JP2018135847A - Axial flow rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial flow rotary machine with a high performance capable of reducing a flow rate of leak flow with a simple structure.SOLUTION: A moving blade 4 has: a moving blade shroud 41 at a tip end; and a shroud side fin 44 projecting toward a casing 2 from the moving blade shroud 41, and forming a micro-gap between it and the casing 2. The casing 2 has casing side fins 42 aligned on the shroud side fin 44 in a direction in which a main flow MF flows, projecting toward the moving blade shroud 41, and forming a micro-gap between it and the moving blade shroud 41. At base ends of respective fins 42, 44, surfaces facing the upstream and downstream sides of the main flow MF have arc surfaces 42a, 44a indented toward center lines CL1, CL2 of the fins 42, 44. In the respective fins 42, 44, the center lines CL1, CL2 are inclined toward the upstream side as they go toward a tip end.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an axial-flow rotating machine.

  Conventionally, as a kind of steam turbine which is an axial flow rotating machine, a casing, a rotating shaft provided to be rotatable with respect to the casing, a stationary blade fixed to an inner peripheral portion of the casing, and a downstream of the stationary blade On the side, there is known one provided with a plurality of stages of rotor blades provided radially on a rotating shaft.

  This steam turbine is roughly classified into an impulse turbine and a reaction turbine depending on the operation method. 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, in the reaction turbine, the shape of the stationary blade is the same as that of the moving blade, and the moving blade is caused by the impact force received from the steam that has passed through the stationary blade and the reaction force against the expansion of the steam generated when passing through the moving blade. Rotate.

  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 rotating shaft. A gap having a predetermined width is formed in the direction. A part of the steam flowing along the rotation axis of the rotation shaft leaks to the downstream side through the gaps 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, and therefore does not become a driving force for rotating the moving blade. Also, the steam that leaks downstream from the gap between the stationary blade and the shaft does not change its speed and does not expand even if it exceeds the stationary blade. It doesn't help. 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.

  Therefore, seal fins are used as means for preventing steam from leaking from the gaps at the tip portions of the moving blades and stationary blades. Here, an example of the seal fin is disclosed in Patent Document 1. The seal fin of Patent Document 1 is provided so as to extend from the casing toward the shroud of the moving blade, and the shroud of the moving blade has a step shape.

JP 2013-19537 A

  By the way, in patent document 1, it is going to reduce the fluid (leakage flow) which passes a clearance gap by the step of a seal fin and a shroud. However, for example, the fluid may adhere to the corner of the step, and as a result, the fluid may pass through the gap and the flow rate of the leak flow may increase.

  Therefore, the present invention provides a high-performance axial flow rotary machine that has a simple structure and reduces the flow rate of the leak flow.

  The axial-flow rotating machine according to the first aspect of the present invention is provided with a blade disposed in a flow path through which a main flow of fluid flows and a front end side of the blade via a gap, and rotates relative to the blade. The blade includes a shroud at a tip portion, and a shroud-side fin that protrudes from the shroud toward the structure and forms a minute gap between the structure and the blade. The structure has a structure-side fin that is arranged side by side in the direction in which the main flow flows with respect to the shroud-side fin and protrudes toward the shroud to form a minute gap with the shroud. At the base end portions of the shroud side fin and the structure side fin, the surfaces facing the upstream side and the downstream side of the mainstream flow are the centers of relative rotation between the blade and the structure in the fins. Has an arcuate surface that is recessed toward the direction of the center line, in the shroud-side fin and the structure side fins, toward the distal end portion, said center line is inclined toward the upstream side.

According to such an axial-flow rotating machine, the fluid that has passed through the minute gap formed at the tip of the fin disposed on the upstream side of the shroud-side fin and the structure-side fin becomes a jet, and this minute gap It collides with the fin arranged on the downstream side. At this time, the jet is guided toward the front end side of the fin along the upstream surface of the fin disposed on the downstream side. Here, in this aspect, in the shroud side fin and the structure side fin, the center line is inclined toward the upstream side toward the tip side. Therefore, the jet that collided with the fin flows so as to be pushed back upstream by the upstream surface of the fin. Therefore, the fluid that tries to pass through the minute gap at the tip of the fin arranged on the downstream side can be pushed back upstream, and the flow rate of the fluid that passes through the minute gap at the tip of the fin arranged on the downstream side can be reduced. Can be reduced. As a result, the flow rate of the leak flow passing through the cavity between the structure and the shroud can be reduced.
Furthermore, since the center line of the fin is inclined toward the upstream side toward the tip side, the fluid flowing along the upstream surface of the fin disposed on the downstream side of the shroud side fin and the structure side fin is upstream. Flows toward the side, contacts the downstream surface of the fin disposed on the upstream side, the flow direction is turned, and a vortex is formed between the fins. As a result, the fluid is guided to the downstream surface of the fin disposed on the upstream side and flows toward the minute gap at the tip of the fin disposed on the upstream side. Thereby, the fluid which is going to pass the micro clearance gap of the front-end | tip part of the fin arrange | positioned upstream can be contracted, pushing back to the upstream.
Thus, the axial-flow rotating machine of this aspect has an opposing fin shape by adjoining the shroud side fin and the structure side fin in the mainstream flow direction. And since the centerline of each fin inclines in the upstream toward the front-end | tip part, the contraction effect to the fluid which passes the micro clearance gap of the front-end | tip part of each fin can be heightened.
Furthermore, circular arc surfaces are formed at the base end portions of the shroud side fin and the structure side fin. Therefore, it is possible to guide the fluid toward the upstream side while smoothly turning the flow direction of the fluid that has passed through the minute gaps at the tips of the fins disposed on the upstream side. Therefore, since the fluid can be guided toward the upstream side by the fin without rapidly decelerating the velocity of the fluid that has passed through the minute gap, the velocity of the vortex formed between the fins can be increased. Therefore, the contraction effect of the fluid passing through the minute gap can be further improved. Moreover, since the dead water area | region of the base end part of a fin can be reduced with such a circular arc surface, the loss of a flow can be reduced.

  In the axial-flow rotating machine according to the second aspect of the present invention, in the first aspect, the shroud-side fin and the structure-side fin have the relative rotation between the blade and the structure relative to a central axis direction. The inclination angle of the center line may be 40 degrees or more and 80 degrees or less.

  By setting the inclination angle in this way, it is possible to improve the effect of contracting while pushing back the fluid that tries to pass through the minute gap at the tip of the fin to the upstream side.

  In the axial flow rotating machine according to the third aspect of the present invention, in the first or second aspect, the arcuate surfaces of the shroud side fin and the structure side fin are R surfaces, and the shroud side fin And in the front-end | tip part of the said structure side fin, the surface which faces the upstream and downstream of the flow of the said main flow may further have the plane extended in the tangential direction of this R surface continuously to the said R surface.

  By providing such an R surface and a flat surface for each of the shroud side fin and the structure side fin, the flow of the fluid that has passed through the minute gap at the tip of the fin is smoothly turned and the fluid is directed upstream. I can guide you. Therefore, the speed of the vortex formed between the fins can be increased, and the contraction effect of the fluid passing through the minute gap can be further improved.

  In the axial flow rotating machine according to the fourth aspect of the present invention, in the third aspect, the radius of curvature of the R surface facing the upstream side of the mainstream flow is the shroud side fin and the structure side. It may be ½ times the length of the center line of the fin.

  By providing the R surface in this way, it is possible to guide the fluid toward the upstream side while smoothly turning the flow direction of the fluid that has passed through the minute gap at the tip of the fin. Therefore, the speed of the vortex flow formed between the fins can be increased, and the contraction effect of the fluid passing through the minute gap can be further improved.

  Moreover, in the axial-flow rotating machine according to the fifth aspect of the present invention, in any one of the first to fourth aspects, at least one of the shroud side fin and the structure side fin is provided, and The inclination angle of the center line with respect to the central axis of the at least two fins may be the same.

  As described above, since at least two of the shroud side fins and the structure side fins are provided, the shroud side fins and the structure side fins are alternately provided. And since the centerline of all these fins inclines toward the upstream side, the upstream surface of the fin disposed on the downstream side can be brought closer to the upstream fin. Therefore, the jet that has passed through the minute gap at the tip of the upstream fin can be reliably brought into contact with the upstream surface of the downstream fin. As a result, it is possible to improve the effect of contracting the fluid that attempts to pass through the minute gap at the tip of the upstream fin.

  In the axial-flow rotating machine according to the sixth aspect of the present invention, in any one of the first to fifth aspects, the structure-side fin is disposed on the most upstream side, and the blade includes the shroud. An upstream inclined surface that is inclined from the upstream side toward the downstream side as it goes radially outward is provided on the end surface facing the upstream side, and the structure is disposed on the upstream side of the shroud. An upstream inclined inner wall surface that is inclined from the upstream side toward the downstream side toward the radially outer side may be provided at a position facing the direction in which the main flow flows.

Thus, at the entrance of the cavity between the structure and the blade, the shroud is provided with the upstream inclined surface, and the structure is provided with the upstream inclined inner wall surface. For this reason, the leak flow that branches off from the main flow and tries to flow into the cavity does not flow straight in the radial direction but flows obliquely toward the downstream side along the upstream inclined surface and the upstream inclined inner wall surface. Therefore, the leak flow when the leak flow branches from the main flow does not branch in completely different directions. Furthermore, since it can avoid that a corner | angular part is formed in a cavity with an upstream inclined surface and an upstream inclined inner wall surface, generation | occurrence | production of a dead water area can be suppressed. As a result, it is possible to suppress fluid separation and reduce loss.
Further, the fluid flowing along the upstream inclined surface contacts the structure-side fin and flows so as to be pushed back toward the upstream side. As a result, a vortex is formed on the upstream side of the structure-side fin in the cavity. Since this vortex is formed so as to extend obliquely along the upstream inclined surface and the upstream inclined inner wall surface, the vortex is formed along the flow direction of the leak flow branched from the main flow. Therefore, it can suppress that a fine vortex is formed around this vortex, and it can suppress that a vibration arises in a rotary machine.

  Moreover, in the axial-flow rotating machine according to the seventh aspect of the present invention, in any one of the first to sixth aspects, the blade has a radially inward end surface facing the downstream side of the shroud. A downstream inclined surface that inclines from the upstream side toward the downstream side is provided, and the structure is disposed on the downstream side of the shroud, and is positioned in a radial direction at a position facing the direction in which the mainstream flows through the shroud. A downstream inclined inner wall surface that is inclined from the upstream side toward the downstream side as it goes inward may be provided.

  Thus, at the exit of the cavity between the structure and the blade, the shroud is provided with the downstream inclined surface, and the structure is provided with the downstream inclined inner wall surface. For this reason, when the leak flow tries to join the main flow, it flows into the main flow obliquely toward the downstream side along the downstream inclined surface and the downstream inclined inner wall surface, instead of straight in the radial direction. Therefore, when the leak flows merge into the main flow, the flow directions can be made closer to each other. Furthermore, since it can avoid that a corner | angular part is formed in a cavity by a downstream inclined surface and a downstream inclined inner wall surface, generation | occurrence | production of a dead water area can be suppressed. As a result, it is possible to suppress fluid separation and reduce loss.

  According to the above axial flow rotating machine, so-called opposed fins are adopted, and the center line of all the fins is inclined toward the upstream side, so that the flow rate of the leak flow is reduced with a simple structure. Performance improvement is possible.

It is a schematic structure sectional view of the steam turbine of a first embodiment of the present invention. It is a figure which shows the principal part of the steam turbine of 1st embodiment of this invention, Comprising: The A section of FIG. 1 is shown. It is a figure which shows the principal part of the steam turbine of 2nd embodiment of this invention, Comprising: The position corresponded to the A section of FIG. 1 is shown.

Hereinafter, the steam turbine (axial flow rotary machine) 100 of 1st embodiment of this invention is demonstrated.
As shown in FIG. 1, a steam turbine 100 according to the present embodiment includes a rotating shaft (structure) 1, a casing (structure) 2, a moving blade stage 3 including a plurality of moving blades (blades) 4, And a stationary blade stage 6 including a plurality of stationary blades (blades) 7.

  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 rotates relative to the rotating shaft 1.
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 (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 inside of 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 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.

  As shown in FIG. 2, the moving blade 4 includes a platform 43 formed on the outer peripheral surface 1 </ b> S of the rotating shaft 1, a moving blade main body 40, and a moving blade shroud 41.

Although not shown in detail, the rotor blade body 40 is formed so as to extend radially outward from the platform 43. The rotor blade body 40 has an airfoil-shaped cross section as viewed from the radial direction Dr.
The moving blade shroud 41 is provided at the radially outer end of the moving blade body 40. The moving blade shroud 41 is set such that the dimension in the central axis direction Da is larger than the dimension of the moving blade body 40 in the central axis direction Da.

  A moving blade accommodating recess 20 for accommodating the moving blade shroud 41 is formed in an inner peripheral side of the casing 2 and in a region facing the moving blade shroud 41 in the radial direction Dr. The moving blade housing recess 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.

  As shown in FIG. 2, the moving blade accommodating recess 20 is called a cavity formed between the moving blade shroud 41 and the casing 2. A leak flow LF flows into the cavity from the main flow MF of the steam flowing in the central axis direction Da around the rotation shaft 1 in the radial direction. The surface facing the downstream side in the moving blade housing recess 20 and the end surface facing the upstream side of the moving blade shroud 41 are arranged with a gap in the radial direction, that is, the downstream side of the moving blade housing recess 20 The facing surface is located on the upstream side of the end surface facing the upstream side of the moving blade shroud 41 and is disposed to face the moving blade shroud 41. This gap is the entrance of the cavity.

  In the present embodiment, two casing-side fins (structure-side fins) 42 that protrude from the casing 2 toward the blade shroud 41 are provided on the bottom surface 23 (the surface facing the inner side of the radial direction Dr) of the blade accommodating recess 20. Are arranged side by side in the central axis direction Da.

  These casing side fins 42 have a thin plate shape extending from the casing 2 toward the inside in the radial direction Dr. A clear lance (a minute gap) is formed in the radial direction Dr between the tip of the casing side fin 42 and the blade shroud 41.

  Further, in each casing-side fin 42, the center line CL1 is inclined toward the upstream side toward the tip end portion (the end portion on the inner side in the radial direction Dr). Here, the center line CL1 is an imaginary line that passes through the central portion of the casing-side fin 42 in the central axis direction Da. The inclination angle α1 of the center line CL1 of each casing-side fin 42 with respect to the central axis direction Da is the same in this embodiment, but may be different from each other. The inclination angle of the center line CL1 is preferably 40 degrees or more and 80 degrees or less, and more preferably 60 degrees.

  Moreover, in the base end part (outer end part of radial direction Dr) of the casing side fin 42, the surface which faces an upstream side and a downstream side has the circular arc surface 42a dented toward the centerline CL1. The arc surface 42a is an R surface in the present embodiment. Further, the curvature radius is different between the arc surface 42a1 facing the upstream side and the arc surface 42a2 facing the downstream side. The radius of curvature of the arcuate surface 42a1 facing the upstream side may be ½ times the length of the center line CL1 of the casing-side fin 42.

Further, the surfaces facing the upstream side and the downstream side of the casing-side fin 42 further have a flat surface 42b that is smoothly continuous with the arcuate surface 42a that is the R surface and that extends in the tangential direction at the connection portion with the R surface. ing. A plane 42b1 is provided on the upstream side, and a plane 42b2 is provided on the downstream side.
The casing-side fin 42 has a tapered shape in which the thickness in the central axis direction Dc gradually decreases from the base end portion to the tip end portion.

  Further, in the moving blade housing recess 20, there is one shroud-side fin 44 protruding from the moving blade shroud 41 toward the casing 2 in the present embodiment, and the casing-side fin 42 from the upstream side and the downstream side in the central axis direction Da. It is provided so as to be sandwiched between. The shroud-side fin 44 has a thin plate shape extending from the blade shroud 41 toward the outside in the radial direction Dr. A clear lance (a minute gap) is formed in the radial direction Dr between the tip portion of the shroud-side fin 44 and the casing 2.

  Further, in the shroud-side fin 44, the center line CL2 is inclined toward the upstream side toward the tip end portion (end portion on the outer side in the radial direction Dr). Here, the center line CL <b> 2 is an imaginary line that passes through the central portion of the shroud-side fin 44 in the central axis direction Da. The inclination angle α2 of the center line CL2 with respect to the central axis direction Da is the same as the inclination angle α1 of the center line CL1 of the casing side fin 42 in the present embodiment, but may be different. The inclination angle of the center line CL2 is preferably 40 degrees or more and 80 degrees or less, and more preferably 60 degrees.

  Moreover, in the base end part (end part inside radial direction Dr) of the shroud side fin 44, the surface which faces an upstream side and a downstream side has the circular arc surface 44a dented toward the centerline CL2. The arc surface 44a is an R surface in the present embodiment. Further, the curvature radius is different between the arc surface 44a1 facing the upstream side and the arc surface 44a2 facing the downstream side. The radius of curvature of the arcuate surface 44a1 facing the upstream side may be 1/2 of the length of the center line CL2 of the shroud-side fin 44.

  Further, the surfaces facing the upstream side and the downstream side of the shroud-side fin 44 further have a flat surface 44b extending smoothly in a tangential direction at a connection portion with the R surface, which is smoothly connected to the arc surface 44a which is the R surface. ing. A flat surface 44b1 is provided on the upstream side, and a flat surface 44b2 is provided on the downstream side.

  The shroud-side fin 44 has a tapered shape in which the thickness in the central axis direction Dc gradually decreases from the proximal end portion to the distal end portion.

  As shown in FIG. 1, 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 inner end of the stationary blade body 70 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 housing recess 8 that is continuous in the direction is formed. The stationary blade shroud 71 of each stationary blade 7 is accommodated in the stationary blade accommodating recess 8.

  According to the steam turbine (axial rotary machine) 100 of the present embodiment described above, the steam that has passed through the clearance formed at the tip of the casing-side fin 42 disposed on the most upstream side becomes a jet, It collides with the shroud side fins 44 arranged on the downstream side of the clearance. At this time, the steam is guided toward the front end side of the shroud fin 44 along the upstream surface of the shroud fin 44. Similarly, the steam that has passed through the clearance formed at the tip of the shroud-side fin 44 becomes a jet and collides with the casing-side fin 42 disposed on the downstream side of the clearance. At this time, the air is guided along the upstream surface of the casing-side fin 42 toward the front end side of the casing-side fin 42, and the leak flow LF joins the main flow MF from the exit of the cavity through the clearance.

  Here, the jet flow that has collided with the shroud-side fin 44 and the casing-side fin 42 flows so as to be pushed back upstream by the upstream surface of the shroud-side fin 44 and the casing-side fin 42. A vortex V1 (in the present embodiment, a counterclockwise vortex) is formed between the shroud side fin 44 and the upstream casing side fin 42. Further, a vortex V2 (clockwise vortex in the present embodiment) is formed between the shroud side fin 44 and the downstream casing side fin 42.

  Then, the vortex V1 can cause the steam that is about to pass through the clearance at the tip of the casing-side fin 42 on the most upstream side to contract toward the inside in the radial direction Dr. Further, the vortex V <b> 2 can contract the steam that attempts to pass through the clearance at the tip of the shroud-side fin 44 toward the outside in the radial direction Dr. Thereby, the flow volume of the vapor | steam which passes a clearance can be reduced. As a result, the flow rate of the leak flow LF passing through the cavity can be reduced.

  In the present embodiment, the shroud-side fin 44 and the casing-side fin 42 are adjacent to each other in the flow direction of the main flow MF so as to have an opposing fin shape. Since the center lines CL1 and CL2 of the fins 42 and 44 are inclined toward the upstream side toward the tip, the steam that is about to pass through the clearance of the tip of the fins 42 and 44 is upstream. The flow can be reduced so as to push back, and the effect of the reduced flow caused by the vortices V1 and V2 can be enhanced. That is, the flow rate of the leak flow LF can be reduced with a simple structure, and the performance of the steam turbine 100 can be improved.

  Further, arcuate surfaces 42 a 1, 42 a 2, 44 a 1, 44 a 2 which are R surfaces are formed at the base end portions of the shroud side fins 44 and the casing side fins 42. Therefore, it is possible to guide the steam toward the upstream side while smoothly turning the flow direction of the steam that has passed through the clearance. Therefore, the steam can be guided toward the upstream side by the shroud-side fins 44 and the casing-side fins 42 without rapidly reducing the speed of the steam that has passed through the clearance. Therefore, the flow speed of the vortices V1 and V2 can be increased. Therefore, the contraction effect of the steam passing through the clearance can be further improved. Moreover, since the dead water area of the base end part of the fins 42 and 44 can be reduced by the circular arc surfaces 42a1, 42a2, 44a1, and 44a2, loss of steam flow can be reduced.

  Further, the inclination angles of the center lines CL1 and CL2 of the fins 42 and 44 are not less than 40 degrees and not more than 80 degrees, preferably 60 degrees, so that the steam passing through the clearance is compressed while being pushed back to the upstream side. The effect of flowing can be further improved.

  Furthermore, since the shroud side fin 42 and the casing side fin 44 are provided with flat surfaces 42b, 44b extending in the tangential direction of the R surface continuously to the arc surfaces 42a, 44a which are the R surface, the shroud side fin 42 and the casing side fin 44 try to pass the clearance. It is possible to further improve the effect of contracting while pushing back the steam to the upstream side.

  Further, when the radius of curvature of the arcuate surface 42a1 which is the R surface facing the upstream side is 1/2 times the length of the center lines CL1 and CL2 of the shroud side fin 44 and the casing side fin 42, the clearance has passed. It is possible to guide the steam toward the upstream side while smoothly turning the flow direction of the steam. Accordingly, the speed of the vortices V1 and V2 formed between the fins 42 and 44 can be increased, and the effect of contraction of the steam passing through the clearance can be further improved.

  In addition, since the inclination angles α1 and α2 of the center lines CL1 and CL2 of the fins 42 and 44 are the same, the center line CL1 is inclined toward the upstream side also in the casing-side fins 42 arranged on the most downstream side. ing. Therefore, the upstream side surface of the most downstream casing side fin 42 can be brought closer to the shroud side fin 44. Therefore, the jet of steam that has passed through the clearance at the tip of the shroud-side fin 44 can be reliably brought into contact with the upstream surface of the casing-side fin 42 on the most downstream side. As a result, it is possible to improve the effect of contracting the steam that attempts to pass through the clearance at the tip of the shroud-side fin 44.

[Second Embodiment]
Next, a steam turbine (axial flow rotary machine) 200 according to a second embodiment of the present invention will be described. In the second embodiment described below, the first embodiment differs from the first embodiment only in the moving blade shroud 41A and the moving blade housing recess 20A. Therefore, the same portions as those in the first embodiment are denoted by the same reference numerals. At the same time, redundant description is omitted.

  As shown in FIG. 3, the end surface facing the upstream side of the moving blade shroud 41 </ b> A is an upstream inclined surface 80 that inclines toward the downstream side toward the outside in the radial direction Dr. The upstream inclined surface 80 is a curved concave surface that is concave toward the downstream side. The radius of curvature of the curved concave surface may be determined so as to follow the shape of the vortex V formed at the entrance of the cavity. In the present embodiment, the steam is guided to the arc surface 42a1 and the flat surface 42b1 of the casing-side fin 42 on the most upstream side and flows upstream toward the outside in the radial direction Dr, thereby forming a counterclockwise vortex V. Is done.

  Further, the moving blade shroud 41A has a curved downstream inclined surface 85 inclined toward the downstream side toward the outer side in the radial direction Dr, and a radial direction Dr of the downstream inclined surface 85 on the end surface facing the downstream side. And a plane 86 extending in the radial direction Dr continuously. The downstream inclined surface 85 is a curved convex surface (R surface) that is convex toward the downstream side.

The surface facing the downstream side of the moving blade housing recess 20A has a radial direction Dr continuous to the inside of the radial direction Dr, the plane 91 extending perpendicularly to the central axis Ac and extending in the radial direction Dr, and the outside of the radial direction Dr of the plane 91. And an upstream inclined inner wall surface 92 that inclines toward the downstream side as it goes outward. The connecting portion between the upstream inclined inner wall surface 92 and the flat surface 91 has no corners, and the upstream inclined inner wall surface 92 and the flat surface 91 are smoothly connected in an arc shape. Further, the connecting portion between the bottom surface 23 and the upstream inclined inner wall surface 92 of the moving blade housing recess 20A has no corners, and the bottom surface 23 and the upstream inclined inner wall surface 92 are smoothly connected in an arc shape.
Here, the upstream inclined inner wall surface 92 may be formed by attaching another member to the moving blade housing recess 20A, or may be provided by forming the surface of the moving blade housing recess 20A into an inclined surface.

  The surface facing the upstream side of the moving blade housing recess 20A and the end surface facing the downstream side of the moving blade shroud 41A are spaced apart from each other in the radial direction Dr, that is, downstream of the moving blade housing recess 20A. Is located on the downstream side of the end surface facing the downstream side of the moving blade shroud 41A, and is disposed to face the moving blade shroud 41A. This gap is the exit of the cavity. At the exit of the cavity, the leak flow LF, which is steam that has passed through the clearance formed between the casing-side fin 42 disposed on the most downstream side and the blade shroud 41A, joins the main flow MF.

  The surface facing the upstream side of the moving blade housing recess 20A has a downstream inclined inner wall surface 96 that is continuous with the bottom surface 23 and is inclined toward the downstream side toward the inner side in the radial direction Dr, and a downstream inclined inner wall surface. 96 has a flat surface 95 extending in the radial direction Dr perpendicular to the central axis Ac and continuously inside the radial direction Dr.

The connecting portion between the downstream inclined inner wall surface 96 and the flat surface 95 has no corners, and these surfaces 95 and 96 are smoothly connected in an arc shape. Further, the connecting portion between the bottom surface 23 of the moving blade accommodating recess 20A and the downstream inclined inner wall surface 96 has no corners, and these surfaces 23 and 96 are smoothly connected in an arc shape.
Here, the downstream inclined inner wall surface 96 may be formed by attaching another member to the moving blade housing recess 20A, or may be provided by forming the surface of the moving blade housing recess 20A into an inclined surface.

  According to the steam turbine 200 of the present embodiment described above, the steam passing through the clearance lances of the tips of the fins 42 and 44 can be pushed back to the upstream side in the same manner as in the first embodiment. The contraction effect by V2 can be enhanced. That is, the flow rate of the leak flow LF can be reduced with a simple structure, and the performance of the steam turbine 200 can be improved.

  Further, at the entrance of the cavity between the casing 2 and the blade shroud 41, the blade shroud 41A is provided with an upstream inclined surface 80, and the casing 2 is provided with an upstream inclined inner wall surface 92. For this reason, the leak flow LF that branches from the main flow MF of steam and flows into the cavity is not straight toward the outside in the radial direction Dr, but along the upstream inclined surface 80 and the upstream inclined inner wall surface 92. It flows obliquely toward the downstream side.

  Therefore, the leak flow LF when the leak flow LF branches from the main flow MF does not branch from the main flow MF in a direction completely different from the main flow MF. Further, the upstream inclined surface 80 and the upstream inclined inner wall surface 92 can prevent the corner portion from being formed in the moving blade accommodating recess 20A. For this reason, generation | occurrence | production of a dead water area can be suppressed. As a result, it is possible to suppress loss of vapor and reduce loss. Thereby, the loss by the branch from the main flow MF of the leak flow LF is suppressed, and the high performance of the steam turbine 200 can be achieved.

  Further, by forming a curved concave surface as the upstream inclined surface 80, the upstream inclined surface 80 can be aligned with the shape of the vortex V formed at the entrance of the cavity. Therefore, friction loss between the vortex V and the upstream inclined surface 80 can be reduced, loss due to branching of the leak flow LF can be suppressed, and high performance of the steam turbine 200 can be achieved.

  Furthermore, the steam flowing along the upstream inclined surface 80 contacts the casing-side fins 42 and flows so as to be pushed back toward the upstream side. As a result, the vortex V on the upstream side of the casing-side fin 42 in the cavity extends obliquely toward the downstream side toward the outer side of the radial direction Dr along the upstream inclined surface 80 and the upstream inclined inner wall surface 92. Formed as follows. For this reason, the vortex V is formed along the flow direction of the leak flow LF branched from the main flow MF. Therefore, it is possible to suppress the formation of fine vortices around the vortex V, and it is possible to suppress the occurrence of axial vibration on the rotating shaft 1 and the like.

  Further, at the exit of the cavity, the moving blade shroud 41 </ b> A is provided with a downstream inclined surface 85, and the casing 2 is provided with a downstream inclined inner wall surface 96. For this reason, when the leak flow LF tries to join the main flow MF, the leak flow LF is not straight in the radial direction, but the leak flow LF is directed in the radial direction Dr along the downstream inclined surface 85 and the downstream inclined inner wall surface 82 toward the downstream side. Into the mainstream MF at an angle toward the inside.

  Therefore, when the leak flow LF joins the main flow MF, the flow direction of the leak flow LF and the flow direction of the main flow MF can be made as close as possible. Furthermore, since it is possible to avoid the formation of a corner in the moving blade housing recess 20A by the downstream inclined surface 85 and the downstream inclined inner wall surface 96, it is possible to suppress the occurrence of a dead water area. As a result, it is possible to suppress loss of vapor and reduce loss. Thereby, the loss by the merge of the leak flow LF to the main flow MF can be suppressed. As a result, the loss due to the merge of the leak flow LF to the main flow MF is suppressed, and the performance of the steam turbine 200 can be improved.

  Further, in the present embodiment, the vortex V3 is formed on the downstream side of the casing-side fin 42 arranged on the most downstream side at the exit portion of the cavity. The vortex V3 is formed by a leak flow LF that has become a jet flow through a clearance between the casing-side fin 42 disposed on the most downstream side and the blade shroud 41A. The vortex V3 is formed so as to extend obliquely toward the downstream side along the downstream inclined surface 85 and the downstream inclined inner wall surface 96 toward the inner side in the radial direction Dr.

  Further, the downstream inclined surface 85, which is a curved convex surface, allows the leak flow LF flowing along the surface of the rotor blade shroud 41A to flow to the main flow MF in a radial direction at a certain distance without flowing straight at the exit portion of the cavity. Without being separated from the downstream inclined surface 85, the leak flow LF can be merged with the main flow MF.

  Accordingly, by appropriately designing the shape of the curved convex surface, the leakage flow LF is adjusted along the flow direction of the main flow MF while avoiding the leakage flow LF from directly flowing into the stationary blade 7 located on the rear stage side. The mainstream MF can be merged. Therefore, the mixing loss of the leak flow LF to the main flow MF can be reduced.

  Here, the upstream-side inclined surface 80 of this embodiment may not be a curved concave surface, but may be a flat inclined surface.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.

  For example, the shape of the blade shroud is not limited to the above embodiment.

  In the above-described embodiment, the shapes of the fins 42 and 44 in the moving blade housing recess 20 (20A) have been described. However, the shapes of the fins 42 and 44 are applied to the fins in the stationary blade housing recess 8. Also good. Moreover, the quantity of each fin 42 and 44 is not limited to the above-mentioned case.

  Moreover, in each said embodiment, it demonstrated based on the example which applied the steam turbine as an axial flow rotary machine. However, the aspect of the axial flow rotary machine is not limited to the steam turbine, and other devices such as a gas turbine and an aircraft jet engine can be applied as the axial flow rotary machine.

  Moreover, you may combine the structure of each embodiment suitably.

1 ... Rotating shaft (structure)
1S ... outer peripheral surface 2 ... casing (structure)
2S ... inner peripheral surface 3 ... blade stage 4 ... blade (blade)
DESCRIPTION OF SYMBOLS 5 ... Bearing apparatus 5A ... Journal bearing 5B ... Thrust bearing 6 ... Stator blade stage 7 ... Stator blade (blade)
8 ... Stator blade accommodating recess 20, 20A ... Rotor blade accommodating recess 23 ... Bottom surface 40 ... Rotor blade body 41, 41A ... Rotor blade shroud 42 ... Casing side fin 42a ... Arc surface 42a1 ... Arc surface 42a2 ... Arc surface 42b ... Plane 42b1 ... plane 42b2 ... plane 43 ... platform 44 ... shroud side fin 44a ... arc surface 44a1 ... arc surface 44a2 ... arc surface 44b ... plane 44b1 ... plane 44b2 ... plane 70 ... stator blade body 71 ... stator blade shroud 80 ... upstream side inclined surface 85 ... Downstream inclined surface 86 ... Flat surface 91 ... Flat surface 92 ... Upstream inclined inner wall surface 95 ... Flat surface 96 ... Downstream inclined inner wall surface 100, 200 ... Steam turbine (axial rotary machine)
Ac ... Center axis Da ... Center axis direction Dr ... Radial direction MF ... Main flow LF ... Leak flow CL1, CL2 ... Centerlines V, V1, V2, V3 ... Vortex

Claims (7)

A blade disposed in a flow path through which a main flow of fluid flows, and a structure that is provided at a tip side of the blade via a gap and rotates relative to the blade;
With
The blade has a shroud at a tip portion, and a shroud side fin that protrudes from the shroud toward the structure and forms a minute gap between the structure and the blade.
The structure has a structure-side fin that is arranged in a direction in which the main flow flows with respect to the shroud-side fin and protrudes toward the shroud to form a minute gap with the shroud. ,
At the base ends of the shroud-side fin and the structure-side fin, the surfaces facing the upstream and downstream sides of the mainstream flow are center lines in the direction of the central axis of the relative rotation between the blade and the structure in the fin. Having an arc surface recessed toward
In the shroud-side fin and the structure-side fin, an axial-flow rotating machine in which the center line is inclined toward the upstream side toward the tip.   2. The inclination angle of the center line with respect to the central axis direction of relative rotation between the blade and the structure is 40 degrees or more and 80 degrees or less between the shroud side fin and the structure side fin. Axial flow rotating machine. The arcuate surfaces of the shroud side fin and the structure side fin are R surfaces,
The front surface of the shroud-side fin and the structure-side fin further have a plane that faces the upstream and downstream sides of the mainstream flow, and further has a plane that extends continuously in the tangential direction of the R-plane. The axial flow rotary machine according to 1 or 2.   4. The axial flow according to claim 3, wherein a radius of curvature of the R surface facing the upstream side of the main flow is ½ times the length of the center line of the shroud fin and the structure fin. 5. Rotating machine.   One of the shroud side fin and the structure side fin is provided with at least two, and the inclination angle of the center line with respect to the central axis of the at least two fins is the same. The axial flow rotating machine according to the item. The structure-side fin is disposed on the most upstream side,
The blade is provided with an upstream inclined surface that is inclined from the upstream side toward the downstream side toward the radially outer side on the end surface facing the upstream side in the shroud,
The structure is disposed on the upstream side of the shroud, and in an upstream inclined side that inclines from the upstream side toward the downstream side toward the radially outer side at a position opposite to the direction in which the main flow flows through the shroud. The axial flow rotating machine according to any one of claims 1 to 5, wherein a wall surface is provided. The blade is provided with a downstream inclined surface that is inclined toward the downstream side from the upstream side toward the radially inner side on the end surface facing the downstream side in the shroud,
The structure is disposed on the downstream side of the shroud, and inclines in a downstream side that inclines from the upstream side toward the downstream side toward the inner side in the radial direction at a position opposite to the direction in which the main flow flows through the shroud. The axial flow rotary machine according to any one of claims 1 to 6, wherein a wall surface is provided.

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