JP2007303440A - Turbine and turbine rotor blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent vibration characteristic, by excellently making mutual adjacent snubbers to contact each other, in a turbine rotor blade having a snubber cover. <P>SOLUTION: This turbine rotor blade 1 is formed by mutually adjacently arranging a plurality in the circumferential direction of a turbine rotor shaft, and is constituted so that the mutual snubber covers 2 of the adjacent turbine rotor blades contact each other on a contact surface 3, by installing the snubber covers 2 on the blade tip of the turbine rotor blade 1. An installation angle α of the contact surface 3 is set so as not to match in the displacement direction 9 of a vibration mode in the primary peripheral direction or the axial direction to a tangent 8 of connecting the front edge and the rear edge of a lower blade shape of the snubber covers 2. The installation angle α of the contact surface 3 is set in a range of 80 to 95 degrees to the tangent 8 of connecting the front edge and the rear edge of the lower blade shape of the snubber covers 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a turbine blade having a snubber cover at the blade tip and a turbine having a plurality of such turbine blades.

  In conventional turbine blades, when connecting to adjacent blades, a tenon is provided at the tip, a shroud cover is attached to the tenon, and then fixed by caulking, and the blade is integrally cut from the blade. There is a welding type in which the cover is welded and joined with adjacent blades. Both of these are spellings as a group, and the connection structure is a rigid connection. In these cases, in terms of static stress, there is a tendency that the stress of the swarm or swarm is higher than that of other wings, and there is a twist as a group, which is impossible for the shroud or weld that joins the wings. Power is a factor that works. In general, the vibration stress is higher in the group-wing spelling structure than in the all-around one-group spelling structure.

In recent years, as a spelling type for turbine rotor blades having more excellent vibration damping characteristics, a snubber cover integrated with the blades is provided at the tip, and as a spelling structure between adjacent blades, the adjacent blades The type which forms a whole circumference group by the contact of the snubber cover is adopted (for example, see Patent Document 1). By adopting this blade, the vibration mode becomes a disc mode as a group of all circumferences, and the vibration stress can be suppressed to ½ or less compared with a rigidly connected blade such as a Tenon shroud blade. In addition, by using one group spelling around the entire circumference, there is no local stress increase in the group tail or group head wing due to the group torsion seen in the group wing spell, and the stress of each wing is made uniform. became.
JP-A-9-209704

  However, in the case of a moving blade having a snubber cover as described above, it is connected by contact with a neighboring blade with a snubber cover, compared to a rigid connection such as a caulking or welding connection such as a Tenon shroud blade. In order to obtain a good contact state, it is necessary to set the reaction force acting on the snubber cover and the contact surface pressure to appropriate values. The reaction force acts on the damping effect on the vibration of the turbine rotor blade having the snubber cover, and the surface pressure of the contact surface of the cover also affects the vibration characteristics.

  For example, if the reaction force of the snubber cover is too small, the vibration suppression effect cannot be obtained so that the contact of the adjacent snubber cover forms a disc mode, and the wing vibrates as a single wing. As a result, the vibration stress is also increased. Conversely, if the reaction force is set excessively, a high stress portion is generated on the lower surface and blade surface of the snubber cover that receives the reaction force. In these cases, the reliability of the turbine blade is significantly reduced.

  Therefore, an object of the present invention is to improve the reliability of turbine blades having good vibration characteristics by making good contact between the snubbers of adjacent blades in a turbine blade having a snubber cover.

  The present invention meets the above-mentioned object, and the invention according to claim 1 is a turbine rotor blade in which a plurality of turbine rotor blades are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft. A snubber cover is attached to the tip of the blade, and the snubber covers of adjacent turbine blades are in contact with each other at the contact surface. The attachment angle of the contact surface is the leading edge and the trailing edge of the blade shape under the snubber cover. Is set so as not to match the displacement direction of the vibration mode in the primary circumferential direction or the axial direction.

  According to a third aspect of the present invention, there is provided a turbine blade in which a plurality of blades are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft, and a snubber cover is attached to the blade tip of the turbine blade, The snubber covers of the turbine rotor blades are configured to come into contact with each other at the contact surface, and at least one corner of the upper surface and the lower surface of the contact surface is chamfered.

  According to a fourth aspect of the present invention, there is provided a turbine blade in which a plurality of blades are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft, and a snubber cover is attached to the blade tip of the turbine blade, The snubber covers of the turbine rotor blades are configured to contact each other at the contact surface, and a step is provided in the vicinity of at least one of the upper surface and the lower surface of the contact surface to reduce the contact area of the contact surface. It is characterized by that.

  According to a fifth aspect of the present invention, there is provided a turbine blade in which a plurality of blades are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft, and a snubber cover is attached to the tip of the blade of the turbine blade. The snubber covers of the turbine rotor blades are configured to contact each other at the contact surface, and the thickness of the snubber cover gradually decreases toward the contact surface in the vicinity of at least one of the upper surface and the lower surface of the contact surface. Is provided with a taper.

  According to a sixth aspect of the present invention, in the turbine in which a plurality of turbine blades are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft, a snubber cover is attached to the blade tip of the turbine blade. The snubber covers of adjacent turbine blades are in contact with each other at the contact surface, and the attachment angle of the contact surface is relative to the tangent line connecting the leading edge and the trailing edge of the blade shape under the snubber cover. It is set so as not to match the displacement direction of the vibration mode in the primary circumferential direction or the axial direction.

  According to a seventh aspect of the present invention, in the turbine in which a plurality of turbine blades are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft, a snubber cover is attached to the blade tip of the turbine blade. The snubber covers of adjacent turbine blades are configured to contact each other at the contact surface, the snubber cover is attached to the tip of the turbine blade, and the snubber covers of the adjacent turbine blades contact each other at the contact surface. The snubber cover is provided with at least one of a chamfer, a step or a taper in the vicinity of the contact surface so as to reduce the area of the contact surface.

  ADVANTAGE OF THE INVENTION According to this invention, the favorable contact state of the snubber covers attached to the blade front-end | tip part of the adjacent turbine blade can be implement | achieved, Therefore The reliability of a turbine and a turbine blade can be improved.

  Embodiments of a turbine rotor blade according to the present invention will be described below with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a structural diagram of a snubber cover at the tip of a turbine blade according to a first embodiment of a turbine blade according to the present invention. A plurality of turbine blades 1 are arranged along the circumferential direction of a turbine rotor (not shown) in substantially the same manner as the steam turbine described in Patent Document 1. And it is comprised so that the snubber covers 2 of the adjacent turbine blade | wing 1 may contact on the contact surface 3. FIG.

  In this embodiment, the attachment angle α of the contact surface 3 of the snubber cover 2 at the tip of the turbine blade 1 is set to a primary line with respect to the tangent line 8 connecting the front and rear edges on the ventral side of the tip blade section. The line 9 indicating the displacement direction of the vibration mode in the circumferential direction or the axial direction is set to an angle that does not coincide with the angle β. As a result, it is possible to prevent the contact surface of the snubber cover from being affected by the vibration of the turbine rotor blade, and to ensure a good contact state. In the figure, reference numeral 11 denotes a snubber cover which is displaced by vibration.

  FIG. 2 is a diagram showing the relationship between the reaction force of the snubber cover 2 and the snubber attachment angle α with respect to the tangent line 8 connecting the front and rear edges on the ventral side of the tip wing cross section. According to this, the attachment angle α approaches the angle β formed by the tangent line 8 connecting the front edge and the rear edge on the ventral side of the tip blade section and the displacement direction 9 of the primary circumferential direction or axial vibration mode. When the direction is set, the snubber reaction force is reduced, and when entering the range where the angles coincide, the reaction force is extremely reduced by vibration. According to FIG. 2, in order to obtain a stable reaction force, the upper limit of the snubber attachment angle α with respect to the tangent line 8 connecting the front edge and the rear edge on the ventral side of the tip blade section is 95 degrees.

  Conversely, the attachment angle α is determined from the angle β formed by the tangent line 8 connecting the front edge and the rear edge on the ventral side of the tip blade section and the displacement direction 9 of the primary circumferential direction or axial vibration mode. When set away, the snubber reaction force increases. The increase in the snubber reaction force increases the stress in the vicinity of the base of the snubber cover or the blade surface that receives it, and setting the reaction force large is not preferable in terms of the strength of the turbine rotor blade. Here, it is important for maintaining the reliability of the turbine rotor blade that the high stress portion generated under the snubber cover does not exceed the proof stress of the material. Therefore, the lower limit value of the attachment angle α is 80 degrees.

  Therefore, by setting the attachment angle α of the contact surface to 80 to 95 degrees, the snubber cover 2 can ensure a good contact state and improve the reliability of the blade.

[Second Embodiment]
FIG. 3 is a structural diagram of the snubber cover at the tip of the turbine blade according to the second embodiment of the turbine blade according to the present invention. The snubber cover 2 is cut out integrally with the blade at the tip of the turbine rotor blade 1, and the snubber cover 2 comes into contact with the adjacent blade at the contact surface 3 on the leading edge side and the trailing edge side. Further, when the cross section of the contact surface 3 is viewed, a chamfer 4 shape is provided at the corners of the contact surface 3 and the upper and lower surfaces of the snubber cover 2.

According to the present embodiment, the area of the contact surface 3 between the snubber covers 2 of adjacent wings can be appropriately reduced, thereby appropriately increasing the surface pressure and making the snubber cover 2 in a good contact state. be able to.
The chamfer 4 may be applied to both corners of the upper surface and the lower surface of the snubber cover 2 or to either one of them.

[Third Embodiment]
FIG. 4 is a structural diagram of the snubber cover at the tip of the turbine rotor blade in the third embodiment of the turbine rotor blade according to the present invention. In contrast to the second embodiment, the area of the contact surface 3 is adjusted by providing a step 5 near the contact surface 3 in the cross-sectional shape of the contact surface 3. Thereby, the same operation and effect as the second embodiment can be obtained.
The step 5 may be provided on both the upper surface side and the lower surface side of the snubber cover 2 or may be provided on either one.

[Fourth Embodiment]
FIG. 5 is a structural diagram of the snubber cover at the tip of the turbine blade according to the fourth embodiment of the turbine blade according to the present invention. In contrast to the second embodiment, a taper 6 is provided on the upper or lower surface of the snubber cover 2 so as to adjust the area of the contact surface 3, and the cover thickness is gradually reduced to the contact surface 3. Thereby, the same operation and effect as the second embodiment can be obtained.
The taper 6 may be provided on both the upper surface side and the lower surface side of the snubber cover 2 or may be provided on either one.

The top view which looked at 1st Embodiment of the turbine rotor blade which concerns on this invention from the blade tip side. The graph which shows the relationship between the snubber cover reaction force and attachment angle of 1st Embodiment of the turbine rotor blade which concerns on this invention. It is a figure which shows 2nd Embodiment of the turbine rotor blade which concerns on this invention, Comprising: (a) is the top view which looked at two turbine rotor blades adjacent from the blade front end side, (b) is (a). BB sectional drawing. It is a figure which shows 3rd Embodiment of the turbine rotor blade which concerns on this invention, Comprising: (a) is the top view which looked at two turbine rotor blades adjacent from the blade front end side, (b) is (a). BB sectional drawing. It is a figure which shows 4th Embodiment of the turbine rotor blade which concerns on this invention, Comprising: (a) is the top view which looked at two turbine rotor blades adjacent from the blade tip side, (b) is (a). BB sectional drawing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Turbine blade, 2 ... Snubber cover, 3 ... Contact surface, 4 ... Chamfered part, 5 ... Step part, 6 ... Tapered part, 8 ... Reference line of front-end | tip blade cross section, 9 ... Line which shows the vibration direction of a blade, 11 ... snubber cover displaced by vibration, α ... contact surface mounting angle, β ... angle between the reference line of the tip blade cross section and the vibration direction.

Claims (7)

In the turbine rotor blade in which a plurality are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft,
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to come into contact with each other at the contact surface.
The mounting angle of the contact surface is set so as not to match the displacement direction of the primary circumferential direction or the axial vibration mode with respect to the tangent line connecting the leading edge and the trailing edge of the wing shape under the snubber cover. is being done,
Turbine blades characterized by   2. The turbine rotor blade according to claim 1, wherein an attachment angle of the contact surface is set in a range of 80 degrees to 95 degrees with respect to a tangent line connecting a leading edge and a trailing edge of the blade shape under the snubber cover. Turbine blades characterized by that. In the turbine rotor blade in which a plurality are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft,
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to come into contact with each other at the contact surface.
Chamfering is applied to at least one corner of the upper surface and the lower surface of the contact surface;
Turbine blades characterized by In the turbine rotor blade in which a plurality are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft,
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to come into contact with each other at the contact surface.
A step is provided in the vicinity of at least one of the upper surface and the lower surface of the contact surface to reduce the contact area of the contact surface;
Turbine blades characterized by In the turbine rotor blade in which a plurality are arranged adjacent to each other in the circumferential direction of the turbine rotor shaft,
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to come into contact with each other at the contact surface.
A taper is provided so that the thickness of the snubber cover gradually decreases toward the contact surface in the vicinity of at least one of the upper surface and the lower surface of the contact surface;
Turbine blades characterized by In a turbine in which a plurality of turbine rotor blades are arranged adjacent to each other in a circumferential direction of a turbine rotor shaft,
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to come into contact with each other at the contact surface.
The mounting angle of the contact surface is set so as not to match the displacement direction of the primary circumferential direction or the axial vibration mode with respect to the tangent line connecting the leading edge and the trailing edge of the wing shape under the snubber cover. is being done,
Turbine characterized by In a turbine in which a plurality of turbine rotor blades are arranged adjacent to each other in a circumferential direction of a turbine rotor shaft,
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to come into contact with each other at the contact surface.
A snubber cover is attached to the blade tip of the turbine blade, and the snubber covers of adjacent turbine blades are configured to contact each other at a contact surface,
Chamfering, at least one of a step or a taper is applied near the contact surface of the snubber cover so as to reduce the area of the contact surface;
Turbine characterized by

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