JP4191621B2 - Turbine blade - Google Patents

Description

  The present invention relates to a turbine rotor blade provided with a shroud at the blade tip.

  Conventionally, for example, in a gas turbine rotor blade, a shroud is provided at the blade tip. This is because, in a long blade disposed mainly on the downstream side of the turbine driving gas, a large vibration that may occur during high-speed rotation of the turbine is suppressed between the shrouds of the blades provided adjacent to each other. It is a thing. Further, by providing a single or a plurality of fins in the turbine circumferential direction on the outer surface of the shroud, the turbine driving gas is prevented from flowing out from a gap formed between the inner surface of the casing and the shroud is bent. Reinforced so as not to stop. The shroud outer peripheral surface corresponds to the turbine outer surface, and is a surface facing the casing inner peripheral surface.

  FIG. 9 is a view of such a conventional turbine blade shroud as seen from the outside of the turbine. The left side of the figure is the turbine drive gas upstream side and the right side is the downstream side. Further, the vertical direction is the turbine circumferential direction. As shown in the figure, a substantially flat shroud 2 that is curved along the outer periphery of the turbine is fixed to a blade end portion indicated by a broken line of a moving blade 1 that rotates at high speed and outputs a driving force. In this case, when vibration is generated in the moving blade 1 during high-speed rotation, this is suppressed by contact between the shrouds 2 provided adjacent to each other as indicated by a two-dot chain line. The shroud 2 is provided over the entire circumference of the turbine.

  Further, contact ribs 3 having a substantially rectangular parallelepiped shape projecting on the outer peripheral surface 2a of the shroud 2 are provided at both ends in the turbine circumferential direction of the shrouds 2 which are adjacent to each other. The contact rib 3 has a longitudinal direction on the outer peripheral surface 2a of the shroud 2 at an angle of, for example, 45 ° with respect to the turbine peripheral direction. The contact ribs 3 of the shroud 2 are in contact with each other at the contact surface 3a. In this manner, the shrouds 2 are brought into contact with each other over a wide surface, so that the reaction force is dispersed by supporting the shrouds 2 with each other and the contact between the shrouds 2 is not released.

  In addition, two rows of fins 4 are erected on the outer peripheral surface 2a of the shroud 2 in the turbine circumferential direction, and the contact ribs 3 are positioned therebetween. The fin 4 closes a gap formed between the blade tip of the rotating rotor blade 1 and the inner peripheral surface of a casing (not shown) that is stationary, so that the turbine driving gas flows out from the gap to the downstream side. The turbine efficiency is prevented from being lowered, and the shroud 2 is reinforced so as not to be bent due to centrifugal load or vibration caused by rotation. Note that the fins 4 are not limited to two rows, and may be one row or three or more rows.

In addition, the static pressure in the cavity formed between the fins is increased, the flow rate of the mainstream gas flowing from the lower surface to the upper surface of the tip shroud blade is reduced, and the cooling effect of the blade tip is improved. A gas turbine chip shroud blade capable of extending the creep life is disclosed (for example, see Patent Document 1). Specifically, among the fins arranged in two rows on the outer circumferential surface of the tip shroud blade in the circumferential direction, the height of the upstream fin is made smaller than that of the downstream fin.
JP 10-317905 A

  However, due to the increase in capacity accompanying the recent increase in turbine output, the blades become longer and the blade height increases, and the centrifugal load and vibration during rotation increase. For this reason, the shroud is required to be reduced in weight. On the other hand, in the conventional configuration as described above, damage such as cracks may occur due to excessive stress generated at the base portion of the contact rib. . This will be specifically described below.

  FIG. 10 is a diagram (stress contour diagram) showing the stress distribution in the shroud of the conventional turbine blade described above. As shown in the figure, a force as indicated by an arrow a from the adjacent shroud 2 is applied to the contact surface 3 a of the contact rib 3, and accordingly, the moving blade 1 of the moving blade 1 from the vicinity of the root of the moving blade side of the contact rib 3 is applied. A stress flow as indicated by an arrow b occurs on both sides of the rotor blade 1 over the leading edge or the trailing edge. A region along the flow at this time becomes a high stress region A1 generated when the adjacent contact ribs 3 are pressed against each other.

  On the other hand, the end of the shroud 2 tends to roll up due to the weight of the contact rib 3 itself due to the centrifugal force associated with the rotation of the rotor blade 1. A high stress portion A2 is generated. As described above, excessive stress is generated at the base of the contact rib 3 and the like, which may cause damage such as cracks.

  In view of such problems, an object of the present invention is to provide a turbine blade having a simple configuration and in which stress generated in a shroud provided at a blade tip is significantly reduced.

To achieve the above object, according to the present invention, a shroud fixed to a blade tip, fins provided in the turbine circumferential direction on the outer peripheral surface of the shroud, and both ends in the turbine circumferential direction on the outer peripheral surface of the shroud. In the turbine rotor blade, the contact ribs of the shrouds adjacent to each other are in contact with each other at their contact surfaces, and the fins are arranged in two rows in the flow direction of the driving gas of the turbine. The contact rib is provided between the fins, a reinforcing rib that connects the end of the fin and the end of the contact rib, and a root of the contact rib on the shroud. It is arranged so as to cross the high stress region generated from the vicinity of the part to the leading edge or the trailing edge of the blade tip part, and the two rows of fins are connected to each other. Characterized by comprising a connecting rib. The reinforcing rib is provided so as to border the shroud.

The said structure WHEREIN: When the length of the circumferential direction is made into 100% from the edge part of the circumferential direction in the said fin, the 25%-75% part of the said fin was made thicker than the other part.

  According to the present invention, it is possible to provide a turbine blade having a simple configuration in which the stress generated in the shroud provided at the blade tip is significantly reduced.

  Specifically, by providing the reinforcing rib for connecting the fin and the contact rib, the stress generated in the shroud can be significantly reduced by directly reinforcing the high stress portion of the shroud.

  Further, by providing connection fins that connect the contact ribs provided at both ends in the turbine circumferential direction on the outer peripheral surface of the shroud, the contact ribs can be reinforced to reduce the stress generated at the high stress portion of the shroud. it can.

  Further, the contact ribs provided at both ends in the turbine circumferential direction on the outer peripheral surface of the shroud are connected by the fins, so that the contact ribs can be reinforced and the stress generated in the high stress portion of the shroud can be reduced. it can.

  Further, by forming a row of contact ribs so as to fill between the contact ribs provided at both ends in the turbine circumferential direction on the outer peripheral surface of the shroud, the contact ribs are reinforced, and the stress generated in the high-stress portion of the shroud Can be reduced.

  Moreover, the stress which generate | occur | produces in the high-stress site | part of a shroud can be reduced by arrange | positioning so that the high-stress area | region of a shroud may be crossed and providing the connection rib which connects 2 rows of fins.

  Moreover, the stress which generate | occur | produces in the high stress site | part of a shroud can be reduced by making the part which crosses the high stress area | region of a shroud in a fin thicker than another part.

  Further, in the shroud, an area extending from one contact rib to the turbine blade front edge among the contact ribs provided at both ends of the turbine circumferential direction on the outer peripheral surface of the shroud, including the high stress region of the shroud, and the other By making the area extending from the contact rib of the turbine blade to the trailing edge of the turbine blade thicker than the other areas, the stress generated in the high stress portion of the shroud can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present invention, the stress generated in the shroud is greatly reduced by reinforcing mainly the high stress portion in the shroud of the conventional turbine blade.

  FIG. 1 is a view of a shroud of a turbine blade according to a first embodiment of the present invention as viewed from the outside of the turbine. The left side of the figure is the upstream side of the turbine driving gas, and the right side is the downstream side. The vertical direction is the turbine circumferential direction. FIG. 2 is a perspective view of a main part of the shroud according to the present embodiment. In the present embodiment, as shown in each drawing, the reinforcing rib 5 is provided so as to connect the end portion of the contact rib 3 and the end portion of the fin 4 so as to trim the shroud 2.

  Specifically, the reinforcing rib 5a is provided so as to connect the rotor blade side end portion of the contact rib 3 and the fin 4 end portion on the upstream side of the turbine driving gas, and the end portion of the contact rib 3 on the turbine circumferential direction end portion side. The reinforcing rib 5b is provided so as to connect the end of the fin 4 on the downstream side of the turbine driving gas. Thereby, the stress which generate | occur | produces in the shroud 2 is reduced significantly by reinforcing the high stress site | part of the shroud 2 directly. It is necessary to reinforce both the reinforcing ribs 5a and 5b by providing them simultaneously. For example, in the reinforcement using only the reinforcing rib 5b, as described in the paragraph [0008], the rigidity in the vicinity of the root of the moving blade side of the contact rib 3 is reduced, so that a high stress region A1 is generated.

  As an example, the stress which generate | occur | produced in the said high stress part A2 is reduced to 1 / (about 1/5-1/8) by taking the structure of a present Example. The reinforcing rib 5a may be provided on the same side as the reinforcing rib 5b, and the contact rib 3 here may be connected to the fin 4 on the same side.

  FIG. 3 is a view of the shroud of the turbine blade according to the second embodiment of the present invention as viewed from the outside of the turbine. In the present embodiment, as shown in the figure, connecting fins 6 for connecting the contact ribs 3 at both ends in the turbine circumferential direction of the shroud 2 are provided, and the fins 4 are combined to form three rows of fins. The contact rib 3 is reinforced by such connection fins 6 to reduce the stress generated in the high stress portion of the shroud 2.

  FIG. 4 is a view of a turbine blade shroud according to a third embodiment of the present invention as viewed from the outside of the turbine. In this embodiment, as shown in the figure, the arrangement width of the two rows of fins 4 is closer to the inside than the conventional one, and the contact ribs 3 at both ends in the turbine circumferential direction of the shroud 2 are connected to each other by these two rows of fins 4. Are connected. The contact rib 3 is reinforced by such fins 4 to reduce the stress generated in the high stress portion of the shroud 2. Further, by setting the two rows of fins 4 to the position close to the inside, it is possible to reduce the outer portions of the fins 4 (upstream and downstream portions of the turbine driving gas) of the shroud 2 and to reduce the weight of the shroud 2. .

  FIG. 5 is a view of a turbine blade shroud according to a fourth embodiment of the present invention as viewed from the outside of the turbine. In this embodiment, as shown in the figure, instead of the fins 4, a row of contact ribs 7 are formed so as to fill the space between the contact ribs 3, and stress generated at a high stress portion of the shroud 2 is applied. Reduced. Moreover, since it is set as the structure which removed the said fin 4, by this, the turbine drive gas upstream side and downstream part of the shroud 2 can be reduced, and the shroud 2 can be reduced in weight.

  FIG. 6 is a view of a turbine blade shroud according to a fifth embodiment of the present invention as viewed from the outside of the turbine. In this embodiment, as shown in the figure, the connecting ribs 8 are provided on both sides of the rotor blade 1 so as to connect the two rows of fins 4 together. The connecting rib 8 is arranged so as to cross the high stress region A1 shown in FIG. 10 so as to reduce the stress here. The angle formed by the connecting rib 8 and the longitudinal direction of the contact rib 3 is 0 °, that is, parallel or within about ± 10 °. In this case, the optimum mounting angle, mounting position, thickness, height, and the like of the connecting rib 8 are determined by stress analysis according to the stress flow.

  FIG. 7 is a view of the turbine blade shroud according to the sixth embodiment of the present invention as viewed from the outside of the turbine. In this embodiment, as shown in the figure, when the total length of the fins 4 is 100%, a portion of 25% to 75% is thicker than one end of each fin 4. Then, the thick portion 4a crosses the high stress region A1 shown in FIG. 10 to reduce the stress here.

  In this case, the high-stress region of the outer peripheral surface 2a of the shroud 2 shows about twice as much stress as the other parts. The thickness of the 75% portion is set to be 1 to 2 times the original thickness.

  FIG. 8 is a view of the turbine blade shroud according to the seventh embodiment of the present invention as viewed from the outside of the turbine. In this embodiment, the outer peripheral surface 2a of the shroud 2 is raised along the line where the stress flows, and this portion is thickened to reduce the stress. Specifically, as indicated by the hatched portion 2aa, the area extending from one contact rib 3 to the leading edge of the moving blade 1 along the high stress region A1 shown in FIG. 10, and the other contact rib The area extending from 3 to the trailing edge of the blade 1 is thickened. And it is set as the structure which takes this thickness in the range of 1 to 2 times the original. Thereby, the stress in the high stress region A1 is reduced.

The figure which looked at the shroud of the turbine blade which concerns on Example 1 from the turbine outer side. The principal part perspective view of the shroud which concerns on a present Example. The figure which looked at the shroud of the turbine blade which concerns on Example 2 from the turbine outer side. The figure which looked at the shroud of the turbine bucket which concerns on Example 3 from the turbine outer side. The figure which looked at the shroud of the turbine bucket which concerns on Example 4 from the turbine outer side. The figure which looked at the shroud of the turbine bucket which concerns on Example 5 from the turbine outer side. The figure which looked at the shroud of the turbine blade which concerns on Example 6 from the turbine outer side. The figure which looked at the shroud of the turbine bucket which concerns on Example 7 from the turbine outer side. The figure which looked at the shroud of the conventional turbine blade from the turbine outer side. The figure which showed the stress distribution in the shroud of the conventional turbine blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor blade 2 Shroud 2a Outer peripheral surface 3 Contact rib 3a Contact surface 4 Fin 4a Thick part 5 Reinforcement rib 6 Connection fin 7 Contact rib 8 Connection rib A1 High-stress area A2 High-stress part

Claims (3)

A shroud fixed to the blade tip, fins provided in the turbine circumferential direction on the outer peripheral surface of the shroud, and contact ribs provided at both ends of the turbine circumferential direction on the outer peripheral surface of the shroud, adjacent to each other In the turbine blade configured such that the contact ribs of the shroud are in contact with each other at their contact surfaces,
The fins are provided in two rows in the flow direction of the driving gas of the turbine,
The contact rib is provided between the fins,
A reinforcing rib connecting the end of the fin and the end of the contact rib;
The shroud includes a connection rib that is arranged so as to cross a high-stress region generated from the vicinity of the base portion of the contact rib to the front edge or the rear edge of the blade tip portion, and connects the two rows of fins. Characteristic turbine blade.   The turbine blade according to claim 1, wherein the reinforcing rib is provided so as to border the shroud.   The portion of 25% to 75% of the fin is thicker than the other portion when the circumferential length from one circumferential end of the fin is 100%. Turbine blades.

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