Turbine airfoil and gas turbine including the same

Abstract

To provide a turbine airfoil capable of realizing effective film cooling.SOLUTION: An airfoil body including an outer wall forming an internal space, wherein cooling holes (H) communicating the internal space with an external space of the airfoil body are formed in the outer wall, An inner surface defining the cooling hole H in the outer wall may include a first inner surface, a second inner surface, and a third inner surface, the third inner surface may have a shape bent with respect to the first inner surface at a boundary between the first inner surface and the third inner surface, and the second inner surface may have a shape bent with respect to the third inner surface at a boundary between the second inner surface and the third inner surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a turbine airfoil and a gas turbine including the airfoil, and more particularly to a turbine airfoil having a hole formed therein and a gas turbine including the airfoil. [Background technology]

[0002] A turbine is a mechanical device that uses the flow of compressible fluid such as steam or gas to generate rotational force through impulse or reaction force. Examples include steam turbines that use steam and gas turbines that use high-temperature combustion gases.

[0003] Among these, a gas turbine is broadly composed of a compressor, a combustor, and a turbine. The compressor is equipped with an air inlet for introducing air, and a number of compressor vanes and compressor blades are arranged alternately inside the compressor casing.

[0004] The combustor supplies fuel to the compressed air compressed by the compressor and ignites it with a burner to generate high-temperature and high-pressure combustion gas.

[0005] The turbine has a plurality of turbine vanes and turbine blades arranged alternately inside a turbine casing, and a rotor arranged to penetrate the center of the compressor, combustor, turbine, and exhaust chamber.

[0006] The rotor is rotatably supported at both ends by bearings. A plurality of disks are fixed to the rotor, and blades are connected to each disk. At the same time, a drive shaft of a generator or the like is connected to the end of the rotor facing the exhaust chamber.

[0007] Such gas turbines do not have a reciprocating mechanism like the pistons in four-stroke engines, so there are no parts that rub against each other like pistons and cylinders, which means that they consume very little lubricating oil, and the amplitude that is characteristic of reciprocating machines is greatly reduced, allowing for high-speed operation.

[0008] To briefly explain the operation of a gas turbine, air compressed by a compressor is mixed with fuel and burned to form high-temperature combustion gases, which are then injected into the turbine. The injected combustion gases pass through the turbine vanes and turbine blades, generating rotational force that rotates the rotor.

[0009] Meanwhile, according to the prior art, a film cooling method has been applied to cool turbine nozzles or turbine blades used in gas turbines. Film cooling refers to a method of protecting the surface of a turbine blade or the like exposed to high-temperature combustion gas by forming holes in the surface of the turbine blade or the like and injecting compressed air through the holes. Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE INVENTION An object of the present invention is to provide a turbine airfoil that can achieve more effective film cooling than the prior art. [Means for solving the problem]

[0011] According to one aspect of the present invention to achieve the above object, there is provided a turbine airfoil body including an outer wall that defines an interior space, wherein cooling holes H are formed in the outer wall to communicate the interior space with an exterior space of the airfoil body, and inner surfaces of the outer wall that define the cooling holes H include a first inner surface that defines an inner hole region H1 of the cooling holes H that communicates with the interior space, a second inner surface that defines an outer hole region H2 of the cooling holes H that communicates with the exterior space, and a third inner surface that defines a connecting hole region H3 that connects the inner hole region H1 and the outer hole region H2 of the cooling holes H, wherein the third inner surface has a shape bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface, and the second inner surface has a shape bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface.

[0012] In a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, the direction in which the third inner surface is bent relative to the first inner surface and the direction in which the second inner surface is bent relative to the third inner surface may be the same.

[0013] In a cross section of the airfoil body taken along a first plane, the cross section includes the first inner surface, the second inner surface, and the third inner surface. In the cross section, the direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole H may be the same as the direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole H.

[0014] In a cross section of the airfoil body taken along a first plane, the cross section includes the first inner surface, the second inner surface, and the third inner surface. In the cross section, the direction in which the second inner surface is bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface located on one side of the cooling hole H may be the same as the direction in which the second inner surface is bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole H.

[0015] In a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, a size of an angle βfwd1 formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole H may be smaller than or equal to a size of an angle γfwd1 formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole H.

[0016] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a first plane, the connecting hole region H3 may include a section whose width decreases as it approaches the external space or a section whose width is constant.

[0017] In a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, a size of an angle βfwd2 formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on one side of the cooling hole H may be smaller than or equal to a size of an angle γfwd2 formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole H.

[0018] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a first plane, the outer hole region H2 may include a section whose width decreases as it approaches the external space or a section whose width is constant.

[0019] In a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, a size of an angle βfwd1 formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole H may be larger than a size of an angle βfwd2 formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the one side of the cooling hole H.

[0020] In a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, the size of an angle γfwd1 formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole H may be larger than the size of an angle γfwd2 formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole H.

[0021] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, the connecting hole region H3 may include a section whose width increases as it approaches the external space.

[0022] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, the outer hole region H2 may include a section whose width increases as it approaches the external space.

[0023] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, the inner hole region H1 may include a section having a constant width.

[0024] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole H may be different from a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole H.

[0025] In a cross section of the airfoil body, which is obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, a size of an angle βlat formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole H may be equal to a size of an angle βlat formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole H.

[0026] In a cross section of the airfoil body, which cuts a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, the second inner surface and the third inner surface may be located on the same plane.

[0027] According to another aspect of the present invention for achieving the above object, there is provided a turbine section including a compressor section for supplying compressed air, a combustor into which the compressed air discharged from the compressor section flows and which burns the compressed air to generate combustion gas, and a turbine section into which the combustion gas generated in the combustor flows and which includes a plurality of turbine airfoils, wherein the turbine airfoil includes an airfoil body including an outer wall that defines an interior space, the outer wall having cooling holes H that communicate the interior space with an exterior space of the airfoil body, and an inner surface of the outer wall that defines the cooling holes H is provided with cooling holes H. a first inner surface defining an inner hall region H1 of the cooling hole H that communicates with the internal space; a second inner surface defining an outer hall region H2 of the cooling hole H that communicates with the external space; and a third inner surface defining a connecting hole region H3 that connects the inner hall region H1 and the outer hall region H2 of the cooling hole H, wherein the third inner surface has a shape bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface, and the second inner surface has a shape bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface. [Effects of the Invention]

[0028] The present invention provides a turbine airfoil that can achieve more effective film cooling than the prior art. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a cross-sectional view illustrating a schematic structure of a gas turbine according to the present invention; [Figure 2] 2 is a perspective view of a turbine blade provided in the turbine section of the gas turbine shown in FIG. 1. [Figure 3] 3 is a perspective view illustrating the shape of a cooling hole formed in the turbine blade illustrated in FIG. 2. FIG. [Figure 4] 4 is a diagram illustrating the shape of the cooling hole illustrated in FIG. 3 cut along a first plane. [Figure 5] 4 is a diagram illustrating the shape of the cooling hole illustrated in FIG. 3 cut along a second plane. DETAILED DESCRIPTION OF THE INVENTION

[0030] A turbine airfoil and a gas turbine according to the present invention will now be described with reference to the drawings.

[0031] Turbine Airfoils and Gas Turbines FIG. 1 is a cross-sectional view illustrating a schematic structure of a gas turbine according to the present invention, and FIG. 2 is a perspective view of a turbine blade provided in a turbine section of the gas turbine illustrated in FIG.

[0032] A gas turbine generally includes a compressor section that supplies compressed air, a combustor that receives the compressed air discharged from the compressor section and burns the compressed air to generate combustion gas, and a turbine section that receives the combustion gas generated in the combustor and includes a plurality of turbine airfoils. Detailed structures of the compressor section, combustor, and turbine section will be described later with reference to the drawings.

[0033] 1, the gas turbine may include a housing 102, and a diffuser 106 may be provided at the rear of the housing 102, through which combustion gases that have passed through the turbine are discharged. Also, a combustor 104 may be disposed in front of the diffuser 106, which receives a supply of compressed air and burns the air.

[0034] In terms of the air flow direction, the compressor section 110 may be located upstream of the housing 102, and the turbine section 120 may be located downstream. In addition, a torque tube 130 may be located between the compressor section 110 and the turbine section 120 as a torque transmission member that transmits the rotational torque generated in the turbine section to the compressor section.

[0035] The compressor section 110 may be provided with a plurality of (e.g., 14) compressor rotor disks 140, each of which may be fastened together by tie bolts 150 so as not to be spaced apart in the axial direction.

[0036] Specifically, each compressor rotor disk 140 may be aligned with respect to the axial direction with the tie bolt 150 passing through approximately the center thereof. Here, adjacent compressor rotor disks 140 may be arranged such that their opposing surfaces are pressed together by the tie bolt 150 and are unable to rotate relative to each other.

[0037] A plurality of blades 144 may be radially coupled to the outer circumferential surface of the compressor rotor disk 140. Each blade 144 may be fastened to the compressor rotor disk 140 by having a root portion 146.

[0038] Vanes (not shown) fixed to the housing may be located between each rotor disk 140. Unlike the rotor disks, the vanes may be fixed so as not to rotate, and may serve to align the flow of compressed air that has passed through the blades of the compressor rotor disk and guide the air to the blades of the rotor disk located downstream.

[0039] The fastening method of the root portion 146 can be either a tangential type or an axial type. This can be selected depending on the required structure of a commercial gas turbine, and can have a commonly known dovetail or fir-tree type. Depending on the case, the blade can be fastened to the rotor disk using fastening devices other than the above types, such as fasteners such as keys or bolts.

[0040] The tie bolt 150 can be arranged to penetrate the center of multiple compressor rotor disks 140 and turbine rotor disks 180, and one end can be fastened into the compressor rotor disk located most upstream, and the other end can be fastened with a fixing nut 190.

[0041] The shape of the tie bolt 150 may have various structures depending on the gas turbine, and is not necessarily limited to the shape shown in Fig. 1. That is, as shown in the figure, it may have a shape in which one tie bolt penetrates the center of the rotor disk, or it may have a shape in which multiple tie bolts are arranged in a cylindrical shape, or a combination of these may be used.

[0042] Although not shown in the drawings, the compressor of the gas turbine may have a vane serving as a guide vane installed next to the diffuser to adjust the flow angle of the fluid entering the inlet of the combustor to the design flow angle after increasing the pressure of the fluid. The vane may be a deswirler.

[0043] The combustor 104 mixes the incoming compressed air with fuel and burns it to form high-energy, high-temperature, high-pressure combustion gases, and raises the combustion gas temperature to the heat limit that the combustor and turbine components can withstand through a constant-pressure combustion process.

[0044] A combustor, which constitutes the combustion system of a gas turbine, may be arranged in large numbers within a casing formed in a cell shape, and may be composed of a burner including a fuel injection nozzle, a combustor liner forming a combustion chamber, and a transition piece connecting the combustor and the turbine.

[0045] Specifically, the liner provides a combustion space where fuel injected from a fuel nozzle is mixed with compressed air from a compressor and burned. The liner may include a flame tube that provides the combustion space where fuel mixed with air is burned, and a flow sleeve that surrounds the flame tube to form an annular space. A fuel nozzle may be coupled to the front of the liner, and a spark plug may be coupled to the side wall.

[0046] On the other hand, a transition piece can be connected to the rear of the liner so that combustion gas burned by the spark plug can be sent to the turbine side. The outer wall of such a transition piece can be cooled by compressed air supplied from the compressor to prevent damage due to the high temperature of the combustion gas.

[0047] For this purpose, the transition piece may be provided with cooling holes so that air can be injected into the interior, and the compressed air can flow to the liner side after cooling the main body inside through the holes.

[0048] Cooling air that has cooled the transition piece flows through the annular space of the liner, and compressed air is provided to the cooling air outside the flow sleeve through cooling holes provided in the flow sleeve, allowing it to collide with the cooling air on the outer wall of the liner.

[0049] Meanwhile, high-temperature, high-pressure combustion gas discharged from the combustor can be supplied to the turbine section 120. As the supplied high-temperature, high-pressure combustion gas expands, it exerts impulse and reaction force on the turbine rotor, generating rotational torque. The rotational torque thus obtained is transmitted to the compressor section via the torque tube, and any power exceeding the power required to drive the compressor can be used to drive a generator, etc.

[0050] The turbine section 120 may basically have a similar structure to the compressor section. That is, the turbine section 120 also includes a plurality of turbine rotor disks 180 similar to the compressor rotor disks of the compressor section. Therefore, the turbine rotor disks 180 may also include a plurality of turbine airfoils 200 arranged radially. The turbine airfoils 200 may also be connected to the turbine rotor disk 180 by a method such as a dovetail. In addition, vanes (not shown) fixed to the housing may also be provided between the turbine airfoils 200 of the turbine rotor disk 180, and the vanes can guide the flow direction of the combustion gas that has passed through the blades.

[0051] 2, the turbine rotor disk 180 may have a substantially circular disk shape, and a plurality of coupling slots 180a may be formed on the outer periphery thereof. The coupling slots 180a may be formed to have a curved surface in the shape of a fir tree.

[0052] A turbine airfoil 200 may be fastened to the joining slot 180a. In FIG. 2, the turbine airfoil 200 may have a flat platform portion 200a approximately in the center. The platform portion 200a may serve to maintain a gap between the adjacent airfoils as the side surfaces of the platform portion 200a of an adjacent turbine airfoil contact each other. Root portions 200b may be formed on the bottom surface of the platform portion 200a. The root portions 200b may have a so-called axial-type shape, which is inserted into the joining slot 180a of the rotor disk 180 along the axial direction of the rotor disk 180.

[0053] The root portion 200b may have a bent portion in a generally fir-tree shape, which may be formed to correspond to the shape of the bent portion formed in the coupling slot. However, the coupling structure of the root portion does not necessarily have to have a fir-tree shape, and may be formed to have a dovetail shape.

[0054] An airfoil body 210 may be formed on an upper surface of the platform portion 200a. The airfoil body 210 may be formed to have an airfoil shape optimized according to the specifications of the gas turbine, and may have a leading edge disposed upstream and a trailing edge disposed downstream based on the flow direction of the combustion gas.

[0055] Unlike the blades in the compressor section, the airfoils in the turbine section are in direct contact with high-temperature, high-pressure combustion gases. Because the temperature of the combustion gases can reach as high as 1700°C, a cooling means is required. To this end, a cooling channel may be provided in the compressor section that adds compressed air and supplies it to the airfoils in the turbine section.

[0056] The cooling passages may extend outside the housing (external passages) or through the interior of the rotor disk (internal passages), and both external and internal passages may be used. In Figure 2, a number of cooling holes H may be formed on the surface of the airfoil body, and the cooling holes H may communicate with an internal space (not shown) formed inside the airfoil body 210 and serve to supply cooling air to the surface of the airfoil body 210.

[0057] Figure 3 is a perspective view illustrating the shape of the cooling hole formed in the turbine blade illustrated in Figure 2, Figure 4 is a diagram illustrating the shape of the cooling hole illustrated in Figure 3 cut along a first plane, and Figure 5 is a diagram illustrating the shape of the cooling hole illustrated in Figure 3 cut along a second plane.

[0058] 3 to 5, a turbine airfoil 200 according to the present invention may include an airfoil body 210 including an outer wall 220 that defines an interior space, and the outer wall 220 may have cooling holes H formed therein that communicate the interior space with an exterior space of the airfoil body 210.

[0059] The cooling holes H may be divided into a plurality of regions. More specifically, the cooling holes H may include an inner hole region H1 communicating with the internal space of the turbine airfoil 200 described above, an outer hole region H2 communicating with the external space, and a connecting hole region H3 connecting the inner hole region H1 and the outer hole region H2.

[0060] Meanwhile, the outer wall 220 may have an inner surface 222 that defines the cooling hole H. Here, according to the present invention, the inner surface 222 may include a first inner surface 222a that defines an inner hole region H1, a second inner surface 222b that defines an outer hole region H2, and a third inner surface 222c that defines a connecting hole region H3.

[0061] According to the present invention, the first to third inner surfaces 222a, 222b, and 222c may be divided based on the boundaries where they are bent. More specifically, at the boundary between the first inner surface 222a and the third inner surface 222c, the third inner surface 222c may have a shape bent relative to the first inner surface 222a, and at the boundary between the second inner surface 222b and the third inner surface 222c, the second inner surface 222b may have a shape bent relative to the third inner surface 222c.

[0062] 3 and 4, in a cross section of the airfoil body 210 taken along a first plane through a region including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, the direction in which the third inner surface 222c is bent relative to the first inner surface 222a and the direction in which the second inner surface 222b is bent relative to the third inner surface 222c may be the same. FIG. 4 illustrates that the direction in which the third inner surface 222c is bent relative to the first inner surface 222a and the direction in which the second inner surface 222b is bent relative to the third inner surface 222c are both counterclockwise.

[0063] 3 and 4, in a cross section of a region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c taken along a first plane, the direction in which the third inner surface 222c is bent relative to the first inner surface 222a at the boundary between the first inner surface 222a and the third inner surface 222c located on one side of the cooling hole H (e.g., the lower side in FIG. 4) and the direction in which the third inner surface 222c is bent relative to the first inner surface 222a at the boundary between the first inner surface 222a and the third inner surface 222c located on the other side of the cooling hole H (e.g., the upper side in FIG. 4) may be the same. Furthermore, in a cross section of the airfoil body 210 taken along the first plane in a region including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, the direction in which the second inner surface 222b is bent relative to the third inner surface 222c at the boundary between the second inner surface 222b and the third inner surface 222c located on one side of the cooling hole H (e.g., the lower side in FIG. 4) and the direction in which the second inner surface 222b is bent relative to the third inner surface 222c at the boundary between the second inner surface 222b and the third inner surface 222c located on the other side of the cooling hole H (e.g., the upper side in FIG. 4) may be the same.

[0064] Meanwhile, in a cross section of a region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, cut along a first plane, an angle formed by a line aligned with the first inner surface 222a and a line aligned with the third inner surface 222c at a boundary between the first inner surface 222a and the third inner surface 222c located on one side of the cooling hole H (e.g., the lower side in reference to FIG. 4) is defined as βfwd1, and an angle formed by a line aligned with the first inner surface 222a and a line aligned with the third inner surface 222c at a boundary between the first inner surface 222a and the third inner surface 222c located on the other side of the cooling hole H (e.g., the upper side in reference to FIG. 4) is defined as γfwd1. The size of βfwd1 may be smaller than or equal to the size of γfwd1. When the size of βfwd1 is smaller than the size of γfwd1, it can be understood that the width of the connecting hole region H3 defined by the third inner side surface 222c becomes smaller with increasing distance from the boundary between the first inner side surface 222a and the third inner side surface 222c in a cross section of the airfoil body 210 cut along the first plane. This can help reduce the overall size of the cooling holes H and prevent the momentum of the cooling fluid discharged to the outside through the cooling holes H from decreasing too much, thereby preventing the cooling fluid from being rapidly diluted with the combustion gas. On the other hand, when the size of βfwd1 is the same as the size of γfwd1, it can be understood that the width of the connecting hole region H3 is constant in a cross section of the airfoil body 210 cut along the first plane. Therefore, in a cross section of the region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c cut along the first plane, the connecting hole region H3 may include a section whose width decreases as it approaches the external space of the turbine airfoil 200 or a section whose width is constant.

[0065] 3 and 4 , in a cross section of a region of the airfoil body 210 including the first inner side surface 222a, the second inner side surface 222b, and the third inner side surface 222c, taken along a first plane, an angle formed by a line aligned with the second inner side surface 222b and a line aligned with the third inner side surface 222c at a boundary between the second inner side surface 222b and the third inner side surface 222c located on one side (e.g., the lower side in FIG. 4 ) of the cooling hole H is defined as βfwd2, and an angle formed by a line aligned with the second inner side surface 222b and a line aligned with the third inner side surface 222c at a boundary between the second inner side surface 222b and the third inner side surface 222c located on the other side (e.g., the upper side in FIG. 4 ) of the cooling hole H is defined as γfwd2. The sizes of βfwd2 and γfwd2 may be different from each other. For example, the size of βfwd2 may be smaller than or equal to the size of γfwd2. When the size of βfwd2 is smaller than the size of γfwd2, it can be understood that the width of the outer hole region H2 defined by the second inner side surface 222b becomes smaller as the distance from the boundary between the second inner side surface 222b and the third inner side surface 222c increases with respect to a cross section of the airfoil body 210 cut along the first plane. This can help reduce the overall size of the cooling holes H and prevent the momentum of the cooling fluid discharged to the outside through the cooling holes H from decreasing too much, thereby preventing the cooling fluid from being rapidly diluted with the combustion gas. On the other hand, when the size of βfwd2 is the same as the size of γfwd2, it can be understood that the width of the outer hole region H2 is constant with respect to a cross section of the airfoil body 210 cut along the first plane. Therefore, in a cross section of the airfoil body 210, cut along the first plane through a region including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, the outer hole region H2 may include a section whose width decreases as it approaches the external space of the turbine airfoil 200, or a section whose width is constant.

[0066] In addition, in one example of the present invention, in a cross section of a region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, taken along a first plane, the size of an angle βfwd1 formed by a line aligned with the first inner surface 222a and a line aligned with the third inner surface 222c at a boundary between the first inner surface 222a and the third inner surface 222c located on one side of the cooling hole H (e.g., the lower side in FIG. 4 ) may be larger than the size of an angle βfwd2 formed by a line aligned with the second inner surface 222b and a line aligned with the third inner surface 222c at a boundary between the second inner surface 222b and the third inner surface 222c located on the same side of the cooling hole H. In addition, in a cross section of the airfoil body 210 taken along the first plane in a region including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, the size of the angle γfwd1 formed by a line aligned with the first inner surface 222a and a line aligned with the third inner surface 222c at the boundary between the first inner surface 222a and the third inner surface 222c located on the other side of the cooling hole H (e.g., the upper side in FIG. 4) is larger than the size of the angle γfwd2 formed by a line aligned with the second inner surface 222b and a line aligned with the third inner surface 222c at the boundary between the second inner surface 222b and the third inner surface 222c located on the other side of the cooling hole H.

[0067] Meanwhile, according to the present invention, the cross-sectional shape of the region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c cut along a first plane and the cross-sectional shape of the region of the airfoil body 210 cut along a second plane intersecting the first plane may be different from each other.

[0068] More specifically, referring to Figures 3 and 5, in a cross section of the airfoil body 210, a region including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, cut along a second plane intersecting the first plane, the outer hole region H2 and the connecting hole region H3 may include sections whose width increases as they approach the external space of the turbine airfoil 200, and the inner hole region H1 may include a section whose width is constant.

[0069] For example, in a cross section of a region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, cut along a second plane intersecting the first plane, the direction in which the third inner surface 222c is bent relative to the first inner surface 222a at the boundary between the first inner surface 222a and the third inner surface 222c located on one side of the cooling hole H (e.g., the left side in FIG. 5) may be different from the direction in which the third inner surface 222c is bent relative to the first inner surface 222a at the boundary between the first inner surface 222a and the third inner surface 222c located on the other side of the cooling hole H (e.g., the right side in FIG. 5). For example, with reference to FIG. 5, on the left side of the cooling hole H, the direction in which the third inner surface 222c is bent relative to the first inner surface 222a may be counterclockwise, and on the right side of the cooling hole H, the direction in which the third inner surface 222c is bent relative to the first inner surface 222a may be clockwise.

[0070] Meanwhile, referring to Figures 3 and 5, in a cross section of a region of the airfoil body 210 including the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, cut along a second plane intersecting the first plane, if the angle formed by a line aligned with the first inner surface 222a and a line aligned with the third inner surface 222c at the boundary between the first inner surface 222a and the third inner surface 222c is βlat, the size of βlat on one side of the cooling hole H (e.g., the left side in Figure 5) and the size of βlat on the other side of the cooling hole H (e.g., the right side in Figure 5) may be the same.

[0071] 3 and 5, in a cross section of the airfoil body 210, which includes the first inner surface 222a, the second inner surface 222b, and the third inner surface 222c, cut along a second plane intersecting the first plane, the second inner surface 222b and the third inner surface 222c may be located on the same plane, while the first plane and the second plane may intersect perpendicularly with each other.

[0072] According to the present invention, the inner surface 222 defining the cooling hole H has a shape that is bent at at least two points, so that the cooling efficiency of the cooling fluid sprayed from the cooling hole H can be increased.

[0073] Although the present invention has been described above using limited examples and drawings, it goes without saying that the present invention is not limited thereto, and that various implementations are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. (Other possible items) (Item 1) an airfoil body including an outer wall defining an interior space; The outer wall is formed with a cooling hole (H) that communicates the inner space with an outer space of the airfoil body, The inner surface of the outer wall defining the cooling hole (H) is a first inner surface defining an inner hole region (H1) of the cooling hole (H) that communicates with the internal space; a second inner surface defining an outer hole region (H2) of the cooling hole (H) that communicates with the external space; a third inner side surface defining a connecting hole region (H3) connecting the inner hole region (H1) and the outer hole region (H2) of the cooling hole (H); At a boundary between the first inner surface and the third inner surface, the third inner surface has a shape bent relative to the first inner surface, a turbine airfoil, wherein at a boundary between the second inner surface and the third inner surface, the second inner surface has a folded shape relative to the third inner surface; (Item 2) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, Item 2. The turbine airfoil of item 1, wherein a direction in which the third inner surface is folded relative to the first inner surface and a direction in which the second inner surface is folded relative to the third inner surface are the same. (Item 3) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil according to claim 1, wherein a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole (H) is the same as a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 4) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil according to claim 1, wherein a direction in which the second inner surface is bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface located on one side of the cooling hole (H) is the same as a direction in which the second inner surface is bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 5) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil according to item 1, wherein a size of an angle (βfwd1) formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole (H) is smaller than or equal to a size of an angle (γfwd1) formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 6) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, The connecting hole region (H3) is Item 1. The turbine airfoil of item 1, including a section of decreasing width or constant width adjacent the external space. (Item 7) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil according to item 1, wherein a size of an angle (βfwd2) formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on one side of the cooling hole (H) is smaller than or equal to a size of an angle (γfwd2) formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 8) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, The outer hole region (H2) is Item 1. The turbine airfoil of item 1, including a section of decreasing width or constant width adjacent the external space. (Item 9) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, Item 2. The turbine airfoil according to item 1, wherein a size of an angle (βfwd1) formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole (H) is greater than a size of an angle (βfwd2) formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the one side of the cooling hole (H). (Item 10) a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, Item 10. The turbine airfoil according to item 9, wherein a size of an angle (γfwd1) formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole (H) is greater than a size of an angle (γfwd2) formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 11) a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, 3. The turbine airfoil according to claim 2, wherein the connecting hole region (H3) includes a section whose width increases as it approaches the external space. (Item 12) a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, The outer hole region (H2) is Item 3. The turbine airfoil of item 2, including a section that increases in width adjacent the exterior space. (Item 13) a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, The inner hole region (H1) is Item 3. The turbine airfoil of item 2, including a section of constant width. (Item 14) a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, 3. The turbine airfoil according to item 2, wherein a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole (H) is different from a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 15) a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, 3. The turbine airfoil according to item 2, wherein a size of an angle (βlat) formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole (H) is the same as a size of an angle (βlat) formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole (H). (Item 16) a cross section of the airfoil body, the cross section being obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, Item 3. The turbine airfoil of item 2, wherein the second inner surface and the third inner surface are coplanar. (Item 17) a compressor section for supplying compressed air; a combustor into which the compressed air discharged from the compressor section flows and which combusts the compressed air to generate combustion gas; a turbine section into which combustion gases generated in the combustor flow and which includes a plurality of turbine airfoils; The turbine airfoil comprises: an airfoil body including an outer wall defining an interior space; The outer wall is formed with a cooling hole (H) that communicates the inner space with an outer space of the airfoil body, The inner surface of the outer wall defining the cooling hole (H) is a first inner surface defining an inner hole region (H1) of the cooling hole (H) that communicates with the internal space; a second inner surface defining an outer hole region (H2) of the cooling hole (H) that communicates with the external space; a third inner side surface defining a connecting hole region (H3) connecting the inner hole region (H1) and the outer hole region (H2) of the cooling hole (H); At a boundary between the first inner surface and the third inner surface, the third inner surface has a shape bent relative to the first inner surface, a gas turbine, wherein the second inner surface has a shape bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface. [Explanation of symbols]

[0074] 100 Gas Turbine 200 Turbine Airfoil 210 Airfoil body 220 Exterior Wall 222 Inner surface 222a 1st inner surface 222b Second inner surface 222c 3rd inner surface H Cooling hole H1 inner hole region H2 outer hole region H3 Connected Hole Region

Claims

1. an airfoil body including an outer wall defining an interior space; a cooling hole is formed in the outer wall, the cooling hole communicating the inner space with an outer space of the airfoil body; The inner surface defining the cooling hole at the outer wall is a first inner surface defining an inner hole region of the cooling hole that communicates with the internal space; a second inner surface defining an outer hole region of the cooling hole that communicates with the external space; a third inner surface defining a connecting hole region connecting the inner hole region and the outer hole region of the cooling hole; At a boundary between the first inner surface and the third inner surface, the third inner surface has a shape bent relative to the first inner surface, a turbine airfoil, wherein at a boundary between the second inner surface and the third inner surface, the second inner surface has a folded shape relative to the third inner surface;

2. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, The turbine airfoil of claim 1 , wherein the direction in which the third inner surface is folded relative to the first inner surface is the same as the direction in which the second inner surface is folded relative to the third inner surface.

3. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil of claim 1, wherein a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole is the same as a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole.

4. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil of claim 1, wherein a direction in which the second inner surface is bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface located on one side of the cooling hole is the same as a direction in which the second inner surface is bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole.

5. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil of claim 1, wherein a size of an angle formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole is smaller than or equal to a size of an angle formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole.

6. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, The connecting hole region is The turbine airfoil of claim 1 , further comprising a section whose width decreases or remains constant as it approaches the external space.

7. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil of claim 1, wherein a size of an angle formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on one side of the cooling hole is smaller than or equal to a size of an angle formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole.

8. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, The outer hole region is The turbine airfoil of claim 1 , further comprising a section whose width decreases or remains constant as it approaches the external space.

9. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 2. The turbine airfoil of claim 1, wherein a size of an angle formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole is greater than a size of an angle formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the one side of the cooling hole.

10. a cross section of the airfoil body taken along a first plane through a region including the first inner surface, the second inner surface, and the third inner surface, 10. The turbine airfoil of claim 9, wherein a size of an angle formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole is greater than a size of an angle formed by a line aligned with the second inner surface and a line aligned with the third inner surface at a boundary between the second inner surface and the third inner surface located on the other side of the cooling hole.

11. a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, The turbine airfoil of claim 2 , wherein the connecting hole region includes a section whose width increases adjacent the external space.

12. a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, The outer hole region is A turbine airfoil according to claim 2 including a section of increasing width adjacent the exterior space.

13. a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, The inner hole region is A turbine airfoil according to any one of claims 2 to 10, including a constant width section.

14. a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, 11. The turbine airfoil of claim 2, wherein a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole is different from a direction in which the third inner surface is bent relative to the first inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole.

15. a cross section of the airfoil body, the cross section being obtained by cutting a region of the airfoil body including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, 11. The turbine airfoil of claim 2, wherein a size of an angle formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on one side of the cooling hole is the same as a size of an angle formed by a line aligned with the first inner surface and a line aligned with the third inner surface at a boundary between the first inner surface and the third inner surface located on the other side of the cooling hole.

16. a cross section of the airfoil body, the cross section being obtained by cutting a region including the first inner surface, the second inner surface, and the third inner surface along a second plane intersecting the first plane, The turbine airfoil of claim 2 , wherein the second inner surface and the third inner surface are coplanar.

17. a compressor section for supplying compressed air; a combustor into which the compressed air discharged from the compressor section flows and which combusts the compressed air to generate combustion gas; a turbine section into which combustion gases generated in the combustor flow and which includes a plurality of turbine airfoils; The turbine airfoil comprises: an airfoil body including an outer wall defining an interior space; a cooling hole is formed in the outer wall, the cooling hole communicating the inner space with an outer space of the airfoil body; The inner surface defining the cooling hole at the outer wall is a first inner surface defining an inner hole region of the cooling hole that communicates with the internal space; a second inner surface defining an outer hole region of the cooling hole that communicates with the external space; a third inner surface defining a connecting hole region connecting the inner hole region and the outer hole region of the cooling hole; At a boundary between the first inner surface and the third inner surface, the third inner surface has a shape bent relative to the first inner surface, a second inner surface having a shape bent relative to the third inner surface at a boundary between the second inner surface and the third inner surface;

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