, in the sixth aspect, the downstream end of the tip shroud has a curved surface that is convex toward the downstream side, and the curved surface is a semicircular circumferential surface. It may be.
According to such a configuration, the separation vortex generated when peeling from the downstream end of the chip shroud can be made smaller, and the trailing edge loss can be further reduced.

According to an eighth aspect of the present invention, in the sixth aspect, the downstream end of the tip shroud has a curved surface that protrudes toward the downstream side, and the curved surface has a long axis at the center. It may be a semi-elliptical circumferential surface that coincides with the axial direction and whose minor axis coincides with the radial direction.
According to such a configuration, the separation vortex generated when peeling from the downstream end of the chip shroud can be made smaller, and the trailing edge loss can be further reduced.

According to a ninth aspect of the present invention, in the sixth aspect, the downstream end of the tip shroud has a curved surface that protrudes toward the downstream side, and the curved surface is an outer side in the radial direction. The first curved surface and the second curved surface inside in the radial direction are formed, and the radius of curvature of the first curved surface may be larger than the radius of curvature of the second curved surface.
According to such a configuration, the radius of curvature of the second curved surface on the radially inner side is smaller than that of the first curved surface on the radially outer side. However, it becomes easy to peel off at the downstream end of the chip shroud. That is, the steam is directed radially inward on the first curved surface side, while the steam is directed in the central axis direction on the second curved surface side. Thereby, it is possible to suppress the main flow of the steam from being involved in the steam leakage flow that merges from the outside in the radial direction, and it is possible to suppress the loss when the steam main flow and the steam leakage flow are mixed.

  In a tenth aspect of the present invention, there is provided a moving blade provided on a radially outer side of a rotating shaft that is rotatably supported around a central axis in a casing in which a working fluid flows from the upstream side toward the downstream side, A rotor blade body provided to extend radially outward from the rotating shaft, a tip shroud provided radially outward of the rotor blade body, and provided on an outer peripheral surface of the tip shroud facing radially outward, from the outer periphery surface And a moving blade fin extending outward in the radial direction. In the moving blade fin, the upstream inner peripheral end portion on the radially inner side of the surface facing the upstream side in the moving blade fin is the downstream inner peripheral end on the radially inner side of the surface facing the downstream side of the moving blade fin. By being located radially outside the portion, the downstream downstream end of the tip shroud is formed with a smaller radial thickness than the upstream upstream end of the tip shroud.

  According to such a configuration, since the radial thickness dimension of the downstream end of the tip shroud is smaller than the upstream end of the tip shroud, the leakage flow of the working fluid through the clearance between the tip shroud and the inner peripheral surface of the casing Peeling vortex generated when peeling from the downstream end of the chip shroud is reduced. Thereby, the loss by the leakage flow of the working fluid in the downstream of a chip shroud is reduced.

  According to the axial flow rotating machine and the moving blade according to the present invention, the mixing loss between the main flow of the working fluid and the leakage flow of the working fluid can be reduced, and the efficiency of the axial flow rotating machine can be increased.

It is a mimetic diagram showing the composition of the steam turbine concerning a first embodiment of the present invention. It is an enlarged view which shows the front-end | tip part of the moving blade of the steam turbine which concerns on said 1st embodiment. It is sectional drawing which shows the shape of the front-end | tip part of the moving blade of the steam turbine which concerns on 2nd embodiment of this invention. It is a figure which shows the 1st modification of the shape of the front-end | tip part of the moving blade of the steam turbine which concerns on said 2nd embodiment. It is a figure which shows the 2nd modification of the shape of the front-end | tip part of the moving blade of the steam turbine which concerns on said 2nd embodiment. It is a figure which shows the 3rd modification of the shape of the front-end | tip part of the moving blade of the steam turbine which concerns on said 2nd embodiment. It is a figure which shows the 4th modification of the shape of the front-end | tip part of the moving blade of the steam turbine which concerns on said 2nd embodiment. It is a figure which shows the modification of the moving blade of the steam turbine which concerns on each said embodiment.

Hereinafter, an axial-flow rotating machine and a moving blade according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram showing a configuration of a steam turbine according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a tip portion of a moving blade of the steam turbine.
As shown in FIG. 1, a steam turbine (axial rotary machine) 100 according to the present embodiment includes a rotating shaft 1, a casing 2, a stationary blade stage 6 including a plurality of stationary blades 7, and a plurality of moving blades 4. And a rotor blade stage 3.

  The rotating shaft 1 has a cylindrical shape extending along the central axis Ac. The rotary shaft 1 is supported at both ends in the central axis direction Da along the central axis Ac by the bearing device 5 so as to be rotatable around the central axis Ac. The bearing device 5 includes a journal bearing 5A provided on each side of the central axis direction Da of the rotating shaft 1 and a thrust bearing 5B provided only on the first side in the central axis direction Da. The journal bearing 5 </ b> A supports a load in the radial direction Dr by the rotating shaft 1. The thrust bearing 5B supports the load in the central axis direction Da by the rotating shaft 1.

The casing 2 has a cylindrical shape extending in the central axis direction Da. The casing 2 covers the rotating shaft 1 from the outer peripheral side.
The casing 2 includes an intake port 10 and an exhaust port 11. The air inlet 10 is formed on the first side in the central axis direction Da of the casing 2 and takes in steam (working fluid) into the casing 2 from the outside. The exhaust port 11 is formed on the second side of the casing 2 in the central axis direction Da and exhausts the steam that has passed through the casing 2 to the outside.
In the following description, the side where the intake port 10 is located when viewed from the exhaust port 11 is referred to as the upstream side, and the side where the exhaust port 11 is located when viewed from the intake port 10 is referred to as the downstream side.

  The stationary blade stage 6 is provided with a plurality of stages on the inner peripheral surface of the casing 2 at intervals along the central axis direction Da. Each stationary blade stage 6 is arranged on the upstream side of each moving blade stage 3. Each stationary blade stage 6 has a plurality of stationary blades 7 arranged at intervals in the circumferential direction around the central axis Ac.

The stationary blade 7 includes a stationary blade body 70 and a stationary blade shroud 71.
The stationary blade body 70 is provided so as to extend from the inner peripheral surface 2S of the casing 2 toward the inside in the radial direction Dr. The stationary blade body 70 has a blade-shaped cross section as viewed from the radial direction Dr.
The stationary blade shroud 71 is attached to the end of the stationary blade body 70 on the inner side in the radial direction Dr.

  On the outer peripheral surface 1S facing the outer side of the radial direction Dr of the rotary shaft 1, on the upstream side of each rotor blade stage 3, the outer peripheral surface 1S of the rotary shaft 1 is recessed from the outer peripheral surface 1S toward the inner side in the radial direction Dr. A groove-shaped stationary blade cavity 8 continuous in the direction is formed. The stationary blade shroud 71 of each stationary blade 7 is accommodated in the stationary blade cavity 8.

  The moving blade stage 3 is provided with a plurality of stages on the outer peripheral surface 1S of the rotating shaft 1 at intervals from the first side to the second side in the central axis direction Da. Each blade stage 3 has a plurality of blades 4 arranged on the outer peripheral surface 1S of the rotary shaft 1 at intervals in the circumferential direction around the central axis Ac.

  The moving blade 4 has a moving blade main body 40 and a tip shroud 41.

The rotor blade body 40 is formed so as to extend outward from the rotary shaft 1 in the radial direction Dr. The rotor blade body 40 has an airfoil-shaped cross section as viewed from the radial direction Dr.
In the present embodiment, the radial direction Dr dimensions of the moving blade body 40 and the stationary blade body 70 are the same. In other words, when viewed from the central axis direction Da, the moving blade main body 40 and the stationary blade main body 70 are arranged so as to overlap each other.

  As shown in FIG. 2, the tip shroud 41 is provided at the end of the rotor blade body 40 on the outer side in the radial direction Dr. The tip shroud 41 is set such that the dimension in the central axis direction Da is larger than the dimension of the rotor blade body 40 in the central axis direction Da.

  A moving blade cavity 20 for accommodating the tip shroud 41 is formed in an inner peripheral side of the casing 2 and in a region facing the tip shroud 41 in the radial direction Dr. The rotor blade cavity 20 is recessed from the inner peripheral surface 2S of the casing 2 toward the outer side in the radial direction Dr, and has a groove shape continuous in the circumferential direction around the central axis Ac.

In the present embodiment, the moving blade 4 further includes a moving blade side fin 42. The rotor blade side fins 42 are provided in the middle part of the tip shroud 41 in the central axis direction Da. The blade-side fin 42 extends from the outer peripheral surface 41s facing the outside in the radial direction Dr in the tip shroud 41 to the outside in the radial direction Dr, and is provided so that the tip thereof faces the blade cavity 20 of the casing 2 with a gap. It has been. The blade-side fin 42 has an upstream surface 43 that faces the upstream side in the central axis direction Da and a downstream surface 44 that faces the downstream side in the central axis direction Da. Here, the upstream surface 43 is located in a plane orthogonal to the central axis direction Da. The downstream surface 44 is formed to be inclined so as to gradually extend inward in the radial direction from the upstream side toward the downstream side along the central axis direction Da.
The rotor blade side fins 42 are formed by integrally molding with the tip shroud 41.

  The chip shroud 41 has a first outer peripheral surface 45A, a second outer peripheral surface 45B, and a step surface 46.

  The first outer peripheral surface 45 </ b> A is formed on the upstream side of the rotor blade side fin 42 on the outer peripheral surface 41 s of the tip shroud 41. The second outer peripheral surface 45 </ b> B is formed on the outer peripheral surface 41 s of the tip shroud 41 on the downstream side of the rotor blade side fin 42. The second outer peripheral surface 45B is formed so as to be positioned on the inner side in the radial direction Dr with respect to the first outer peripheral surface 45A. The first outer peripheral surface 45A and the second outer peripheral surface 45B constituting the outer peripheral surface 41s of the chip shroud 41 are each formed in parallel to the central axis Ac (see FIG. 1).

  The step surface 46 is provided between the first outer peripheral surface 45A and the second outer peripheral surface 45B and is formed to face the downstream side in the central axis direction Da. On the outer side of the step surface 46 in the radial direction Dr, the rotor blade side fins 42 are continuously provided. In other words, the rotor blade side fins 42 are formed to extend outward in the radial direction Dr from the downstream end of the first outer peripheral surface 45A. In the rotor blade side fin 42, a part of the downstream surface 44 facing the downstream side inside the radial direction Dr forms a step surface 46.

In this way, in the rotor blade side fin 42, the upstream inner peripheral end 43 a inside the radial direction Dr of the upstream surface 43 is more radial than the downstream inner peripheral end 44 a inside the radial direction Dr of the downstream surface 44. Located on the outside.
Further, an inner peripheral surface 41t facing the inside in the radial direction Dr in the chip shroud 41 is formed to be inclined outward in the radial direction Dr from the upstream side toward the downstream side.
Thereby, the moving blade 4 is formed so that the thickness dimension in the radial direction Dr of the downstream end 41 b on the downstream side of the tip shroud 41 is smaller than the upstream end 41 a on the upstream side of the tip shroud 41.

Case-side fins 22 </ b> A and 22 </ b> B are provided outside the tip shroud 41 in the radial direction Dr as described above. The case side fins 22 </ b> A and 22 </ b> B are provided on the upstream side and the downstream side with respect to the rotor blade side fin 42. Each of the case-side fins 22A and 22B extends inward in the radial direction Dr from the casing 2, and the inner end of the radial direction Dr is spaced from the first outer peripheral surface 45A and the second outer peripheral surface 45B of the chip shroud 41. Facing each other.
Here, the difference between the positions of the first outer peripheral surface 45A and the second outer peripheral surface 45B in the radial direction Dr is the distance (clearance) between the front end portion of the case side fin 22A in the radial direction Dr and the first outer peripheral surface 45A. ) Is better than

The operation of the steam turbine 100 configured as described above will be described with reference to FIG.
In operating the steam turbine 100, first, high-temperature and high-pressure steam supplied from a steam supply source (not shown) such as a boiler is introduced into the casing 2 through the intake port 10.
The steam introduced into the casing 2 sequentially collides with the moving blade 4 (the moving blade stage 3) and the stationary blade 7 (the stationary blade stage 6). In each stationary blade stage 6, the steam flowing from the upstream side hits the stationary blade 7, whereby a swirl component around the rotating shaft 1 is added to the flow of the steam. Thereby, on the downstream side of each stationary blade stage 6, the steam flow swirls around the rotating shaft 1. Each moving blade stage 3 reaches the flow of steam swirling around the rotary shaft 1 through the upstream stationary blade stage 6. When the swirling steam flow hits each rotor blade 4, the rotating shaft 1 obtains rotational energy and rotates around the central axis Ac. The rotational movement of the rotary shaft 1 is taken out by a generator or the like (not shown) connected to the shaft end.
The above cycle is repeated continuously.

  As described above, the steam flows alternately from the upstream side to the downstream side through the stationary blades 7 and the moving blades 4 to form the mainstream FM. The mainstream FM is rectified by sequentially colliding with the stationary blade 7 and the moving blade 4 as described above, and gives energy to the moving blade 4.

Here, in each moving blade stage 3, the components other than the main flow FM out of the steam flowing from the upstream side flow into the moving blade cavity 20 to form the moving blade leakage flow FL.
This blade leakage flow FL is upstream of the tip shroud 41 and between the upstream end 41a of the tip shroud 41 and the upstream side surface 21A of the blade cavity 20 located upstream thereof in the radial direction Dr. It flows toward.
Here, on the outside of the upstream end 41a of the tip shroud 41 in the radial direction Dr, a part of the leakage flow FL of the working fluid toward the outside of the radial direction Dr is separated, and a separation vortex S1 is generated. Since the upstream end 41a of the tip shroud 41 has a larger thickness dimension in the radial direction Dr than the downstream end 41b, the leakage flow FL of the working fluid flowing outward in the radial direction Dr is along the upstream end 41a of the tip shroud 41. It flows for a long time. Thereby, the generated separation vortex S1 is strengthened.

  A part of the leakage flow FL of the working fluid toward the outer side in the radial direction Dr is between the case-side fin 22A on the upstream side and the first outer peripheral surface 45A of the tip shroud 41, between the blade-side fin 42 and the blade-cavity 20 Between the case-side fins 22B on the downstream side and the second outer peripheral surface 45B of the tip shroud 41.

The leakage flow FL of the working fluid that has passed between the downstream case-side fin 22B and the second outer peripheral surface 45B of the tip shroud 41 flows backward from the downstream end 41b of the tip shroud 41, and merges with the main flow FM of the working fluid. To do. Here, since the thickness dimension in the radial direction Dr of the downstream end 41b of the tip shroud 41 is smaller than the upstream end 41a of the tip shroud 41, the steam leakage flow FL through the gap between the tip shroud 41 and the rotor blade cavity 20 , The separation vortex S2 generated when the chip shroud 41 is peeled from the downstream end 41b of the chip shroud 41 is reduced. By reducing the separation vortex S2, the steam leakage flow FL separated from the downstream end 41b of the tip shroud 41 is likely to be moved inward in the radial direction Dr. As a result, the mixing of the steam main flow FM and the steam leakage flow FL is started at a position closer to the downstream end 41 b of the tip shroud 41.
The steam leakage flow FL mixed with the steam main flow FM in this manner flows to the stationary vane 7 on the downstream side.

According to the steam turbine 100 and the moving blade 4 as described above, since the thickness dimension in the radial direction Dr of the downstream end 41b of the tip shroud 41 is smaller than the upstream end 41a of the tip shroud 41, the steam leakage flow FL is caused by the tip. The peeling vortex S2 generated when peeling from the downstream end 41b of the shroud 41 is reduced. Thereby, the loss due to the steam leakage flow FL on the downstream side of the chip shroud 41 is reduced.
In addition, since the separation vortex S2 is reduced, the steam leakage flow FL separated from the downstream end 41b of the tip shroud 41 tends to be closer to the inside in the radial direction Dr. Thus, mixing of the steam main flow FM and the steam leakage flow FL is started at a position close to the downstream end 41 b of the tip shroud 41. Thus, the steam leakage flow FL is prevented from reaching the downstream side surface 21B of the rotor blade cavity 20 facing the downstream end 41b of the tip shroud 41. Therefore, the loss caused by the vapor leakage flow FL colliding with the downstream side surface 21B is reduced.
Further, since the upstream end 41a of the tip shroud 41 has a larger thickness dimension in the radial direction Dr than the downstream end 41b, the upstream end 41a of the tip shroud 41 is separated from the steam leakage flow FL outside the upstream direction Dr. The peeled vortex S1 is strengthened. Thus, when the separation vortex S1 on the upstream end 41a side of the tip shroud 41 becomes stronger, the steam leakage flow FL is less likely to pass through the gap between the tip shroud 41 and the upstream case side fin 22A. Therefore, the amount of steam leakage flow FL is reduced.

  In addition, since the moving blade side fin 42 has a stepped surface 46 partially formed on the downstream surface 44 facing the downstream side, the moving blade side fin 42 does not protrude further downstream than the stepped surface 46. Accordingly, when the casing 2 and the stationary blade 7 and the rotary shaft 1 and the moving blade 4 are relatively displaced in the central axis direction Da due to thermal expansion or the like, the downstream case-side fin 22B interferes with the moving blade-side fin 42. This can be suppressed.

  Further, the outer peripheral surface 41s of the chip shroud 41 is formed in parallel to the central axis Ac. Thus, the clearance between the case-side fins 22A and 22B and the first outer peripheral surface 45A and the second outer peripheral surface 45B of the chip shroud 41 can be easily maintained appropriately.

  Further, the inner peripheral surface 41t facing the inside in the radial direction Dr in the tip shroud 41 is inclined outward in the radial direction Dr from the upstream side toward the downstream side. With this configuration, the thickness dimension in the radial direction Dr of the downstream end 41b of the tip shroud 41 can be made smaller than the thickness dimension of the upstream end 41a of the tip shroud 41 in the radial direction Dr. Become.

(Second embodiment)
Next, a second embodiment of the axial-flow rotating machine and the moving blade according to the present invention will be described. In the second embodiment described below, only the shape of the downstream end 41b of the tip shroud 41 is different from that of the first embodiment. Is omitted.

FIG. 3 is a cross-sectional view showing the shape of the tip of the rotor blade of the steam turbine according to the second embodiment of the present invention.
The moving blade 4 of the steam turbine 100 in this embodiment has a moving blade main body 40, a tip shroud 41, and a moving blade side fin 42 (see FIG. 2) similar to the first embodiment.

  As shown in FIG. 3, the downstream end 41b of the tip shroud 41 in this embodiment has a curved surface 48A that is semicircular when viewed from the circumferential direction so that the thickness in the radial direction Dr gradually decreases toward the downstream side. Is formed by.

  According to such a configuration, the separation vortex S2 generated when the steam leakage flow FL passing through the gap between the tip shroud 41 and the rotor blade cavity 20 is separated from the downstream end 41b of the tip shroud 41 is further reduced. . Thereby, the loss due to the steam leakage flow FL on the downstream side of the tip shroud 41 can be further reduced.

(First modification of the second embodiment)
FIG. 4 is a view showing a first modification of the shape of the tip of the moving blade of the steam turbine according to the second embodiment.
As shown in FIG. 4, the downstream end 41b of the tip shroud 41 is formed by a semi-elliptical curved surface 48B whose thickness in the radial direction Dr gradually decreases toward the downstream side. Here, the curved surface 48B is preferably formed in a semi-elliptical shape in which the major axis direction A1 coincides with the central axis direction Da and the minor axis direction A2 coincides with the radial direction Dr.

  Even with such a configuration, the separation vortex S <b> 2 generated when the steam leakage flow FL passing through the gap between the tip shroud 41 and the blade cavity 20 separates from the downstream end 41 b of the tip shroud 41 is further reduced. Thereby, the loss due to the steam leakage flow FL on the downstream side of the tip shroud 41 can be further reduced.

(Second modification of the second embodiment)
FIG. 5 is a view showing a second modification of the shape of the tip of the moving blade of the steam turbine according to the second embodiment.
As shown in FIG. 5, the downstream end 41 b of the tip shroud 41 is formed by an inclined surface 48 </ b> C that gradually decreases inward in the radial direction toward the downstream side, so that the thickness in the radial direction Dr gradually decreases.

  Even with such a configuration, the separation vortex S <b> 2 generated when the steam leakage flow FL passing through the gap between the tip shroud 41 and the blade cavity 20 separates from the downstream end 41 b of the tip shroud 41 is further reduced. Thereby, the loss due to the steam leakage flow FL on the downstream side of the tip shroud 41 can be further reduced.

(Third modification of the second embodiment)
FIG. 6 is a view showing a third modification of the shape of the tip portion of the moving blade of the steam turbine according to the second embodiment.
The inclined surface 48C may be a curved surface protruding downstream. In this curved surface, the inclination angle θ with respect to the radial direction Dr of the tangent in the vicinity of the central portion in the radial direction Dr satisfies 0 ° <θ <90 °.

(Fourth modification of the second embodiment)
FIG. 7 is a view showing a fourth modification of the shape of the tip of the moving blade of the steam turbine according to the second embodiment.
As shown in FIG. 7, the downstream end 41b of the tip shroud 41 is formed so that the thickness in the radial direction Dr gradually decreases toward the downstream side. In this modification, a first curved surface 48D is formed outside the radial direction Dr and a second curved surface 48E is formed inside the radial direction Dr at the downstream end 41b of the tip shroud 41. The curvature radius Rd of the outer curved surface 48D in the radial direction Dr is set to be larger than the curvature radius Re of the inner curved surface 48E in the radial direction Dr. Further, the curved surface 48D and the curved surface 48E are smoothly connected by a plane 49 extending in the radial direction Dr.

Even with such a configuration, the separation vortex S <b> 2 generated when the steam leakage flow FL passing through the gap between the tip shroud 41 and the blade cavity 20 separates from the downstream end 41 b of the tip shroud 41 is further reduced. Thereby, the loss due to the steam leakage flow FL on the downstream side of the tip shroud 41 can be further reduced.
Here, at the downstream end 41b of the tip shroud 41, the first curved surface 48D on the outer side in the radial direction Dr has a larger radius of curvature R1 than the second curved surface 48E on the inner side in the radial direction Dr. The steam leakage flow FL flowing outside the radial direction Dr of the tip shroud 41 is unlikely to be separated from the downstream end 41b. Accordingly, the steam leakage flow FL can be turned toward the inside of the radial direction Dr on the downstream side of the first curved surface 48D. On the other hand, at the downstream end 41b of the tip shroud 41, the second curved surface 48E on the inner side in the radial direction Dr has a smaller radius of curvature R2 than the first curved surface 48D on the outer side in the radial direction Dr. However, it becomes easy to peel off at the downstream end 41b of the chip shroud 41. That is, the steam is directed inward in the radial direction Dr on the first curved surface 48D side, while the steam is directed in the central axis direction Dc on the second curved surface 48E side. Accordingly, the steam main flow FM is restrained from being caught in the steam leakage flow FL joined from the outside in the radial direction Dr, and the loss when the steam main flow FM and the steam leakage flow FL are mixed is suppressed. .

  Here, as a further modification of the third modification and the fourth modification, the curvature radius Rd of the outer curved surface 48D in the radial direction Dr and the curvature radius Re of the inner curved surface 48E in the radial direction Dr May be the same. In this case, the angle θ with respect to the radial direction Dr of the plane 49 extending in the radial direction Dr between the curved surface 48D and the curved surface 48E is 0 degree.

Note that the present invention is not limited to the above-described embodiments, and includes various modifications made to the above-described embodiments without departing from the spirit of the present invention. That is, the specific shapes, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.
For example, in each of the above-described embodiments and modifications thereof, the blade-side fin 42 is integrated with the tip shroud 41, but this is not a limitation.
FIG. 8 is a view showing a modification of the moving blade of the steam turbine of each of the above embodiments.
For example, as shown in FIG. 8, the rotor blade side fins 42F may be separated from the tip shroud 41F. In this case, the rotor blade side fins 42F are arranged along the step surface 46F between the first outer peripheral surface 45A and the second outer peripheral surface 45B formed on the outer peripheral surface 41s of the tip shroud 41F. The rotor blade side fin 42F is fixed by fitting its base end portion 42g into a groove 47 formed in the second outer peripheral surface 45B.

  In such a configuration, the blade-side fin 42F hits the step surface 46F, so that only the portion outside the first outer peripheral surface 45A in the radial direction Dr has the upstream surface 43F facing the upstream side in the blade-side fin 42F. Form. Therefore, the upstream inner peripheral end 43f on the inner side in the radial direction Dr of the upstream surface 43F facing the upstream side in the rotor blade side fin 42F is the downstream inner side in the radial direction Dr of the downstream surface 44F facing the downstream side in the rotor blade side fin 42F. It is located on the outer side in the radial direction Dr from the peripheral end 44g. Thereby, the thickness dimension of the radial direction Dr of the downstream end 41b of the chip | tip shroud 41 is formed smaller than the upstream end (not shown) of the upstream side of the chip | tip shroud 41F similarly to said 1st, 2nd embodiment.

  Moreover, you may combine suitably the structure of embodiment mentioned above and each modification.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 1S Outer peripheral surface 2 Casing 2S Inner peripheral surface 3 Rotor blade stage 4 Rotor blade 5 Bearing device 5A Journal bearing 5B Thrust bearing 6 Stator blade 7 Stator blade 8 Stator blade cavity 10 Inlet port 11 Exhaust port 20 Rotor blade cavity 21A Upstream side surface 21B Downstream side surface 22A, 22B Case side fin 40 Moving blade body 41, 41F Tip shroud 41a Upstream end 41b Downstream end 41s Outer surface 41t Inner surface 42, 42F Moving blade side fin 42g Base end 43, 43F Upstream surface 43a, 43f Upstream inner peripheral end 44, 44F Downstream surface 44a, 44g Downstream inner peripheral end 45A First outer peripheral surface 45B Second outer peripheral surface 46, 46F Step surface 47 Grooves 48A, 48B Curved surface 48D First curved surface 48E First Two curved surfaces 48C Inclined surface 49 Flat surface 70 Stator blade body 71 Stator blade shroud 100 Steam turbine A1 Long axis direction A2 Short axis direction Ac central axis Da central axis direction Dr radial FM main FL leakage flow R1, R2, Rd, Re radius of curvature S1, S2 separation vortex

Claims (10)

A rotating shaft that rotates about a central axis;
A cylindrical casing that is disposed on the radially outer side of the rotating shaft, and in which the working fluid flows from the upstream side toward the downstream side along the central axis direction on the radially inner side;
A stationary blade having a stationary blade body provided to extend radially inward from the casing;
A rotor blade body provided radially outward from the rotating shaft, a tip shroud provided radially outward of the rotor blade body, and extending radially outward from an outer peripheral surface facing radially outward in the tip shroud; A moving blade provided with a moving blade fin facing the inner peripheral surface of the casing;
A case-side fin provided on each of the upstream and downstream sides of the blade fin, extending radially inward from the casing and facing the outer peripheral surface of the tip shroud;
With
In the moving blade fin, the upstream inner peripheral end portion on the radially inner side of the surface facing the upstream side in the moving blade fin is the downstream inner peripheral end on the radially inner side of the surface facing the downstream side of the moving blade fin. An axial flow in which the downstream thickness of the downstream end of the tip shroud is smaller than that of the upstream end of the tip shroud. Rotating machine. The blade is
A first outer peripheral surface formed on the upstream side of the bucket fin on the outer peripheral surface of the tip shroud;
A second outer peripheral surface formed on the downstream side of the bucket fin on the outer peripheral surface of the tip shroud, and positioned radially inward from the first outer peripheral surface;
The axial-flow rotating machine according to claim 1, further comprising a step surface provided between the first outer peripheral surface and the second outer peripheral surface and facing the downstream side in the central axis direction. The blade fin is formed to extend radially outward from the downstream end of the first outer peripheral surface,
The axial flow rotary machine according to claim 2, wherein a part of a radially inner side of a surface facing the downstream side of the moving blade fin forms the step surface.   The axial flow rotating machine according to any one of claims 1 to 3, wherein the outer peripheral surface of the tip shroud is formed in parallel to the central axis.   5. The axial-flow rotating machine according to claim 1, wherein an inner peripheral surface facing radially inward in the tip shroud is inclined radially outward from the upstream side toward the downstream side. .   The axial flow rotation according to any one of claims 1 to 5, wherein the downstream end of the tip shroud has a curved surface or an inclined surface in which the radial thickness gradually decreases toward the downstream side. machine.   The axial flow rotating machine according to claim 6, wherein the downstream end of the tip shroud has a curved surface that protrudes toward the downstream side, and the curved surface is a semicircular circumferential surface.   The downstream end of the tip shroud has a curved surface convex toward the downstream side, and the curved surface has a semi-ellipse whose major axis coincides with the central axis direction and whose minor axis coincides with the radial direction. The axial-flow rotating machine according to claim 6, which has a circumferential surface of The downstream end of the tip shroud has a curved surface that is convex toward the downstream side. The curved surface includes a first curved surface on the radially outer side and a second curved surface on the radially inner side. And are formed,
The axial flow rotary machine according to claim 6, wherein a radius of curvature of the first curved surface is larger than a radius of curvature of the second curved surface. In a casing in which the working fluid flows from the upstream side toward the downstream side, the moving blade is provided on the radially outer side of the rotating shaft that is rotatably supported around the central axis,
A rotor blade body provided to extend radially outward from the rotating shaft;
A tip shroud provided on the radially outer side of the rotor blade body;
A blade fin provided on an outer peripheral surface facing radially outward in the tip shroud and extending radially outward from the outer peripheral surface;
With
The upstream inner peripheral end portion on the radially inner side of the surface facing the upstream side in the blade fin is more radial than the downstream inner peripheral end portion on the radially inner side of the surface facing the downstream side of the blade fin. The moving blade in which the radial dimension of the downstream downstream end of the tip shroud is smaller than the upstream upstream end of the tip shroud by being positioned outside.

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