JP2007064074A - Axial flow turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial flow turbine which can surely supporting each moving blade constituting a turbine moving blade group with neighboring moving blade in drive of an axial flow turbine and thereby reduce or damping vibrations generated in each moving blade. <P>SOLUTION: The axial flow turbine has a rotatable rotor 3, and the turbine moving blade group constituted of a plurality of moving blades 1 attached to the rotor 3 and disposed at the regular positions. Each moving blade 1 has a shroud 5. The sum of the length in a rotor outer peripheral direction of the shroud 5 before all of the moving blades 1 are attached to the regular positions is larger than the sum of the length in the rotor outer peripheral direction of the shroud 5 after all of the moving blades 1 are attached to the regular positions. Therefore, the shroud 5 of each moving blade 1 disposed at the regular position constituting the turbine moving blade group is brought into contact with the shroud 5 of the neighboring moving blade 1 with predetermined pressure, and each moving blade 1 is supported by the neighboring moving blade 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an axial flow turbine capable of effectively reducing and attenuating vibration generated in each rotor blade.

  The axial flow turbine includes moving blades arranged in the outer circumferential direction of the rotor so as to form a group of blade rows, and is driven by flowing a working fluid between the moving blades. When the axial turbine is driven, various forces such as centrifugal stress, thermal stress, bending stress, and torsional stress are applied to each rotor blade jointly or individually. In particular, the increase in capacity of power plants in recent years has led to an increase in the amount of working fluid flowing in an axial turbine and an increase in operating conditions such as high temperature and high pressure in the operating environment. Power is also increasing. The various increased forces act as excitation forces for the moving blades and may cause intense vibrations in the moving blades.

  The occurrence of intense vibrations in the rotor blades is not preferable from the viewpoint of operating the axial flow turbine safely and efficiently. Therefore, it is very important to give the axial turbine the functions of vibration reduction and vibration damping for each blade.

  Various means have been considered as means for reducing and attenuating such vibration of the moving blade. For example, there are a method of reducing and attenuating vibration of a moving blade by connecting adjacent moving blades with a rigid connecting member, a method of connecting holes with a connecting wire or the like by providing a hole in the moving blade.

  However, in these methods, stress concentration may occur at the connection point between the rigid connecting member and the moving blade. Further, when the rotor blade having a twist rotates around the rotor, the rotor blade returns torsion, and conversely, a torsional stress is generated in the rigid connecting member, so that the rotor blade is likely to vibrate. In addition, stress concentration is likely to occur around the hole provided in the rotor blade, and corrosion components are likely to accumulate with time in the hole. Furthermore, since the attachment and detachment of the moving blade connected by the rigid connecting member complicates the operation, it is difficult to remove the moving blade and check the quality of the remaining life of the rotor and the moving blade implantation portion. It is difficult to respond appropriately to the current situation where the number of aging degradation units is increasing.

  On the other hand, a turbine blade group having a snubber structure is conceivable as another means for reducing the vibration of the blade. The snubber structure is a structure in which a shroud formed integrally with the blade is provided at the top of the moving blade, and the shrouds of adjacent moving blades are in contact with each other when the rotor rotates, and a typical snubber structure is shown in FIG. 12 to 15.

  FIG. 12 shows a state in which a rotor blade having a large torsion is incorporated into the rotor from the root of the rotor blade to the tip of the rotor blade. A shroud 5 is provided at the tip of the moving blade 1 so that the shrouds 5 of adjacent moving blades 1 come into contact with each other during rotation. The shrouds 5 of the adjacent moving blades 1 are usually assembled with a minute gap during assembly. During the rotation of the rotor 3, the gap between the shrouds 5 disappears due to an untwist phenomenon in which the centrifugal force acts on the rotor blade 1 and the twist of the blade portion 6 returns. Adjacent shrouds 5 are in contact with each other with a predetermined pressure, and the vibration generated by the friction between the shrouds 5 suppresses the vibration generated in each blade 1.

  As described above, the snubber structure shown in FIG. 12 uses the phenomenon in which the twist of the blade section 6 returns when the rotor 3 rotates, so that the adjacent shrouds 5 come into contact with each other with a predetermined pressure while the rotor 3 rotates. Let And the vibration which arose in the moving blade 1 can be reduced and attenuated by the damping effect by this contact friction.

FIGS. 13A and 13B are diagrams showing another example of the snubber structure of the turbine rotor blade group, showing a state in which the rotor blade is viewed from the tip of the rotor blade, and FIG. A state is shown, (b) shows the state which assembled the moving blade. As shown in FIG. 13 (a), the contact surface of the shroud 5 has a predetermined angle θ1 with respect to the axial direction of the axial flow turbine, the pitch l ₁ between both sides of the contact surfaces, the diameter of the contact portion and It is set slightly larger than the geometric pitch calculated from the number of blades. At the time of assembly, as shown in FIG. 13B, a twist θ2, that is, a pre-twist is applied between the root portion of the moving blade 1 and the shroud 5, and the pitch of the contact portion of the shroud 5 is a geometric pitch. It is adapted to. For this reason, in a state in which the turbine blade group is assembled, a predetermined pressure is generated on the contact surface between the shrouds 5 due to the return force of the pre-twist of the blade 1 to reduce and attenuate the vibration generated in the blade 1. be able to.

  FIG. 14 is a view showing another example of the snubber structure having the pre-twist, and shows a state where the moving blade is viewed from the tip of the moving blade 1. The shroud 5 has a polygonal shape that is convex on the front surface in the rotational direction of the rotor 3 and concave on the back surface, and the other convex portion is fitted into one concave portion of the shrouds 5 adjacent to each other. In addition, a part 5c of one shroud 5 forming the concave part and a part 5d of the other shroud 5 forming the convex part are predetermined by the pretwist returning force applied to the moving blade 1 during assembly. Are brought into contact with each other at a pressure of 3 mm to bring about effects of vibration reduction and damping of the rotor blade 1. A minute gap is formed between the concave portion and the convex portion other than the contact portion of the adjacent shroud 5.

  15 (a) and 15 (b) are diagrams showing examples of still another snubber structure, and FIG. 15 (a) is a partial view of the assembled state of the rotor blades as seen from the axial direction of the rotor. FIG. 15B is a cross-sectional view of the rotor blade as seen from the outer peripheral direction of the rotor. In the drawing, 1c is referred to as an offset rotor blade, and a shroud surface is formed on the shroud 5c so as to become narrower toward the outside in the rotational radius direction (in the direction of arrow R in FIG. 15A) around the rotation axis of the rotor 3. is doing. The moving blade 1d adjacent to the offset moving blade 1c is referred to as a normal moving blade 1d. The shroud 5d of the regular rotor blade 1d is formed with a tapered surface that narrows toward the inside in the rotational radius direction (see FIG. 15A). Further, blade implantation portions 7c and 7d of the blades 1c and 1d are inserted and fitted into the blade implantation groove 9 formed in the outer circumferential surface of the rotor 3 so that the offset blade 1c and the regular blade 1d are fitted. At the time of assembly, a gap m is provided between the implantation load surface 7a of each rotor blade 1c, 1d and the implantation load surface 9a of the rotor (see FIG. 15B). The offset rotor blade 1 c is disposed at a position offset to the inner side in the rotational radius direction of the rotor blade around the rotation axis of the rotor 3. When the rotor 3 rotates, the offset rotor blade 1c is lifted radially outward by a centrifugal force and shifted. As the offset moving blade 1c rises, the shroud 5c of the offset moving blade 1c and the shroud 5d of the moving blade 1d fixed to the rotor 3 adjacent to the moving blade 1c are closely connected. Then, a group of structures over the outer periphery of the rotor 3 is formed by the rotor blades 1c and 1d, and the effect of reducing and attenuating the vibration generated in the rotor blades 1c and 1d is brought about.

  In a group blade structure in which a plurality of moving blades are connected by a rigid connecting member, the moving blades may be affected by a vibration mode in which the moving blades move together in the same phase and swing in the circumferential direction. In particular, in the low-order circumferential vibration mode, the vibration response level at the time of resonance is high, so that intense vibration is likely to occur in each rotor blade.

  However, in the snubber structure shown in FIGS. 12 to 15 described above, the shrouds of adjacent moving blades come into contact with each other when the rotor rotates, and the moving blades are integrally formed as a group. For this reason, even when a forced external force that excites the vibration mode is applied to the moving blade having the snubber structure, the vibration energy is canceled as a whole of the turbine moving blade group over the outer periphery of the rotor. For this reason, even if a forced external force is applied to each blade, it has an excellent characteristic that it hardly appears as a vibration response of the blade.

In addition, there is known a technique in which the throat pitch ratio of a turbine blade is offset before operation, and at the time of blade torsional return that occurs during operation, the turbine blade is allowed to maintain an appropriate value and more turbine-driven steam flows (Patent Document) 1).
JP 2000-045704 A

  However, in the untwisted snubber blade structure shown in FIG. 12, in order to form a turbine blade group integrally with the rotor 3 while ensuring a sufficient return of torsion in each blade 1, the blades of the blade portion 6 are used. It is necessary to increase the length to increase the degree of torsion from the blade root to the blade tip. Further, even when the blade length is sufficiently large, when the rotation of the rotor 3 is low, the centrifugal force acting on the moving blade 1 is small, so that the return of torsion of each moving blade is small. For this reason, the shroud 5 which adjoins does not mutually contact, and the effect which reduces and attenuates the vibration which arose in each moving blade 1 may not be expectable. Furthermore, in many steam turbines, the moving blade 1 having a relatively small blade length of the blade portion 6 is used. However, since such a moving blade 1 has a small twist itself, the moving blade is also at the rated rotation of the rotor 3. Almost no twist return of 1 occurs. Therefore, it is difficult to apply the untwisted snubber blade structure shown in FIG. 12 to such an axial flow turbine.

  As described above, the pretwisted snubber blade structure shown in FIG. 13 is assembled in a state where pretwist is applied from the blade root portion to the blade tip portion. The initial pressure is generated on the snubber contact surface by utilizing the repulsive force of the moving blade 1 to return the twist.

  However, the torsional rigidity of the moving blade 1 is generally extremely high, and in order to provide a pretwist for bringing the adjacent shrouds 5 into contact with each other, an excessive stress is generated in the blade effective portion or the implanted portion. In particular, due to the torsional deformation of the moving blade side implantation portion, the implantation portion which is a fixed portion of the moving blade 1 may cause a single contact with the implantation groove on the rotor side, and local high stress is generated. It is not preferable because it causes the occurrence. In particular, in the moving blade 1 having a small blade length of the blade portion 6, almost no torsional deformation can be expected in the blade effective portion, so that the stress generated in the implanted portion is further increased. Furthermore, since the blade 1 having a small blade length is generally used in a high-temperature and high-pressure portion, when the margin in the material strength of the blade 1 is small, additional torsional stress and increase in local stress are This will affect the reliability of the rotor blade 1 itself.

  In the modified example of the pretwisted snubber blade structure shown in FIG. 14, as a pretwisted characteristic, the adjacent shrouds 5 are in contact with each other only in a part of the shape of the shroud 5 that is uneven. For this reason, in addition to the above-described problems, there may be cases where a sufficient damping force cannot be exerted against a forced external force that imparts torsional vibration to the rotor blade 1.

  The radial shift type snubber blade structure by centrifugal force shown in FIG. 15 uses the gap m between the implanted portion 7 of the moving blade 1 and the implanted groove 9 of the rotor 3 to move radially outward when the rotor 3 rotates. In this configuration, the moving blade 1 can be shifted. Therefore, when there is no gap between the implanted portion 7 of the moving blade 1 and the implanted groove 9 of the rotor 3, it cannot be applied to each moving blade 1 at all.

  By the way, the ideal state of a moving blade is a state that always brings about the effect of vibration reduction and vibration damping on the moving blade under all operating conditions such as when rotating up, when rotating down, and at rated rotation. . For this purpose, it is preferable that the snubber gap is always kept at zero, and adjacent blades are in contact with each other under any operating conditions. For that purpose, it is necessary to make the snubber gap zero at least from the time of assembly. Therefore, a method in which adjacent shrouds are brought into light contact with each other at the time of assembly can be considered. However, during operation, the rotor extends in the radial direction and the rotor blade itself extends due to thermal expansion due to centrifugal force and high-temperature working fluid, so that the rotation radius of the shroud centering on the rotation axis of the rotor is larger than that during assembly. For this reason, during the operation of the axial flow turbine, a slight gap is generated between the adjacent shrouds according to the increase in the rotation radius of the shroud, and it is difficult to maintain the contact state of the adjacent moving blades. In addition, if there is a gap between adjacent blades during operation or if they are just in contact with each other, the blades may be damaged by collision or wear between the blades. It is not preferable from the viewpoint of reliability and safety.

  On the other hand, when the adjacent moving blades are in close contact with each other with a certain pressure during operation, a large vibration damping effect can be obtained. The blades are connected together as a group on the entire circumference, and the vibration control effect as a group blade can be expected.

  The present invention has been made in consideration of such points, and when driving an axial flow turbine, each rotor blade constituting the turbine rotor blade group is reliably supported by an adjacent rotor blade, and each rotor blade is attached to each rotor blade. An object of the present invention is to provide an axial turbine that can reduce and dampen the generated vibration.

  In the present invention, a plurality of moving blades are implanted at a predetermined position along the outer periphery of the rotor, and a predetermined moving blade of the plurality of moving blades is offset in the radial direction as an offset blade. In the axial turbine configured to contact the shrouds of adjacent moving blades with a predetermined pressure by mounting the remaining moving blades as normal blades in a normal position, The rotor formed with the implantation groove, and fitted into the implantation groove formed in the rotor, and contacted with the axially downstream side surface of the implantation groove and formed with a gap on the upstream side in the axial direction The offset blade having an implanted portion and the implanted blade formed in the rotor are fitted into the implanted groove, are in contact with the axially upstream side surface of the implanted groove, and are formed so as to form a gap on the axially downstream side. And the normal blade having a write portion, an axial flow turbine, characterized in that the offset wing was placed on a piece every or several sheets every respect to the normal wing.

  The present invention relates to an axial flow turbine comprising a rotatable rotor and a turbine blade group composed of a plurality of blades planted at predetermined positions along the outer periphery of the rotor. The blade has a shroud, and the sum of the circumferential lengths of the shrouds of each rotor blade constituting the turbine rotor blade group before all the rotor blades constituting the turbine rotor blade group are installed in the normal position is the turbine The turbine blade group is configured to be larger than the sum of the circumferential lengths of the shrouds of the blades constituting the turbine blade group after all the blades constituting the blade group are mounted at the normal positions. The axial flow turbine is characterized in that each blade shroud arranged in a normal position is in contact with an adjacent blade shroud with a predetermined pressure, and each blade is supported by the adjacent blade. Ah .

  According to the present invention, an axial flow turbine can be adjusted by appropriately adjusting a predetermined pressure at a contact surface between a shroud of each moving blade and a shroud of an adjacent moving blade arranged at a normal position constituting the turbine moving blade group. Each blade can be appropriately supported by the adjacent blade during driving.

  According to the present invention, in the above-described method of manufacturing an axial flow turbine, provisional assembly is performed in which all of a plurality of rotor blades constituting a turbine rotor blade group are arranged at positions offset from normal positions and attached along the outer periphery of the rotor. And moving the moving blades arranged at positions offset from the normal positions to the normal positions, and the shrouds of the respective moving blades arranged at the normal positions with the shrouds of the adjacent moving blades and a predetermined pressure And a final assembling step for making contact with each other.

  According to the present invention, the moving blades arranged at the position offset from the normal position in the temporary assembly process are arranged at the normal position in the final assembly process, so that all the moving blades of the turbine blade group can be easily and reliably obtained. It can arrange | position in a regular position and can make the shroud of an adjacent moving blade contact appropriately with a predetermined pressure.

  According to the present invention, in the above-described method for manufacturing an axial turbine, a part of the plurality of blades constituting the turbine blade group is arranged at a position offset from the normal position on the outer periphery of the rotor. Along with the temporary assembly process where other blades are placed along the outer circumference of the rotor along the outer periphery of the rotor, and the blades placed at positions offset from the normal position are moved and placed at the normal position. And a final assembling step of bringing a shroud of each moving blade disposed at a normal position into contact with a shroud of an adjacent moving blade with a predetermined pressure.

  According to the present invention, the sum of the circumferential lengths of the shrouds of the rotor blades constituting the turbine rotor blade group is larger before attaching the rotor blades to the rotor than after attaching the rotor blades to the rotor. The shrouds of the blades arranged at the normal positions come into contact with the shrouds of adjacent blades with a predetermined pressure, and the blades are supported. In particular, by adjusting the predetermined pressure between the shrouds, it is possible to maintain contact between the shrouds regardless of the rotational state of each rotor blade. For this reason, when operating the axial flow turbine, each moving blade is reliably supported by the adjacent moving blade, and vibration generated in each moving blade can be effectively reduced and attenuated.

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

First Embodiment FIGS. 1 to 5 are views showing a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram showing a state where a rotor blade is attached to a rotor, FIG. 2A is a diagram showing a rotor and a rotor blade in a temporarily assembled state, and FIG. 2B is a final assembly. It is a figure which shows the rotor and rotor blade of a state. FIG. 3 (a) is a diagram showing the configuration of the moving blades arranged at offset positions in the temporarily assembled state, that is, the configuration of the implanted portion of the offset blade and the implantation groove of the rotor, and FIG. It is a figure which shows the structure of the moving blade arrange | positioned in the regular position in the assembly state, ie, the implantation part of a regular blade, and the implantation groove | channel of a rotor. FIG. 4A is a configuration diagram showing a state in which the implanted portion of the regular wing is fitted and fixed to the implantation groove of the rotor with the stop pin, and FIG. 4B is a diagram showing the state of the rotor blade pin hole of the rotor blade and the rotor It is a figure which shows the positional relationship with a rotor pin hole. FIG. 5 is a diagram for explaining the structural relationship between a leakage prevention structure including a nozzle diaphragm, convex fins, and concave fins, and a shroud of a moving blade.

  First, the configuration of the axial turbine will be outlined.

  The axial turbine includes a rotatable rotor 3 and a plurality of turbine blade groups 50 planted along the outer periphery of the rotor 3. Each turbine blade group 50 includes a plurality of blades 1 of the same type, and the blades 1 are made of a compressible cobalt-based or nickel-based superalloy material. Further, each rotor blade 1 constituting the turbine rotor blade group 50 has a blade portion 6 having a predetermined twist and a tip portion of the blade portion 6 as shown in FIG. 1 and FIGS. 3 (a) and 3 (b). It has a shroud 5 provided and a planting part 7 provided with a fork-shaped fitting tooth 8 provided at the base end part of the wing part 6.

  As shown in FIGS. 1 and 5, a plurality of shroud recesses 11 a that are notched in the circumferential direction of the rotor 3 (in the direction of arrow A shown in FIG. 1) are formed on the upper surface of the shroud 5 of each rotor blade 1. Each shroud 5 has a substantially rectangular parallelepiped shape having an uneven shape on the upper surface. In addition, convex shroud convex portions 11b are formed at both ends and a central portion of the upper surface of each shroud 5 in the rotor axial direction (direction of arrow B shown in FIG. 1), and a concave shape is formed between the respective shroud convex portions 11b. The shroud recess 11a is formed. The shrouds 5 of the adjacent moving blades 1 can be compressed in the circumferential direction by being in close contact with each other at the side surface portions. Then, the shrouds 5 of the adjacent rotor blades 1 attached to the rotor 3 at regular positions after the final assembly process of the turbine rotor blade group 50 described later come into contact with each other in a compressed state with a predetermined pressure in the circumferential direction. ing. Therefore, the circumferential length α of the shroud 5 before the final assembly of the turbine blade group 50 is larger than the outer circumferential length β of the shroud 5 after the final assembly (FIG. 2A). (See (b)). Further, a moving blade pin hole 13 for inserting a stop pin 21 to be described later is formed in the implanted portion 7 at a predetermined location.

  On the other hand, as shown in FIG. 1, a plurality of implantation grooves 9 are formed in the outer peripheral portion of the rotor 3, and a stop pin 21 is provided at a predetermined position on the side surface portion of the rotor 3 forming the implantation grooves 9. A rotor pin hole 15 for insertion is formed. The rotor pin hole 15 is reamed after the fitting teeth 8 of the rotor blade 1 are inserted into the implantation grooves 9 and the positions of the rotor blade 1 and the rotor 3 are determined. It is formed large (see FIG. 4B).

  Then, the fork-type fitting teeth 8 forming the implanted portion 7 of the moving blade 1 are fitted into the implanted groove 9 (see FIG. 1), and the rotor pin hole 15 of the rotor 3 and the moving blade pin hole 13 of the moving blade 1 are engaged. A wedge-shaped stop pin 21 is inserted into the shaft. The front end portion of the wedge-shaped set pin 21 has a form that can be fitted into the rotor blade pin hole 13, and the body portion of the set pin 21 has a form that can be fitted into the rotor pin hole 15. The moving blade 1 and the rotor 3 arranged in the normal position are fixed without looseness by the stop pin 21 fitted and inserted into the moving blade pin hole 13, and the shrouds 5 of the adjacent moving blades 1 are contact-connected to each other. It is possible to maintain the state. Note that the arrangement relationship between the rotor pin hole 15 and the corresponding rotor blade pin hole 13 when the stop pin 21 is inserted is the rotor blade pin when viewed from the insertion direction of the stop pin 21 (the direction of arrow D in FIG. 4). The holes 13 are arranged so as to be located inside the rotor pin holes 15 (see FIGS. 4A and 4B).

  Further, the axial flow turbine is provided with a nozzle diaphragm 23 outside the radial direction of the rotor 3 (the direction of the arrow R shown in FIGS. 2A and 2B). It arrange | positions so that the upper surface of the shroud 5 of each moving blade 1 which comprises the group 50 may oppose through a predetermined gap. In addition, convex fins 25 a and concave fins 25 b protrude from the nozzle diaphragm 23 toward the upper surface of the shroud 5. The convex fin 25a protrudes toward the corresponding shroud convex portion 11b on the upper surface of the shroud 5, and a convex portion gap C1 is formed between the convex fin 25a and the shroud convex portion 11b. Similarly, the recessed fin 25b protrudes toward the shroud recessed portion 11a on the upper surface of the corresponding shroud 5, and a recessed portion gap C2 is formed between the recessed fin 25b and the shroud recessed portion 11a. The convex gap C1 is set smaller than the concave gap C2. As described above, the nozzle diaphragm 23, the convex fins 25a, and the concave fins 25b constitute a labyrinth-type leakage prevention structure so that the working fluid is prevented from leaking from between the rotor blades 1 of the turbine rotor blade group 50. It has become.

  Next, a method for attaching the turbine rotor blade group 50 to the outer periphery of the rotor 3 will be described in detail.

  The turbine rotor blade group 50 is implanted on the outer periphery of the rotor 3 through a temporary assembly process and a final assembly process.

  In the temporary assembly process, some of the plurality of blades 1 constituting the turbine blade group 50 are moved from the normal positions where they are arranged in the final assembled state to the outside in the rotational radius direction of the rotor 3. It is arranged at an offset position and is attached along the outer periphery of the rotor 3. On the other hand, the other rotor blades 1 constituting the turbine rotor blade group 50 are disposed at regular positions and attached along the outer periphery of the rotor 3. And the shroud 5 of each moving blade 1 is arrange | positioned in contact with the shroud 5 of the adjacent moving blade 1 in a side part (refer Fig.2 (a)).

  At this time, the moving blade 1b arranged at the normal position includes the lower surfaces of the implantation shoulder portions 7b located at both outermost portions in the rotor axial direction of the implantation portion 7 of the moving blade 1b and both outermost portions of the rotor 3 in the rotor axial direction. The position of the rotor blade 1 in the rotor rotational radius direction is determined by the contact position with the upper surface of the rotor side receiving shelf 10 that forms the convex portion of the implantation groove 9 positioned at the position (see FIG. 3B). . On the other hand, a shim 27 having a predetermined thickness h is sandwiched between the implanted shoulder 7a of the rotor blade 1a disposed at the offset position and the rotor side receiving shelf 10 of the rotor 3. (See FIG. 3 (a)), the implanted portion 7 of the rotor blade 1 a is fitted in the implanted groove 9 of the rotor 3 via a shim 27. For this reason, the offset amount of the moving blade 1 arranged at the offset position is adjusted by the thickness h of the shim 27.

  In the final assembly step, the moving blade 1a arranged at a position offset from the normal position is moved and arranged at the normal position (see FIG. 2B). Thereby, all the rotor blades 1 constituting the turbine rotor blade group 50 are arranged at the normal positions. Further, the shroud 5 of each rotor blade 1 arranged at the normal position can be brought into contact with the shroud 5 of the adjacent rotor blade 1 with a predetermined pressure, and each rotor blade 1 constituting the turbine rotor blade group 50 is The shroud 5 is connected to the adjacent moving blade 1, and the shroud 5 forms an annular shape along the outer periphery of the rotor 3 (annular connecting shroud).

  By the way, in the final assembly state in which all the rotor blades 1 constituting the turbine rotor blade group 50 are arranged at the normal positions, the circumferential length between the front surface in the rotational direction and the rear surface in the rotational direction of the shroud 5 of each rotor blade 1. β is determined by the total number of moving blades 1 constituting the turbine moving blade group 50. On the other hand, since the shrouds 5 of the moving blades 1 are not compressed in the temporarily assembled state, the circumferential length α of the shroud 5 of each moving blade 1 is larger than the circumferential length β of the shroud 5 in the final assembled state. Is also big. For this reason, when the moving blade 1a arranged at the offset position in the final assembly process is moved to the normal position, a wedge effect occurs, and the shroud 5 of each moving blade 1 is compressed in the circumferential direction. Therefore, the shroud 5 of each moving blade 1b arranged at the normal position comes into contact with the shroud 5 of the adjacent moving blade 1 with a predetermined pressure. Note that a slight gap is provided between the tip of the fitting tooth 8 in the implanted portion 7 of each rotor blade 1 and the bottom of the groove of the rotor 3. The arranged rotor blade 1 can be adjusted to a normal position (see FIG. 3A).

  When each rotor blade 1 is disposed at the normal position, the stopper pin 21 is inserted into the rotor pin hole 15 and the rotor blade pin hole 13, and the leading end of the stopper pin 21 is fitted into the rotor pin hole 15 and the stopper pin 21. Each of the blades 1 and the rotor 3 are securely fixed to each other by fitting the body portion of the blades into the blade pin holes 13 and maintaining the contact state between the shrouds 5 of the adjacent blades 1. Yes. The fixing by the stop pin 21 can be applied to the moving blade 1 arranged at the normal position in the temporary assembly process or the moving blade 1 arranged at the normal position in the final assembly process.

  Next, the relationship between the blades 1 of the turbine blade group 50 will be described in more detail.

As shown in FIG. 2A, the offset amount of the moving blades 1a arranged at the offset position is h, the total number of moving blades 1 constituting the turbine moving blade group 50 is n, of which Let Δn be the number of blades 1 arranged at the position, and r be the average radius of rotation when the rotational axis of the rotor 3 of the annular connection shroud in the final assembled state of the turbine blade group 50 is centered. At this time, the circumferential length L in the circumferential direction of the annular coupling shroud 5 in the final assembled state of the turbine blade group 50 is given by the following equation (1) using the average turning radius r of the annular coupling shroud 5 described above. .
L = 2πr (1)
On the other hand, the sum of the circumferential length of the shroud 5 of the moving blade 1a arranged at the offset position and the circumferential length of the moving blade 1 arranged at the normal position in the temporary assembly state is the final assembled state. Is set to be larger than the circumferential length L of the annular coupling shroud 5. The total value La of the circumferential length of the shroud 5 of the moving blade 1 arranged at the offset position and the total length of the circumferential direction of the shroud 5 of the moving blade 1 arranged at the normal position in the temporarily assembled state. The value Lb is given by the following equations (2) and (3), respectively.
La = 2π (r + h) Δn / n (2)
Lb = 2πr (n−Δn) / n (3)
Then, by pushing the moving blade 1a arranged at the offset position into the normal position, each shroud 5 is compressed in the circumferential direction, and the shroud 5 of each moving blade 1 constituting the turbine blade group 50 in the circumferential direction is compressed. The total value ΔL of the compression amount is given by the following equation (4).
ΔL = (La + Lb) −L = 2πhΔn / n (4)
Therefore, when the Young's modulus of the material of the moving blade 1 is E, the average compressive stress σ applied to each shroud 5 in the circumferential direction in the final assembled state of the turbine moving blade group 50 is given by the following equation (5). .
σ = EΔL / L = (h / r) (Δn / n) E (5)
Thus, when the turbine blade group 50 is finally assembled, a predetermined pressure corresponding to the compressive stress σ is generated on the contact surface between the adjacent shrouds 5.

  Next, the operation of the present embodiment having such a configuration will be described.

  A predetermined working fluid such as water vapor flows between the rotor blades 1 of each turbine rotor blade group 50 from upstream to downstream in the rotation axis direction of the rotor 3, so that each turbine rotor blade group 50 and the rotor 3 together with the rotor 3. And the axial turbine is driven.

  At this time, since the shrouds 5 of the adjacent moving blades 1 are compressed and connected with a predetermined pressure without being separated from each other, each of the moving blades 1 is contact-supported by the adjacent moving blades 1 at the shroud 5 portion. For this reason, even when an external force is applied to each moving blade 1 by a working fluid or the like, each moving blade 1 is supported by the adjacent moving blade 1, and vibration generated in each moving blade 1 is reduced and quickly attenuated.

  During the operation of such an axial turbine, the rotor 3 and each rotor blade 1 themselves extend in the rotor rotational radius direction due to the centrifugal force, and the rotational radius of the annular coupling shroud 5 centering on the rotational axis of the rotor 3 is Since it becomes larger than when the axial flow turbine is stopped, the shrouds 5 of the adjacent rotor blades 1 are easily opened. For this reason, in order for each blade to be supported by the adjacent blade in the shroud portion even when the axial flow turbine is driven, the adjacent shroud is considered in consideration of the loosening of the pressure between the shrouds 5 during operation of the axial flow turbine. It is necessary to set a predetermined pressure between the five.

  However, as is apparent from the above equation (5), in the present invention, the predetermined pressure between the adjacent shrouds 5 can be freely set by appropriately selecting the offset amount h and the number Δn of the offset moving blades 1. Is possible. Further, the contact surface angle formed between the front surface in the rotational direction and the rear surface in the rotational direction of the shroud 5a of each blade 1 in the final assembled state can be calculated from the total number of the turbine blade group 50. It is also possible to change the predetermined pressure between the shrouds 5 of the adjacent rotor blades 1 by changing the angle. As described above, the degree of freedom in setting the predetermined pressure between the shrouds 5 of the adjacent rotor blades 1 is very high. For this reason, it is possible to easily secure an appropriate pressure between the shrouds 5 so as to maintain the contact without separating the shrouds 5 even during operation of the axial flow turbine.

  As a result, regardless of whether the axial flow turbine is stopped or operating, each moving blade 1 is contacted and supported by the adjacent moving blade 1, and even if an excitation force is applied to each moving blade 1 to generate vibration, the adjacent moving blade 1 Vibration is reduced and attenuated by the support of 1.

  By the way, during operation of the axial flow turbine, a predetermined working fluid is caused to flow between the rotor blades 1 from upstream to downstream in the rotation axis direction of the rotor 3. May flow in (see FIG. 5). The working fluid that has flowed to the outside of the moving blade 1 in this way flows into the convex gap C1 and the concave gap C2 while meandering while being blocked by the convex fin 25a and the concave fin 25b. The working fluid loses kinetic energy while traveling through the convex gap C <b> 1 and the concave gap C <b> 2, and stagnates between the nozzle diaphragm 23 and the shroud 5. As a result, it is possible to prevent a new working fluid from flowing into the outer side of the moving blade 1 from flowing into the convex gap C1 and the concave gap C2, and to effectively flow the working fluid between the moving blades 1. be able to.

  In general, the shroud 5 and the fins 25a and 25b are considered in consideration of the elongation of the rotor blade 1 due to centrifugal force during operation, expansion due to heat, and deformation of the casing in a thermally unsteady state such as during startup. Is provided between the shroud 5 and the fins 25a and 25b. However, when the shrouds 5 of the rotor blades 1 are integrally configured as in the present embodiment, the shroud recess 11a and the recess fins 25b are in contact with each other when the axial turbine is started. As the rotor rotates, frictional heat is generated between the shroud recess 11a and the recess fin 25b. At this time, since the shroud recess 11a has less heat escape space than the shroud protrusion 11b, the shroud 5 is very hot, but the shrouds 5 are integrally formed, so that each shroud 5 expands. Can not do it. For this reason, the shroud recessed part 11a which contacts the recessed part fin 25b will yield. When the contact between the shroud recess 11a and the recess fin 25b is lost in a steady state, the temperature of the shroud recess 11a decreases, and the shroud 5 contracts. The shrinkage of the shroud 5 may cause a gap between the shrouds 5, so that the shrouds 5 cannot be integrally formed, and the reliability of the turbine blade group 50 is significantly reduced. May end up. On the other hand, setting a large gap between the shroud 5 and the fins 25a and 25b is not preferable from the viewpoint of performance in that the working fluid is prevented from flowing outside the rotor blade 1.

  However, in the present invention, the convex gap C1 is set to be smaller than the concave gap C2, so that the shroud 5 of each rotor blade 1 is moved in the radial direction of the rotor 3 by centrifugal force generated during operation of the axial turbine. Even when moved outward, the convex fin 25a contacts the shroud convex portion 11b before the concave fin 25b contacts the shroud concave portion 11a. Moreover, the shroud convex part 11b is easy to release heat compared with the shroud concave part 11a.

  Therefore, even when frictional heat is generated between the convex fin 25a and the shroud convex portion 11b, the fin effect and the cooling effect by leaked steam are improved by appropriately selecting the width and height of the shroud convex portion 11b. Can be made. Thereby, it can avoid that a material yields by overheating in the contact part of the convex part fin 25a and the shroud convex part 11b. Further, when the axial flow turbine is started, an axial expansion difference is generated between the casing (not shown) of the axial flow turbine and the rotor 3. For this reason, if the width of the shroud convex portion 11b and the axial position of the fin are appropriately set and the axial position deviation due to the axial expansion difference between the casing and the rotor 3 is used, the contact itself is avoided. Even it becomes possible.

  As described above, the labyrinth type leakage prevention structure constituted by the nozzle diaphragm 23, the convex fin 25a, and the concave fin 25b effectively prevents leakage of the working fluid without impairing the reliability of the axial turbine. be able to.

  As described above, in the present embodiment, the shroud 5 of each rotor blade 1 constituting the turbine rotor blade group 50 comes into contact with the shroud 5 of the adjacent rotor blade 1 in a compressed state with a predetermined pressure. As a result, even when the turbine blade group 50 rotates around the rotor 3, the shrouds 5 are compressed and connected to each other, so that each blade 1 is surely secured by the adjacent blade 1 in the shroud 5 portion. Supported. Therefore, even when an excitation force is applied to each moving blade 1 by a working fluid or the like, each moving blade 1 is supported by the adjacent moving blade 1, so that vibration generated in each moving blade 1 is reduced and quickly damped. .

  Moreover, since each moving blade 1 is supported by the contact with the predetermined pressure between shrouds 5, it is not necessary to connect the adjacent moving blades 1 by rigid connection members, such as a connection wire. For this reason, it is not necessary to consider inconveniences associated with the introduction of the rigid connecting member such as stress concentration generated between the rigid connecting member and the rotor blade 1 and accumulation of corrosion components.

  Further, regardless of the magnitude of the centrifugal force acting on each rotor blade 1 during operation of the axial flow turbine, the degree of torsion formed on each rotor blade 1, the size of each rotor blade 1, etc. By adjusting the pressure to an appropriate magnitude, each rotor blade 1 is appropriately supported by the adjacent rotor blade 1, and vibration generated in each rotor blade 1 is effectively reduced and attenuated. In this respect, it differs from the conventional axial turbine as shown in FIGS. Therefore, the axial turbine according to the present invention generates excessive torsional stress in the effective portion of the moving blade and the implanted portion 7 as seen in the conventional axial flow turbine having the pretwisted snubber rotor blade 1 and local fragments. There is no phenomenon of increased stress due to contact, and the structure is highly desirable from the viewpoint of reliability and safety.

  Therefore, by applying the present invention to the high-temperature high-pressure stage of an axial flow turbine, replacement of an existing machine, etc., remarkable effects such as improved reliability and stability, longer life of the apparatus, and further improved axial-flow turbine performance can be obtained. is there.

  The rotor blade 1 is made of a cobalt-based or nickel-based superalloy material having inherent high temperature characteristics. For this reason, in addition to the high temperature characteristics of these superalloys, effects such as improvement of the operation efficiency of an axial turbine whose operating environment is high and reduction of the load on the environment are also expected.

  Moreover, since each turbine blade group 50 is attached to the rotor 3 through the above-mentioned temporary assembly process and final assembly process, each blade 1 constituting the turbine blade group 50 can be easily arranged at a normal position. Is possible. In particular, since all the blades 1 constituting the turbine blade group 50 are placed in the normal position by pushing the blades 1 arranged in the offset position in the temporary assembly step to the normal position in the final assembly step. It is possible to reliably arrange each rotor blade 1 at a normal position.

  In the present embodiment, a case has been described in which several of the blades 1 constituting the turbine blade group 50 are arranged at offset positions in the temporary assembly process. May be arranged at positions offset in the temporary assembly process. Also in this case, the moving blade 1 arranged at the offset position is appropriately arranged at the normal position in the final assembly process. Therefore, even in such a modified example, it is possible to easily and surely arrange each rotor blade 1 at an appropriate regular position.

  The offset amount of the moving blade 1 arranged at the offset position in the temporary assembly process is adjusted by the thickness of the shim 27 interposed between each moving blade 1 and the rotor 3. For this reason, by adjusting the thickness of the shim 27 to a desired thickness, the offset amount of the moving blade 1 can be adjusted easily and reliably, and the pressure between the shrouds 5 can be reliably controlled. The reliability and stability of the rotor blade 1 can be maintained and improved.

  Further, each rotor blade 1 and the rotor 3 are fixed in a fitted state by a stop pin 21 inserted into the rotor pin hole 15 and the rotor blade pin hole 13, and the shrouds 5 of the adjacent rotor blades 1 are in contact with each other. The state can be maintained. In this manner, the moving blade 1 can be securely and easily attached to the rotor 3 and held by the stop pin 21.

  In the present embodiment, the case where the turbine blade group 50 is configured by the moving blades 1 having the same shape has been described. However, the moving blades 1 do not necessarily have the same shape. That is, the total sum of the circumferential lengths α of the shrouds 5 of the rotor blades 1 constituting the turbine rotor blade group 50 before all the rotor blades 1 constituting the turbine rotor blade group 50 are attached to the regular positions It is larger than the sum total of the circumferential lengths β of the shrouds 5 of the rotor blades 1 constituting the turbine rotor blade group 50 after all the rotor blades 1 constituting the turbine rotor blade group 50 are attached to the regular positions. It suffices that each rotor blade 1 has such a shape. Also in this case, the shroud 5 of each rotor blade 1 arranged at a normal position constituting the turbine rotor blade group 50 is in contact with the shroud 5 of the adjacent rotor blade 1 with a predetermined pressure, and each rotor blade 1 is adjacent. Supported by the moving blade 1. For this reason, the vibration generated in each moving blade 1 is reduced by the support of the adjacent moving blade 1 and is quickly damped.

Second Embodiment FIG. 6 and FIGS. 7A and 7B show a second embodiment of the present invention. FIG. 6 is a view of the shroud of each rotor blade constituting the turbine rotor blade group as viewed from the outer side in the radial direction of rotation about the rotation axis of the rotor. FIG. 7A is a diagram showing a fitting and fixing state between the implanted portion of the predetermined moving blade constituting the turbine moving blade group and the implantation groove of the rotor, and FIG. 7B is the predetermined moving blade. It is a figure which shows the fitting fixation state of the planting part of the moving blade adjacent to and the implantation groove | channel of a rotor.

  In the second embodiment, as shown in FIG. 6, the shroud 5 of each rotor blade 1 constituting the turbine rotor blade group 50 has a side surface portion inclined with respect to the rotation axis direction of the rotor 3. The shroud 5 of each moving blade 1 attached to the rotor 3 through the final assembly process described above and the shroud 5 of the moving blade 1 adjacent to the moving blade 1 are brought into contact with each other with a predetermined pressure. The contact surface forms a slope inclined with respect to the rotor rotation axis direction.

  Further, the turbine rotor blade group 50 is configured by two types of rotor blades 1 having different implantation parts 7, and a rotor blade 1 a having an implantation part 7 shown in FIG. 7A and an implantation shown in FIG. 7B. The moving blades 1 b having the portions 7 are alternately arranged along the outer periphery of the rotor 3. Therefore, the implanted part 7 of each moving blade 1 has a different type from the implanted part 7 of the adjacent moving blade 1.

  When the moving blade 1 a having the planting part 7 shown in FIG. 7A is attached to the rotor 3, each fitting tooth 8 of the planting part 7 is in the direction of the rotation axis of the rotor 3 among the side walls of the implantation groove 9 of the rotor 3. In contact with the downstream side wall at a predetermined pressure. Therefore, the implanted portion 7 of the rotor blade 1 a is supported by the downstream side wall of the implanted groove 9 of the rotor 3. On the other hand, when the moving blade 1 b having the planting portion 7 shown in FIG. 7B is attached to the rotor 3, each fitting tooth 8 of the planting portion 7 rotates the rotor 3 among the side walls of the implantation groove 9 of the rotor 3. It contacts the upstream side wall in the axial direction with a predetermined pressure. Therefore, the implanted portion 7 of the rotor blade 1 b is supported by the downstream side wall of the implanted groove 9 of the rotor 3. A slight gap exists in the direction of the rotation axis of the rotor between each fitting tooth 8 of each rotor blade 1 and the implantation groove 9 of the rotor 3.

  Other configurations are substantially the same as those of the first embodiment shown in FIGS.

  6 and FIGS. 7A and 7B, the same parts as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, as shown in FIG. 6, the shroud 5 of each moving blade 1 arranged at the normal position is in contact with the shroud 5 of the adjacent moving blade 1 with a predetermined pressure. The contact surface between them forms a predetermined slope with respect to the rotation axis direction of the rotor 3. For this reason, each moving blade 1 that has undergone the above-described final assembly process is supported from the direction of the contact surface between the shrouds 5. For this reason, the contact surface direction component between the shrouds 5 among the vibrations generated in the rotor blade 1 can be effectively reduced and attenuated.

Moreover, in this Embodiment, since the contact area between the shrouds 5 is large compared with the case where the side part of the shroud 5 is provided in parallel with the rotation axis direction of the rotor 3,
Each blade 1 is firmly supported by the shroud 5 portion, and vibration generated in each blade 1 can be reduced and damped.

  Each rotor blade 1 is also supported by a rotor 3 that is fixedly attached to the planting portion 7 via a stop pin 21, and each rotor blade 1 is supported by each rotor blade 1 supported by the rotor 3. The generated vibration is reduced and damped. In particular, in the present embodiment, as shown in FIGS. 7A and 7B, the angle of the contact surface between the shrouds 5 is such that the implanted portion 7 of each rotor blade 1 and the sidewall of the implanted groove 9 of the rotor 3. This is different from the angle of the contact surface. Therefore, each rotor blade 1 is supported not only in the support direction in the shroud 5 part but also in the support direction by the rotor 3 in the implantation part 7.

  Further, since the adjacent moving blades 1 are compression-coupled to each other at the shroud 5 portion, the adjacent moving blades 1 are integrally supported via the shroud 5 portion at a normal position. For this reason, each moving blade 1 is fitted in the supporting direction from the side wall of the implantation groove 9 to which the moving blade 1 is fitted, the supporting direction in the shroud 5 portion from the adjacent moving blades 1 adjacent to each other, and the adjacent moving blade 1. The rotor 3 is supported from four directions, that is, from the side wall of the implantation groove 9 of the rotor 3.

  As described above, each rotor blade 1 is supported from multiple directions (four directions), can flexibly cope with the excitation force applied from various directions, and can exert a great vibration damping effect. Therefore, even when vibrations traveling in various directions occur in each rotor blade 1, the vibrations can be effectively reduced and attenuated by the support in the shroud 5 portion and the support by the rotor 3 in the implantation portion 7.

Third Embodiment FIG. 8 is a diagram showing a third embodiment of the present invention, in which a shroud of each rotor blade constituting a turbine rotor blade group is rotated in the radial direction around the rotation axis of the rotor. It is the figure seen from the outside.

  In the third embodiment, as shown in FIG. 8, the shroud 5 of each rotor blade 1 constituting the turbine rotor blade group 50 has a rotor on the front side surface portion in the rotor rotation direction and the rear side surface portion in the rotor rotation direction. 3 is inclined with respect to the rotation axis direction. Further, the inclination angle of the front side surface portion in the rotor rotation direction and the inclination angle of the rear side surface portion in the rotor rotation direction in each rotor blade 1 are different, and the top surface of each shroud 5 when each shroud 5 is viewed from above. Is trapezoidal.

  Then, the moving blades 1 in which the upstream side surface portion and the downstream side surface portion of the shroud 5 are reversed are arranged alternately along the outer periphery of the rotor 3 to constitute the turbine moving blade group 50. For this reason, the side surface part 5a of the shroud 5 with a large inclination angle which each moving blade 1 arranged at the normal position has a predetermined pressure with the side surface part 5a of the shroud 5 with a large inclination angle which one adjacent moving blade 1 has. Will be in compression contact. On the other hand, the side surface portion 5b of the shroud 5 having a small inclination angle of each moving blade 1 is in compression contact with the side surface portion 5b of the shroud 5 having a small inclination angle of the other adjacent moving blade 1 with a predetermined pressure. It becomes. For this reason, each moving blade 1 is contact-supported by one adjacent moving blade through a contact surface with a small inclination angle, and is contact-supported by the other moving blade adjacent through a contact surface with a large inclination angle. .

  Other configurations are substantially the same as those of the second embodiment shown in FIGS. 6 and 7A and 7B.

  In FIG. 8, the same parts as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the shroud 5 of each moving blade 1 is inclined with respect to the rotation axis direction of the rotor 3 at the front side surface portion in the rotor rotation direction and the rear side surface portion in the rotor rotation direction. And with a predetermined pressure. Therefore, each moving blade 1 is supported by the adjacent moving blade 1 from the contact surface direction between the shrouds 5, and the vibration generated in the moving blade 1 is reduced and attenuated. Particularly, since the angle of the contact surface at the front side surface portion in the rotor rotation direction and the angle of the contact surface at the rear side surface portion in the rotor rotation direction are different from each other, each rotor blade 1 is supported from two different directions in the shroud 5 portion. Will be.

  The implanted portion 7 of each rotor blade 1 is in compression contact with one side surface of the implantation groove 9 of the rotor 3, and each rotor blade 1 is also supported from the implantation groove 9 of the rotor 3 that is in compression contact. Furthermore, each moving blade 1 is connected at a portion of the shroud 5 and is formed integrally with an adjacent moving blade. For this reason, each blade 1 is also supported from the direction in which the adjacent blade 1 is supported by the rotor 3.

  As described above, each blade 1 is supported from various directions in the shroud 5 portion and the implantation portion 7, and thus can flexibly cope with the excitation force applied from various directions. Even when vibrations traveling in various directions are generated in each rotor blade 1, the vibrations can be effectively reduced and attenuated.

Fourth Embodiment FIG. 9 is a diagram showing a fourth embodiment of the present invention, in which the shrouds of the rotor blades constituting the turbine rotor blade group are rotated in the radial direction around the rotation axis of the rotor. It is the figure seen from the outside.

  In the fourth embodiment, as shown in FIG. 9, the shroud 5 of each blade 1 constituting the turbine blade group 50 has a convex polygonal shape at the front side surface in the rotor rotation direction, and the rotor rotates. It has a concave polygonal shape at the rear side surface in the direction. The front side surface portion in the rotor rotation direction includes an upstream back side surface portion 5e, a midstream back side surface portion 5f, and a downstream back side surface portion 5g from the upstream side to the downstream side in the rotation axis direction of the rotor 3 through which the working fluid flows. They are formed sequentially, and each surface has a different inclination angle. Similarly, the rotor rotation direction rear side surface portion sequentially forms the upstream ventral side surface portion 5h, the midstream ventral side surface portion 5i, and the downstream ventral side surface portion 5j from the upstream side to the downstream side in the rotation axis direction of the rotor 3. Each surface has a different inclination angle.

  And the convex front side part of the shroud 5 which the other rotor blade 1 has is compression-fitted to the concave rear side surface part of the shroud 5 which one rotor blade 1 has among the adjacent rotor blades 1, Adjacent rotor blades 1 arranged at positions are connected by a shroud 5 portion.

  When the adjacent blades 1 are connected to each other in this way, the upstream abdomen side surface portion 5h of the shroud 5 of one blade 1 and the upstream back side surface portion 5e of the shroud 5 of the other blade 1 are formed. While contacting with a predetermined pressure, the downstream abdomen side surface part 5j of the shroud 5 of one rotor blade 1 and the downstream back side surface part 5g of the shroud 5 of the other rotor blade 1 have a predetermined pressure. To come into contact.

  Note that a gap is provided between the midstream abdominal side surface portion 5i of the shroud 5 of one of the blades 1 and the midstream back side surface portion 5f of the shroud 5 of the other blade 1. And the water | moisture content adhering to each moving blade 1 is escaped from this gap | interval, and the corrosion etc. of each moving blade 1 are prevented effectively.

  Other configurations are substantially the same as those of the second embodiment shown in FIGS. 6 and 7A and 7B.

  In FIG. 9, the same parts as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The shroud 5 of each rotor blade 1 constituting the turbine rotor blade group 50 has a predetermined pressure with the shroud 5 of one of the adjacent rotor blades 1 in the upstream back side surface portion 5e and the downstream back side surface portion 5g having different inclination angles. , And at the upstream ventral side surface portion 5h and the downstream ventral side surface portion 5j having different inclination angles, compressively contact with the shroud 5 of the other adjacent rotor blade 1 with a predetermined pressure. Therefore, each blade 1 shroud 5 of the turbine blade group 50 is in compression contact with the adjacent shroud 5 on the four surfaces, and each blade 1 is supported at four locations in the shroud 5 portion.

  In particular, since the two contact surfaces on the rear side surface portion or the front side surface portion of the shroud 5 form different inclination angles, the adjacent shrouds 5 are supported from two directions. Therefore, even when the excitation force is applied to each blade 1 from various directions, the adjacent blades 1 are supported through the contact surfaces having different inclination angles in the shroud 5 and are generated in each blade 1. The vibration is reduced and damped.

In this way, the shrouds 5 are in contact with each other with a predetermined pressure on two surfaces (multiple surfaces) having different angles, and each contact surface is formed with a different angle.
Adjacent rotor blades 1 are supported from two directions (multidirectional). Thereby, it is possible to effectively reduce and attenuate the vibration generated in each rotor blade 1 in various directions. Further, as a matter of course, each of the moving blades 1 is provided with sufficient vibration reduction and damping effects against a forced external force that gives vibration to the moving blades 1. Therefore, the present invention overcomes the weak points of the conventional pretwist structure shown in FIG.

  In the present embodiment, the case where the shrouds 5 of the adjacent moving blades 1 are in contact with each other through two surfaces having different angles has been described. Similar actions and effects can be achieved even when contact is made with pressure. Also in this case, adjacent blades 1 are mutually supported from a plurality of directions, and even when excitation force acts on each blade 1 from various directions, vibration generated in each blade 1 is effectively reduced. Can be attenuated.

Fifth Embodiment FIG. 10 is a diagram showing a fifth embodiment of the present invention, in which the shrouds of the rotor blades constituting the turbine rotor blade group are rotated in the radial direction around the rotation axis of the rotor. It is the figure seen from the outside.

  In the fifth embodiment, as shown in FIG. 10, when the rotor blades 1 constituting the turbine rotor blade group 50 are connected by the shroud 5 portion, the upstream ventral side surface of the shroud 5 included in the rotor blades 1. The portion 5h and the upstream back side surface portion 5e of the shroud 5 of the one adjacent blade 1 are brought into compression contact with a predetermined pressure. Further, the downstream back side surface portion 5g of the shroud 5 included in each blade 1 and the downstream ventral side surface portion 5j of the shroud 5 included in the other adjacent blade 1 are in compression contact with a predetermined pressure. It has become.

  The shroud 5 of the moving blade 1a shown in FIG. 10 is supported by the force from the upstream side toward the downstream side, while the shroud 5 of the adjacent moving blade 1b is supported by the force from the downstream side toward the upstream side.

  That is, when the implanting portion 7 of each rotor blade 1 is fitted into the implantation groove 9 of the rotor 3, it is supported in a direction opposite to the support direction in the rotor rotation axis direction in the shroud 5 portion. For example, each fitting tooth 8 of the implanted portion 7 of the moving blade 1a shown in FIG. 10 is in contact with the downstream side surface of the implanted groove 9 with a predetermined pressure as shown in FIG. 1a is supported in the planting part 7 from the downstream side to the upstream side. Further, each fitting tooth 8 of the implantation portion 7 of the moving blade 1b shown in FIG. 10 is in contact with the upstream side surface of the implantation groove 9 with a predetermined pressure as shown in FIG. 3B, and this moving blade 1b. Is supported from the upstream side to the downstream side in the implantation portion 7.

  In addition, between the part which is not in contact with the shroud 5 of the adjacent moving blade 1 and the shroud 5 of the adjacent moving blade 1 among the rotating side front side part and the rotor rotating direction rear side part of the rotor of the shroud 5 Is provided with a gap.

  Other configurations are substantially the same as those of the fourth embodiment shown in FIG.

  In FIG. 10, the same parts as those in the fourth embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 10, each blade 1 constituting the turbine blade group 50 is supported by the adjacent blade 1 in the shroud 5 portion and supported by the rotor 3 in the implantation portion 7. Therefore, the vibration generated in each rotor blade 1 is reduced and attenuated by the support in the shroud 5 portion and the rotor 3 portion.

  In particular, the support direction from the rotor 3 in the implanted portion 7 of each blade 1 and the support direction from the adjacent blade 1 in the shroud 5 portion are opposite to each other.

  As described above, each blade 1 is supported from multiple directions in the shroud 5 portion and the planting portion 7, so that even when excitation force is applied to each blade 1 from various directions, it is generated in each blade 1. The vibration is effectively reduced and damped.

Sixth Embodiment FIG. 11 is a diagram showing a sixth embodiment of the present invention, and is a diagram showing a configuration when an implanted portion of a moving blade is fitted into an implanted groove of a rotor.

  In 6th Embodiment, as shown in FIG. 11, the protrusion part 17 is provided in the root part of the predetermined | prescribed fitting tooth 8a in the implantation part 7 of the moving blade 1. As shown in FIG. The protrusion 17 forms a slope having a predetermined inclination angle with respect to the extending direction of the fitting tooth 8a. When the fitting tooth 8a is fitted into the implantation groove 9, the protrusion 17 is implanted in the implantation groove. 9 is provided so as to protrude in the direction of the transverse cross section.

  And the cross-sectional diameter of the implantation groove | channel 9 before the moving blade 1 is attached to the rotor 3 in a normal position becomes smaller than what added the cross-sectional diameter of the fitting tooth | gear 8a, and the protrusion amount of the protrusion part 17. FIG. The protruding amount of the protruding portion 17 is set in the above. Thereby, when fitting the fitting tooth 8 of the implantation part 7 into the implantation groove 9 of the rotor 3, one side part of each fitting tooth 8 contacts the downstream side part of the implantation groove 9 with a predetermined pressure. It is like that. In addition, the other side surface portion of the predetermined fitting tooth 8 a is in contact with the upstream side surface portion of the corresponding side surface portion of the implantation groove 9 with a predetermined pressure via the protruding portion 17.

  Of the rotor 3 in which the implantation groove 9 is formed, the portion where the projection is pressed when the implantation portion 7 of the rotor blade 1 and the implantation groove 9 of the rotor 3 are fitted and fixed is chamfered. Thus, a chamfered portion 19 is formed. And the predetermined pressure which arises between the planting part 7 and the implantation groove | channel 9 can be adjusted with the shape of the chamfering part 19. FIG.

  Other configurations are substantially the same as those of the first embodiment shown in FIGS.

  In FIG. 11, the same parts as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Each fitting tooth 8 of the planting portion 7 of each rotor blade 1 constituting the turbine rotor blade group 50 is fitted in a corresponding implantation groove 9 of the rotor 3. At this time, as shown in FIG. 11, each fitting tooth 8 contacts the downstream side surface of the implantation groove 9 with a predetermined surface pressure, so that each rotor blade 1 is moved from the downstream side to the upstream side by the rotor 3. It is supported in the rotor rotation axis direction. Further, the fitting teeth 8a provided with the protrusions 17 are brought into contact with the upstream side surface of the corresponding implantation groove 9 via the protrusions 17 with a predetermined surface pressure. It is supported in the direction of the rotor rotation axis from the upstream side toward the downstream side.

  Therefore, each blade 1 fitted and fixed to the rotor 3 is supported by the rotor 3 in the planting portion 7 from the upstream side toward the downstream side in the rotor rotation axis direction, and from the downstream side toward the upstream side. It is supported in the rotor rotation axis direction.

  Further, each blade 1 is supported in the rotor rotating direction by the adjacent blade 1 in the shroud 5 portion.

  In this way, each blade 1 is supported from multiple directions in the shroud 5 portion and the implantation portion 7 and can exert a large vibration suppressing force. Even if excitation force is applied from various directions, each blade 1 The vibration generated in is effectively reduced and damped. In particular, since the implanting part 7 is supported from both upstream and downstream sides and downstream to upstream, vibrations generated in the moving blades 1 can be effectively reduced and attenuated in the implanting part 7. .

  In addition, when the protrusion 17 is provided on the side wall of the implantation groove 9 of the rotor 3 instead of being provided on the one implantation part 7 side of the rotor blade, the implantation groove before the rotor blade 1 is attached to the rotor 3 at the normal position. The protrusion amount of the protrusion part 17 should just be set so that the cross-sectional diameter of 9 may become smaller than what added the cross-sectional diameter of the fitting tooth 8a, and the protrusion amount of the protrusion part 17. FIG. Also in this case, when fitting the fitting teeth 8 of the implantation portion 7 into the implantation grooves 9 of the rotor 3, one side surface portion of each fitting tooth 8 has a predetermined pressure with the downstream side surface portion of the implantation groove 9. It comes to contact. Moreover, since the other side surface part of the predetermined fitting tooth 8a comes into contact with the upstream side surface part among the side surface parts of the corresponding implantation groove 9 with a predetermined pressure via the protruding part 17, the above-mentioned The same operations and effects as those in the present embodiment can be achieved.

The schematic block diagram which shows the state which attached the rotor blade to the rotor. The figure which shows the assembly state of a rotor and a moving blade. The figure which shows the structure of the implantation part of a moving blade and the implantation groove | channel of a rotor. The figure which shows the state which carries out fitting fixation of the planting part of the moving blade arrange | positioned in the regular position with a stop pin to the implantation groove | channel of a rotor. The figure explaining the structural relationship of the leakage prevention structure which consists of a nozzle diaphragm, a convex part fin, and a recessed part fin, and the shroud of a moving blade. The figure which looked at the shroud of each rotor blade which comprises a turbine rotor blade group from the rotation radial direction outer side centering on the rotating shaft of a rotor. The figure which shows the fitting fixed state of the implantation part of a moving blade, and the implantation groove | channel of a rotor. The figure which looked at the shroud of each rotor blade which comprises a turbine rotor blade group from the rotation radial direction outer side centering on the rotating shaft of a rotor. The figure which looked at the shroud of each rotor blade which comprises a turbine rotor blade group from the rotation radial direction outer side centering on the rotating shaft of a rotor. The figure which looked at the shroud of each rotor blade which comprises a turbine rotor blade group from the rotation radial direction outer side centering on the rotating shaft of a rotor. The figure which shows the structure at the time of the planting part of a moving blade fitting to the implantation groove | channel of a rotor. The figure which shows the state which assembled | attached the rotor blade which has a big twist from a rotor blade root part to a rotor blade front-end | tip part in a rotor. The figure which shows an example of each rotor blade of the turbine rotor blade group which has a snubber structure. The figure which shows an example of each rotor blade of the turbine rotor blade group which has a snubber structure. The figure which shows an example of each rotor blade of the turbine rotor blade group which has a snubber structure.

Explanation of symbols

1, 1a, 1b, 1c, 1d Rotor blade 3 Rotor 5 Shroud 6 Wing portion 7 Planting portion 8 Fitting tooth 9 Planting groove 10 Rotor side receiving shelf 11a Shroud recess 11b Shroud projection 13 Rotor pin hole 15 Rotor pin hole 17 Projection Part 19 Chamfered part 21 Stopping pin 23 Nozzle diaphragm 25a Concave fin 25b Convex fin 27 Shim C1 Convex part C2 Concave part 50 Turbine blade group h Offset amount l1, l2 Blade pitch m Clearance r Shroud average rotation radius α , Β Shroud circumferential length θ1 Shroud face angle θ2 Torsion angle of rotor blade

Claims (9)

A plurality of moving blades are implanted at a predetermined position along the outer periphery of the rotor, and a predetermined moving blade of the plurality of moving blades is mounted as an offset blade in the radial direction, and the remaining blades are mounted. In an axial flow turbine configured to contact shrouds of adjacent moving blades with a predetermined pressure by mounting the moving blades as normal blades in a normal position,
A rotor formed with an implantation groove as an implanted portion of the moving blade;
An offset wing having an implantation portion that is fitted in the implantation groove formed in the rotor, contacts the axial downstream side surface of the implantation groove, and is formed to form a gap on the upstream side in the axial direction;
A regular wing having an implantation portion that is fitted in the implantation groove formed in the rotor, contacts the axial upstream side surface of the implantation groove, and is formed to form a gap on the downstream side in the axial direction;
An axial flow turbine characterized in that the offset blades are arranged at intervals of one or several with respect to the regular blades. A blade pin hole is formed in the implanted portion of each blade,
A rotor pin hole is formed in the implantation groove of the rotor,
2. The axial flow turbine according to claim 1, further comprising a wedge-shaped stop pin inserted into the rotor blade pin hole of each rotor blade and the rotor pin hole of the rotor to fix each rotor blade and the rotor. The implanted portion of the moving blade has a fitting tooth that fits into the implantation groove of the rotor,
At least one of the sidewall of the implantation groove of the rotor and the sidewall of the fitting tooth of the rotor blade is provided with a protruding portion that projects in the cross-sectional direction of the implantation groove,
The cross-sectional diameter of the implantation groove before the moving blade is attached to the normal position is smaller than the sum of the cross-sectional diameter of the fitting tooth and the protrusion amount of the protrusion,
The fitting teeth of the rotor blades fitted in the implantation groove of the rotor are in contact with the protrusion with a predetermined pressure, and are pressed by the protrusion and are in contact with the sidewall of the implantation groove with a predetermined pressure.
The axial-flow turbine according to claim 1, wherein the axial-flow turbine is characterized in that: The angle of the contact surface between the shroud of each blade constituting the turbine blade group and the shroud of the blade adjacent to this blade is the angle of the contact surface between the implanted portion of this blade and the side wall of the rotor implantation groove. The axial turbine according to claim 1, wherein the axial flow turbine is different from the axial turbine according to claim 1. A concave portion and a convex portion are formed on the upper surface of the shroud of each blade,
A nozzle diaphragm provided on the outer side in the rotational radial direction of the rotor so as to face the upper surface of the shroud of each rotor blade constituting the turbine rotor blade group via a predetermined gap;
A concave fin attached to the nozzle diaphragm and extending toward the concave portion on the upper surface of the shroud; and a convex fin extending toward the convex portion on the upper surface of the shroud;
The gap formed between the convex portion on the upper surface of the shroud and the convex fin is smaller than the gap formed between the concave portion on the upper surface of the shroud and the concave fin. The axial flow turbine according to claim 1. The axial turbine according to any one of claims 1 to 5, wherein the rotor blades constituting the turbine rotor blade group are made of a cobalt-based or nickel-based superalloy material. In the method of manufacturing an axial turbine according to any one of claims 1 to 6,
A temporary assembly step in which all of the plurality of rotor blades constituting the turbine rotor blade group are disposed along the outer periphery of the rotor by being arranged at a position offset from the normal position;
The moving blades arranged at positions offset from the normal positions are moved and arranged at the normal positions, and the shrouds of the moving blades arranged at the normal positions are brought into contact with the shrouds of the adjacent moving blades with a predetermined pressure. The final assembly process,
A method for manufacturing an axial-flow turbine, comprising: A method of manufacturing an axial turbine according to any one of claims 1 to 7,
Among the multiple blades that make up the turbine blade group, place some of the blades at positions offset from the normal position and attach them along the outer periphery of the rotor, and place other blades at the normal position. A temporary assembly step for mounting along the outer periphery of the rotor;
The moving blades arranged at positions offset from the normal positions are moved and arranged at the normal positions, and the shrouds of the moving blades arranged at the normal positions are brought into contact with the shrouds of the adjacent moving blades with a predetermined pressure. The final assembly process,
A method for manufacturing an axial-flow turbine, comprising: In the manufacturing method of the axial flow turbine given in any 1 paragraph among Claims 7 thru / or 8,
In the temporary assembly process, the rotor blade disposed at a position offset from the normal position is attached to the rotor via a shim having a predetermined thickness, and the offset amount from the normal position is equal to the predetermined thickness of the shim. It can be adjusted by adjusting
A method of manufacturing an axial-flow turbine, comprising: removing a shim in a final assembly step to move a moving blade arranged at a position offset from a normal position to be arranged at a normal position.

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