JP2014152765A - Rotary machine blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variation of an eigen frequency to improve an attenuation effect, and to suppress vibration of a blade.SOLUTION: Provided is a turbine blade 10 including: a blade body in which a cavity part 13 is formed by respective rear surfaces 11a, 12a of a belly side member 11 and a back side member 12; a waveform plate spring 20 that is arranged in the cavity part 13; a viscoelastic member 30 that is interposed in at least a part of contact parts between the waveform plate spring 20 and the respective rear surfaces 11a, 12a, and is made of a soft material having smaller rigidity than the member of the waveform plate spring 20 such as fluororubber, silicone gel, or graphite fiber.

Description

  The present invention relates to a rotary machine blade used in, for example, a steam turbine.

  Conventionally, in order to reduce the weight of a steam turbine, a turbine blade having a hollow structure in which a cavity is defined by the back surfaces of the abdomen and the back is known. In such a turbine blade, as a technique for suppressing vibration, a damper such as a leaf spring member is used to reduce the vibration response level of the turbine blade (see, for example, Patent Document 1). In this case, since the blade and the leaf spring member are in contact with each other inside the blade at the time of resonance, a damping effect is obtained by causing friction in both of them.

  In Patent Document 1, a stationary blade in which a hollow portion formed inside a turbine blade is formed and a slit that communicates the hollow portion and the outside is formed between the ventral member and the back member. Further, there is described a configuration in which a corrugated leaf spring is provided which is in sliding contact with at least one of the abdominal member and the dorsal member and generates friction between at least one of both members.

JP 2008-133825 A

However, the conventional turbine blade has the following problems.
That is, during actual operation of the turbine, there is a problem in that variations in the natural frequency occur due to the initial irregularity of the leaf spring shape, and the turbine blades vibrate, leading to fatigue failure.
In addition, the blade has a damping effect due to the contact between the blade and the leaf spring in the cavity of the turbine blade. Variations occur due to shortage and the gradual change in the natural frequency of the turbine blades. For this reason, the effect of reducing the vibration response level of the blade is reduced, and as a result, the above-described damping effect is reduced.

  The present invention has been made in view of the above-described problems, and provides a rotary machine blade that can reduce variations in natural frequency, improve a damping effect, and suppress blade vibration. For the purpose.

  In order to achieve the above object, in the rotary machine blade according to the present invention, a blade body in which a cavity is defined by the back surfaces of the abdomen and the back, and a leaf spring member disposed in the cavity, And a viscoelastic member interposed in at least a part of a contact portion between the leaf spring member and each of the back surfaces.

In the present invention, since the leaf spring member in which at least a part of the abdominal portion and the dorsal side is in sliding contact is disposed between the ventral portion and the dorsal portion, the leaf spring member is elastically deformed when the wing body is elastically deformed. Will cause friction between at least one of the ventral portion and the dorsal portion. By this friction, the relative position fluctuation between the ventral part and the dorsal part can be attenuated.
Furthermore, in addition to this friction damping, since a viscoelastic member having low rigidity is interposed at least at a part of the contact portion between the back side and the back side, the viscoelastic member is caused by the frictional force. Since shear deformation occurs and internal damping occurs in the viscoelastic member itself, an effect of reducing variations in the natural frequency can be obtained, and the damping effect can be improved.
As described above, the present invention can effectively exhibit a damping effect, and thus has an advantage that it is not necessary to provide a large design margin for the vibration strength of the blade body.

Further, since the contact surface pressure between the leaf spring member and the wing body (abdomen side portion and back side portion) can be reduced, it is possible to prevent the blade body from being thinned and to maintain the vibration characteristics of the wing.
Even when the viscoelastic member is worn, it can be repaired and replaced easily and at a lower cost than when the leaf spring member is replaced.

  In the rotary machine blade according to the present invention, it is preferable that the leaf spring member has a laminated structure with a viscoelastic material interposed therebetween.

  In this case, when the blade body vibrates and the internal shape of the blade changes, the leaf spring member undergoes frictional damping with the blade and internal damping due to the viscoelastic material. Can be reduced. That is, since it has internal damping accompanying deformation of the leaf spring member itself, the above-described damping effect of the wing can be further improved.

  According to the rotary machine blade of the present invention, a viscoelastic member capable of internal damping is interposed in at least a part of the contact portion between the leaf spring member and the blade body, thereby reducing variation in natural frequency and reducing the damping effect. The vibration of the wing can be suppressed.

It is the figure which showed typically schematic structure of the steam turbine by the 1st Embodiment of this invention. It is the external view which looked at the steam turbine shown in FIG. 1 from the low-pressure last stage side. It is the enlarged view which looked at the stationary blade (turbine blade) from the back side. It is sectional drawing which shows the airfoil of a turbine blade. It is sectional drawing which shows the airfoil of the turbine blade by 2nd Embodiment, Comprising: It is a figure corresponding to FIG.

  Hereinafter, a rotary machine blade according to an embodiment of the present invention will be described with reference to the drawings. This embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention.

(First embodiment)
As shown in FIG. 1, the steam turbine to which the turbine blade 10 (rotary machine blade) of the present embodiment is applied is used in a power plant or the like. For example, such a steam plant includes a steam generator 2 that generates high-pressure steam, a high-pressure steam turbine 3 to which high-pressure steam is directly supplied from the steam generator 2, and the steam generator 2 and the high-pressure steam turbine 3. A moisture separator / heater 4 that separates and heats the moisture from the steam and a low-pressure steam turbine (hereinafter referred to as steam turbine 1) to which low-pressure steam is supplied from the moisture separator / heater 4 are provided. .

  In the steam turbine 1, steam from the moisture separation heater 4 is supplied to the steam inlet 1 </ b> A, and the steam passage 1 </ b> B formed in the steam turbine 1 is indicated by the axial direction of the rotor shaft 5 (indicated by an arrow A in the figure). ) Flow along. In the steam passage 1 </ b> B, the moving blades 6 and the stationary blades 10 (turbine blades 10) are alternately arranged. The steam turbine 1 generates kinetic energy by the pressure drop in the stationary blades 10. Is converted into rotational torque.

  The rotor blade 6 is coupled to the rotor shaft 5 and rotationally drives it. On the other hand, as shown in FIGS. 1 to 3, the stationary blade 10 has an inner end in the radial direction (indicated by an arrow R) of the rotor shaft 5 at the shroud 7 and an outer end in the radial direction R at the blade root. Each ring 8 is joined by welding (the welded portion is indicated by symbol E in FIG. 3).

The moving blade 6 and the stationary blade 10 constitute a single “stage” as a pair, and the steam turbine 1 is provided with a number of stages. These stages are configured such that the blade widths of the moving blades 6 and the stationary blades 10 (the lengths of the blades in a direction substantially perpendicular to the rotor shaft 5) become longer as the steam passage 1B moves from the upstream side to the downstream side. Yes. The stage on the most downstream side of the steam passage 1B is referred to as “low pressure final stage”. The low-pressure final stage stationary blade 10 has a particularly large blade width compared to the stationary blade 10 in the upstream stage. In the low-pressure final stage, as shown in FIG. 1, a plurality of stationary blades 10 are arranged at a predetermined interval in the circumferential direction of the rotor shaft 5 (arrow P in the figure) to form a blade group.
In the following description, the stationary blade 10 is described as the “turbine blade 10”.

  As shown in FIG. 4, the turbine blade 10 includes an abdominal member 11 that mainly constitutes the abdomen and a back member 12 that mainly constitutes the dorsal side. The abdominal member 11 and the dorsal member 12 are formed by bending metal plate-like members with different warping methods. The abdomen side member 11 is warped so that the surface thereof becomes the abdomen surface 10 a of the turbine blade 10. On the other hand, the back member 12 is warped so that the surface thereof becomes the back surface 10 b of the turbine blade 10.

The ventral member 11 and the dorsal member 12 extend in the wing span direction over substantially the same length.
The “blade width direction” is a direction perpendicular to the cross section of the airfoil shown in FIG. 4, and is orthogonal to the average warp line of the turbine blade 10 (also referred to as a skeleton line, indicated by a one-dot chain line C in the figure). Direction. In this embodiment, the “blade width direction” is substantially the same as the radial direction of the rotor shaft 5 shown in FIG. 1.

  The outer shape of the turbine blade 10 is formed by combining the abdominal member 11 and the back member 12 and joining them by welding at the front edge portion 10c and the rear edge portion 10d. As a result, a cavity 13 extending along the blade width direction is formed inside the turbine blade 10, that is, between the back surface 11 a of the abdominal member 11 and the back surface 12 a of the back member 12. Inside the turbine blade 10, the blade inner surface (11 a, 12 a) is formed by the back surface 11 a of the abdominal member 11 and the back surface 12 a of the back member 12.

As described above, in the turbine blade 10 of the present embodiment, the ventral member 11 constitutes the ventral portion of the present invention, which is a portion on the ventral side of the cavity 13 of the turbine blade 10, and the back member 12 is The back side part of this invention used as the part of the back side from the cavity part 13 of the turbine blade 10 is comprised.
Further, the wing body of the present invention is configured by a cavity portion 13 defined by the back surfaces 11a and 12a of the abdominal member 11 and the back member 12.

  The hollow turbine blade 10 having the hollow portion 13 has a relatively low natural frequency as compared with a solid stationary blade having no hollow portion 13 therein, and during operation of the steam turbine 1, Self-excited vibration (flutter) is likely to occur. When the self-excited vibration occurs, the turbine blade 10 is bent or twisted due to elastic deformation, and a relative positional variation occurs between the abdomen side member 11 and the back side member 12 of the turbine blade 10.

  In order to attenuate this relative position fluctuation, the turbine blade 10 according to the present embodiment is provided with a sliding member that can slide from the cavity 13 to the blade inner surface (11a, 12a). When 10 is elastically deformed, the sliding contact member is caused to generate friction between the blade inner surfaces (11a, 12a), and will be described in detail below.

  In the turbine blade 10 of the present embodiment, as shown in FIG. 4, as the sliding contact member, a corrugated leaf spring 20 (plate spring member) having a corrugated cross section is provided as an abdominal member 11 and a dorsal member 12. Are provided via a viscoelastic member 30.

  In the corrugated leaf spring 20, a top portion 20 a on the front side (hereinafter referred to as a front side top portion) is in contact with the back surface 11 a of the abdominal member 11 with a viscoelastic member 30 interposed therebetween. Further, the corrugated leaf spring 20 has a back side top portion 20 b (hereinafter referred to as a back side top portion) in contact with the back surface 12 a of the back side member 12 via a viscoelastic member 30.

  The corrugated leaf spring 20 is formed of a metal flat plate-like member extending in a longitudinal direction (a direction orthogonal to the paper surface in FIG. 4), and a mountain fold and a valley along a width direction (indicated by an arrow W in FIG. 4). The folds are bent so as to continue alternately. The corrugated leaf spring 20 is formed so that an envelope connecting a plurality (two in this case) of the front side top 20a is formed along the back surface 11a of the abdominal member 11, and a plurality of (here, three) back side tops. An envelope connecting 20 b is formed along the back surface 12 a of the back member 12. The corrugated leaf spring 20 is positioned so that the longitudinal direction thereof is the blade width direction of the turbine blade 10, and is inserted into the cavity 13 between the abdominal member 11 and the back member 12.

  Thus, in the state (initial state) arrange | positioned in the cavity part 13, the waveform leaf | plate spring 20 is formed so that it may be elastically deformed slightly by bending. As shown in FIG. 4, the wave-shaped leaf spring 20 causes the front side top portion 20 a to press the abdominal member 11 from the back surface 11 a and the back side top portion 20 b presses the back side member 12 from the back surface 12 a by this elastic force. It has become. That is, when the corrugated leaf spring 20 is disposed in the cavity portion 13, it is configured to urge (push and spread) the ventral member 11 and the back member 12 outward in the blade thickness direction of the turbine blade 10. Has been.

The “blade thickness direction” is a direction parallel to the cross section of the airfoil shown in FIG. 4, and means a direction orthogonal to the average warp line of the blade (shown by a one-dot chain line C in the figure).

  The viscoelastic member 30 is made of a soft material having a lower rigidity than that of the corrugated leaf spring 20 such as, for example, fluororubber, silicon gel, graphite fiber, and the like. And it adheres to at least one of the corrugated leaf springs 20. The viscoelastic member 30 is not limited to being fixed, and may not be fixed.

  In the turbine blade 10 configured as described above, between the front side top portion 20a of the corrugated leaf spring 20 and the back surface 11a of the ventral member 11, and between the back side top portion 20b of the corrugated leaf spring and the back surface 12a of the back side member 12. An urging force (pressing force) due to the bending of the corrugated leaf spring 20 acts between them, and the turbine blade 10 is elastically deformed to cause a relative position fluctuation between the ventral member 11 and the dorsal member 12. When this occurs, a dynamic friction force having a magnitude corresponding to the biasing force can be applied.

Next, the operation of the turbine blade 10 having the above-described configuration will be specifically described based on the drawings.
As shown in FIG. 1, in the present embodiment, during operation of the steam turbine 1, depending on the operating conditions, self-excited vibration may occur in the turbine blade 10 (static blade), and the turbine blade 10 may be elastically deformed. is there. For example, the abdominal member 11 is elastically deformed toward the rear edge portion 10d and the back member 12 is elastically deformed toward the front edge portion 10c. There may be a relative positional variation between the distance 12a and 12a.

  At this time, the corrugated leaf spring 20 is in sliding contact between at least one of the front side top portion 20a and the back surface 11a of the ventral member 11 and between the back side top portion 20b and the back surface 12a of the back side member 12. A dynamic friction force is generated in a direction that suppresses relative positional fluctuation between the ventral member 11 and the dorsal member 12. By this dynamic friction force, the relative positional fluctuation between the abdominal member 11 and the back member 12 is attenuated, and the elastic deformation of the turbine blade 10 is attenuated, thereby suppressing the self-excited vibration generated in the turbine blade 10. be able to.

Furthermore, in the present embodiment, in addition to this friction damping, the low-rigidity viscoelastic member 30 is interposed in at least part of the contact portion between the back surface of the ventral member 11 and the back member 12, Since the viscoelastic member 30 is shear-deformed by the frictional force and internal damping occurs in the viscoelastic member 30 itself, an effect of reducing variation in natural frequency can be obtained, and the damping effect can be improved.
As described above, since the damping effect can be effectively exhibited, there is an advantage that it is not necessary to provide a large design margin for the vibration strength of the blade body.

  Further, since the contact surface pressure between the corrugated leaf spring 20 and the blade body (the abdominal member 11 and the back member 12) can be reduced, the blade body is prevented from being thinned and the vibration characteristics of the turbine blade 10 are maintained. can do.

  Even when the viscoelastic member 30 is worn, repair and replacement can be performed easily and at a lower cost than when the corrugated leaf spring 20 is replaced.

  Further, by selecting the rigidity of the corrugated leaf spring 20 as the urging member and adjusting the urging force in the state of being disposed in the cavity (initial state), between the abdominal member 11 and the dorsal member 12. The attenuation characteristic of the position variation can be set to a desired characteristic.

  Further, the turbine blade 10 of the present embodiment has a plate shape extending along the blade width direction, and the corrugated leaf spring 20 as a plate spring member that presses the abdominal member 11 and the dorsal member 12 by elastic force due to bending. The corrugated leaf spring 20 is a biasing member that extends in the longitudinal direction of the plate member, that is, in the blade width direction of the turbine blade 10 only by bending the rectangular plate member in the width direction by press molding or the like. Can be easily realized.

  In the turbine blade 10 of the present embodiment, the corrugated leaf spring 20 has a corrugated cross section, and the corrugated top portions 20a and 20b are in contact with the ventral member 11 and the dorsal member 12. Therefore, by making the plate-like spring member into such a wave shape, it is possible to make sliding contact with both the abdominal member 11 and the dorsal member 12 at a plurality of top portions. Thereby, the corrugated leaf | plate spring 20 can produce a favorable friction between the abdominal member 11 and / or the back member 12. FIG.

  In the rotary machine blade according to the present embodiment described above, a viscoelastic member 30 capable of internal damping is interposed in at least a part of the contact portion between the corrugated leaf spring 20 and the blade body (the abdominal member 11 and the dorsal member 12). The variation in the natural frequency can be reduced, the damping effect can be improved, and the vibration of the turbine blade 10 can be suppressed.

  Next, another embodiment of the rotating machine blade according to the present invention will be described with reference to the accompanying drawings. The same reference numerals are used for members or parts that are the same as or similar to those of the first embodiment described above. A description is omitted, and a configuration different from the first embodiment will be described.

(Second Embodiment)
As shown in FIG. 5, the turbine blade 10A (rotary machine blade) according to the second embodiment has a laminated structure in which a corrugated leaf spring 20A (leaf spring member) sandwiches a viscoelastic material. That is, in the corrugated leaf spring 20A, the viscoelastic material layer 22 is sandwiched between the pair of high-rigidity material layers 21, and viscoelasticity is applied to the curved surface of the blade inner surface (11a, 12a) as in the first embodiment. It has a bent structure in sliding contact with the member 30.

  In the second embodiment, when the wing body (the abdominal member 11 and the dorsal member 12) vibrates and the internal shape of the wing changes, the corrugated leaf spring 20A has frictional damping between the wing and viscosity. Internal damping is caused by the elastic material layer 22, and the vibration response level of the blade can be reduced. That is, since it has internal damping accompanying deformation of the corrugated leaf spring 20A itself, the damping effect of the wing according to the first embodiment described above can be further improved.

  As mentioned above, although embodiment of the rotary machine blade by this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably.

  For example, in the present embodiment, all of the front side top portion 20a and the back side top portion 20b of the corrugated leaf spring 20 are configured to contact the inner surface via the viscoelastic member 30, but the present invention is not limited thereto. You may make it provide the viscoelastic member 30 only in the location where vibration is large among the front side top part 20a and the back side top part 20b.

  Further, in the present embodiment, the stationary blade (turbine blade 10) of the steam turbine 1 is an application target. However, the present invention is not limited to this, and the rotary blade can be applied to other targets. It is.

  Furthermore, in the turbine blade 10A of the second embodiment described above, the single viscoelastic material layer 22 is sandwiched between the pair of high-rigidity material layers 21, but is limited to such a laminated structure. In other words, for example, a structure in which a plurality of viscoelastic material layers 22 and high-rigidity material layers 21 are alternately stacked may be employed.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Steam turbine 2 Steam generator 5 Rotor shaft 6 Rotor blade 10, 10A Turbine blade, stationary blade (rotary machine blade)
DESCRIPTION OF SYMBOLS 11 Abdominal side member 11a Back surface 12 Back side member 12a Back surface 13 Cavity part 20, 20A Wave plate spring (plate spring member)
20a Front side top part 20b Back side top part 21 High rigidity material layer 22 Viscoelastic material layer 30 Viscoelastic member

Claims (2)

A wing body in which a cavity is defined by each back surface of the ventral side and the back side;
A leaf spring member disposed in the cavity,
A viscoelastic member interposed in at least a part of a contact portion between the leaf spring member and each of the back surfaces;
A rotary machine blade comprising:   The rotary machine blade according to claim 1, wherein the leaf spring member has a laminated structure with a viscoelastic material interposed therebetween.

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