JP2015175336A - Turbine rotor blade and steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine rotor blade and a steam turbine capable of reducing fluid loss at the extremity end of the rotor blade and restricting an excessive contact surface pressure between the adjoining rotor blades.SOLUTION: A rotor blade 22 in this preferred embodiment comprises a front edge snubber 51 protruding at the front edge side of a blade extremity end toward a rear side 43, and a rear edge snubber 52 protruding at the rear edge side of a blade extremity end toward a belly side 44. During operation, a thickness of a snubber structure 70 between a front edge 71 and a rear edge 72 of the snubber structure 70 becomes maximum at a sectional surface in a steam flow direction of the snubber structure 70 formed by contacting the front edge snubber 51 of the rotor blade 22 adjacent to the rear edge snubber 52 or the rear edge snubber 52 of the rotor blade 22 adjacent to the front edge snubber 51.

Description

  Embodiments described herein relate generally to a turbine blade and a steam turbine.

  In a thermal power plant or a nuclear power plant, steam generated by a boiler, a heat exchanger, a steam generator, or the like is introduced into a steam turbine. In the steam turbine, the heat energy of the introduced steam is converted into rotational energy.

  Such steam turbines are required to have high output and high efficiency. As a countermeasure for increasing the output, it has been studied to increase the blade length in the turbine stage at the turbine outlet represented by the final stage. In addition, measures for suppressing the vibration of the moving blade during operation, which becomes a problem with the increase in the length of the blades, are being studied at the same time. Reduction of turbine loss is being studied as a measure for improving efficiency.

  FIG. 13 is a perspective view of a moving blade 300 in a conventional steam turbine. 14 and 15 are plan views of a moving blade 300 in a conventional steam turbine as viewed from the outside in the radial direction. FIG. 14 shows the moving blade 300 when stationary, and FIG. 15 shows the rotating blade 300 when rotating. 13 and 14 show the steam flow direction Ds, the rotational direction Dr of the rotor blade 300, and the turbine rotor axial direction Da. FIG. 16 is a view showing a CC cross section of FIG. FIG. 16 shows only a cross section of the snubber 310. Here, a low-pressure turbine is illustrated. Moreover, as the moving blade 300, what constitutes the turbine stage of the final stage is illustrated.

  As shown in FIG. 13, a snubber 310 is integrally formed at the tip of the rotor blade 300 at the final stage. The snubber 310 includes a leading edge snubber 311 that protrudes toward the back side 302 on the leading edge 301 side of the moving blade 300, and a trailing edge snubber 312 that protrudes toward the ventral side 304 on the trailing edge 303 side of the moving blade 300. The leading edge snubber 311 is adjacent to the trailing edge snubber 312 of the adjacent moving blade 300 in the circumferential direction, and the trailing edge snubber 312 is adjacent to the leading edge snubber 311 of the adjacent moving blade 300 in the circumferential direction.

  At rest, as shown in FIG. 14, a gap G is formed between adjacent snubbers 310. This is because if the gap G is not formed between the adjacent snubbers 310 at rest, the assembly becomes difficult, and the restraint moment generated during the operation increases, and an excessive stress is applied to the snubber.

  On the other hand, during rotation, the blade 300 is twisted back (untwisted), and as shown in FIG. 15, the contact surface 311 a of the leading edge snubber 311 and the contact surface of the trailing edge snubber 312 in the adjacent blade 300. 312a contacts. As a result, a whole-group connection structure is formed. In this manner, by bringing the adjacent snubbers 310 into contact with each other during rotation, an increase in the restraining moment is minimized, and the vibration of the moving blade 300 is suppressed.

  Since the moving blade 300 rotates as described above, there is a gap between the snubber 310 and the diaphragm outer ring that is a stationary member provided around the moving blade 300 (snubber 310). Suppressing the flow rate of the steam leaking from this gap also leads to improvement of turbine efficiency.

  Here, as shown in FIG. 16, the cross-sectional shape of the snubber 310 is a rectangle. That is, the tip part between the moving blades 300 through which the steam flows has a block-like structure including the trailing edge snubber 312 and the leading edge snubber 311. Therefore, the front edge 312b of the rear edge snubber 312 facing the steam flow direction is a flat surface. In addition, the rear edge 311b of the leading edge snubber 311 on the side from which the steam flows is also a flat surface.

  Since the snubber 310 is provided at the blade tip having the largest outer diameter, the circumferential speed is the largest. At the tip of the last stage moving blade 300 having a long blade length, the relative inflow speed of the flow may exceed the sound speed due to the high peripheral speed. When a supersonic flow field is formed from the inlet at the tip of the moving blade 300 at the final stage, a separation shock wave 320 is formed in front of the leading edge 312b of the trailing edge snubber 312 as shown in FIG. There is. A wake 330 is generated from the rear edge 311b of the leading edge snubber 311.

Japanese Patent No. 4105528

  As described above, since the block-shaped snubber 310 exists at the tip between the moving blades 300 through which steam flows, it becomes a fluid loss factor due to the blockage effect on the flow. When the separation shock wave 320 is formed in front of the front edge 312b of the trailing edge snubber 312, a total pressure loss occurs before and after the separation shock wave 320, and the generated separation shock wave 320 interferes with the main flow of steam and flows. Disturbs the fluid and causes a fluid loss. As the blade length of the final stage moving blade 300 increases, the peripheral speed of the tip increases and the inlet relative inflow velocity increases, and a strong separation shock wave 320 is induced, so these losses tend to increase. Furthermore, fluid loss occurs due to the wake 330 generated from the trailing edge 311b of the leading edge snubber 311.

  In order to reduce the loss as described above, it is conceivable to reduce the thickness T of the snubber 310 as a whole. As a result, the strength of the separation shock wave 320 can be reduced and the shock wave loss can be reduced. Further, the fluid loss due to the blockage effect and the wake 330 can also be reduced. However, when the thickness T of the snubber 310 is reduced as a whole, the contact area between the leading edge snubber 311 and the trailing edge snubber 312 becomes small, and the contact surface pressure becomes excessive. Therefore, excessive stress is generated in the snubber 310.

  The problem to be solved by the present invention is a turbine blade and steam capable of reducing fluid loss at the tip of the blade and suppressing excessive contact surface pressure between the contact surfaces of adjacent blades. A turbine is provided.

  The turbine rotor blade according to the embodiment includes a front edge connecting member that protrudes to the back side on the front edge side of the blade tip portion, and a rear edge connection member that protrudes to the ventral side on the rear edge side of the blade tip portion. In operation, the leading edge coupling member of the turbine blade adjacent to the trailing edge coupling member or the coupling formed by contacting the trailing edge coupling member of the turbine blade adjacent to the leading edge coupling member. In the cross section in the steam flow direction of the partial structure, the thickness of the connecting part structure is maximized between the front edge and the rear edge of the connecting part structure.

It is a figure which shows the meridional section of the perpendicular direction of the steam turbine provided with the moving blade of 1st Embodiment. It is a perspective view of the moving blade of 1st Embodiment. It is a top view when the moving blade of 1st Embodiment is seen from the radial direction outer side. It is a top view when the moving blade of 1st Embodiment is seen from the radial direction outer side. It is a figure which shows the AA cross section of FIG. It is a figure which shows the cross section equivalent to the AA cross section of FIG. 4 of the snubber structure of the other structure of the moving blade of 1st Embodiment. It is a figure which shows the cross section equivalent to the AA cross section of FIG. 4 of the snubber structure of the other structure of the moving blade of 1st Embodiment. It is a top view when the snubber structure provided with the seal fin in the moving blade of 1st Embodiment is seen from the radial direction outer side. It is a figure which shows the BB cross section of FIG. It is a figure which shows the cross section equivalent to the AA cross section of FIG. 4 of the snubber structure of the moving blade of 2nd Embodiment. FIG. 6 is a view showing a cross section corresponding to the AA cross section of FIG. 4 of a snubber structure having another configuration in the moving blade of the second embodiment. It is a figure which shows the cross section equivalent to the AA cross section of FIG. 4 of the snubber structure of the moving blade of 3rd Embodiment. It is a perspective view of the moving blade in the conventional steam turbine. It is a top view when the moving blade in the conventional steam turbine is seen from the radial direction outer side. It is a top view when the moving blade in the conventional steam turbine is seen from the radial direction outer side. It is a figure which shows CC cross section of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a meridional section in the vertical direction of a steam turbine 10 including a moving blade 22 according to the first embodiment. Here, a low-pressure turbine will be described as an example.

  As shown in FIG. 1, the steam turbine 10 includes a casing 20, and a turbine rotor 21 is provided in the casing 20. The turbine rotor 21 is formed with a rotor disk 21a. A plurality of rotor blades 22 are implanted in the rotor disk 21a in the circumferential direction to constitute a rotor blade cascade. The rotor blade cascade is formed in a plurality of stages in the axial direction of the turbine rotor 21. The turbine rotor 21 is rotatably supported by a rotor bearing (not shown).

  A diaphragm outer ring 23 is installed on the inner periphery of the casing 20, and a diaphragm inner ring 24 is installed inside the diaphragm outer ring 23. A plurality of stationary blades 25 are arranged in the circumferential direction between the diaphragm outer ring 23 and the diaphragm inner ring 24 to constitute a stationary blade cascade. The stationary blade cascade is provided in a plurality of stages alternately with the moving blade cascade in the axial direction of the turbine rotor 21. The turbine blade cascade and the rotor blade cascade located on the downstream side thereof constitute one turbine stage.

  An annular steam passage 29 through which main steam flows is formed between the diaphragm outer ring 23 and the diaphragm inner ring 24. A ground seal portion 26 is provided between the turbine rotor 21 and the casing 20 to prevent leakage of steam to the outside. In addition, a seal portion 27 is provided between the turbine rotor 21 and the diaphragm inner ring 24 in order to prevent the steam from passing downstream between the turbine rotor 21 and the diaphragm inner ring 24.

  Further, the steam turbine 10 is provided with a steam inlet pipe (not shown) through which the steam from the crossover pipe 28 is introduced into the steam turbine 10 through the casing 20. An exhaust passage (not shown) is provided on the downstream side of the turbine stage at the final stage for exhausting steam that has expanded in the turbine stage. This exhaust passage communicates with a condenser (not shown).

  Next, the configuration of the moving blade 22 of the first embodiment will be described.

  FIG. 2 is a perspective view of the moving blade 22 according to the first embodiment. 3 and 4 are plan views of the moving blade 22 according to the first embodiment as viewed from the outside in the radial direction. FIG. 3 shows the moving blade 22 when stationary, and FIG. 4 shows the rotating blade 22 when rotating. 2 to 3 show the steam flow direction Ds, the rotational direction Dr of the rotor blade 22, and the turbine rotor axial direction Da. FIG. 5 is a view showing a cross section taken along the line AA of FIG. FIG. 5 shows only a cross section of the snubber structure 70. Here, as the moving blade 22, a moving blade provided in the turbine stage of the final stage will be described as an example.

  As shown in FIG. 2, the moving blade 22 includes a blade effective portion 40 twisted from the blade root to the blade tip, a snubber 50 formed at the blade tip of the blade effective portion 40, and a radial direction from the blade root. And a wing implantation portion 60 formed inside. Here, the snubber 50 functions as a connecting member. In addition, a connection member may be called a shroud etc., for example.

  The snubber 50 includes a leading edge snubber 51 projecting toward the back side 43 on the leading edge 41 side of the blade tip portion, and a trailing edge snubber 52 projecting toward the ventral side 44 on the trailing edge 42 side of the blade tip portion. For example, the snubber 50 is formed integrally with the blade effective portion 40. The leading edge snubber 51 functions as a leading edge connecting member, and the trailing edge snubber 52 functions as a trailing edge connecting member.

  As shown in FIG. 3, when stationary, a gap G is formed between the trailing edge snubber 52 and the leading edge snubber 51 adjacent to the trailing edge snubber 52. For example, when the gap G is not formed between the trailing edge snubber 52 and the leading edge snubber 51 at rest, the assembling becomes difficult, and the restraint moment generated during the operation increases, and the snubber 50 is excessively stressed.

  On the other hand, during operation (during rotation), as shown in FIG. 4, for example, the leading edge snubber 51 contacts the trailing edge snubber 52 of the adjacent moving blade 22. Further, during operation, the trailing edge snubber 52 contacts the leading edge snubber 51 of the adjacent moving blade 22. In this way, during operation, the moving blade cascade including the moving blades 22 has a connection structure of a whole circumference group. Here, the structure in which the leading edge snubber 51 and the trailing edge snubber 52 are in contact with each other is referred to as a snubber structure 70. And a snubber structure functions as a connection part structure.

  Next, the configuration of the snubber 50 will be described.

  FIG. 5 shows the snubber structure 70 in the AA cross section shown in FIG. 4, that is, the cross section in the steam flow direction. In the cross section shown in FIG. 5, the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72 of the snubber structure 70. It should be noted that the front edge 71 and the rear edge 72 are not included between the front edge 71 and the rear edge 72 here. That is, between the front edge 71 and the rear edge 72 means between the front edge 71 and the rear edge 72 excluding the front edge 71 and the rear edge 72. The thickness T is the thickness (width) of the snubber structure 70 in the radial direction.

  Here, the maximum thickness Tm exists on the leading edge snubber 51 side of the contact portion 80 between the trailing edge snubber 52 and the leading edge snubber 51. That is, the maximum thickness Tm is obtained in the cross section of the leading edge snubber 51.

  As shown in FIG. 5, the thickness T of the snubber structure 70 monotonously decreases from the position where the maximum thickness Tm is reached toward the front edge 71 side and the rear edge 72 side of the snubber structure 70. In other words, the snubber structure 70 has a tapered shape that tapers from the position having the maximum thickness Tm toward the front edge 71 side and the rear edge 72 side of the snubber structure 70.

  In both the trailing edge snubber 52 and the leading edge snubber 51, the inner circumferential side forms a surface that is inclined toward the outer circumferential side from the position where the maximum thickness Tm is reached toward the leading edge 71 side and the trailing edge 72 side. On the other hand, on the outer peripheral side, both the rear edge snubber 52 and the front edge snubber 51 form a surface that is inclined toward the inner peripheral side from the position where the maximum thickness Tm is reached toward the front edge 71 side and the rear edge 72 side.

  The cross sections of the contact surface 52a of the trailing edge snubber 52 and the contact surface 51a of the leading edge snubber 51 are formed in the same shape, for example. Thereby, the contact part 80 without a level | step difference in the flow direction of a vapor | steam is formed in the inner peripheral side and outer peripheral side of the contact part 80. FIG.

  Here, the cross section in the steam flow direction (see FIG. 4) at the approximate center between the adjacent moving blades is shown in FIG. 5, but the same configuration applies to the cross section in the steam flow direction other than the center. That is, the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72.

  Here, an example in which the maximum thickness Tm is present on the leading edge snubber 51 side from the contact portion 80 is shown, but the maximum thickness Tm is also present on the trailing edge snubber 52 side from the contact portion 80. Good.

  Next, the operation of the snubber 50 of the moving blade 22 will be described.

  When the turbine rotor 21 rotates, a centrifugal force acts on the blade effective portion 40 from the blade root toward the blade tip as the rotational speed increases. Since the blade effective portion 40 is twisted, untwist is generated in the blade effective portion 40 due to centrifugal force. At this time, as shown in FIGS. 4 and 5, the contact surface 52a of the trailing edge snubber 52 and the contact surface 51a of the leading edge snubber 51 of the moving blades 22 adjacent to each other contact each other. As a result, a whole-group connection structure is formed.

  Here, if the inlet relative Mach number at the tip of the moving blade 22 exceeds 1, a separation shock wave S may be formed on the upstream side of the leading edge 71 of the trailing edge snubber 52 as shown in FIG. The separation shock wave S has a shape curved toward the upstream side.

  Here, let L be the central axis extending in the steam flow direction in the cross section of the snubber structure 70 shown in FIG. When the shock wave angle, which is the angle formed between the streamline of the steam on the central axis L and the separation shock wave S, is 90 degrees or close to 90 degrees, the steam flow is decelerated from supersonic to subsonic via the separation shock wave S. Is done. This causes a large total pressure loss. On the other hand, at a position sufficiently away from the central axis L of the snubber structure 70, the shock wave angle is almost equal to the Mach angle. Therefore, almost no total pressure loss occurs.

  In order to reduce the total pressure loss due to the separation shock wave S, it is important to reduce the region where the shock wave angle is 90 degrees or close to 90 degrees. In the snubber 50 of the present embodiment, the thickness T decreases monotonously from the position where the maximum thickness Tm is reached toward the front edge 71 of the snubber structure 70. Therefore, for example, the thickness T of the leading edge 71 can be made thinner than that of a snubber structure having a constant thickness T. As a result, the shock wave angle of the separation shock wave S is reduced as a whole, and the total pressure loss due to the separation shock wave S can be reduced. Here, in order to obtain the above-described effect, it is effective to reduce the wedge angle α at the front edge 71 of the snubber structure 70.

  Further, a wake W is generated from the rear edge 72 of the snubber structure 70. Thereby, fluid loss occurs and the performance of the turbine stage is degraded. In the snubber 50 of the present embodiment, the thickness T decreases monotonously from the position where the maximum thickness Tm is reached toward the rear edge 72 of the snubber structure 70. Therefore, for example, the thickness T of the trailing edge 72 can be reduced as compared with a snubber structure having a constant thickness T. Thereby, the loss due to the wake W can be reduced. Here, in order to obtain the above-described effect, it is effective to reduce the wedge angle β at the trailing edge 72 of the snubber structure 70.

  In addition, since the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72, a sufficient contact area can be ensured in the contact portion 80. Thereby, it is possible to suppress the contact surface pressure from becoming excessive in the contact portion 80.

  As described above, according to the moving blade 22 of the first embodiment, the fluid loss at the tip of the moving blade 22 is reduced, and at the contact portion 80 between the trailing edge snubber 52 and the leading edge snubber 51. Generation of excessive contact pressure can be suppressed.

  Here, the configuration of the snubber structure 70 of the moving blade 22 according to the first embodiment is not limited to the configuration described above. 6 and 7 are views showing a cross-section corresponding to the AA cross-section of FIG. 4 of a snubber structure 70 having another configuration of the rotor blade 22 of the first embodiment.

  As shown in FIG. 6, the position where the snubber structure 70 has the maximum thickness Tm may be a contact portion 80 where the trailing edge snubber 52 and the leading edge snubber 51 contact each other. As described above, in order to reduce the loss due to the separation shock wave S and the wake W, it is effective to reduce the wedge angle α and the wedge angle β. Therefore, by setting the position having the maximum thickness Tm as the contact portion 80, the wedge angle α and the wedge angle β can be reduced under a limited length in the steam flow direction in the snubber structure 70. it can.

  In addition, by setting the position having the maximum thickness Tm as the contact portion 80, the maximum contact area can be obtained in the contact portion 80. Thereby, generation | occurrence | production of the excessive contact surface pressure in the contact part 80 can be suppressed.

  Further, as shown in FIG. 7, in the contact portion 80 where the trailing edge snubber 52 and the leading edge snubber 51 are in contact with each other, the thickness T of the contact surface 52a of the trailing edge snubber 52 is set to the thickness of the contacting surface 51a of the leading edge snubber 51. The thickness may be equal to or greater than T. That is, in the contact portion 80, if the thickness T of the contact surface 52a of the trailing edge snubber 52 is greater than or equal to the thickness T of the contact surface 51a of the leading edge snubber 51, the thickness T of each contact surface is the same. It does not have to be. FIG. 7 illustrates a configuration in which the contact portion 80 is located at a position where the thickness T of the snubber structure 70 becomes the maximum thickness Tm.

  Here, in the contact portion 80, the case where the thickness T of the contact surface 52a of the trailing edge snubber 52 and the thickness T of the contact surface 51a of the leading edge snubber 51 are the same has already been described with reference to FIG. 5 or FIG. doing.

  The difference between the thickness T of the contact surface 52a and the thickness T of the contact surface 51a is preferably small in order to reduce the flow loss at the step. For example, when the thickness T of the contact surface 52a is 1, the thickness T of the contact surface 51a is preferably 0.8 or more and less than 1. The central axis L of the trailing edge snubber 52 and the leading edge snubber 51 in the steam flow direction Ds is preferably coaxial.

  Thus, even if the thickness T of the contact surface 52a of the upstream trailing edge snubber 52 is increased within the above-described range, the steam expands in the flow direction Ds at the level difference, so that the loss due to the level difference can be almost ignored. . Further, the generation of the separation shock wave S due to the step can be suppressed.

  FIG. 8 is a plan view of the snubber structure 70 including the seal fins 90 in the rotor blade 22 of the first embodiment when viewed from the outside in the radial direction. FIG. 8 shows the moving blade 22 during rotation. FIG. 9 is a view showing a BB cross section of FIG. Note that FIG. 9 shows only a cross section of the snubber structure 70 including the seal fin 90.

  As shown in FIGS. 8 and 9, seal fins 90 may be provided on the outer surfaces of the leading edge snubber 51 and the trailing edge snubber 52. The configuration of the seal fin 90 is not particularly limited and may be a structure that is generally widely used. As shown in FIG. 8, during operation (during rotation), for example, the seal fins 90 of adjacent moving blades 22 come into contact with each other. As described above, also in the seal fin 90, a group of connection structures is formed in the circumferential direction.

  The seal fin 90 protrudes from the outer surfaces of the leading edge snubber 51 and the trailing edge snubber 52 so as to face the inner surface of a diaphragm outer ring (not shown). A predetermined gap is provided between the tip of the seal fin 90 and the inner surface of the diaphragm outer ring that covers the outer periphery of the seal fin 90.

  Thus, in the snubber structure 70 provided with the seal fin 90, the loss due to the separation shock wave S and the wake W is reduced, and the flow rate of the leaked steam from between the snubber structure 70 and the diaphragm outer ring is reduced. Can do.

(Second Embodiment)
FIG. 10 is a view showing a cross section corresponding to the AA cross section of FIG. 4 of the snubber structure 70 of the moving blade 22 according to the second embodiment. In addition, the same code | symbol is attached | subjected to the component same as the structure of 1st Embodiment, and the overlapping description is abbreviate | omitted or simplified.

  In the cross section shown in FIG. 10, the contact point P between the trailing edge snubber 52 and the leading edge snubber 51 at the inner peripheral edge of the snubber structure 70 is a part of the inner peripheral edge of the trailing edge snubber 52 and the inner edge of the leading edge snubber 51. It lies on a straight line M formed by a part of the periphery. That is, the inner peripheral edge of the trailing edge snubber 52 on the contact point P side is constituted by a straight line M1, and the inner peripheral edge of the front edge snubber 51 on the contact point P side is constituted by a straight line M2. These straight lines M1 and M2 intersect linearly to form the same straight line, and a straight line M is formed.

  Similar to the first embodiment, the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72 of the snubber structure 70. Here, an example is shown in which the contact portion 80 between the trailing edge snubber 52 and the leading edge snubber 51 has a maximum thickness Tm.

  According to the snubber structure 70 of the second embodiment, the loss due to the separation shock wave S and the wake W can be reduced as in the first embodiment. Further, at the inner peripheral edge of the snubber structure 70, a part of the inner peripheral edge of the trailing edge snubber 52 and a part of the inner peripheral edge of the leading edge snubber 51 are continuously connected in a straight line, so that the flow separation at the contact point P is performed. Etc. are suppressed. Therefore, fluid loss can be reduced.

  The inner peripheral surface of the snubber structure 70 is a surface with which the steam flowing through the blade effective portion 40 comes into contact. Therefore, by having a surface that is continuously connected in a straight line, the interference between the steam flowing along this surface and the steam flowing through the blade effective portion 40 is reduced. As a result, fluid loss can be reduced.

  In addition, since the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72, a sufficient contact area can be ensured in the contact portion 80. Thereby, it is possible to suppress the contact surface pressure from becoming excessive in the contact portion 80.

  Here, at the inner peripheral edge of the snubber structure 70, the wider the range formed by the straight line M, the smaller the interference between the steam flowing along the inner peripheral surface of the snubber structure 70 and the steam flowing through the blade effective portion 40. Is done. FIG. 11 is a view showing a cross section corresponding to the AA cross section of FIG. 4 of the snubber structure 70 having another configuration in the moving blade 22 of the second embodiment.

  As shown in FIG. 11, the inner peripheral edge of the snubber structure 70 may be a straight line. This is a configuration in which the range of the straight line M on the inner peripheral edge of the snubber structure 70 shown in FIG. 10 is maximized. In this case, both the rear edge snubber 52 and the front edge snubber 51 form a surface inclined toward the inner peripheral side from the position where the maximum thickness Tm is reached toward the front edge 71 side and the rear edge 72 side.

  With this configuration, interference between the steam flowing along the inner peripheral surface of the snubber structure 70 and the steam flowing through the blade effective portion 40 is further reduced. Further, since no projecting surface is formed on the inner peripheral surface of the snubber structure 70, no expansion wave is generated from the inner peripheral surface of the snubber structure 70. Therefore, the interference between the expansion wave and the steam flowing through the blade effective portion 40 is prevented, and fluid loss can be reduced.

(Third embodiment)
FIG. 12 is a view showing a cross section corresponding to the AA cross section of FIG. 4 of the snubber structure 70 of the rotor blade 22 of the third embodiment.

  In the cross section shown in FIG. 12, the outer peripheral edge of the snubber structure 70 is a straight line. Similar to the first embodiment, the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72 of the snubber structure 70. As shown in FIG. 12, the thickness T of the snubber structure 70 monotonously decreases from the position where the maximum thickness Tm is reached toward the front edge 71 side and the rear edge 72 side of the snubber structure 70.

  In this snubber structure 70, both the rear edge snubber 52 and the front edge snubber 51 have surfaces that are inclined toward the outer peripheral side from the position having the maximum thickness Tm toward the front edge 71 side and the rear edge 72 side. Configure. Here, an example in which the contact portion 80 between the trailing edge snubber 52 and the leading edge snubber 51 has a maximum thickness Tm is shown.

  According to the snubber structure 70 of the third embodiment, the loss due to the separation shock wave S and the wake W can be reduced as in the first embodiment. In addition, since the snubber structure 70 has a portion where the thickness T is the maximum thickness Tm between the front edge 71 and the rear edge 72, a sufficient contact area can be ensured in the contact portion 80. Thereby, it is possible to suppress the contact surface pressure from becoming excessive in the contact portion 80.

  Furthermore, the outer peripheral surfaces of the trailing edge snubber 52, the leading edge snubber 51, and the blade effective portion 40 can be made the same plane during processing. Thereby, machinability can be improved.

  In the above-described embodiment, the long blades constituting the final stage turbine stage have been illustrated and described as the moving blades 22, but the configuration of the present embodiment can also be applied to the short blades.

  According to the embodiment described above, it is possible to reduce the fluid loss at the tip of the moving blade and to suppress the contact surface pressure at the contact surface between the adjacent moving blades from becoming excessive.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Steam turbine, 20 ... Casing, 21 ... Turbine rotor, 21a ... Rotor disk, 22 ... Rotor blade, 23 ... Diaphragm outer ring, 24 ... Diaphragm inner ring, 25 ... Stator blade, 26 ... Ground seal part, 27 ... Seal part, 28 ... Crossover tube, 29 ... Steam passage, 40 ... Wing effective part, 41,71 ... Front edge, 42,72 ... Rear edge, 43 ... Back side, 44 ... Ventral side, 50 ... Snubber, 51 ... Front edge snubber , 51a ... contact surface, 52 ... trailing edge snubber, 52a ... contact surface, 60 ... wing implantation part, 70 ... snubber structure, 80 ... contact part, 90 ... seal fin.

Claims (8)

A leading edge connecting member protruding to the back side at the leading edge side of the wing tip,
A trailing edge connecting member protruding to the ventral side on the trailing edge side of the wing tip,
In operation, the leading edge connecting member of the turbine blade adjacent to the trailing edge connecting member, or the connecting portion structure formed by contacting the trailing edge connecting member of the turbine blade adjacent to the leading edge connecting member. The turbine rotor blade according to claim 1, wherein a thickness of the connecting portion structure is maximum between a front edge and a rear edge of the connecting portion structure in a cross section in a steam flow direction of the body.   The thickness of the connecting part structure monotonously decreases from the position where the thickness of the connecting part structure becomes maximum toward the front edge side and the rear edge side of the connecting part structure. Item 2. The turbine rotor blade according to Item 1.   3. The turbine blade according to claim 1, wherein a position where the thickness of the connecting portion structure is maximum is a position where the trailing edge connecting member and the leading edge connecting member are in contact with each other.   In the position where the trailing edge connecting member and the leading edge connecting member are in contact, the thickness of the contact surface of the trailing edge connecting member is equal to or greater than the thickness of the contacting surface of the leading edge connecting member. The turbine rotor blade according to any one of claims 1 to 3.   In the cross section, a contact point between the rear edge connecting member and the front edge connecting member at an inner peripheral edge of the connecting portion structure is a part of the inner peripheral edge of the rear edge connecting member and the front edge connecting member. The turbine rotor blade according to any one of claims 1 to 3, wherein the turbine rotor blade is located on a straight line formed by a part of the periphery.   4. The turbine rotor blade according to claim 1, wherein an outer peripheral edge of the connecting portion structure is a straight line in the cross section. 5.   4. The turbine rotor blade according to claim 1, wherein an inner peripheral edge of the connecting portion structure is a straight line in the cross section. 5.   A steam turbine comprising the turbine rotor blade according to claim 1.

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