JP2018003812A - Bucket and turbine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict the increase in head loss due to the detachment of the leakage flow from a diffuser wall surface.SOLUTION: A bucket 21d whose tip is opposed to a seal fin that comprises: a turbine rotor 12 and a stationary body 14; among a plurality of stages of a turbine 9 having a diffuser 10 connected to the outlet side of working fluid 22 of the stationary body 14, a seal fin 38 disposed in the last stage which is closest to the diffuser 10 and provided in the stationary body 14; and that comprises: a vane 26; a cover 27 provided at the tip 30 of the vane 26; and a guide 32 provided on a bucket apical surface 31 which is an opposed surface of the stationary body 14 of the cover 27. When assembled to the turbine 9, the bucket apical surface 31 extends in the direction of the rotation axis of the turbine rotor 12 as viewed in a cross section cut along a plane including the rotation axis of the turbine rotor 12; the guide 32 is located on the closer side to the diffuser 10 with respect to the seal fin 38 and having a guide surface 41 formed upwardly inclining in a direction from the seal fin 38 to the diffuser 10.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a moving blade and a turbine using the same.

  In order to meet the demand for higher output and higher efficiency of turbines in recent years, the moving blades at the final stage of the low-pressure turbine (hereinafter referred to as the final moving blades) tend to be longer blades (see Patent Document 1, etc.).

JP 2003-65002 A

  When the last stage blade is made longer, the peripheral speed of the last stage blade increases, and in order to obtain a large stage heat drop that matches the increased peripheral speed, the upstream of the last stage blade in the flow direction of the working fluid. It is necessary to increase the pressure of the working fluid on the side (hereinafter referred to as the upstream side). On the other hand, the pressure of the working fluid on the downstream side (hereinafter referred to as the downstream side) in the flow direction of the working fluid of the final stage rotor blade is substantially determined by the pressure in the condenser disposed on the downstream side of the turbine. Therefore, when the pressure of the working fluid upstream of the last stage blade is increased, the ratio of the upstream pressure to the downstream pressure of the working fluid of the last stage blade increases.

  By the way, in the turbine, there is a gap between the rotor blade of the turbine rotor that is a rotating body and the stationary body that covers the turbine rotor, and part of the working fluid on the upstream side of the final stage rotor blade can pass through the gap. Thus, a flow that does not pass through the blade portion (profile portion) of the moving blade but passes through the gap between the tip of the moving blade and the stationary body facing the blade is referred to as a leakage flow in the present specification. Leakage flow may be suppressed by providing a seal fin on the opposed surface of the rotor blade tip and stationary body, but even in this case, a minute gap remains between the seal fin tip and the opposed part, and the leakage flow is completely eliminated. Can not be suppressed.

  As described above, when the ratio of the upstream pressure to the downstream pressure of the final stage rotor blade becomes large and the pressure ratio before and after the seal fin of the leak flow exceeds the critical pressure ratio, the leak flow also flows out from a minute gap at supersonic speed. . In general, a supersonic flow, contrary to a subsonic flow, increases in flow velocity and decreases in pressure as the cross-sectional area of the flow increases. Therefore, the flow velocity of the supersonic leakage flow increases at the portion of the diffuser provided so that the cross-sectional area of the flow increases in order to decelerate the mainstream subsonic flow. Further downstream, a shock wave is generated and becomes a subsonic flow. At this time, the pressure of the leakage flow that has dropped along with the passage of the seal fins rapidly increases due to the shock wave (discontinuous pressure change) in the diffuser. When the wall boundary layer flow with a slow flow velocity near the diffuser wall passes through this shock wave, it separates from the diffuser wall, reducing the effect of expanding the channel area as a diffuser, reducing pressure recovery performance, and pressure. Loss can increase.

  The present invention has been made in view of the above, and an object of the present invention is to provide a moving blade capable of suppressing an increase in pressure loss due to separation of leakage flow from a diffuser wall surface.

  To achieve the above object, the present invention provides a turbine rotor and a stationary body that covers the turbine rotor, and the diffuser among a plurality of paragraphs of a turbine in which a diffuser is connected to a working fluid outlet side of the stationary body. In a moving blade that is disposed at the final stage closest to the tip and faces the seal fin provided on the stationary body, a blade, a cover provided at the tip of the blade, and the stationary body of the cover And a guide provided on the front end surface of the moving blade, which is a surface to be rotated, and when assembled to the turbine, the front end surface of the moving blade is The guide extends in the direction of the rotation axis, and the guide is positioned on the side closer to the diffuser with respect to the seal fin and is inclined upward in the direction from the seal fin toward the diffuser. Characterized in that it is configured to have a formed guide surfaces.

  ADVANTAGE OF THE INVENTION According to this invention, the increase in the pressure loss by peeling from the diffuser wall surface of a leak flow can be suppressed.

It is the schematic showing the whole structure of one structural example of the steam turbine power generation equipment to which the moving blade which concerns on 1st Embodiment of this invention is applied. It is sectional drawing showing the internal structure of the principal part of the low pressure turbine to which the moving blade which concerns on 1st Embodiment of this invention is applied. It is a perspective view showing the schematic structure of the last stage moving blade which concerns on 1st Embodiment of this invention. It is a perspective view showing the state which fixed the last stage moving blade which concerns on 1st Embodiment of this invention to the rotor disk. It is the figure which looked at FIG. 4 from the radial direction outer side. It is the elements on larger scale showing the front-end | tip part of the last stage moving blade which concerns on 1st Embodiment of this invention. It is the elements on larger scale showing the front-end | tip part of the last stage rotor blade which concerns on a comparative example. It is the elements on larger scale showing the front-end | tip part of the last stage moving blade which concerns on 2nd Embodiment of this invention. It is the figure which looked at the last stage rotor blade which concerns on 3rd Embodiment of this invention from the radial direction outer side. It is the figure which looked at the last stage rotor blade which concerns on 4th Embodiment of this invention from the radial direction outer side. It is the elements on larger scale showing the front-end | tip part of the last stage moving blade which concerns on 5th Embodiment of this invention.

<First Embodiment>
(Constitution)
1. Steam Turbine Power Generation Facility FIG. 1 is a schematic diagram showing the overall configuration of a configuration example of a steam turbine power generation facility to which a moving blade according to this embodiment is applied. Hereinafter, although the case where the moving blade according to the present embodiment is applied to the steam turbine power generation facility will be described, the application target of the moving blade according to the present embodiment is not limited to the steam turbine power generation facility, for example, to the gas turbine power generation facility. It can also be applied.

  As shown in FIG. 1, the steam turbine power generation facility 100 includes a steam generation source 1, a high pressure turbine 3, an intermediate pressure turbine 6, a low pressure turbine 9, a condenser 11, and a load device 13.

  The steam generation source (boiler) 1 heats the water supplied from the condenser 11 and generates high-temperature and high-pressure steam. Steam generated in the boiler 1 is guided to the high-pressure turbine 3 through the main steam pipe 2 to drive the high-pressure turbine 3. The steam depressurized by driving the high-pressure turbine 3 flows down the high-pressure turbine exhaust pipe 4 and is guided to the boiler 1, where it is heated again to become reheated steam.

  The reheat steam heated by the boiler 1 is guided to the intermediate pressure turbine 6 through the reheat steam pipe 5 to drive the intermediate pressure turbine 6. The steam depressurized by driving the intermediate pressure turbine 6 is guided to the low pressure turbine 9 via the intermediate pressure turbine exhaust pipe 7 to drive the low pressure turbine 9. The steam decompressed by driving the low-pressure turbine 9 flows through the diffuser 10 and is guided to the condenser 11. The condenser 11 is provided with a cooling water pipe (not shown), and condenses the steam by exchanging heat between the steam guided to the condenser 11 and the cooling water flowing in the cooling water pipe. The condensate generated by the condenser 11 is sent again to the boiler 1 by the feed water pump 56 as feed water.

  The high-pressure turbine 3, the intermediate-pressure turbine 6, and the low-pressure turbine 9 are coaxially connected by a turbine rotor 12. The load device (generator in this embodiment) 13 is connected to the turbine rotor 12, and the generator 13 is driven by the rotational power of the high-pressure turbine 3, the intermediate-pressure turbine 6, and the low-pressure turbine 9. The rotational power of the intermediate pressure turbine 6 and the low pressure turbine 9 is converted into electric power.

  In the present embodiment, the configuration in which the high-pressure turbine 3, the intermediate-pressure turbine 6, and the low-pressure turbine 9 that are connected drive the generator 13 is illustrated. However, the high-pressure turbine 3, the intermediate-pressure turbine 6, and the low-pressure turbine 9 each serve as a generator. It is good also as a structure which drives and converts into electric power separately, and it is good also as a structure which drives a generator and connects with arbitrary two among the high pressure turbine 3, the intermediate pressure turbine 6, and the low pressure turbine 9 and converts it into electric power. . Moreover, although the structure provided with the high pressure turbine 3, the intermediate pressure turbine 6, and the low pressure turbine 9 was illustrated, it is good also as a structure which abbreviate | omits the intermediate pressure turbine 6 and includes the high pressure turbine 3 and the low pressure turbine 9. Furthermore, although the structure provided with the boiler was illustrated as the steam generation source 1, the structure provided with the waste-heat recovery steam generator (HRSG) which uses the exhaust heat of a gas turbine as the steam generation source 1, ie, a steam turbine The equipment may be combined cycle power generation equipment. Moreover, it is good also as a nuclear power generation equipment provided with a nuclear reactor as the steam generation source 1.

2. FIG. 2 is a cross-sectional view showing an internal structure of a main part of the low-pressure turbine 9 to which the moving blade according to the present embodiment is applied. As shown in FIG. 2, the low-pressure turbine 9 includes a turbine rotor 12 and a stationary body 14 that covers the turbine rotor 12, and the diffuser 10 is connected to the outlet side (the most downstream side) of the working fluid 22 of the stationary body 14. doing. In the present specification, the rotation direction and rotation axis direction of the turbine rotor 12 are simply “rotation direction”, “rotation axis direction”, the radially inner side and the radially outer side of the turbine rotor 12 are simply “radially inner”, Say “radially outside”.

  The stationary body 14 includes a casing 16, outer diaphragms 17a to 17d, stationary blades 18a to 18d, and inner diaphragms 19a to 19d.

  The casing 16 is a cylindrical member that forms the outer peripheral wall of the low-pressure turbine 9. In the casing 16, outer diaphragms 17a to 17d, stationary vanes 18a to 18d, inner diaphragms 19a to 19d, and the turbine rotor 12 are accommodated.

  The outer diaphragms 17 a to 17 d are supported on the inner peripheral surface of the casing 16. The outer diaphragms 17a to 17d are cylindrical members extending in the rotation direction. In the present embodiment, the outer diaphragms 17a to 17d are configured by combining members formed in a semicircular shape. The outer diaphragms 17a to 17d are formed such that the inner peripheral surface extends radially outward toward the downstream side. Of the outer diaphragms 17a to 17d, the outer peripheral wall 10A of the diffuser 10 is connected to the downstream end of the protrusion 55 of the outer diaphragm 17d provided on the most downstream side. In addition, in this embodiment, although the structure which supports the outer side diaphragms 17a-17d with the inner peripheral surface of the casing 16 is illustrated, respectively, the outer side diaphragms 17a-17d are integrally formed, and the inner peripheral surface of the casing 16 is formed. It is good also as a structure to support.

  A plurality of stationary blades 18a to 18d are provided along the rotation direction on the inner peripheral surfaces of the outer diaphragms 17a to 17d. The stationary blades 18a to 18d are provided to extend radially inward from the inner peripheral surfaces of the outer diaphragms 17a to 17d.

  The inner diaphragms 19a to 19d are provided on the radially inner side of the outer diaphragms 17a to 17d. The inner diaphragms 19a to 19d are cylindrical members extending in the rotation direction. In the present embodiment, the inner diaphragms 19a to 19d are configured by combining members formed in a semicircular shape. The stationary blades 18a to 18d are connected to the outer peripheral surfaces of the inner diaphragms 19a to 19d. That is, the stationary blades 18a to 18d are fixed between the outer diaphragms 17a to 17d and the inner diaphragms 19a to 19d.

  In the present embodiment, the outer diaphragm 17a, the stationary blade 18a and the inner diaphragm 19a are the first stage stationary blade cascade 15a, and the outer diaphragm 17b, the stationary blade 18b and the inner diaphragm 19b are the second stage stationary blade cascade 15b, Diaphragm 17c, stationary blade 18c and inner diaphragm 19c constitute a third stage stationary blade cascade 15c, and outer diaphragm 17d, stationary blade 18d and inner diaphragm 19d constitute a fourth stage (final stage) stationary blade cascade 15d. .

  An annular space formed between the platforms (described later) of the inner diaphragms 19a to 19d and the moving blades 21a to 21d and the outer diaphragms 17a to 17d and a cover (described later) is a flow path (annular) through which the working fluid 22 flows. Flow path) 23 is formed. The inner peripheral wall of the annular flow path 23 is formed by the outer peripheral surfaces of the inner diaphragms 19a to 19d and the outer peripheral surface of the platform of the moving blades 21a to 21d, and the outer peripheral wall extends along the inner peripheral surface of the outer diaphragms 17a to 17d and the radially inner side of the cover. It is formed with the facing side.

  The turbine rotor 12 includes rotor disks 20a to 20d and rotor blades 21a to 21d.

  The rotor disks 20a to 20d are disk-shaped members arranged side by side in the rotation axis direction. The rotor disks 20a to 20d may be alternately overlapped with spacers (not shown).

  A plurality of rotor blades 21a to 21d are provided at equal intervals along the rotation direction on the outer peripheral surfaces of the rotor disks 20a to 20d, respectively. The rotor blades 21a to 21d are provided to extend radially outward from the outer peripheral surfaces of the rotor disks 20a to 20d. The rotor blades 21a to 21d rotate around the rotation axis R together with the rotor disks 20a to 20d by the working fluid 22 flowing through the annular flow path 23.

  In the present embodiment, the rotor disk 20a and the rotor blade 21a are the first stage blade cascade 53a, the rotor disk 20b and the rotor blade 21b are the second stage blade cascade 53b, and the rotor disk 20c and the rotor blade 21c are the first stage. The rotor disk 20d and the moving blade 21d constitute a fourth stage (final stage) moving blade cascade 53d.

  The stationary blades 18a to 18d and the moving blades 21a to 21d are arranged from the inlet side (the most upstream side) of the working fluid 22 of the stationary body 14 toward the downstream side, so that the stationary blade 18a, the moving blade 21a, the stationary blade 18b, and the moving blade 21b. Are arranged alternately in the direction of the rotation axis, and the stationary blades 18a to 18d are arranged so as to face the moving blades 21a to 21d in the direction of the rotation axis.

  A pair of stationary blade cascades and moving blade cascades adjacent to each other in the rotational axis direction from the inlet side of the working fluid 22 of the stationary body 14 constitutes a blade stage. In the present embodiment, the first stage stationary blade cascade 15a and the first stage moving blade cascade 53a are the first blade stage 24a, and the second stage stationary blade cascade 15b and the second stage blade cascade 53b are the first stage. The second blade stage 24b, the third stage blade cascade 15c and the third stage blade cascade 53c are the third blade stage 24c, the fourth stage blade cascade 15d and the fourth stage blade cascade 53d. Constitutes the fourth wing stage 24d. The fourth blade stage 24 d is the final stage disposed on the outlet side of the working fluid 22 of the stationary body 14, and is disposed at a position closest to the diffuser 10. The blade lengths (radial lengths) of the moving blades 21a to 21d arranged in the first to fourth blade stages are formed to be longer as they are located on the downstream side, and the fourth blade stage The blade length of the moving blade (final stage moving blade) 21d arranged at 24d is the longest of the moving blades 21a to 21c. Specifically, the final stage moving blade 21d is a motion obtained by dividing the rotational peripheral speed of the tip portion of the blade portion 26 (described later) by the sound speed of the working fluid 22 flowing through the tip portion of the blade portion 26 while the turbine rotor 12 is rotating. The blade tip has a blade tip circumferential speed Mach number exceeding 1.0.

  FIG. 3 is a perspective view illustrating a schematic configuration of the final stage moving blade 21d. As shown in FIG. 3, the final stage moving blade 21 d includes a platform 25, a blade portion 26, an integral cover 27, and a tie boss 28.

  The platform 25 has a size that covers the entire end face of the root portion (radially inner portion) 29 of the wing portion 26, and is formed in a rhombus shape when viewed from the radially outer side in this embodiment. . A planting portion (not shown) that protrudes on the opposite side of the wing portion 26 is provided on the lower surface (the radially inner surface) of the platform 25. The planting part is formed, for example, in an inverted Christmas tree shape. The final stage moving blade 21d is fixed to the rotor disk 20d by fitting the implanted portion with a groove (not shown) formed on the outer peripheral surface of the rotor disk 20d (see FIG. 2). In the present embodiment, the case where the implanted portion is formed in an inverted Christmas tree shape is illustrated, but it fits into the groove formed on the outer peripheral surface of the rotor disk 20d and resists centrifugal force generated when the turbine rotor 12 rotates. If the final stage moving blade 21d can be fixed to the rotor disk 20d, the shape of the implanted portion is not limited to the inverted Christmas tree type.

  The wing portion 26 is attached to the outer peripheral surface of the platform 25 and extends radially outward from the outer peripheral surface of the platform 25. The wing part 26 is formed by twisting.

  The integral cover (cover) 27 is provided at the tip end (radially outer end) 30 of the wing 26. The cover 27 extends a back side integral cover (first cover) 27A extending in the rotation direction at the back side portion of the last stage moving blade 21d and a ventral side portion of the last stage blade 21d in the rotation direction. A ventral integral cover (second cover) 27B is provided. As described above, the surface of the cover 27 that faces radially inward constitutes a part of the outer peripheral wall of the annular flow path 23, thereby defining the annular flow path 23. Further, the cover 27 contacts the cover of the final stage moving blade (adjacent blade) adjacent to the final stage moving blade 21d on both sides in the rotation direction during the rotation of the turbine rotor 12, and connects the final stage moving blade 21d and the adjacent blade. To do. The operation of the cover 27 during the rotation of the turbine rotor 12 will be described later.

  When the final stage moving blade 21d is assembled to the low pressure turbine 9, the cover 27 is viewed from a cross section (hereinafter referred to as a meridian cross section) cut along a plane including the rotation axis R of the turbine rotor 12, and the outer diaphragm 17d (stationary) The body 14) has a surface facing the inner peripheral surface and extending in the direction of the rotation axis. In the present specification, a surface facing the radially outer side of the cover 27 and facing the inner peripheral surface of the outer diaphragm 17d is referred to as a moving blade tip surface 31 for convenience. In the present embodiment, the blade tip surface 31 is formed to have a size that covers the entire end surface of the tip 30 of the final stage blade 21d. That is, when the last stage moving blade 21d is assembled to the low pressure turbine 9, the length in the rotation axis direction of the moving blade tip surface 31 is the blade portion 26 at the tip 30 of the last stage moving blade 21d when viewed in the meridional section. Is longer than the length in the direction of the rotation axis. Between the moving blade tip surface 31 and the inner peripheral surface of the outer diaphragm 17d, there is a gap 42 that communicates the space upstream and downstream of the final stage moving blade 21d (see FIG. 2). A guide 32 is provided on the blade tip surface 31. The guide 32 will be described later.

  The tie boss 28 is provided between the root portion 29 and the tip portion 30 of the wing portion 26. In the present embodiment, the tie boss 28 is provided at an intermediate portion in the radial direction of the wing portion 26. The tie boss 28 includes a back tie boss (first tie boss) 28A provided on the back side of the final stage moving blade 21d, and a ventral tie boss (second tie boss) 28B provided on the ventral side. The tie boss 28 contacts the tie boss of the adjacent blade during the rotation of the turbine rotor 12 and connects the final stage moving blade 21d and the adjacent blade. The operation of the tie boss 28 during the rotation of the turbine rotor 12 will be described later. In the present embodiment, the case where the tie boss 28 is provided in the intermediate portion in the radial direction of the wing portion 26 is illustrated. However, the tie boss 28 is arranged in the radial direction from the intermediate portion of the wing portion 26 according to the torsional rigidity or the like of the wing portion 26. It may be shifted inward or radially outward.

  4 is a perspective view showing a state in which the final stage moving blade 21d is fixed to the rotor disk 20d, and FIG. 5 is a view of FIG. 4 as viewed from the outside in the radial direction. In FIG. 4, the rotor disk 20d is omitted.

  As the rotational speed of the turbine rotor 12 increases, centrifugal force acts from the root portion 29 toward the tip portion 30 on the blade portion 26 of the final stage moving blade 21d. As described above, since the wing portion 26 is twisted, the wing portion 26 is twisted back (untwisted) due to the centrifugal force. As a result, as shown in FIG. 4, the untwisted moment 33 is at the tip 30 of the wing 26, the untwisted moment 34 is at the middle, and the untwisted moment 35 is at the root 29. Act on. Similarly, an untwist moment 33 ′ is present at the tip 30 ′ of the blade portion 26 ′ of the final stage moving blade 21d ′ adjacent to the final stage moving blade 21d in the rotational direction, and an untwist moment 34 ′ is present at the intermediate portion. The untwist moment 35 'acts on the root portion 29' in the direction indicated by the arrow.

  As shown in FIG. 5, in the present embodiment, when the final stage moving blade 21d is assembled to the low pressure turbine 9, the downstream side in the rotational direction of the first cover 27A of the final stage moving blade 21d when viewed from the outside in the radial direction. The end face 36 of the second stage and the end face 36 'on the upstream side in the rotational direction of the second cover 27B' of the final stage moving blade 21d 'restrain the untwist moments 33, 33' during the rotation of the turbine rotor 12. . Further, the second tie boss 28B of the final stage moving blade 21d and the first tie boss 28A 'of the final stage moving blade 21d' constrain the untwist moments 34, 34 '. Thereby, during rotation of the turbine rotor 12, the end surface 36 and the end surface 36 'are in surface contact, the second tie boss 28B and the first tie boss 28A' are in surface contact, and the last stage blades 21d and 21d 'are in the rotational direction. Connected to

  FIG. 6 is a partially enlarged view showing the tip portion 30 of the final stage moving blade 21d.

  In the present embodiment, when the last stage moving blade 21d is assembled to the low pressure turbine 9, as shown in FIG. 6, the surface of the protrusion 55 of the outer diaphragm 17d that faces the last stage moving blade 21d as seen in the meridional section. Are provided with seal fins 38 (no seal fins are provided on the rotor blade tip surface 31 of the cover 27). In the specification of the present application, a portion of the inner peripheral surface of the protrusion 55 of the outer diaphragm 17d that extends in the rotation axis direction and faces the final stage moving blade 21d is referred to as a moving blade facing surface 40 for convenience. In the present embodiment, the configuration in which the outer diaphragm 17d and the protruding portion 55 are integrally formed is exemplified. However, the protruding portion 55 is attached to the outer diaphragm 17d by welding or the like as an inner casing outside the final stage moving blade 21d. It is also good. When the final stage blade 21d is assembled to the low-pressure turbine 9, the seal fin 38 is configured to suppress the leakage flow 43 flowing through the gap 42 between the cover 27 and the blade facing surface 40 when viewed in the meridian plane cross section. It extends from the moving blade facing surface 40 toward the final moving blade 21d. In other words, the final stage moving blade 21d is arranged such that the tip (cover 27) faces the seal fin 38. In the present embodiment, one seal fin 38 is provided on the moving blade facing surface 40 in the rotation axis direction. In order to avoid contact between the stationary body 14 and the turbine rotor 12, there is a small gap between the front end portion (end portion on the radially inner side) of the seal fin 38 and the moving blade front end surface 31.

  As shown in FIG. 6, the guide 32 is provided on the moving blade tip surface 31 of the cover 27 so as to be positioned on the side closer to the diffuser 10 with respect to the seal fin 38. 6 illustrates the case where one seal fin 38 is provided in the rotation axis direction on the moving blade facing surface 40 of the outer diaphragm 17d, but a plurality of seal fins are provided in the rotation axis direction. The guide 32 may be provided so as to be positioned closer to the diffuser 10 with respect to the seal fin closest to the diffuser 10 among the plurality of seal fins.

  As shown in FIG. 5, in the present embodiment, when the final stage blade 21d is assembled to the low-pressure turbine 9, the guide 32 extends in the rotational direction when viewed from the outside in the radial direction, and is adjacent to both sides in the rotational direction. It is provided so that both ends may face the edge part of each guide of the last stage rotor blade to match. That is, the downstream end portion of the last stage blade 21d in the rotation direction of the guide 32 is located upstream of the rotation direction of the guide 32 ′ of the last stage blade 21d ′ adjacent to the last stage blade 21d in the rotation direction. Opposite the end. In the present embodiment, the guide 32 is provided on the rotor blade tip surface 31 of the cover 27 from the upstream end to the downstream end in the rotational direction. With this configuration, when the final stage moving blade 21d is assembled to the low pressure turbine 9, the guide 32 covers the outside of the plurality of final stage moving blades arranged in the rotation direction when viewed from the upstream side. It is formed in a ring shape.

  As shown in FIG. 6, in this embodiment, when the final stage moving blade 21 d is assembled to the low pressure turbine 9, the guide 32 is seen from the moving blade front end surface 31 toward the moving blade facing surface 40 when viewed in the meridional section. It is provided as a protruding portion that protrudes. The guide 32 includes a wall surface 37 and a guide surface 41.

  The wall surface 37 extends from the blade tip surface 31 of the cover 27 toward the blade facing surface 40 of the outer diaphragm 17d. The height of the wall surface 37 (the length in the radial direction from the blade tip surface 31) is shorter than the length in the radial direction from the blade tip surface 31 to the tip of the seal fin 38 during rotation. As a result, even when the relative position in the rotational axis direction of the final stage moving blade 21d and the seal fin 38 changes due to the difference in thermal expansion between the rotating part such as the rotor and the stationary part such as the casing, the guide 32 contacts the seal fin 38. This can be avoided, and the reliability of the low-pressure turbine 9 can be ensured.

  When the final stage moving blade 21d is assembled to the low-pressure turbine 9, the guide surface 41 is formed so as to be inclined upward in the direction from the seal fin 38 toward the diffuser 10 when viewed from the meridional section. In the present embodiment, the guide surface 41 is formed in a convex shape toward the rotation axis from the end portion (upstream edge portion) on the seal fin 38 side to the end portion (downstream edge portion) on the diffuser 10 side.

  The design and manufacturing method of the guide 32 and the method of application to the final stage moving blade 21d will be described.

As shown in FIG. 6, in the present embodiment, when the final stage moving blade 21 d is assembled to the low pressure turbine 9, the supersonic leakage flow 43 flowing on the downstream side of the seal fin 38 in the gap 42 as viewed in the meridional section. Impacts the guide surface 41 when passing through the upstream edge of the guide surface 41, and the incident point (diagonal shock wave) of the shock wave (diagonal shock wave) W inclined outward in the radial direction is generated at the upstream edge of the guide surface 41. P is located on the moving blade facing surface 40 of the outer diaphragm 17d on the upstream side of the outer peripheral wall 10A of the diffuser 10. In this case, the inclination angle of the oblique shock wave W with respect to the rotor blade tip surface 31 (rotation axis R) is β, and the rotation axis direction from the upstream edge portion of the guide surface 41 to the connection portion between the outer diaphragm 17d and the outer peripheral wall 10A of the diffuser 10 Where L is L and the radial length from the blade tip surface 31 to the blade facing surface 40 is d, the following equation (1) must be satisfied.
tan β ≧ d / L (1)

On the other hand, if the inclination angle with respect to the moving blade tip surface 31 (rotation axis R) connecting the upstream edge portion and the downstream edge portion of the guide surface 41 is θ, it can be expressed as the following equation (2).
tan θ = {2cot β (M1 ² sin ² β−1)} / {M1 ² (κ + cos2β) +2} (2)

  However, κ is a specific heat ratio of the working fluid, and is 1.1 to 1.14, for example, in the case of the working fluid (wet steam) flowing through the final stage moving blade. In this embodiment, κ is set to 1.135. M 1 is the Mach number of the supersonic leakage flow 43 flowing into the gap 42.

  The guide 32 is designed and manufactured by determining the tilt angle θ using the formula (2) and determining the height of the wall surface 37 so that the tilt angle β satisfies the formula (1). When the final stage moving blade 21d is assembled to the low-pressure turbine 9, the manufactured guide 32 is positioned on the side closer to the diffuser 10 with respect to the seal fin 38 provided on the moving blade facing surface 40 when viewed in the meridional section. The cover 27 is attached to the blade tip surface 31 of the cover 27 by welding or the like.

(Operation)
-Main flow (flow passing through blades of moving blades) The main flow of the working fluid 22 flows between the stationary blades 18a of the first-stage stationary blade cascade 15a, and turns the flow along the shape of the stationary blades 18a. It accelerates and flows out between the stationary blades 18a. The main flow that flows out between the stationary blades 18a flows into the moving blades 21a of the first-stage moving blade cascade 53a arranged on the downstream side of the first-stage stationary blade cascade 15a, and rotates the turbine rotor 12. The main flow that flows out between the rotor blades 21a flows between the stationary blades 18b of the second-stage stationary blade cascade 15b arranged on the downstream side of the first-stage movable blade cascade 53a. Thereafter, the mainstream flows into the diffuser 10 provided on the downstream side of the final stage moving blade 21d while repeating turning and applying acceleration components by the stationary blade and rotational driving of the moving blade.

About Leakage Flow As shown in FIG. 6, a part of the working fluid 22 passes through a minute gap between the tip of the seal fin 38 and the cover 27 and flows into the gap 42 as a leakage flow 43.

  When the pressure of the working fluid 22 on the upstream side of the final stage moving blade 21d is increased, the rotational speed of the final stage moving blade 21d is increased, and the rotational peripheral speed of the tip portion of the blade part 26 is increased. In order for the working fluid to give a rotational driving force to the moving blade, it is necessary to increase the stagnation point pressure at the moving blade inlet as the peripheral speed increases. Therefore, the pressure ratio before and after the seal fin 38 is increased, and the rotor blade tip peripheral speed Mach number obtained by dividing the rotational peripheral speed of the tip of the blade part 26 by the sound speed of the working fluid 22 flowing into the blade part 26 is 1.0. When the pressure is larger than that, the pressure ratio before and after the seal fin 38 becomes more likely to exceed the critical pressure ratio, which becomes supersonic downstream after passing through the seal fin 38.

  The supersonic leakage flow 43 flowing on the downstream side of the seal fin 38 in the gap 42 collides with the guide surface 41 when passing through the upstream edge of the guide surface 41 of the guide 32 provided on the rotor blade tip surface 31. At this time, an oblique shock wave W is generated from the upstream edge of the guide surface 41 toward the incident point P of the moving blade facing surface 40. A supersonic leakage flow 43 passing through the upstream edge of the guide surface 41 and flowing along the guide surface 41 is decelerated by interfering with the oblique shock wave W, and the flow is turned radially outward by the oblique shock wave W. Is done. After that, the leakage flow 43 flows into the diffuser 10 from the gap 42 but is turned outward, so that the flow area becomes a throttle flow path instead of an enlarged flow path as shown in FIG. It is decelerated to subsonic flow without significant pressure loss.

(effect)
(1) FIG. 7 is a partially enlarged view showing the tip of the final stage moving blade A according to the comparative example. As shown in FIG. 7, the guide B is not provided in the cover B of the final stage moving blade A according to the comparative example. Therefore, the supersonic leakage flow D that passes through the minute gap F between the front end portion of the seal fin G and the cover B and flows through the gap between the cover B and the outer diaphragm C increases the flow velocity to increase the diffuser E. After that, it becomes a subsonic flow with a total pressure loss by a shock wave. At this time, the pressure of the leakage flow D, which has decreased with the passage of the seal fin, rapidly increases as it passes through the shock wave H in the diffuser E and becomes subsonic. When the wall boundary layer flow with a slow flow velocity near the diffuser wall surface passes through this shock wave, it peels off from the wall surface of the diffuser E, and the effect of expanding the channel area as a diffuser is reduced, resulting in a decrease in pressure recovery performance. May increase the pressure loss.

  On the other hand, in the present embodiment, when the final stage moving blade 21d is assembled to the low pressure turbine 9, as seen in the meridian plane cross section, as shown in FIG. 6, it is inclined upward in the direction from the seal fin 38 toward the diffuser 10. A guide 32 having a formed guide surface 41 is provided on the rotor blade tip surface 31 of the cover 27. Therefore, the supersonic leakage flow 43 flowing on the downstream side of the seal fin 38 in the gap 42 is turned along the guide surface 41 to generate an oblique shock wave W, and the supersonic leakage flow 43 can be decelerated. Further, since the leakage flow passes through the oblique shock wave W, the flow of the supersonic leakage flow 43 can be turned radially outward to reduce the flow cross-sectional area, and the supersonic leakage flow 43 is further decelerated. be able to. From the above, it is possible to suppress a sudden increase in pressure due to a shock wave when the supersonic leakage flow 43 flows into the diffuser 10 to become a subsonic flow, and to reduce the intensity of the shock wave generated in the diffuser 10. . Therefore, when a shock wave generated in the diffuser 10 is passed, it is possible to avoid separation of a wall surface boundary layer flow having a low flow velocity flowing in the vicinity of the outer peripheral wall 10A of the diffuser 10 from the outer peripheral wall 10A of the diffuser 10, and pressure loss. Can be suppressed.

  (2) In the present embodiment, when the last stage moving blade 21d is assembled to the low pressure turbine 9, the guide surface 41 rises from the moving blade tip surface 31 in the direction from the seal fin 38 toward the diffuser 10 when viewed from the meridional section. Inclined. Therefore, the cross-sectional area of the leakage flow 43 flowing on the downstream side of the seal fin 38 in the gap 42 can be reduced from the upstream edge portion of the guide surface 41 toward the downstream edge portion. Accordingly, the cross-sectional area of the supersonic leakage flow 43 can be reduced, and the supersonic leakage flow 43 can be further decelerated. This also contributes to avoiding the separation of the wall boundary layer flow having a low flow velocity from the outer peripheral wall 10A of the diffuser 10 and suppressing an increase in pressure loss.

  (3) As shown in FIG. 7, in the final stage moving blade A according to the comparative example, a part of the supersonic leakage flow D flowing through the diffuser E passes through the blade part K of the final stage moving blade A and the diffuser E. Interference loss due to fluid mixing at different speeds may occur due to interference with the main flow L flowing into the. In contrast, in the present embodiment, as described above, the flow of the supersonic leakage flow 43 can be diverted radially outward, so that it flows into the diffuser 10 through the blade portion 26 of the final stage moving blade 21d. It is possible to avoid interference with the mainstream.

  (4) In the present embodiment, when the last stage moving blade 21d is assembled to the low pressure turbine 9, the guide 32 is positioned on the moving blade tip surface 31 from the upstream end in the rotational direction to the downstream side when viewed from the radially outer side. It is provided over the end portion, and both ends thereof are opposed to the end portion of each guide of the final stage moving blade adjacent to both sides in the rotation direction. As a result, the guide 32 can be formed in a ring shape so as to cover the outer sides of the plurality of final stage rotor blades as viewed from the upstream side, and the supersonic leakage flow 43 flowing through the gap 42 can be The increase in pressure loss can be reliably suppressed.

Second Embodiment
(Constitution)
FIG. 8 is a partially enlarged view showing the tip portion 30 of the final stage moving blade 44d according to the present embodiment. In FIG. 8, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The final stage moving blade 44d according to the present embodiment is different from the final stage moving blade 21d according to the first embodiment in that the shape of the guide 45 is different. Other configurations are the same as those of the final stage moving blade 21d according to the first embodiment.

  In this embodiment, when the last stage moving blade 44d is assembled to the low pressure turbine 9, as shown in FIG. It is provided as a recessed part recessed on the blade part 26 side) of the final stage moving blade 44d. The guide 45 includes a wall surface 46 and a guide surface 47.

  The wall surface 46 is formed so as to extend from the rotor blade tip surface 31 of the cover 27 to the rotating shaft side. The depth of the wall surface 46 (the length from the blade tip surface 31 toward the inside in the radial direction) is smaller than the thickness of the cover 27 (the length in the radial direction). The guide surface 47 is formed to be inclined upward in the direction from the seal fin 38 toward the diffuser 10, and connects the end portion on the radially inner side of the wall surface 46 and the blade tip surface 31.

  The design and manufacturing method of the guide 45 and the application method to the final stage moving blade 44 will be described.

  In the present embodiment, when the final stage moving blade 44d is assembled to the low pressure turbine 9, as shown in FIG. 8, a line extending in the rotation axis direction through the upstream edge of the guide surface 47 as viewed in the meridional section is used as a reference. Assuming that the inclination angle θ of the oblique shock wave W with respect to the reference line X is β and the length in the radial direction from the moving blade facing surface 40 to the reference line X is d, the inclination angle θ is obtained from equations (1) and (2). The guide 45 is designed and manufactured by determining the depth of the wall 46. When the final stage moving blade 21d is assembled to the low pressure turbine 9, the manufactured guide 45 is positioned on the side closer to the diffuser 10 with respect to the seal fin 38 provided on the moving blade facing surface 40 when viewed in the meridional section. Thus, the rotor blade tip surface 31 of the cover 27 is formed by cutting or the like.

(effect)
In the present embodiment, when the final stage moving blade 21d is assembled to the low pressure turbine 9, as shown in FIG. 8, the guide is formed so as to be inclined upward in the direction from the seal fin 38 toward the diffuser 10 when viewed from the meridional section. A guide 45 having a surface 47 is provided on the blade tip surface 31. Therefore, as in the first embodiment, it is possible to avoid separation of the wall surface boundary layer flow having a low flow velocity flowing in the vicinity of the outer peripheral wall 10A of the diffuser 10 from the outer peripheral wall 10A of the diffuser 10, and to suppress an increase in pressure loss. it can. In addition, in the present embodiment, the following effects can be obtained.

  In the present embodiment, since the guide 45 is provided as a recess recessed from the rotor blade tip surface 31 toward the rotating shaft, the interference between the guide 45 and the seal fin 38 can be avoided more reliably, and the reliability of the low-pressure turbine 9 is improved. Can increase the sex.

<Third Embodiment>
(Constitution)
FIG. 9 is a view of the final stage moving blade 48d according to the present embodiment as viewed from the outside in the radial direction. In FIG. 9, parts that are the same as in the first embodiment are given the same reference numerals, and descriptions thereof are omitted as appropriate.

  The final stage moving blade 48d according to the present embodiment is different from the final stage moving blade 21d according to the first embodiment in that the shape and position of the guide 49 are different. Other configurations are the same as those of the final stage moving blade 21d according to the first embodiment.

  As shown in FIG. 9, in this embodiment, the guide 49 is along the rear edge (the edge on the diffuser 10 side) of the rotor blade tip surface 31 of the cover 27 when viewed from the radially outer side (stationary body side). Is provided. Other configurations are the same as those of the guide 32 according to the first embodiment.

  In the configuration illustrated in FIG. 9, the trailing edge of the moving blade tip surface 31 of the cover 27 extends in the rotational direction while meandering, and the guide 49 extends along the trailing edge of the moving blade tip surface 31 of the cover 27. And meandering. In the present embodiment, the case where the guide 49 is a projecting portion is illustrated, but as in the second embodiment, a recess that is recessed from the blade tip surface 31 toward the rotating shaft may be used.

(effect)
Also in this embodiment, the same effect as the first embodiment can be obtained. In addition, in the present embodiment, the following effects can be obtained.

  In the present embodiment, since the guide 49 is provided along the rear edge portion of the blade tip surface 31 of the cover 27, the diffuser 10 side from the seal fin 38 (see FIG. 6) provided on the blade facing surface 40. It can be provided at a position distant from each other. Therefore, the interference between the guide 32 and the seal fin 38 can be avoided more reliably, and the reliability of the low-pressure turbine 9 can be further improved.

<Fourth embodiment>
(Constitution)
FIG. 10 is a view of the final stage moving blade 50d according to the present embodiment as viewed from the outside in the radial direction. In FIG. 10, parts that are the same as in the first embodiment are given the same reference numerals, and descriptions thereof are omitted as appropriate.

  The final stage moving blade 50d according to the present embodiment is different from the final stage moving blade 21d according to the first embodiment in that the shape and position of the guide 51 are different. Other configurations are the same as those of the final stage moving blade 21d according to the first embodiment.

  In the present embodiment, when viewed from the outside in the radial direction, the guide 51 is flowed to a region on the back side of the blade portion 26 (first cover 27A) in the blade tip surface 31 of the cover 27 of the last stage blade 50d. 52 is provided so as to block. In the present embodiment, as in the first embodiment, the case where the guide 51 is a projecting portion is illustrated. However, as in the second embodiment, the recess may be recessed from the blade tip surface 31 toward the rotating shaft. .

(effect)
As shown in FIG. 10, the working fluid flowing out from the stationary blade (not shown) provided upstream of the final stage moving blade 50d flows into the final stage moving blade 50d in the direction indicated by the vector V, and When 50d rotates about the rotation axis in the direction indicated by the vector U, the working fluid flowing in the direction indicated by the vector V is represented by the vector V when viewed in the relative coordinate system rotating together with the final stage moving blade 50d. By the synthesis of the vector U, it flows in the direction indicated by the vector W and flows into the flow path 52 between the blade part 26 of the final stage moving blade 50d and the blade part 26 'of the final stage moving blade 50d' adjacent to the back side. .

  In the present embodiment, since the guide 51 is provided so as to block the flow path 52 in the region on the back side of the blade portion 26 of the blade tip surface 31 of the cover 27 when viewed from the outside in the radial direction, When 50d is viewed from the direction indicated by the vector W described above, the guide 51 is formed in a ring shape so as to cover the outer sides of the plurality of final stage rotor blades that rotate about the rotation axis. Therefore, also in this embodiment, the same effect as that of the first embodiment can be obtained. In addition, in the present embodiment, the following effects can be obtained.

  In the present embodiment, since the guide 51 may be provided in the region on the back side of the blade portion 26 of the rotor blade tip surface 31 of the cover 27, the guide 32 is disposed on the rotor blade tip surface 31 of the cover 27 on the upstream side in the rotation direction. It is not necessary to provide from the edge part of this to the edge part of a downstream side, The increase in the manufacturing cost of a guide can be suppressed by that much.

<Fifth Embodiment>
(Constitution)
FIG. 11 is a partially enlarged view showing the tip portion 30 of the final stage moving blade 54d according to the present embodiment. In FIG. 11, parts that are the same as in the first embodiment are given the same reference numerals, and descriptions thereof are omitted as appropriate.

  This embodiment is different from the final stage moving blade 21d according to the first embodiment in that the positions of the guide 32 and the seal fin 38 are interchanged. Other configurations are the same as those of the final stage moving blade 21d according to the first embodiment.

  As shown in FIG. 11, in this embodiment, the seal fin 38 is provided on the moving blade front end surface 31 of the cover 27 instead of the moving blade facing surface 40 of the outer diaphragm 17d, and the guide 32 is replaced with the moving blade front end surface 31. And provided on the moving blade facing surface 40. In the present embodiment, the guide surface 41 of the guide 32 is formed to be inclined downward in the direction from the seal fin 38 toward the diffuser 10 when viewed from the meridional section when the final stage moving blade 54d is assembled to the low pressure turbine 9. Yes. The guide surface 41 is formed in a concave shape from the upstream edge to the downstream edge toward the rotation axis.

(effect)
As in the present embodiment, the seal fin 38 is provided on the blade front surface 31 instead of the blade facing surface 40 and the guide 32 is provided on the blade facing surface 40 instead of the blade front surface 31. The supersonic leakage flow 43 flowing downstream of the 42 seal fins 38 is caused to collide with the guide surface 41 to generate an oblique shock wave W, and the leakage flow 43 can be decelerated. Therefore, as in the first embodiment, it is possible to avoid separation of the wall boundary layer flow having a low flow velocity flowing in the vicinity of the outer peripheral wall 10A of the diffuser 10 from the outer peripheral wall 10A of the diffuser 10 and to suppress an increase in pressure loss. it can.

<Others>
The present invention is not limited to the above-described embodiments, and includes various modifications. For example, each of the above-described embodiments has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

  In each embodiment mentioned above, the case where the guide surface was formed in the convex shape or the concave shape toward the rotation axis from the upstream edge portion to the downstream edge portion was exemplified. However, an essential effect of the present invention is to provide a moving blade that can suppress an increase in pressure loss due to separation of leakage flow from the diffuser wall surface. As long as this essential effect is obtained, the configuration described above is not necessarily required. It is not limited. For example, the guide surface may be formed linearly from the upstream edge to the downstream edge.

  Moreover, in each embodiment mentioned above, the structure which the outer side diaphragm 17d opposes to the cover 27 was illustrated. However, as long as the essential effects of the present invention described above are obtained, the configuration is not necessarily limited to that described above. The member facing the cover 27 is the stationary body 14. For example, the casing 16 may be opposed to the cover 27.

  Moreover, although each embodiment mentioned above demonstrated the case where the moving blade which concerns on this invention was applied to the last stage of the low pressure turbine 9, the application object of the moving blade which concerns on this invention is not limited to the last stage of a low pressure turbine. For example, the present invention can be applied to the final stage of the high-pressure turbine 3 or the intermediate-pressure turbine 6.

9 Low pressure turbine
10 Diffuser 12 Turbine rotor 14 Stationary body 21d Final stage moving blade (moving blade)
22 Working fluid 26 Blade 27 Cover 31 Moving blade tip 32 Guide 38 Seal fin 41 Guide

Claims (9)

A turbine rotor and a stationary body covering the turbine rotor, the turbine rotor being arranged at a final stage closest to the diffuser among a plurality of paragraphs of a turbine in which a diffuser is connected to a working fluid outlet side of the stationary body, and the stationary body In the moving blade whose tip faces the seal fin provided in
The wings,
A cover provided at the tip of the wing,
A guide provided on a tip surface of a moving blade, which is a surface facing the stationary body of the cover,
When assembled to the turbine, the rotor blade tip surface extends in the direction of the rotation axis of the turbine rotor when viewed in a cross section cut along a plane including the rotation axis of the turbine rotor, and the guide is in contact with the seal fin. A moving blade having a guide surface that is located on a side close to the diffuser and is formed to be inclined upward in a direction from the seal fin toward the diffuser. The moving blade according to claim 1,
The moving blade according to claim 1, wherein the guide is a protruding portion that protrudes from the moving blade tip surface toward the stationary body or a concave portion that is recessed from the moving blade tip surface toward the rotating shaft. The moving blade according to claim 2,
A moving blade having a moving blade tip peripheral speed Mach number obtained by dividing the rotational peripheral speed of the tip of the blade by the sound speed of the working fluid flowing through the tip of the blade exceeds 1.0. The moving blade according to claim 2,
The moving blade according to claim 1, wherein the guide surface is a curved surface convex toward the rotation axis. The moving blade according to claim 2,
The moving blade according to claim 1, wherein the guide extends in the rotation direction of the turbine rotor, and is provided so that both ends thereof are opposed to the end portions of the guides of the moving blade adjacent to both sides in the rotation direction. The moving blade according to claim 2,
The moving blade according to claim 1, wherein the guide is provided along a rear edge portion of the moving blade front end surface. The moving blade according to claim 2,
When viewed from the stationary body side, the guide is provided in a region on the back side of the blade portion of the moving blade tip surface, and a flow between the blade portion and a blade portion of the moving blade adjacent to the back surface side. A moving blade characterized by being provided so as to block the road.   A turbine comprising: a turbine rotor including the moving blade according to claim 1; and a stationary body including a stationary blade disposed to face the moving blade in the rotation axis direction. The turbine according to claim 8.
The seal fin is provided on the moving blade tip surface instead of the stationary body,
The guide is provided on a moving blade facing surface, which is a surface facing the moving blade tip surface of the stationary body, instead of the moving blade tip surface,
When assembled to the turbine, the moving blade-facing surface extends in the direction of the rotation axis of the turbine rotor when viewed in a cross-section cut along a plane including the rotation axis of the turbine rotor, and the guide extends from the seal fin to the seal fin. A turbine configured to have a guide surface formed in a downward slope in a direction toward a diffuser.

Images