Patent Application
20180010460
The present disclosure relates to a turbine blade, a turbine, and a method for producing a turbine blade.
A known turbine for a turbine is obtained by joining casted components by welding.
For instance, Patent Document 1 discloses a turbine stator vane obtained by joining a casted blade portion and a casted shroud portion by welding. In this turbine stator vane, to reduce the restriction of thermal deformation of a shroud, the blade portion and the shroud portion are welded partially in the thickness direction from the cooling surface side of the shroud, and clearance (non-welded portion) is left between the blade portion and the shroud portion in the vicinity of the high-temperature fluid surface of the shroud.
If the blade portion and the shroud portion are welded partially in the thickness direction of the shroud and clearance is formed like the turbine stator vane described in Patent Document 1, the clearance permits the blade portion and the shroud portion to deform slightly when an external force or heat is applied to the turbine blade. Thus, stress is reduced compared to a case in which the blade portion and the shroud portion are welded entirely without leaving the clearance. On the other hand, if the clearance is formed by partial welding of the blade portion and the shroud portion between a flow passage of combustion gas and the welded section, high-temperature combustion gas enters the clearance to increase the temperature of the welded section, raising the risk of thermal damage to the welded section, which may shorten the lifetime of the turbine blade.
Thus, it is desirable to suppress a temperature increase of a welded section of a turbine blade.
In view of the above, an object of at least one embodiment of the present invention is to provide a turbine blade whereby it is possible to suppress a temperature increase of a welded section.
(1) A turbine blade disposed along a radial direction of a turbine according to at least one embodiment of the present invention comprises: an airfoil portion positioned in a fluid flow passage of the turbine; and a shroud portion positioned on an inner side or an outer side of the airfoil portion in the radial direction, and having an opening with which an end portion of the airfoil portion is to be engaged. A clearance is formed between a wall surface forming the opening of the shroud portion and an outer peripheral surface of the end portion of the airfoil portion. The wall surface of the shroud portion and the outer peripheral surface of the airfoil portion are joined to each other via a welded section on an opposite side to the flow fluid passage across the clearance. At least one of the shroud portion or the airfoil portion has a cooling hole formed thereon, the cooling hole having an opening into the clearance and being configured to supply the clearance with a cooling fluid.
With the above configuration (1), the clearance formed between the shroud portion and the airfoil portion permits slight deformation of the airfoil portion and the shroud portion, and thereby it is possible to suppress stress concentration to the welded section during operation of the turbine. The cooling hole formed on at least one of the shroud portion or the airfoil portion supplies the clearance formed between the shroud portion and the airfoil portion with the cooling fluid, and thus it is possible to prevent high-temperature fluid flowing through the fluid flow passage from entering the clearance. Accordingly, it is possible to suppress a temperature increase of the welded section at the opposite side to the fluid flow passage across the clearance, and to increase the lifetime of the turbine blade.
(2) In some embodiments, in the above configuration (1), the shroud portion includes an inner shroud and an outer shroud which are disposed on the inner side and the outer side of the airfoil portion in the radial direction, respectively, and each of which has the opening. The clearance is formed between the wall surface of each of the inner shroud and the outer shroud and the outer peripheral surface of each end portion of the airfoil portion. The wall surface of each of the inner shroud and the outer shroud and the outer peripheral surface of each end portion of the airfoil portion are joined to each other via the welded section on the opposite side to the fluid flow passage across the clearance.
With the above configuration (2), the cooling fluid is supplied from the cooling hole to the clearance formed between the inner shroud and the airfoil portion and between the outer shroud portion and the airfoil portion, and thus it is possible to prevent high-temperature fluid from entering the clearance more effectively. Accordingly, it is possible to suppress a temperature increase of each welded section at the opposite side to the fluid flow passage across each clearance, and to increase the lifetime of the turbine blade even further.
(3) In some embodiments, in the above configuration (1) or (2), the airfoil portion has a hollow portion configured such that the cooling fluid flows through the hollow portion. The cooling hole includes a first cooling hole configured such that the hollow portion of the airfoil portion and the clearance are in communication through the first cooling hole.
With the above configuration (3), the cooling fluid flowing through the hollow portion can be supplied to the clearance via the first cooling hole configured to bring the hollow portion of the airfoil portion and the clearance into communication, and thus it is possible to prevent high-temperature fluid from entering the clearance.
(4) In some embodiments, in any one of the above configurations (1) to (3), the turbine blade comprises a shield plate disposed inside the shroud portion, and forming a cooling passage configured to let the cooling fluid flow through the cooling passage, together with an inner wall surface of the shroud portion. The cooling hole includes a second cooling hole configured such that the cooling passage inside the shroud portion and the clearance are in communication through the second cooling hole.
With the above configuration (4), the cooling fluid flowing through the cooling passage formed by the inner wall surface of the shroud portion and the shield plate can be supplied to the clearance via the second cooling hole configured to bring the clearance and the cooling passage into communication, and thus it is possible to prevent high-temperature fluid from entering the clearance.
(5) In some embodiments, in any one of the above configurations (1) to (4), the welded section includes a first welded section along an extending direction of the clearance.
(6) Furthermore, in some embodiments, in any one of the above configurations (1) to (5), the welded section includes a second welded section along a width direction of the clearance.
With the above configuration (5) or (6), with the first welded section and/or the second welded section, the airfoil portion and the shroud portion can be joined firmly.
(7) In some embodiments, in any one of the above configurations (1) to (6), the shroud portion has an injection hole formed thereon, the injection hole being disposed around the clearance so as to have an opening into the fluid flow passage and being configured to inject the cooling fluid. The injection hole is inclined with respect to the radial direction so as to be closer to the airfoil portion toward the fluid flow passage.
With the above configuration (7), the cooling fluid is injected from the injection hole disposed in the shroud portion around the clearance toward the airfoil portion, and thus it is possible to further suppress entry of the high-temperature fluid inside the fluid flow passage to the clearance. Accordingly, with the high-temperature fluid being prevented from entering the clearance, it is possible to suppress a temperature increase of the welded section and to suppress a temperature increase of the airfoil portion. Accordingly, it is possible to increase the lifetime of the turbine blade even more.
(8) In some embodiments, in any one of the above configurations (1) to (7), an edge of the opening facing the fluid flow passage of the shroud portion has a curved cross-sectional shape along an extending direction of the airfoil portion.
With the above configuration (8), the surface of the airfoil portion is less likely to be damaged when the end portion of the airfoil portion is fitted into the opening of the shroud portion during assembly of the turbine blade, even if the edge of the opening of the shroud portion makes contact with the airfoil portion, for the edge of the opening of the shroud portion has a curved smooth cross-sectional shape. Accordingly, it is possible to increase the lifetime of the turbine blade even more.
(9) A turbine according to at least one embodiment of the present invention comprises a rotor which comprises the turbine blade according to any one of the above (1) to (8).
With the above configuration (9), the clearance formed between the shroud portion and the airfoil portion permits slight deformation of the airfoil portion and the shroud portion, and thereby it is possible to suppress stress concentration to the welded section during operation of the turbine. The cooling hole formed on at least one of the shroud portion or the airfoil portion supplies the clearance formed between the shroud portion and the airfoil portion with the cooling fluid, and thus it is possible to prevent high-temperature fluid flowing through the fluid flow passage from entering the clearance. Accordingly, it is possible to suppress a temperature increase of the welded section at the opposite side to the fluid flow passage across the clearance, and to increase the lifetime of the turbine blade.
(10) A method of producing a turbine blade which comprises an airfoil portion disposed in a fluid flow passage of a turbine and a shroud portion having an opening with which an end portion of the airfoil portion is to be engaged, according to at least one embodiment of the present invention, comprises: a step of fitting the end portion of the airfoil portion into the opening of the shroud portion so that a cooling hole formed on at least one of the shroud portion or the airfoil portion has an opening into a clearance formed between a wall surface forming the opening of the shroud portion and an outer peripheral surface of the end portion of the airfoil portion; and a step of welding the wall surface of the shroud portion and the outer peripheral surface of the airfoil portion at an opposite side to the flow fluid passage across the cooling hole. The welding step includes forming a welded section in the clearance only on an opposite side to the fluid flow passage as seen from the cooling hole so that the clearance remains at least at an opening position of the cooling hole and at a side closer to the fluid flow passage than the opening position.
With a turbine blade produced by the above method (10), the clearance formed between the shroud portion and the airfoil portion permits slight deformation of the airfoil portion and the shroud portion, and thereby it is possible to suppress stress concentration to the welded section during operation of the turbine. The cooling hole formed on at least one of the shroud portion or the airfoil portion supplies the clearance formed between the shroud portion and the airfoil portion with the cooling fluid, and thus it is possible to prevent high-temperature fluid flowing through the combustion gas flow passage from entering the clearance. Accordingly, it is possible to suppress a temperature increase of the welded section at the opposite side to the fluid flow passage across the clearance, and to increase the lifetime of the turbine blade.
(11) In some embodiments, in the above configuration (10), the method further comprises a casting step of casting each of the airfoil portion and the shroud portion separately.
According to the above method (11), with each of the airfoil portion and the shroud portion casted individually, the casted products have a relatively simple structure compared to a case in which the airfoil portion and the shroud portion are casted integrally. Thus, it is possible to reduce casting defects and to improve the yield.
(12) In some embodiments, in the above configuration (10) or (11), the shroud portion includes an inner shroud and an outer shroud disposed on a first side and a second side of the airfoil portion, respectively, each of the inner shroud and the outer shroud having the opening. The fitting step includes fitting each end portion of the airfoil portion into the opening of each of the inner shroud and the outer shroud so that the cooling hole has an opening into the clearance formed between the wall surface forming the opening of each of the inner shroud and the outer shroud and the outer peripheral surface of each end portion of the airfoil portion. The welding step includes welding the wall surface of each of the inner shroud and the outer shroud and the outer peripheral surface of each end portion of the airfoil portion on the opposite side to the fluid flow passage across the cooling hole.
With a turbine blade produced by the above method (12), the cooling fluid is supplied from the cooling hole to the clearance formed between the inner shroud and the airfoil portion and the clearance between the outer shroud portion and the airfoil portion, and thus it is possible to prevent high-temperature fluid from entering the clearance more effectively. Accordingly, it is possible to suppress a temperature increase of each welded section at the opposite side to the fluid flow passage across each clearance, and to increase the lifetime of the turbine blade even further.
According to at least one embodiment of the present invention, provided is a turbine blade whereby it is possible to suppress a temperature increase of a welded section.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.
First, with reference to
As depicted in
The configuration example of components in the gas turbine 1 will be described in detail.
The compressor 2 includes a compressor casing 10, an air inlet 12 for sucking in air, disposed on an inlet side of the compressor casing 10, a rotor 8 disposed so as to penetrate through both of the compressor casing 10 and a turbine casing 22 described below, and a variety of blades disposed in the compressor casing 10. The variety of blades includes an inlet guide vane 14 disposed adjacent to the air inlet 12, a plurality of stator vanes 16 fixed to the compressor casing 10, and a plurality of rotor blades 18 implanted on the rotor 8 so as to be arranged alternately with the stator vanes 16. The compressor 2 may include other constituent elements not illustrated in the drawings, such as an extraction chamber. In the above compressor 2, the air introduced from the air inlet 12 flows through the plurality of stator vanes 16 and the plurality of rotor blades 18 to be compressed to turn into compressed air having a high temperature and a high pressure. The compressed air having a high temperature and a high pressure is sent to the combustor 4 of a latter stage from the compressor 2.
The combustor 4 is disposed in a casing 20. As illustrated in
The turbine 6 includes a turbine casing 22 and a variety of blades disposed inside the turbine casing 22. The variety of blades includes a plurality of stator vanes 24 fixed to the turbine casing 22 and a plurality of rotor blades 26 implanted on the rotor 8 so as to be arranged alternately with the stator vanes 24. The plurality of stator vanes 24 and the plurality of rotor blades 26 include a turbine blade 100 described below in detail. The stator vanes 5 of each stage include a plurality of turbine stator vane bodies (airfoil portions 30) arranged at a regular interval in an annular shape in the circumferential direction of the rotor 8, fixed to the side of the turbine casing 22 in a radial fashion toward the rotor 8. Furthermore, the rotor blades 26 of each stage include a plurality of turbine rotor blade bodies (airfoil portions 30) arranged at a regular interval in an annular shape in the circumferential direction of the rotor 8, fixed to the side of the rotor 8 in a radial fashion toward the turbine casing 22.
Furthermore, the turbine 6 includes a bypass flow passage (not shown) for supplying air inside the compressor 2 from the compressor 2 bypassing the combustor 4. Air supplied to the turbine 6 through the bypass flow passage flows through the inside of each of the turbine stator vane bodies and the turbine rotor blade bodies as a cooling fluid G2 (see
The turbine 6 may include other constituent elements, such as outlet guide vanes and the like. In the turbine 6, a combustion gas G1 (see
An exhaust chamber 29 is connected to the downstream side of the turbine casing 22 via an exhaust casing 28. The exhaust gas having driven the turbine 6 is discharged outside via the exhaust casing 28 and the exhaust chamber 29.
Next, as a turbine blade 100 according to an embodiment, the configuration of the turbine blade applied to the stator vane 24 will be described.
As depicted in
As shown in
Each shroud portion 40 (40A, 40B) of each unit structure U has a coupling portion 40a, and may be connectable at the coupling portion 40a via the coupling portion 40a of the adjacent unit structure U.
The fluid flow passage 72 carrying the combustion gas G1 is formed in a range where the airfoil portions 30 are arranged, surrounded by the outer shroud 40A and the inner shroud 40B being partition walls.
As shown in
Furthermore, the airfoil portion 30 has a hollow portion 74 formed to penetrate through along the radial direction of the turbine 6. A cooling fluid G2 from the compressor 2 flows through the hollow portion 74. The cooling fluid G2 cools the airfoil portion 30, and thereby the airfoil portion 30 is protected from damage due to high-temperature fluid (combustion gas) flowing through the fluid flow passage 72. The airfoil portion 30 may have a plurality of holes (not depicted) formed thereon, through which the hollow portion 74 and the fluid flow passage 72 communicate with each other, so that the cooling fluid G2 from the hollow portion 74 passes through the holes to cool the airfoil portion 30 even more effectively.
In some embodiments, the turbine blade 100 may include only one of the outer shroud 40A or the inner shroud 40B having the above configuration.
As shown in
The clearance 50 formed between the shroud portion 40 and the airfoil portion 30 permits slight deformation of the airfoil portion 30 and the shroud portion 40, and thereby it is possible to suppress stress concentration to the welded section 51 during operation of the turbine 6.
In the turbine blade 100 according to an embodiment shown in
Further, in the turbine blade 100 according to an embodiment shown in
Accordingly, with the first welded section 52 or the second welded section 54 (54a to 54c), the airfoil portion 30 and the shroud portion 40 of the turbine blade 100 can be joined firmly. Furthermore, as depicted in
In the turbine blade 100, at least one of the shroud portion 40 or the airfoil portion 30 has a cooling hole (34, 44) formed to have an opening into the clearance 50 and configured to supply the cooling fluid G2 to the clearance 50.
The cooling hole (34, 44) supplies the clearance 50 formed between the shroud portion 40 and the airfoil portion 30 with the cooling fluid G2, and thus it is possible to prevent high-temperature fluid (combustion gas G1) flowing through the fluid flow passage 72 from entering the clearance 50. Accordingly, it is possible to suppress a temperature increase of the welded section 51 (52, 54) at the opposite side to the fluid flow passage 72 across the clearance 50, and to increase the lifetime of the turbine blade 100.
In the turbine blade 100 shown in
A plurality of such first cooling holes 34 may be provided for the airfoil portion 30 in the circumferential direction, or in the radial direction of the turbine 6. By providing a plurality of first cooling holes 34, it is possible to prevent high-temperature fluid (combustion gas G1) flowing through the fluid flow passage 72 from entering the clearance 50 even more effectively.
In the turbine blade 100 shown in
A plurality of such second cooling holes 44 may be provided for the shroud portion 40 in the circumferential direction, or in the radial direction of the turbine 6. With a plurality of second cooling holes 44, it is possible to prevent high-temperature fluid (combustion gas G1) flowing through the fluid flow passage 72 from entering the clearance 50 even more effectively.
While the first cooling hole 34 is provided for each turbine blade 100 in the embodiments shown in
In the turbine blade 100, the shroud portion 40 may have an injection hole 46 separately provided from the cooling hole (second cooling hole 44). In the embodiment depicted in
In this turbine blade 100, the cooling fluid is injected from the injection hole 46 disposed in the shroud portion 40 toward the airfoil portion 30, and thus it is possible to further suppress entry of the high-temperature fluid inside the fluid flow passage 72 to the clearance 50.
Further, as depicted in
With the edge 41 of the shroud portion 40 having the above described curved shape, the surface of the airfoil portion 30 is less likely to get damaged when the end portion 32 of the airfoil portion 30 is fitted into the opening 42 of the shroud portion 40 during assembly of the turbine blade 100, even if the edge 41 of the opening 42 of the shroud portion 40 makes contact with the airfoil portion 30. Accordingly, it is possible to increase the lifetime of the turbine blade 100 even more.
Next, a method of producing the turbine blade 100 described above with reference to
A method of producing the turbine blade 100 according to an embodiment includes a fitting step and a welding step described below.
The end portion 32 of the airfoil portion 30 is fitted into the opening 42 of the shroud portion 40. At this time, the clearance 50 is formed between the wall surface 43 forming the opening 42 of the shroud portion 40 and the outer peripheral surface 33 of the end portion 32 of the airfoil portion 30, and a cooling hole (the first cooling hole 34 or the second cooling hole 44) formed on at least one of the shroud portion 40 or the airfoil portion 30 has an opening into the clearance 50 (fitting step).
Next, on the opposite side to the fluid flow passage 72 across the cooling hole (the first cooling hole 34 or the second cooling hole 44), the wall surface 43 of the shroud portion 40 and the outer peripheral surface 33 of the airfoil portion 30 are welded (welding step). In the welding step, the welded section 51 is formed on the clearance 50 on the opposite side to the fluid flow passage 72 as seen from the cooling hole (the first cooling hole 34 or the second cooling hole 44) so that the clearance 50 remains at the opening position of the cooling hole (the first cooling hole 34 or the second cooling hole 44) and at the side closer to the fluid flow passage 72 than the opening position.
The first welded section 52 along the extending direction of the clearance 50 shown in
Various welding methods can be employed, such as laser welding, electronic beam welding, plasma welding, TIG welding, etc.
The depth of the slit to be formed (the length of the clearance 50 in the extending direction) is determined depending on the welding penetration depth, and the welding penetration depth can be controlled by welding conditions.
Further, it is possible to adjust the flow rate of cooling gas by adjusting the width of the slit (clearance 50) formed during welding. Specifically, it is possible to prevent the combustion gas G1 from entering the clearance 50 by making the cooling fluid G2 flow through the cooling hole (the first cooling hole 34 or the second cooling hole 44) at such a pressure that the combustion gas G1 does not enter the clearance 50. Accordingly, it is possible to maintain the efficiency of the turbine 6 appropriately by appropriately adjusting the flow rate of the cooling fluid G2 flowing through the cooling hole (the first cooling hole 34 or the second cooling hole 44).
The second welded section 54 (54a to 54c) along the width direction of the clearance 50 shown in
If welding is performed from a side, it is possible to increase the penetration depth by increasing the layer of welding, and thus a desired penetration depth can be obtained relatively easily. Thus, the slit (clearance 50) is formed relatively easily between the wall surface 43 of the opening 42 of the shroud portion 40 and the outer peripheral surface 33 of the end portion 32 of the airfoil portion 30. In
Various welding methods can be employed, such as laser welding, electronic beam welding, etc.
Further, in the turbine blade 100 depicted in
Accordingly, with a flange (101, 102) of one of the airfoil portion 30 or the shroud portion 40 making contact with a contact surface (84, 86) of the other one, it is possible to determine the position in the radial direction of the turbine 6 easily during welding.
In this case, the second welded section (54a, 54d) is formed by welding to join the butting surfaces of the flange (101, 102) of one of the airfoil portion 30 or the shroud portion 40 and the contact surface (84, 86) of the other, and then the layer of welding (the second welded section (54a, 54c, 54e, 54f) is formed so as to obtain a predetermined welding depth, which makes it possible to form the second welded section 54 of a desired length easily, and to obtain a slit of a desired length (clearance 50).
When the second welded section 54 is formed by joining the wall surface 43 of the opening 42 of the shroud portion 40 and the outer peripheral surface 33 of the end portion 32 of the airfoil portion 30 and performing penetration welding from a side, a part of the shroud portion 40 or the airfoil portion 30 may remain after welding depending on the welding conditions. In
A method of producing the turbine blade 100 according to some embodiments further includes a casting step of casting each of the airfoil portion 30 and the shroud portion 40 (outer shroud 40A and/or inner shroud 40B). Then, by using the airfoil portion 30 and the shroud portion 40 casted in the casting step, the above described fitting step and welding step are performed to produce the turbine blade 100.
As described above, with each of the airfoil portion 30 and the shroud 40 casted individually, the casted products have a relatively simple structure compared to a case in which the airfoil portion 30 and the shroud portion 40 are casted integrally. Thus, it is possible to reduce casting defects and to improve the yield.
While various casting methods can be employed without particular limitation, precision casting suitable for making a precise casted product may be employed. For instance, lost-wax process can be used to produce an airfoil portion 30 and a shroud portion 40 having a complicated structure.
Embodiments of the present invention were described in detail above, but the present invention is not limited thereto, and various amendments and modifications may be implemented.
Further, in the present specification, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-013140 | Jan 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/077152 | 9/25/2015 | WO | 00 |
