JP5501611B2 - Turbine blade and gas turbine - Google Patents

Description

  The present invention relates to a turbine blade and a gas turbine.

  Generally, a cantilever type stationary blade provided with a shroud separately or a shroud type stationary blade provided integrally with a shroud is used as a stationary blade in a compressor of a gas turbine.

  Compared to cantilever type stationary blades, shrouded type stationary blades are less susceptible to air leakage from the tip of the airfoil, and the inner periphery of the shroud is free of air leakage between the stationary blades and the rotor. A constraining rotor seal structure can be provided. From this, the type of stationary blade with shroud is advantageous in terms of performance because the amount of leaked air can be reduced to an appropriate amount.

The above-described type of stationary blade with a shroud is provided with a circumferential base portion called a shroud portion at the inner and outer ends of the airfoil portion (profile portion).
For fixing between the airfoil part and the shroud part, the tenon type fixing method in which the insertion part protruding from the airfoil part is inserted into the insertion port provided in the shroud part, or the airfoil part in the above-mentioned insertion port. A pork chop type fixing method in which an insertion brim portion formed so as to spread out is inserted.

In these tenon type fixing methods and pork chop type fixing methods, the insertion part or insertion collar part may be mechanically inserted into the insertion port, or may be fixed by brazing or welding. Good. In this manner, the shroud portion of the stationary blade is assembled in a ring shape.
Further, the airfoil portion and the shroud portion may be molded or processed as an integral structure.

  In general, the shroud part absorbs thermal expansion in the circumferential direction in a state of being assembled in a ring shape, so as to improve the workability and assemblability of the shroud part, in order to improve the maintainability of the shroud part, etc. It is divided into a plurality in the circumferential direction. For example, in the case of a stationary blade with a shroud, the shroud portion is divided for each stationary blade.

Further, a seal structure such as a labyrinth seal or a honeycomb seal is provided between the shroud portion and the rotating rotor shaft (see, for example, Patent Document 1).
This sealing structure may be formed separately from the airfoil portion or the shroud portion in consideration of ease of processing and repair, and may be combined with the airfoil portion or the shroud portion after formation.

  As a configuration in which the shroud portion and the seal structure are combined, a configuration in which the seal structure is fitted into a groove structure provided in the shroud portion can be exemplified in addition to the structure described in Patent Document 1.

On the other hand, the stationary blade is applied with an excitation force having a frequency that matches the natural frequency of the stationary blade in the air or gas flow field inside the compressor of the gas turbine, or an integer multiple of the rotational frequency. It is known that the airfoil portion and the shroud portion of the stationary blade shake greatly (respond to vibration).
Examples of the above-described excitation force include an excitation force caused by a wake flow (wake) of a rotating moving blade, an excitation force caused by an interference flow (potential), and the like.

If the stress acting on the stator blades due to the vibration response described above increases beyond the fatigue strength of the material constituting the stator blades, there is a risk of fatigue cracks occurring in the stator blades, which may damage the stator blades. .
For this reason, the airfoil and shroud parts are designed to have a physique strength that does not cause fatigue cracks even if vibration response occurs, and the natural frequency of the stationary blade is applied to the stationary blade. It is necessary to deviate from the expected excitation frequency, in other words, to detune.

  On the other hand, profile parts such as expansion of blade profile width (chord) and extension of blade length (span) in the profile part due to the recent increase in output, performance, and cost reduction of gas turbines. Is becoming larger.

  When the profile portion is increased in size, the aerodynamic force or gas force acting on the airfoil portion increases, and the load or moment applied to the base portion of the airfoil portion, in other words, the connection portion between the airfoil portion and the shroud portion is reduced. To increase. In order to withstand this increase in load or moment, it is necessary to increase the radius of curvature R of the fillet shape formed at the base of the airfoil to ensure sufficient strength.

  On the other hand, from the viewpoint of aerodynamics, it is necessary to reduce the fillet-shaped radius of curvature R formed at the base of the airfoil, which is opposite to ensuring sufficient strength at the base of the airfoil. There is also.

  The profile portion is driven to rotate and compresses air or the like containing gas, while receiving resistance to air (including gas) in the flow field. Therefore, in order to reduce this air resistance, the profile shape is optimized, the diameter of the leading edge in the profile part and the diameter of the trailing edge are reduced, and the thickness of the airfoil in the profile part itself is reduced. Is planned.

  However, the above-described reduction in diameter and thickness are factors that reduce the strength of the stationary blade, particularly the strength against resonance response. Therefore, in the design of the profile portion, there are restrictions on the above-described reduction in diameter and thickness in order to ensure the strength of the profile portion.

  In addition, in order to avoid destruction of the stationary blade due to resonance with the excitation force, the natural frequency of the entire stationary blade ring in which multiple stationary blades are combined is shifted from the frequency of the excitation source, that is, A detuning design is made so that they do not match.

  However, since the above natural frequency depends on the shape of the profile part, the shape of the shroud part, etc., giving priority to the detuning of the natural frequency and the frequency of the hypocenter will sacrifice the aerodynamic characteristics of the stationary blade. In many cases, it is necessary to design a stationary blade.

  Patent Document 1 proposes a technique for pressing a stationary blade with a corrugated leaf spring in order to restrain relative movement by the stationary blade.

  Furthermore, in order to reduce the vibration response in the stationary blade, a technique for attenuating the vibration due to the vibration response in the stationary blade by vibration damping (damping) using a friction force using a spring is also known.

Specifically, a donut ring-shaped spring is inserted between the shroud ring arranged on the inner peripheral side and the seal holder that holds the seal, and the spring is pressed against the shroud ring, so that the stationary blade A structure for damping vibration is known.
By doing in this way, when the shroud part connected with the profile part vibrates and deforms by resonance, the shroud part and the spring slide, and a frictional force acts between the shroud part and the spring. Then, vibration energy is converted into friction energy (thermal energy) on the sliding surface between the shroud portion and the spring, and the vibration of the stationary blade is attenuated.
JP 2002-276304 A

  However, when the blade body such as a stationary blade is increased, vibration energy due to vibration is also relatively increased. Therefore, it is necessary to increase a damping force in a mechanism for damping the vibration of the stationary blade. For example, in the case of a structure in which the above-described spring is pressed against the shroud ring, it is necessary to increase the spring force in order to obtain a sufficient damping force due to friction.

  The structure described in Patent Document 1 does not have a structure that takes into account the replacement of the above-described spring. Therefore, when the spring is worn out due to wear due to long-term use, a spring with increased spring force as described above is used. There was a problem that it was difficult to exchange.

  The present invention has been made to solve the above-described problem, and provides a turbine blade and a gas turbine that can attenuate vibration caused by an excitation force and can easily replace an elastic member such as a spring. The purpose is to provide.

In order to achieve the above object, the present invention provides the following means.
The turbine blade of the present invention has a shroud portion disposed at an end portion of the airfoil portion, an end that is slidable with respect to the shroud portion and is detachable, and forms a space between the shroud portion. And an elastic part that is arranged in the space and urges in a direction to separate the shroud part and the end case from each other and is relatively movable with respect to the shroud part. Features.

According to the present invention, when the airfoil portion and the shroud portion vibrate and slide relative to the end housing, the elastic portion and the shroud portion move relative to each other, that is, the elastic portion and the shroud portion slide. Therefore, the energy related to the vibration of the airfoil portion and the shroud portion is converted into thermal energy (friction energy) by sliding, and the vibration of the airfoil portion and the shroud portion is attenuated.
On the other hand, the elastic portion can be easily exchanged by sliding the elastic portion together with the end housing from the shroud portion and detaching it.

  In the said invention, the said shroud part is independently arrange | positioned at each of the said several airfoil part, and the said one edge part housing | casing can be attached or detached with respect to the said some shroud part. desirable.

According to the present invention, since the shroud portion is independently arranged on each of the plurality of airfoil portions, each of the airfoil portions and the shroud is compared with the case where the plurality of shroud portions are integrally formed. The part is easy to move relative to the elastic part. In other words, the sliding distance between the shroud portion and the elastic portion is increased.
Therefore, more energy related to the vibration of the airfoil portion and the shroud portion is converted into thermal energy (friction energy) by sliding, and the vibration of the airfoil portion and the shroud portion is more easily damped.

  In the above invention, the elastic portion is a leaf spring that extends along a direction in which the plurality of shroud portions are arranged and is substantially wave-shaped, and the top portion of the leaf spring is the shroud portion or the end housing. It is desirable to be in contact with.

According to the present invention, since the elastic portion is a plate spring formed in a wave shape, a larger pressing force can be applied to the shroud portion as compared with the case where another spring is used.
On the other hand, a plurality of shroud portions are slid with respect to one leaf spring by bringing each top portion of the leaf spring into contact with the shroud portion.

  The gas turbine of the present invention is provided with the turbine blade of the present invention.

  According to the present invention, since the turbine blade of this embodiment is provided, the energy related to the vibration of the airfoil portion and the shroud portion of the turbine blade is converted into thermal energy (friction energy) by sliding, and the airfoil And shroud vibrations are damped.

According to the turbine blade and the gas turbine of the present invention, since the elastic portion and the shroud portion move relative to each other, that is, the elastic portion and the shroud portion slide, energy related to vibration of the airfoil portion and the shroud portion is slid. It is converted into thermal energy (friction energy) due to motion, and the vibration of the airfoil portion and the shroud portion can be damped.
On the other hand, the elastic part can be easily exchanged by sliding the elastic part together with the end housing from the shroud part to be detached.

  A gas turbine according to an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the turbine blade of the present invention will be described by applying it from the first-stage stationary blade to the third-stage stationary blade in the compression section 2 of the gas turbine 1, the 5-stage stationary blade to the 17-stage stationary blade, or the 10-stage stationary blade to the 14-stage stationary blade.

FIG. 1 is a schematic diagram illustrating the configuration of a gas turbine according to the present embodiment.
As shown in FIG. 1, the gas turbine 1 is provided with a compression unit 2, a combustion unit 3, a turbine unit 4, and a rotating shaft 5.

As shown in FIG. 1, the compression unit 2 sucks and compresses air, and supplies the compressed air to the combustion unit 3. A rotational driving force is transmitted from the turbine unit 4 to the compression unit 2 via the rotary shaft 5, and the compression unit 2 sucks and compresses air by being driven to rotate.
In addition, as a compression part 2, a well-known structure can be used and it does not specifically limit.

FIG. 2 is a schematic diagram for explaining the configuration of the rotor disk and the stationary blade in the compression section of FIG.
As shown in FIGS. 1 and 2, the compressor 2 includes a stationary blade (turbine blade) 10 attached to the casing 6 of the gas turbine 1 and a disk-shaped rotor disk that is rotationally driven by the rotating shaft 5 (see FIG. 1). And a rotor blade disposed on a circumferential surface of the rotor (not shown).
The stationary blades 10 and the moving blades are arranged at equal intervals in the circumferential direction of the rotating shaft 5 and are arranged alternately in the axial direction of the rotating shaft 5.

As shown in FIG. 1, the combustion unit 3 mixes fuel supplied from the outside and supplied compressed air, burns the air-fuel mixture to generate a high-temperature gas, and generates the generated high-temperature gas to the turbine unit 4. To supply.
In addition, as a combustion part 3, a well-known thing can be used and it does not specifically limit.

As shown in FIG. 1, the turbine unit 4 extracts a rotational driving force from the supplied high-temperature gas and rotationally drives the rotary shaft 5.
In addition, as a turbine part 4, a well-known structure can be used and it does not specifically limit.

Next, the stationary blade 10 that is a feature of the present embodiment will be described.
FIG. 3 is a cross-sectional view illustrating the configuration in the vicinity of the seal holder in the stationary blade of FIG.
In the present embodiment, description will be made by applying the stationary blade 10 to a stationary blade having a fixed pitch, in other words, a stationary blade having a fixed angle of attack with respect to the flow of fluid flowing inside the compression unit 2.
2 and 3, the stationary blade 10 includes an outer shroud portion 11, an airfoil portion 12, an inner shroud portion (shroud portion) 13, a seal holder (end housing) 14, and a spring ( An elastic portion) 15 and a honeycomb seal 17 are provided.

As shown in FIG. 2, the outer shroud portion 11 is a member that constitutes a part of the wall surface of the flow path through which the fluid flows in the compression portion 2. Further, the outer shroud portion 11 is a curved plate-like member disposed at the radially outer end of the airfoil portion 12, and one outer shroud portion 11 is disposed for the plurality of airfoil portions 12. ing. In other words, the outer shroud part 11 is obtained by dividing a cylindrical member into a plurality of parts, and a plurality of airfoil parts 12 are connected to the inner peripheral surface thereof.
As a shape of the outer shroud portion 11 and a connection method with the airfoil portion 12, a known shape and method can be used and are not particularly limited.

As shown in FIG. 2, the airfoil portion 12 is a member in which a cross section extending in the radial direction of the rotary shaft 5 is formed in a wing shape, and together with a moving blade rotated by the rotary shaft 5, a fluid such as air Is compressed and fed toward the combustion unit 3.
The airfoil 12 includes a leading edge LE that is an upstream end in a flow of surrounding fluid, a trailing edge TE that is a downstream end, a suction surface that is a convex curved surface, and a concave curved shape. And a positive pressure surface.

  As shown in FIGS. 2 and 3, the inner shroud portion 13 constitutes a part of the flow path through which the fluid flows inside the compression portion 2, similarly to the outer shroud portion 11. Further, the inner shroud portion 13 is a curved plate-like member disposed at the radially inner end of the airfoil portion 12, and one inner shroud portion 13 is disposed with respect to one airfoil portion 12. Yes. In other words, the inner shroud portion 13 is obtained by dividing a cylindrical member into a plurality of parts, and the airfoil portion 12 is connected to the outer peripheral surface thereof.

  A fitting groove 13 </ b> A that extends in the circumferential direction (perpendicular to the paper surface of FIG. 3) and fits with the seal holder 14 is provided at the end of the inner shroud 13 on the front edge LE and rear edge TE side. Yes.

As shown in FIG. 3, the seal holder 14 is attached to the inner peripheral side (lower side in FIG. 3) of the inner shroud portion 13 and forms a space for accommodating the spring 15 together with the inner shroud portion 13. It is a member that supports the seal 17.
As with the outer shroud portion 11, the seal holder 14 is provided with one seal holder 14 for the plurality of airfoil portions 12 and the inner shroud portion 13.

The seal holder 14 is provided with a pair of side wall portions 14S extending along the radial direction on the front edge LE side and the rear edge TE side, and a bottom plate portion 14B connecting the radially inner ends of the pair of side wall portions 14S. It has been.
In other words, the seal holder 14 is formed with a groove that opens toward the outer circumferential side (the upper side in FIG. 3).

  A protruding portion 14A that protrudes toward the inner side of the seal holder 14 and extends in the circumferential direction and fits with the fitting groove 13A of the inner shroud portion 13 is provided at the radially outer end of the side wall portion 14S. .

  As shown in FIGS. 2 and 3, the spring 15 is an elastic member that biases the inner shroud portion 13 and the seal holder 14 in a direction away from each other. Furthermore, the spring 15 is configured to attenuate the vibration of the stationary blade 10, that is, the airfoil portion 12 and the inner shroud portion 13 by sliding with the inner shroud portion 13.

  Thus, by energizing the inner shroud portion 13 and the seal holder 14 by the spring 15 in a direction to separate the inner shroud portion 13 and the seal holder 14, the fitting groove 13 </ b> A and the projecting portion 14 </ b> A are pressed and brought into close contact with each other. The sealing property between the two can be ensured.

  The spring 15 is a plate spring that is formed in a substantially rectangular shape and has a substantially waveform. The spring force of the spring 15 is adjusted by adjusting the plate thickness of the plate spring. As a material constituting the spring 15, a material that can maintain a required spring characteristic during operation of the gas turbine 1, that is, even when the spring 15 reaches a high temperature is desirable.

  The spring 15 is disposed in a space formed by the inner shroud portion 13 and the seal holder 14, more specifically, between the inner shroud portion 13 and the seal holder 14. Furthermore, two springs 15 in total, one on the front edge LE side and one on the rear edge TE side, are arranged in parallel.

  In this embodiment, the description is applied to an example in which the two springs 15 are arranged in the same phase, in other words, an example in which the tops of the two springs 15 are in contact with the inner shroud portion 13 and the seal holder 14 at the same position. To do.

FIG. 4 is a schematic diagram for explaining another arrangement example of the spring of FIG.
The two springs 15 may be arranged in the same phase as described above, or may be arranged in different phases as shown in FIG. 4, and are not particularly limited.
In the arrangement of the spring 15 shown in FIG. 4, the top of one spring 15 is in contact with the inner shroud portion 13, and the top of the other spring 15 is in contact with the seal holder 14.

  By doing in this way, even if the arrangement | positioning space | interval of the top part in the one spring 15 is wider than the arrangement | positioning space | interval of the inner shroud part 13, the spring 15 is made to contact | abut with respect to all the inner shroud parts 13. Can do. That is, the springs 15 are brought into contact with all the inner shroud parts 13 by bringing the top parts of the other springs 15 into contact with the inner shroud part 13 that does not come into contact with the top part of one spring 15. Can do.

  The shape of the spring 15 is such that the amplitude of the waveform (distance from the top to the top in the radial direction) is longer than the distance from the inner peripheral surface of the inner shroud portion 13 to the outer peripheral surface of the seal holder 14 and each inner shroud. It is determined so that the top of the spring 15 abuts against the inner peripheral surface of the portion 13.

  More specifically, the amplitude in the waveform of the spring 15 is determined based on the frictional force that attenuates the vibration of the stationary blade 10, that is, the amount of compression of the spring 15 necessary to generate the spring force. The wavelength (distance from the top to the top in the circumferential direction) in the waveform of the spring 15 is determined based on the arrangement interval, that is, the pitch of the inner shroud portion 13.

As shown in FIG. 3, the honeycomb seal 17, together with seal fins 22 provided on the rotor 21, suppresses leakage of fluid flowing between the stationary blade 10 and the rotor 21.
A known seal can be used as the honeycomb seal 17 and is not particularly limited.

Next, a vibration damping method in the stationary blade 10 having the above configuration will be described.
When the gas turbine 1 is operated, the stationary blade 10 vibrates due to the influence of the fluid flowing through the compression unit 2. Specifically, a vibration is generated in which the airfoil portion 12 and the inner shroud portion 13 of the stationary blade 10 swing in the circumferential direction.

  When the inner shroud portion 13 vibrates as described above, sliding occurs between the top portion of the spring 15 pressed against the inner shroud portion 13 and the inner peripheral surface of the inner shroud portion 13. Between the inner shroud portion 13 and the spring 15, a pressing force by the spring 15 and a friction force according to a friction coefficient between the inner shroud portion 13 and the spring 15 work.

  The vibration energy of the airfoil portion 12 and the inner shroud portion 13 is converted into friction energy such as heat energy by the above-described sliding, and the vibration in the stationary blade 10 is attenuated.

  According to the above configuration, when the airfoil portion 12 and the inner shroud portion 13 vibrate and slide relative to the seal holder 14, the spring 15 and the inner shroud portion 13 move relative to each other, that is, the spring 15 and the inner shroud portion. 13 slides. Therefore, the energy related to the vibration of the airfoil portion 12 and the inner shroud portion 13 is converted into thermal energy (friction energy) by sliding, and the vibration of the airfoil portion 12 and the inner shroud portion 13 can be attenuated.

On the other hand, the spring 15 can be easily exchanged by sliding the spring 15 together with the seal holder 14 from the inner shroud portion 13 and removing it. Therefore, even if the spring 15 is worn away due to wear due to long-term use, the spring 15 can be easily replaced.
Further, since the spring 15 is disposed in a space surrounded by the seal holder 14 and the inner shroud portion 13, even if the spring 15 is broken, it jumps out of the space and damages the airfoil portion 12. Can be prevented.

Since the inner shroud portion 13 is independently arranged on each of the plurality of airfoil portions 12, compared to the case where the plurality of inner shroud portions 13 are integrally formed, each of the airfoil portions 12 and the inner airfoil portions 13 are arranged. The shroud portion 13 is easy to move relative to the spring 15. In other words, the sliding distance between the inner shroud portion 13 and the spring 15 is increased.
Therefore, more energy related to the vibration of the airfoil portion 12 and the inner shroud portion 13 is converted into thermal energy (friction energy) due to sliding, and the vibration of the airfoil portion 12 and the inner shroud portion 13 is further damped. Can do.

FIG. 5 is a schematic diagram for explaining still another arrangement example of the springs of FIG.
Note that, as in the above-described embodiment, two springs 15 may be disposed between the inner shroud portion 13 and the seal holder 14, and as shown in FIG. 5, the four springs 15 are arranged on the inner shroud portion 13. The number of springs 15 is not particularly limited.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the turbine blade of the present invention has been described as applied to the stationary blade in the compression portion of the gas turbine. However, the turbine blade can also be applied to the stationary blade in the turbine portion of the gas turbine.

It is a mimetic diagram explaining the composition of the gas turbine concerning one embodiment of the present invention. It is a schematic diagram explaining the structure of the rotor disk and stationary blade in the compression part of FIG. It is sectional drawing explaining the structure of the seal holder vicinity in the stationary blade of FIG. It is a schematic diagram explaining the other example of arrangement | positioning of the spring of FIG. It is a schematic diagram explaining another example of arrangement | positioning of the spring of FIG.

Explanation of symbols

1 Gas turbine 10 Static blade (turbine blade)
12 Airfoil part 13 Inner shroud part (shroud part)
14 Seal holder (end housing)
15 Spring (elastic part)

Claims (4)

A plurality of shroud portions respectively disposed at ends of the plurality of airfoil portions;
An end housing that is slidable with respect to the plurality of shroud portions and is detachable, and forms a space between the plurality of shroud portions;
It urges in a direction in which is positioned in the space separating the said end housing and the plurality of shroud portions, and a plurality of shroud portions and relatively movable arranged elastic portion,
The elastic portion extends along a direction in which the plurality of shroud portions are arranged, and is a plurality of plate-like springs formed in a substantially waveform.
The tops of the plurality of springs are in contact with the plurality of shroud parts or the end housing,
The plurality of springs are arranged substantially in parallel, and the tops of the other springs of the plurality of springs are arranged so as to be shifted with respect to the tops of the one of the plurality of springs . Turbine blades characterized by that. The plurality of shroud portions are disposed independently for each of the plurality of airfoils,
Said plurality of sheets against the shroud portion, a turbine blade according to claim 1, wherein said end housing, characterized in that it is detachable. Gas turbine, characterized in that claim 1 is a turbine blade is provided according to claim 2.   When the shroud portions arranged at the ends of the plurality of airfoils vibrate,
  A sliding generation step for generating sliding between the top of the plurality of elastic portions pressed against the shroud portion and the shroud portion;
  An energy conversion step of converting vibration energy of the vibration into friction energy generated between the shroud portion and the plurality of elastic portions by the sliding generated in the sliding generation step;
In a vibration damping method comprising:
  The elastic portion extends along a direction in which the plurality of shroud portions are arranged, and is a plurality of plate-like springs formed in a substantially waveform.
  A turbine blade vibration damping method in which a spring is brought into contact with all the shroud parts by bringing a top part of another spring into contact with a shroud part that is not in contact with the top part of one spring.

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