Turbine vane and gas turbine including the same

Abstract

A turbine vane and a gas turbine including the same are provided. The turbine vane including an airfoil; an outer shroud formed at a top of the airfoil; and an inner shroud including a stress canceling part formed at a bottom of the airfoil and configured to cancel a stress applied to the airfoil by flowing combustion gas.

Claims

1. An inner shroud of a turbine vane comprising: a platform part configured to support a single airfoil; a root part configured to be connected to a bottom surface of the platform part; and a stress canceling part formed at a bottom of the single airfoil and configured to cancel a stress applied to the single airfoil by flowing combustion gas, wherein the stress canceling part comprises a protrusion configured to protrude from a bottom of one surface of the root part and a recess configured to be recessed from a bottom of the other surface of the root part, the protrusion formed in the root part of one airfoil being inserted into and contacting the recess formed in the root part of an adjacent airfoil, wherein the protrusion formed in the root part and the recess formed in the root part include inclined surfaces at predetermined angles, wherein the stress applied to the single airfoil by the flowing combustion gas is canceled based on an upward displacement caused at the protrusion and a downward displacement caused at the recess during a normal operation of the turbine, and wherein a cooling passage for cooling is formed inside the platform part and the root part.

2. The inner shroud of the turbine vane of claim 1, wherein the angles of the inclined surfaces are 5° to 45°.

3. The inner shroud of the turbine vane of claim 1, wherein if a length of the root part is 100, lengths of the protrusion and the recess are 5 to 30.

4. The inner shroud of the turbine vane of claim 1, wherein if a height of the root part is 100, heights of the protrusion and the recess are 10 to 40.

5. A turbine vane comprising: a single airfoil; an outer shroud formed at a top of the single airfoil; and an inner shroud including a stress canceling part formed at a bottom of the single airfoil and configured to cancel a stress applied to the single airfoil by flowing combustion gas, wherein the inner shroud comprises a platform part configured to support the single airfoil and a root part configured to be connected to a bottom surface of the platform part, and wherein the stress canceling part comprises a protrusion configured to protrude from a bottom of one surface of the root part and a recess configured to be recessed from a bottom of the other surface of the root part, the protrusion formed in the root part of one airfoil being inserted into and contacting the recess formed in the root part of an adjacent airfoil, wherein the protrusion formed in the root part and the recess formed in the root part include inclined surfaces at predetermined angles, wherein the stress applied to the single airfoil by the flowing combustion gas is canceled based on an upward displacement caused at the protrusion and a downward displacement caused at the recess during a normal operation of the turbine, and wherein a cooling passage for cooling is formed inside the platform part and the root part.

6. The turbine vane of claim 5, wherein the angles of the inclined surfaces are 5° to 45°.

7. The turbine vane of claim 5, wherein if a length of the root part is 100, lengths of the protrusion and the recess are 5 to 30.

8. The turbine vane of claim 5, wherein if a height of the root part is 100, heights of the protrusion and the recess are 10 to 40.

9. The turbine vane of claim 5, wherein the root part is inserted into an annular U ring having a U-shaped cross section in a non-fixed manner, and the root part is slid radially inside the U ring based on an operating state of a gas turbine.

10. A gas turbine comprising: a compressor configured to compress air drawn thereinto from an outside; a combustor configured to mix fuel with air compressed by the compressor and combust a mixture of the fuel and the compressed air; and a turbine including a turbine vane configured to generate power by combustion gas discharged from the combustor and to guide the combustion gas on a combustion gas path and a turbine blade configured to be rotated by the combustion gas on the combustion gas path, wherein the turbine vane comprises a single airfoil; an outer shroud formed at a top of the single airfoil; and an inner shroud including a stress canceling part formed at a bottom of the single airfoil and configured to cancel a stress applied to the single airfoil by flowing combustion gas, wherein the inner shroud comprises a platform part configured to support the single airfoil and a root part configured to be connected to a bottom surface of the platform part, and wherein the stress canceling part comprises a protrusion configured to protrude from a bottom of one surface of the root part and a recess configured to be recessed from a bottom of the other surface of the root part, the protrusion formed in the root part of one airfoil being inserted into and contacting the recess formed in the root part of an adjacent airfoil, wherein the protrusion formed in the root part and the recess formed in the root part include inclined surfaces at predetermined angles, wherein the stress applied to the single airfoil by the flowing combustion gas is canceled based on an upward displacement caused at the protrusion and a downward displacement caused at the recess during a normal operation of the turbine, and wherein a cooling passage for cooling is formed inside the platform part and the root part.

11. The gas turbine of claim 10, wherein the angles of the inclined surfaces are 5° to 45°.

12. The gas turbine of claim 10, wherein if a length of the root part is 100, lengths of the protrusion and the recess are 5 to 30.

13. The gas turbine of claim 10, wherein if a height of the root part is 100, heights of the protrusion and the recess are 10 to 40.

14. The gas turbine of claim 10, wherein the root part is inserted into an annular U ring having a U-shaped cross section in a non-fixed manner, and the root part is slid radially inside the U ring based on an operating state of the gas turbine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other aspects will become more apparent from the following description of the exemplary embodiments with reference to the accompanying drawings, in which:

(2) FIG. 1 is a diagram illustrating an internal structure of a gas turbine according to an exemplary embodiment;

(3) FIG. 2 is a diagram illustrating a cross section of the gas turbine according to an exemplary embodiment;

(4) FIG. 3 is a diagram illustrating a related art turbine vane;

(5) FIG. 4 is a diagram for explaining a problem which occurs upon an operation of the gas turbine having the turbine vane illustrated in FIG. 3;

(6) FIG. 5 is a diagram illustrating another related art turbine vane;

(7) FIG. 6 is a front diagram illustrating a turbine vane according to an exemplary embodiment;

(8) FIG. 7 is a side diagram illustrating the turbine vane of FIG. 6;

(9) FIG. 8 is a diagram illustrating a case in which the turbine vane of FIG. 6 is inserted into an annular U ring in a non-fixed manner; and

(10) FIG. 9 is a diagram for explaining a process of cancelling stress which is applied to an airfoil by the turbine vane according to an exemplary embodiment.

DETAILED DESCRIPTION

(11) Various modifications and various embodiments will be described in detail with reference to the drawings so that those skilled in the art can easily carry out the disclosure. It should be understood, however, that the various embodiments are not for limiting the scope of the disclosure to the specific embodiment, but they should be interpreted to include all modifications, equivalents, and alternatives of the embodiments included within the spirit and scope disclosed herein.

(12) The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the disclosure. In the specification, when a part “includes” a certain component, it means that the component may further include other components rather than excluding other components unless otherwise stated. Further, when an element is referred to as being “above” or “on” another element, it may be directly on the other element while making contact with the other element or may be above the other element without making contact with the other element.

(13) Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. Further, detailed descriptions of well-known functions and configurations which may obscure the gist of the present disclosure will be omitted. For the same reason, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated.

(14) FIG. 1 is a diagram illustrating an internal structure of a gas turbine according to an exemplary embodiment, and FIG. 2 is a diagram illustrating a cross section of the gas turbine according to an exemplary embodiment.

(15) Referring to FIGS. 1 and 2, a gas turbine 1 includes a compressor 10, a combustor 20, and a turbine 30. The compressor 10 serves to compress the introduced air at a high pressure, and transfers the compressed air to the combustor 20. The compressor 10 including a plurality of compressor blades radially installed rotates the compressor blade by receiving a part of power which is generated by the rotation of the turbine 30, and the air is compressed and moved to the combustor 20 by the rotation of the compressor blade. A size and installation angle of the blade may be changed according to an installation location.

(16) The air compressed by the compressor 10 moves to the combustor 20 and is mixed with fuel through a plurality of combustion chambers and fuel nozzle modules, which are arranged in an annular shape, to be combusted. The high-temperature combustion gas is discharged to the turbine 30, and the turbine is rotated by the combustion gas.

(17) The turbine 30 is arranged in multiple stages through a center tie rod 400 which axially couples turbine rotor disks 300. The turbine rotor disks 300 include a plurality of turbine blades 100 which are arranged radially. The turbine blade 100 may be coupled to the turbine rotor disk 300 in a dovetail or the like manner. Further, turbine vanes 200 fixed to a housing 31 are provided between the turbine blades 100 to guide the flow direction of the combustion gas passing through the turbine blades 100.

(18) As illustrated in FIG. 2, the turbine 30 may include the turbine vanes 200 and the turbine blades 100 which are alternately arranged along an axis direction of the gas turbine 1. The high-temperature combustion gas passes through the turbine vanes 200 and the turbine blades 100 along the axis direction and rotates the turbine blades 100.

(19) FIG. 3 is a diagram illustrating a related art turbine vane, and FIG. 4 is a diagram for explaining a problem which occurs upon an operation of the gas turbine having the turbine vane illustrated in FIG. 3.

(20) Referring to FIG. 3, the related art turbine vane 200a includes an airfoil 210a, an outer shroud 220a formed on a top of the airfoil 210a, and an inner shroud 230a formed on a bottom of the airfoil 210a.

(21) The airfoil 210a includes a leading edge 211a and a trailing edge 212a. The leading edge 211a is an end of a front portion which receives the fluid flowing in the airfoil 210a, and the trailing edge 212a is an end of a rear portion of the airfoil 210a. The airfoil 210a has a pressure side and a suction side which are formed by connecting the leading edge 211a with the trailing edge 212a, and the flowing fluid applies pressure to the pressure side.

(22) The inner shroud 230a and the outer shroud 220a are disposed at both ends of the airfoil 210a to support the airfoil 210a, and may include a platform part and a root part, respectively. The turbine vane 200a includes the inner shroud 230a which is disposed toward an inner rotational axis of the gas turbine, and the outer shroud 220a which is disposed toward an outside of the gas turbine.

(23) The platform part 231a of the inner shroud 230a has a plate shape so that the plate surface faces the airfoil 210a, and the root part 232a of the inner shroud 230a is disposed on a surface opposite to an outer plate surface of the platform part 231a, that is, the plate surface contacting the airfoil 210a, and formed to extend outward from the platform part 231a. A U-ring 240a having substantially a U shape is fastened to a bottom of the root part 232a, and the turbine rotor disk 300 is formed to be spaced apart from a bottom of the U-ring 240a. The U-ring 240a prevents the root part 232a from contacting the turbine rotor disk 300.

(24) When the gas turbine is operated by using the related art turbine vane 200a, the turbine rotor disk 300 expands toward the turbine vane 200a (i.e., an arrow E1), and the turbine vane 200a fixed to a case expands toward the turbine rotor disk 300 (i.e., an arrow E2) by a centrifugal force caused by the rotation of the turbine rotor disk 300 and heat applied to the turbine rotor disk 300 during the initial operation but the turbine rotor disk 300 and the turbine vane 200a may vertically move inside the U-ring 240a, thereby preventing the root part 232a of the turbine vane 200a from contacting the turbine rotor disk 300.

(25) However, as illustrated in FIG. 4, if the combustion gas generated by the combustor 20 collides with the turbine vane 200a, gas flows from the pressure side of the turbine vane 200a to the suction side based on the shape of the airfoil. The gas flow applies a force in one direction to the turbine vane 200a. There is a concern that a bending stress is generated by this force on a top portion of the turbine vane 200a, that is, a portion in which the airfoil 210a and the outer shroud are connected, and the turbine vane is damaged by the generation of the continuous bending stress. Meanwhile, one side of the bottom portion of the turbine vane moves upward, and the other side of the bottom portion of the turbine vane moves downward by this force. Here, the portion in which the airfoil and the outer shroud are connected acts as a fixed end, and one side of the bottom portion of the turbine vane acts as a free end because there is no fixed portion, which may cause damage to the seal plate of the turbine vane.

(26) Meanwhile, another related art turbine vane 200b, which is designed to solve the problems in FIGS. 3 and 4, is illustrated in FIG. 5. FIG. 5 is a diagram illustrating another related art turbine vane.

(27) Referring to FIG. 5, another related art turbine vane 200b is a multi-airfoil in which a plurality of airfoils 210b are integrally formed. The turbine vane 200b integrally forms a plurality of airfoils 210b between the outer shroud 220b and the inner shroud 230b, thereby partially eliminating the bending stress of the portion in which the airfoil 210b and the outer shroud 220b are connected.

(28) However, the related art turbine vane 200b causes problems. For example, there are problems in that because the plurality of airfoils 210b are integrally formed, it is difficult to perform a coating work which coats the surface of the airfoil 210b by spatial interference between the airfoils 210b, and it is also difficult to perform a cooling hole processing work which forms a cooling hole in the surface of the airfoil 210b. As a result, there is a problem in that the efficiency of the gas turbine is reduced.

(29) The turbine vane according to an exemplary embodiment is to solve the problems of the related art turbine vane described above, and it is possible to prevent the collision between the turbine rotor disk and the turbine vane upon an initial operation of the gas turbine, and to prevent the bending stress generated in the turbine vane upon a normal operation of the gas turbine.

(30) FIG. 6 is a front diagram illustrating a turbine vane according to an exemplary embodiment, FIG. 7 is a side diagram illustrating the turbine vane of FIG. 6, FIG. 8 is a diagram illustrating a case in which the turbine vane of FIG. 6 is inserted into an annular U ring in a non-fixed manner, and FIG. 9 is a diagram for explaining a process of cancelling stress which is applied to an airfoil by the turbine vane according to an exemplary embodiment.

(31) Referring to FIGS. 6 and 7, the turbine vane 200 according to an exemplary embodiment includes an airfoil 210, an outer shroud 220 formed on a top of the airfoil 210, and an inner shroud 230 formed at a bottom of the airfoil 210, and a stress canceling part 1000 formed on the inner shroud 230.

(32) The airfoil 210 includes a leading edge 211 and a trailing edge 212. The leading edge 211 is an end of a front portion which receives the fluid flowing in the airfoil 210, and the trailing edge 212 is an end of a rear portion of the airfoil 210. The airfoil 210 includes a pressure side and a suction side which are formed by connecting the leading edge 211 with the trailing edge 212, and the flowing fluid applies pressure to the pressure side.

(33) The inner shroud 230 and the outer shroud 220 are disposed at both ends of the airfoil 210 to support the airfoil 210, and may include a platform part and a root part, respectively. The inner shroud 230 is disposed at the turbine rotor disk 300, and the outer shroud 220 is disposed at the case of the gas turbine.

(34) The platform part 231 of the inner shroud 230 has a plate shape so that the plate surface faces the airfoil 210, and the root part 232 extends downward from the platform part 231. A cooling passage 233 for cooling is formed inside the platform part 231 and the root part 232.

(35) The stress canceling part 1000 cancels the stress which is applied to the airfoil 210 by the flowing combustion gas. The stress canceling part 1000 includes a protrusion 1100 and a recess 1200.

(36) The protrusion 1100 is formed to protrude in one direction from a bottom of one surface of the root part 232, and the recess 1200 is formed to be recessed in one direction from a bottom of the other surface of the root part 232. The protrusion 1100 formed in the root part 232 of any one airfoil is inserted into and contacts the recess 1200 formed in the root part 232 of an adjacent airfoil.

(37) For example, the protrusion 1100 and the recess 1200 have inclined surfaces 1101, 1201 at predetermined angles. The angles (θ) of the inclined surfaces 1101, 1201 is not particularly limited, but is preferably 5° to 30°. There is a disadvantage in that assembly is impossible due to an interference during assembly if angles of the inclined surfaces 1101, 1201 are smaller than 5°, and there is a disadvantage in that a bending is not cancelled each other if angles of the inclined surfaces 1101, 1201 exceed 45°.

(38) In addition, although not particularly limited, assuming that a length (L) of the root part 232 is 100, lengths (L1, L2) of the protrusion 1100 and the recess 1200 are preferably 5 to 30. There is a disadvantage in that the bending is not canceled each other due to a gap between the vanes if the lengths (L1, L2) are smaller than 5, and there is a disadvantage in that a stress is concentrated in corners if the lengths (L1, L2) exceed 30.

(39) Further, although not particularly limited, assuming that a height (H) of the root part 232 is 100, heights (H1, H2) of the protrusion 1100 and the recess 1200 are preferably 10 to 40. There is a disadvantage in that breaking is occurred due to stress concentration in the corners if the heights (H1, H2) are smaller than 10, and there is a disadvantage in that an amount of canceling the bending each other is insignificant if the heights (H1, H2) exceed 40.

(40) Referring to FIG. 8, the turbine vane 200 is inserted into an annular U-ring 240 having a U-shaped cross section in a non-fixed manner. A constant gap is formed between the root parts 232 of the plurality of turbine vanes 200.

(41) During the initial operation of the gas turbine, the turbine rotor disk 300 expands toward the turbine vane 200 by a centrifugal force caused by the rotation of the turbine rotor disk 300 and the heat applied to the turbine rotor disk 300, and the turbine vane 200 fixed to the case expands toward the turbine rotor disk 300, but the turbine rotor disk 300 and the turbine vane 200 may vertically slide inside the U-ring 240, thereby preventing the root part 232 of the turbine vane 200 from contacting the turbine rotor disk 300.

(42) Referring to FIG. 9, during the normal operation of the gas turbine, an upward displacement (i.e., an arrow E3) is caused at one side of the turbine vane 200 and the protrusion 1100 by the flow of the combustion gas, and a downward displacement (i.e., an arrow E4) is caused at the other side of the turbine vane 200 and the recess 1200.

(43) Because the displacements caused by the protrusion 1100 and the recess 1200 are in directions opposite to each other, it is possible to entirely cancel the stress applied to the airfoil 210, thereby improving a design life of the airfoil 210.

(44) Further, because the airfoil is manufactured in a single airfoil rather than a multi-airfoil type, there is no spatial interference problem between the airfoils 210 unlike the turbine vane 200b of FIG. 5 manufactured in the multi-airfoil form for a reduction in the stress, such that it is possible to easily perform a coating work which coats the surface of the airfoil 210, and to easily perform a cooling hole processing work which forms the cooling hole in the surface of the airfoil 210, thereby improving the efficiency of the gas turbine.

(45) While one or more exemplary embodiments have been described with reference to the accompanying drawings, it is to be understood by those skilled in the art that various modifications and changes in form and details may be made therein without departing from the spirit and scope as defined by the appended claims. Accordingly, the description of the exemplary embodiments should be construed in a descriptive sense only and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.