Turbine blade and turbine and gas turbine including the same

Abstract

The present invention provides a turbine blade, a turbine, and a gas turbine with improved torque and power output. [Solution] A turbine blade according to one aspect of the present invention includes an airfoil having an airfoil shape and having an inlet surface and a pressure surface, a platform portion connected to the lower part of the airfoil, and a root portion protruding downward from the platform portion and connected to a rotor disk. The airfoil includes a cooling passage formed therein and an exhaust hole connected to the upper part of the cooling passage and discharging cooling air, the exhaust hole being formed extending from the inside to the outside at an angle toward the tip of the turbine blade.

Description

[Technical field]

[0001] The present invention relates to a turbine blade and a turbine and a gas turbine including the same. [Background technology]

[0002] A gas turbine is a power plant that rotates a turbine using the high-temperature gas generated by mixing compressed air and fuel, which is compressed by a compressor. Gas turbines are used to drive generators, aircraft, ships, trains, etc.

[0003] Generally, a gas turbine includes a compressor, a combustor, and a turbine. The compressor takes in external air, compresses it, and then sends it to the combustor. The air compressed by the compressor is in a high-pressure, high-temperature state. The combustor mixes the compressed air from the compressor with fuel and burns it. The combustion gas generated by the combustion is discharged to the turbine. The combustion gas rotates turbine blades inside the turbine, thereby generating power. The generated power is used in a variety of fields, such as generating electricity and driving mechanical devices.

[0004] Recently, in order to increase turbine efficiency, the temperature of the gas flowing into the turbine (Turbine Inlet Temperature: TIT) has been steadily increasing, highlighting the importance of heat-resistant treatment and cooling of turbine blades.

[0005] Methods for cooling turbine blades include film cooling and internal cooling. Film cooling is a method in which a coating film is formed on the outer surface of the turbine blade to prevent heat transfer from the outside to the blade. In the film cooling method, the heat-resistant paint applied to the blade determines the heat-resistant characteristics and mechanical durability of the blade.

[0006] The internal cooling method is a method of cooling the blades by heat exchange between a cooling fluid and the blades. Generally, the turbine blades are cooled by compressed cooling air extracted from the compressor of the gas turbine.

[0007] The airfoil tip, which is the outermost part of the turbine blade in the radial direction, is located adjacent to the turbine shroud, and cooling it is extremely difficult. For this reason, in the past, a tip rib was formed extending in the circumferential direction of the airfoil tip, and the tip rib was formed to surround the tip plate of the airfoil, and the airfoil tip was cooled by injecting air from the tip plate. Injecting air from the tip plate can prevent pressure loss and cool the tip plate, but there is a problem that the torque and output of the turbine rotational force cannot be increased. Summary of the Invention [Problem to be solved by the invention]

[0008] Based on the above technical background, the present invention aims to provide a turbine blade, a turbine, and a gas turbine having improved torque and power output. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a turbine blade comprising: an airfoil having an airfoil shape and including an inlet surface and a pressure surface; a platform portion coupled to a lower portion of the airfoil; and a root portion protruding downward from the platform portion and coupled to a rotor disk. The airfoil includes a cooling passage formed therein; and an exhaust hole connected to an upper portion of the cooling passage for exhausting cooling air, the exhaust hole being formed to extend from the inside to the outside at an angle toward a tip of the turbine blade.

[0010] According to one aspect of the present invention, the exhaust holes are formed only on the pressure surface out of the suction surface and the pressure surface.

[0011] According to one aspect of the present invention, the exhaust holes are formed to extend parallel to a rotation direction of the turbine blades.

[0012] According to one aspect of the present invention, the diameter of the exhaust hole is greater than the thickness of the wall of the turbine blade.

[0013] The turbine blade according to one aspect of the present invention is formed with a plurality of cooling holes for discharging cooling air, and the discharge holes are positioned outside the cooling holes and are formed to have a larger diameter.

[0014] According to one aspect of the present invention, the exhaust hole has an inclination angle of 5 to 15 degrees, or 35 to 45 degrees with respect to a plane perpendicular to the height direction of the turbine blade.

[0015] The airfoil according to one aspect of the present invention may further include a tip plate connected to the suction surface and the pressure surface, disposed on the outside, and formed of a sealed plate having no openings.

[0016] According to one aspect of the present invention, the cooling channel may include a flow extension portion that protrudes into the cooling channel and is connected to the exhaust hole, and the flow extension portion may include an upper extension portion that protrudes at an incline toward the inner surface of the chip plate, and a side extension portion that protrudes at an incline toward the pressure surface.

[0017] According to one aspect of the present invention, the cooling passage includes a flow guide portion protruding into the cooling passage and connected to the exhaust hole, and the flow guide portion may include a first guide portion protruding from a lower surface of the chip plate and the suction surface and connected to the exhaust hole, the first guide portion having a curved surface, and a second guide portion protruding from the pressure surface and connected to the exhaust hole.

[0018] According to one aspect of the present invention, the exhaust hole may include a compression passage having an inner diameter that gradually decreases toward an outer side, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter.

[0019] In one aspect of the present invention, an injection ratio is calculated by multiplying the discharge speed of air discharged from the inside to the outside of the turbine blade by the density of the air, and dividing the product by the product of the speed of combustion gas passing through the outer surface of the turbine blade by the density of the gas. The injection ratio between the air discharged through the exhaust holes and the gas passing through the turbine blade is 4 to 10.

[0020] According to one aspect of the present invention, there is provided a turbine including a rotatable rotor disk and a plurality of turbine blades provided on the rotor disk, the turbine blade including an airfoil having an airfoil shape and an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to the rotor disk, the airfoil including a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage for exhausting cooling air, the exhaust hole extending from the inside to the outside at an angle toward a tip of the turbine blade.

[0021] According to one aspect of the present invention, the exhaust holes are formed only on the pressure surface out of the suction surface and the pressure surface.

[0022] According to one aspect of the present invention, the exhaust holes are formed to extend parallel to a rotation direction of the turbine blades.

[0023] According to one aspect of the present invention, the diameter of the exhaust hole is greater than the thickness of the wall of the turbine blade.

[0024] The turbine blade according to one aspect of the present invention may be formed with a plurality of cooling holes for discharging cooling air, and the discharge holes may be positioned outside the cooling holes and may have a larger diameter.

[0025] According to one aspect of the present invention, the exhaust hole has an inclination angle of 5 to 15 degrees, or 35 to 45 degrees with respect to a plane perpendicular to the height direction of the turbine blade.

[0026] The airfoil according to one aspect of the present invention may further include a tip plate connected to the suction surface and the pressure surface, disposed on the outside, and formed of a sealed plate having no openings.

[0027] According to one aspect of the present invention, the cooling channel may include a flow extension portion that protrudes into the cooling channel and is connected to the exhaust hole, and the flow extension portion may include an upper extension portion that protrudes at an incline toward the inner surface of the chip plate, and a side extension portion that protrudes at an incline toward the pressure surface.

[0028] According to one aspect of the present invention, there is provided a gas turbine including a compressor that compresses air flowing in from the outside, a combustor that mixes the compressed air compressed by the compressor with fuel and burns the mixture, and a turbine including a plurality of turbine blades that rotate by combustion gas combusted in the combustor, the turbine blade including an airfoil having an airfoil shape and an intake surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil including a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole may extend from the inside to the outside at an angle toward a tip of the turbine blade. Effect of the Invention

[0029] According to the turbine blade, turbine, and gas turbine according to one aspect of the present invention, the exhaust holes are formed at an angle and only on the pressure surface, so that the torque and output of the turbine can be improved by the cooling air discharged through the exhaust holes. [Brief description of the drawings]

[0030] [Figure 1]1 is a view showing the inside of a gas turbine according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a vertical sectional view of the gas turbine of FIG. 1, with a part cut away. [Diagram 3] FIG. 1 is a perspective view showing a turbine blade according to a first embodiment of the present invention. [Figure 4] 1 is a perspective view showing a portion of a turbine blade according to a first embodiment of the present invention. FIG. [Diagram 5] 1 is a vertical cross-sectional view showing a portion of a turbine blade according to a first embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing a portion of a turbine blade according to a first embodiment of the present invention. [Figure 7] 4 is a graph showing a torque increase rate according to a change in an inclination angle of a discharge hole formed in the blade according to the first embodiment of the present invention. [Figure 8] 5 is a graph showing an output increase rate according to a change in an inclination angle of a discharge hole formed by the blade according to the first embodiment. [Figure 9] FIG. 4 is a cross-sectional view showing a portion of a turbine blade according to a modified example of the first embodiment of the present invention. [Figure 10] FIG. 6 is a vertical cross-sectional view showing a portion of a turbine blade according to a second embodiment of the present invention. [Figure 11] FIG. 7 is a vertical cross-sectional view showing a portion of a turbine blade according to a third embodiment of the present invention. [Figure 12] FIG. 10 is a perspective view showing a portion of a turbine blade according to a fourth embodiment of the present invention. [Figure 13] FIG. 10 is a vertical cross-sectional view showing a portion of a turbine blade according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Since the present invention can be implemented in various ways, a specific embodiment will be described in detail in the detailed description, but it should be understood that this is not intended to limit the present invention to the specific embodiment, and includes any modifications, equivalents, or alternatives within the spirit and technical scope of the present invention.

[0032] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0033] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that in the accompanying drawings, the same components are represented by the same reference numerals as much as possible. Also, detailed description of known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components are exaggerated, omitted, or illustrated in a schematic manner in the accompanying drawings.

[0034] Hereinafter, a gas turbine according to a first embodiment of the present invention will be described.

[0035] FIG. 1 is a diagram showing the inside of a gas turbine according to a first embodiment of the present invention, and FIG. 2 is a vertical sectional view in which a part of the gas turbine of FIG. 1 is cut away.

[0036] Explaining with reference to FIG. 1 and FIG. 2, the thermodynamic cycle of the gas turbine 1000 according to this embodiment can be ideally based on the Brayton cycle. The Brayton cycle consists of four processes, which are isentropic compression (adiabatic compression), constant pressure rapid heating, isentropic expansion (adiabatic expansion), and constant pressure heat dissipation. That is, after atmospheric air is taken in and compressed to high pressure, fuel is burned in a constant pressure environment to release thermal energy, and the high-temperature combustion gas is expanded to convert it into kinetic energy, after which the exhaust gas containing the residual energy can be released into the atmosphere. That is, the cycle is performed in four processes, namely compression, heating, expansion, and heat dissipation.

[0037] A gas turbine 1000 that realizes such a Brayton cycle can include a compressor 1100, a combustor 1200, and a turbine 1300, as shown in Fig. 1. The following description will refer to Fig. 1, but the description of the present invention can be widely applied to turbine engines having a configuration equivalent to that of the gas turbine 1000 exemplarily shown in Fig. 1.

[0038] 1, a compressor 1100 of a gas turbine 1000 can take in air from the outside and compress it. The compressor 1100 can supply compressed air compressed by compressor blades 1130 to a combustor 1200 and can also supply cooling air to a high-temperature area that needs to be cooled in the gas turbine 1000. At this time, the taken-in air undergoes an adiabatic compression process in the compressor 1100, so that the pressure and temperature of the air passing through the compressor 1100 increase.

[0039] The compressor 1100 is designed as a centrifugal compressor or an axial compressor, but while a centrifugal compressor is applied to a small gas turbine, a multi-stage axial compressor 1100 is generally applied to a large gas turbine 1000 as shown in Fig. 1 because a large amount of air must be compressed. In this case, in the multi-stage axial compressor 1100, the blades 1130 of the compressor 1100 rotate due to the rotation of the center tie rod 1120 and the rotor disk, compressing the air that is introduced and moving the compressed air to the compressor vanes 1140 in the subsequent stage. The air is gradually compressed to higher pressure as it passes through the blades 1130 formed in multiple stages.

[0040] The compressor vanes 1140 are mounted inside the housing 1150, and the multiple compressor vanes 1140 can be mounted to form a stage. The compressor vanes 1140 guide the compressed air transferred from the compressor blades 1130 of a previous stage to the blades 1130 of a subsequent stage. In one embodiment, at least a portion of the multiple compressor vanes 1140 can be mounted rotatably within a range determined for adjusting the amount of inflow of air, etc.

[0041] The compressor 1100 can be driven by a portion of the power output from the turbine 1300. For this purpose, as shown in FIG. 1, the rotating shaft of the compressor 1100 and the rotating shaft of the turbine 1300 can be directly connected by a torque tube 1170. In the case of a large-scale gas turbine 1000, approximately half of the output produced by the turbine 1300 is used to drive the compressor 1100.

[0042] Meanwhile, the combustor 1200 can produce high-energy combustion gas by mixing the compressed air supplied from the outlet of the compressor 1100 with fuel and performing isobaric combustion. The combustor 1200 produces high-energy, high-temperature, high-pressure combustion gas by mixing the incoming compressed air with fuel and burning it, and raises the temperature of the combustion gas to the heat resistance limit that the combustor and turbine components can withstand during the isobaric combustion process.

[0043] The combustor 1200 is configured to include a plurality of burners arranged in a cellular housing, each of which includes a fuel injection nozzle, a combustor liner that forms a combustion chamber, and a transition piece that serves as a connection between the combustor and the turbine.

[0044] Meanwhile, high-temperature, high-pressure combustion gas discharged from combustor 1200 is supplied to turbine 1300. As the high-temperature, high-pressure combustion gas expands, it exerts impulse and reaction force on turbine blades 1400 of turbine 1300, generating rotational torque. The rotational torque thus obtained is transmitted to compressor 1100 via torque tube 1170, and the power exceeding the power required to drive compressor 1100 is used to drive a generator, etc.

[0045] The turbine 1300 includes a rotor disk 1310, a plurality of turbine blades 1400 arranged radially on the rotor disk 1310, and a turbine vane 1500. The rotor disk 1310 has a generally circular plate shape, and a plurality of grooves are formed on its outer periphery. The grooves are formed to have a curved surface, and the turbine blades 1400 are inserted into the grooves. The turbine blades 1400 can be coupled to the rotor disk 1310 by a method such as a dovetail. The turbine vane 1500 is fixed so as not to rotate, and guides the flow direction of the combustion gas that has passed through the turbine blades 1400.

[0046] FIG. 3 is an oblique view showing a turbine blade according to the first embodiment of the present invention, FIG. 4 is an oblique view showing a portion of the turbine blade according to the first embodiment of the present invention, FIG. 5 is a longitudinal cross-sectional view showing a portion of the turbine blade according to the first embodiment of the present invention, and FIG. 6 is a transverse cross-sectional view showing a portion of the turbine blade according to the first embodiment of the present invention.

[0047] 3 to 6, the turbine blade 1400 includes a wing-shaped airfoil 1410, a platform portion 1420 coupled to the lower portion of the airfoil 1410, and a root portion 1425 protruding below the platform portion 1420 and coupled to a rotor disk. The airfoil 1410 may be made of a wing-shaped curved plate, and is formed to have an airfoil shape optimized according to the specifications of the gas turbine 1000.

[0048] The platform portion 1420 is located between the airfoil 1410 and the root portion 1425 and may have a substantially rectangular plate or rectangular prism shape. The platform portion 1420 and its side surface of the adjacent turbine blades 1400 contact each other to maintain the distance between the turbine blades 1400.

[0049] The root portion 1425 has a bent portion having a substantially bent shape, which is formed to correspond to the shape of the bent portion formed in the slot of the rotor disk 1310. Here, the coupling structure of the root portion 1425 does not necessarily have to have a bent shape, and may be formed to have a dovetail shape. An inlet for supplying cooling air is formed at the lower end of the root portion 1425.

[0050] The airfoil 1410 may have a leading edge LE disposed on the upstream side based on the flow direction of the combustion gas and a trailing edge TE disposed on the downstream side. In addition, the airfoil 1410 has an inlet surface S1 that protrudes outwardly as a convex curved surface on the front side into which the combustion gas flows, and a pressure surface S2 that is a concave curved surface on the inlet surface side on the rear side of the airfoil. A pressure difference occurs between the inlet surface S1 and the pressure surface S2 of the airfoil 1410, causing the turbine 1300 to rotate.

[0051] A plurality of cooling channels CP are formed inside the airfoil 1410, and coolant air is supplied to the cooling channels CP. The cooling channels CP are formed to extend in the height direction of the airfoil 1410. The airfoil 1410 may have no cooling holes and may have a structure for only internal cooling, or may have a structure with a plurality of cooling holes for film cooling on the outer surface.

[0052] Meanwhile, the airfoil 1410 is formed with a tip plate 1430 facing the platform portion 1420 at its radially outer end, and the tip plate 1430 is spaced apart from the shroud 1350 of the turbine 1300. The tip plate 1430 is fixed to a side wall of the airfoil 1410 to form a cooling space inside the side wall. The tip plate 1430 has a shape corresponding to the cross section of the airfoil 1410. A rib 1450 protruding outward is formed around the tip plate 1430.

[0053] The airfoil 1410 may further include exhaust holes 1460 connected to the cooling flow passage CP to exhaust the cooling air. The turbine blade 1400 according to the first embodiment does not have cooling holes for film cooling, and the cooling air supplied from the inside of the turbine blade 1400 cools the inside of the turbine blade 1400 and is then exhausted through the exhaust holes 1460 and the trailing edge TE. The exhaust holes 1460 are formed only on the pressure surface S2 out of the suction surface S1 and the pressure surface S2.

[0054] The exhaust hole 1460 is formed on the side of the cooling passage CP and on the upper end of the side. The exhaust hole 1460 is connected to the pressure surface S2 to exhaust the cooling air from the cooling passage CP to the pressure surface S2. The exhaust hole 1460 has a larger diameter than a general cooling hole, and the diameter D1 of the exhaust hole 1460 is formed to be larger than the thickness T1 of the wall surface 1411 of the turbine blade 1400.

[0055] The diameter D1 of the exhaust holes 1460 is 1.2 to 100 times the thickness T1 of the wall surface 1411 of the turbine blade 1400. This increases the speed of the air exhausted through the exhaust holes 1460, allowing a large amount of air to be quickly exhausted. 50% to 70% by weight of the air supplied to the inside of the turbine blade 1400 can be exhausted through the exhaust holes 1460.

[0056] The exhaust hole 1460 extends from the inside to the outside at an inclination toward the tip of the turbine blade 1400, and the inclination angle A1 that the exhaust hole 1460 makes with an imaginary plane P1 perpendicular to the height direction of the turbine blade 1400 is 5 degrees to 15 degrees, or 35 degrees to 45 degrees. Here, the tip of the turbine blade 1400 is the outer end portion of the turbine blade 1400.

[0057] FIG. 7 is a graph showing a torque increase rate depending on a change in the inclination angle of the discharge hole formed in the blade according to the first embodiment of the present invention, and FIG. 8 is a graph showing an output increase rate depending on a change in the inclination angle of the discharge hole formed in the blade according to the first embodiment of the present invention.

[0058] 7 and 8 show the torque and power increase rate of the gas turbine due to changes in the inclination angle when the rotation speed of the turbine blades 1400 is 3600 rpm, the compression ratio is 18.16, and the flow rate ratio of the air discharged through the exhaust holes 1460 to the flow rate of the combustion gas passing through the turbine blades 1400 is 0.6%, and the turbine is operated at full speed and full load (FSFL).

[0059] 7 and 8, when the tilt angle A1 is 0 degrees, the torque value is the largest, but the output is low. Also, when the tilt angle A1 is 0 degrees, a problem may occur in which air cannot flow into the tip plate 1430 well.

[0060] 7 and 8, if the inclination angle A1 is greater than 50 degrees, there is a problem that the torque increase rate and the output increase rate are reduced. Also, if the inclination angle A1 is between 15 degrees and 35 degrees, there is a problem that the output is reduced.

[0061] Meanwhile, the exhaust holes 1460 are formed to extend parallel to the rotation direction of the turbine blade 1400. That is, the exhaust holes 1460 are formed to extend in a direction perpendicular to the direction of the central axis X1 of the turbine 1300. In general, the cooling holes formed in the turbine blade 1400 are formed to extend in a direction perpendicular to the surface of the turbine blade 1400, which is a curved surface. However, if the exhaust holes 1460 extend perpendicular to the surface of the turbine blade 1400, it is difficult to sufficiently increase the rotational force of the turbine blade 1400.

[0062] The exhaust holes 1460 are formed to extend parallel to the rotation direction of the turbine blades 1400, and if air is exhausted in the opposite direction to the rotation direction of the turbine blades 1400, the rotational force of the turbine blades 1400 can be increased by the air exhausted through the exhaust holes 1460.

[0063] However, the present invention is not limited thereto, and the discharge hole 1461 may be formed to extend at an inclination from the inside to the outside in the direction toward the leading edge LE as shown in Fig. 9. That is, the discharge hole 1460 may be formed to be inclined at a preset inclination angle A2 toward the central axis X1 of the turbine 1300, where the inclination angle A2 is 60 degrees to 85 degrees.

[0064] Meanwhile, the velocity of the air discharged through the exhaust holes 1460 is faster than the velocity of the air discharged through the conventional cooling holes. Also, the blowing ratio (BR) of the air discharged through the exhaust holes 1460 to the gas passing through the turbine blades 1400 is 4 to 10.

[0065] The injection ratio is defined as the product of the exhaust velocity (VA) of the air exhausted from the inside to the outside of the turbine blade 1400 and the density of the air (DA), divided by the product of the velocity (VG) of the combustion gases passing through the outer surface of the turbine blade 1400 and the density of the combustion gases (DG).

[0066] As a result, the injection ratio (BR) can be expressed as the following equation 1. (Number 1) Injection ratio (BR)=(VA*DA) / (VG*DG)

[0067] If the injection ratio is less than 4, there is a problem that the turbine output increase rate is low, and if the injection ratio is more than 10, there is a problem that the compressor load increases. The tip plate 1430 is connected to the suction surface S1 and the pressure surface S2, is disposed on the outside, and is a closed plate with no openings. If the tip plate 1430 has a closed structure, more air can be discharged through the exhaust hole 1460, improving the output and torque.

[0068] As described above, according to the first embodiment, a plurality of inclined exhaust holes 1460 are formed on the upper portion of the turbine blade 1400, so that the torque and output of the turbine 1300 can be improved by the force of the air exhausted from the exhaust holes 1460. In addition, the air exhausted from the exhaust holes 1460 moves to the tip plate 1430, preventing pressure leakage and cooling the tip plate 1430.

[0069] Hereinafter, a turbine according to a second embodiment of the present invention will be described. Fig. 10 is a vertical cross-sectional view showing a part of a turbine blade according to a second embodiment of the present invention.

[0070] Referring to FIG. 10, the turbine according to the second embodiment has the same structure as the turbine according to the first embodiment except for the turbine blade 2400, and therefore a duplicated description of the same configuration will be omitted.

[0071] The turbine blade 2400 according to this embodiment includes an airfoil 2410 in the shape of an airfoil, which may be a curved sheet of airfoil shape and is formed to have an airfoil shape optimized according to the specifications of the turbine.

[0072] The airfoil 2410 has an intake surface S1 that protrudes outwardly as a convex curved surface on the front side where the combustion gas flows in, and a pressure surface S2 that is a concave curved surface that is depressed on the intake surface side on the rear side of the airfoil.

[0073] A plurality of cooling channels CP are formed inside the airfoil 2410, and coolant air is supplied to the cooling channels CP. The cooling channels CP are formed to extend in the height direction of the airfoil 2410. The airfoil 2410 may have no cooling holes and may have a structure for only internal cooling, or may have a structure with a plurality of cooling holes for film cooling on the outer surface.

[0074] Meanwhile, the airfoil 2410 has a tip plate 2430 formed at its radially outer end, the tip plate 2430 being spaced apart from a shroud 2350 of the turbine 2300. The tip plate 2430 has a rib 2450 formed at its outer end extending in the circumferential direction.

[0075] The airfoil 2410 may further include exhaust holes 2460 connected to the cooling passage CP to exhaust the cooling air. The exhaust holes 2460 are formed only on the pressure surface among the suction surface S1 and the pressure surface S2. The exhaust holes 2460 extend from the inside to the outside at an angle toward the tip of the turbine blade 2400. The exhaust holes 2460 are also formed extending parallel to the rotation direction of the turbine blade 2400. The tip plate 2430 is disposed at the outer end of the airfoil 2410 and is a closed plate having no openings.

[0076] A flow extension 2470 protruding into the cooling channel CP is formed at a corner where the tip plate 2430 and the wall surface 2411 of the airfoil 2410 meet. The flow extension 2470 may include an upper extension 2471 protruding inward from the tip plate 2430 and a side extension 2472 protruding inward from the pressure surface S2.

[0077] The upper extension 2471 protrudes at an angle relative to the inner surface of the tip plate 2430 and is connected to the exhaust hole 2460. The upper extension 2471 is formed to have a thickness that gradually decreases as it gets farther from the exhaust hole 2460. The side extension 2472 protrudes at an angle relative to the pressure surface S2 and is connected to the exhaust hole 2460.

[0078] When the flow extension 2470 is formed in this manner, the length of the discharge hole 2460 can be increased, and the flow of the cooling air can be made uniform. In addition, since the upper extension 2471 and the side extension 2472 are formed at an incline with respect to the surface of the cooling channel CP, the air can be guided to the discharge hole while preventing the generation of vortexes, thereby improving the injection speed of the air.

[0079] Hereinafter, a turbine according to a third embodiment of the present invention will be described. Fig. 11 is a vertical sectional view showing a part of a turbine blade according to a third embodiment of the present invention.

[0080] 11, the turbine according to the third embodiment has the same structure as the turbine according to the first embodiment except for the turbine blade 2400, and therefore a duplicated description of the same configuration will be omitted.

[0081] The turbine blade 2400 according to this embodiment includes an airfoil 2410 in the shape of an airfoil, which may be a curved sheet of airfoil shape and is formed to have an airfoil shape optimized according to the specifications of the turbine.

[0082] The airfoil 2410 has an intake surface S1 that protrudes outwardly as a convex curved surface on the front side where the combustion gas flows in, and a pressure surface S2 that is a concave curved surface that is recessed toward the intake surface on the rear side of the airfoil.

[0083] A plurality of cooling channels CP are formed inside the airfoil 2410, and coolant air is supplied to the cooling channels CP. The cooling channels CP are formed to extend in the height direction of the airfoil 2410. The airfoil 2410 may have no cooling holes and may have a structure for only internal cooling, or may have a structure with a plurality of cooling holes for film cooling on the outer surface.

[0084] Meanwhile, the airfoil 2410 has a tip plate 2430 formed at its radially outer end, the tip plate 2430 being spaced apart from a shroud 2350 of the turbine 2300. The tip plate 2430 has a rib 2450 formed at its outer end extending in the circumferential direction.

[0085] The airfoil 2410 may further include exhaust holes 2460 connected to the cooling passage CP to exhaust the cooling air. The exhaust holes 2460 are formed only on the pressure surface among the suction surface S1 and the pressure surface S2. The exhaust holes 2460 extend from the inside to the outside at an angle toward the tip of the turbine blade 2400. The exhaust holes 2460 are also formed extending parallel to the rotation direction of the turbine blade 2400. The tip plate 2430 is disposed at the outer end of the airfoil 2410 and is a closed plate having no openings.

[0086] A flow guide portion 2480 is formed at a corner where the tip plate 2430 and the wall surface 2411 of the air foil 2410 meet, to guide air discharged through the discharge hole 2460. The flow guide portion 2480 may include a first guide portion 2481 extending from the tip plate 2430 to the suction surface S1, and a second guide portion 2482 protruding inward from the pressure surface S2.

[0087] The first guide portion 2481 may be formed of a curved surface and protrudes from the lower surface and the suction surface S1 of the tip plate 2430 to be connected to the discharge hole 2460. The second guide portion 2482 protrudes from the pressure surface to be connected to the discharge hole 2460.

[0088] When the flow guide unit 2480 is formed in this manner, the air moving from the inside to the outside of the cooling passage CP can be guided to the discharge hole 2460 to prevent the generation of vortexes and increase the injection speed. In addition, since the flow guide unit 2480 becomes narrower toward the discharge hole 2460, the air discharge speed can be improved.

[0089] Hereinafter, a turbine according to a fourth embodiment of the present invention will be described.

[0090] FIG. 12 is a perspective view showing a portion of a turbine blade according to a fourth embodiment of the present invention, and FIG. 13 is a vertical sectional view showing a portion of a turbine blade according to the fourth embodiment of the present invention.

[0091] Referring to Figures 12 and 13, the turbine of this fourth embodiment has the same structure as the turbine of the first embodiment described above, except for the turbine blade 3400, so duplicated descriptions of the same configuration will be omitted.

[0092] The turbine blade 3400 of this embodiment includes an airfoil 3410 in the shape of an airfoil, which may be made of a curved plate in the shape of an airfoil and is formed to have an airfoil shape optimized according to the specifications of the gas turbine 3000.

[0093] The airfoil 3410 has an intake surface S1 on the front side where the combustion gas flows in, which protrudes outward as a convex curved surface, and the rear side of the airfoil has a pressure surface S2 which is a concave curved surface towards the intake surface side.

[0094] A plurality of cooling channels CP are formed inside the airfoil 3410, and coolant air is supplied to the cooling channels CP. The cooling channels CP are formed extending in the height direction of the wall surface 3411 of the airfoil 3410. The airfoil 3410 is formed with a plurality of cooling holes for film cooling.

[0095] Meanwhile, the airfoil 3410 has a tip plate 3430 formed at its radially outer end facing the platform portion 3420, and the tip plate 3430 is spaced apart from a shroud 3350 of the turbine 3300. A rib 3450 extending in the circumferential direction is formed at the outer end of the tip plate 3430.

[0096] The airfoil 3410 may further include exhaust holes 3460 connected to the cooling passage CP to exhaust the cooling air. A portion of the cooling air moving along the cooling passage CP is exhausted through the cooling holes 3480, and the remaining air is exhausted through the exhaust holes 3460. The exhaust holes 3460 are formed only on the pressure surface S2 among the suction surface S1 and the pressure surface S2.

[0097] The exhaust holes 3460 extend from the inside to the outside at an incline toward the tip of the turbine blade 3400. The exhaust holes 3460 and the cooling holes 3480 are formed extending in different directions, but the cooling holes 3480 extend in a direction perpendicular to the surface of the curved turbine blade 3400, whereas the exhaust holes 3460 extend parallel to the rotation direction of the turbine blade 3400. In addition, the cooling holes 3480 extend parallel to an imaginary plane perpendicular to the height direction of the turbine blade 3400, whereas the exhaust holes 3460 extend at an incline with respect to the imaginary plane perpendicular to the height direction of the turbine blade 3400.

[0098] The discharge hole 3460 is formed to extend from a corner where the tip plate 3430 and the side wall of the turbine blade 3400 meet to the pressure surface S2. The discharge hole 3460 may include a compression passage 3461 whose inner diameter gradually decreases as it goes outward, and a guide passage 3462 that extends from the compression passage 3461 to the pressure surface S2 and has a uniform inner diameter. When the compression passage 3461 is formed, the cooling air moving along the cooling hole 3460 can more easily flow into the discharge hole 3460, and the cooling air can be compressed during the process of moving along the discharge hole 3460 and discharged more strongly.

[0099] The discharge holes 3460 are disposed outside the cooling holes 3480, and have a larger diameter than the cooling holes 3480. The minimum diameter D2 of the discharge holes 3460 is two to five times the maximum diameter D3 of the cooling holes 3480.

[0100] In addition, the air injected through the exhaust holes 3460 has a higher velocity than the air injected through the cooling holes 3480 , and the injection ratio at the exhaust holes 3460 is greater than the injection ratio at the cooling holes 3480 .

[0101] This allows a large amount of air to be exhausted through the exhaust hole 3460, improving the torque and power of the turbine 3300.

[0102] Although one embodiment of the present invention has been described above, a person having ordinary knowledge in the art can modify and change the present invention in various ways by adding, changing, deleting or adding components without departing from the spirit of the present invention described in the claims, and this is also within the scope of the claims of the present invention. The following items are also disclosed: [Item 1] an airfoil having an airfoil shape and having an inlet surface and a pressure surface; a platform portion coupled to a lower portion of the airfoil; and a root portion protruding downward from the platform portion and coupled to a rotor disk, The airfoil includes a cooling passage formed therein, and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, The exhaust hole extends from the inside to the outside at an angle toward the tip of the turbine blade, The turbine blade has a plurality of cooling holes formed therein for discharging cooling air, the discharge holes being located outside the plurality of cooling holes and having a larger diameter. [Item 2] an airfoil having an airfoil shape and having an inlet surface and a pressure surface; a platform portion coupled to a lower portion of the airfoil; and a root portion protruding downward from the platform portion and coupled to a rotor disk, The airfoil includes a cooling passage formed therein, and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, The exhaust hole extends from the inside to the outside at an angle toward the tip of the turbine blade, The exhaust hole is a turbine blade including a compression passage having an inner diameter gradually decreasing toward the outside, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter. [Item 3] 3. The turbine blade according to item 1 or 2, wherein the exhaust holes are formed only on the pressure surface. [Item 4] The turbine blade according to any one of claims 1 to 3, wherein the exhaust holes are formed extending parallel to a rotation direction of the turbine blade. [Item 5] 4. The turbine blade according to any one of claims 1 to 3, wherein the exhaust holes extend from the inside to the outside at an angle toward the leading edge of the turbine blade. [Item 6] 6. The turbine blade according to any one of items 1 to 5, wherein the inclination angle of the exhaust hole with respect to a plane perpendicular to a height direction of the turbine blade is 5 degrees to 15 degrees, or 35 degrees to 45 degrees. [Item 7] 7. The turbine blade according to any one of claims 1 to 6, wherein the airfoil further comprises a tip plate connected to the suction surface and the pressure surface, disposed outwardly, and comprising a closed plate having no openings. [Item 8] The cooling passage has a flow extension portion protruding into the cooling passage and connected to the discharge hole, 8. The turbine blade of claim 7, wherein the flow extension includes an upper extension that protrudes at an angle relative to an inner surface of the tip plate and a side extension that protrudes at an angle relative to the pressure surface. [Item 9] The cooling passage includes a flow guide portion protruding into the cooling passage and connected to the discharge hole. 8. The turbine blade according to item 7, wherein the flow guide portion includes a first guide portion having a curved surface protruding from the lower surface of the tip plate and the suction surface and connected to the discharge hole, and a second guide portion protruding from the pressure surface and connected to the discharge hole. [Item 10] an injection ratio is calculated by multiplying the discharge speed of air discharged from the inside of the turbine blade to the outside by the density of the air and dividing the product by the product of the speed of combustion gas passing through the outer surface of the turbine blade by the density of the gas; 10. The turbine blade according to any one of items 1 to 9, wherein an injection ratio of the air discharged through the exhaust holes to the gas passing through the turbine blade is 4 to 10. [Item 11] A turbine including a rotatable rotor disk and a plurality of turbine blades disposed on the rotor disk, the plurality of turbine blades are shaped like an airfoil and include an airfoil having an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil includes a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole extending from the inside to the outside at an angle toward tips of the plurality of turbine blades, The turbine blade has a plurality of cooling holes formed therein for discharging cooling air, the discharge holes being located outside the plurality of cooling holes and having a larger diameter. [Item 12] A turbine including a rotatable rotor disk and a plurality of turbine blades disposed on the rotor disk, the plurality of turbine blades are shaped like an airfoil and include an airfoil having an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil includes a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole extending from the inside to the outside at an angle toward tips of the plurality of turbine blades, The exhaust hole includes a compression passage having an inner diameter gradually decreasing toward an outer side, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter. [Item 13] 13. The turbine according to item 11 or 12, wherein the exhaust hole is formed only on the pressure surface out of the suction surface and the pressure surface. [Item 14] The turbine according to any one of items 11 to 13, wherein the exhaust holes are formed extending parallel to a rotation direction of the plurality of turbine blades. [Item 15] 14. The turbine according to any one of claims 11 to 13, wherein the exhaust holes extend from the inside to the outside at an angle in a direction toward the leading edges of the turbine blades. [Item 16] 16. The turbine according to any one of items 11 to 15, wherein an inclination angle of the exhaust hole with respect to a plane perpendicular to a height direction of the plurality of turbine blades is 5 degrees to 15 degrees, or 35 degrees to 45 degrees. [Item 17] 17. The turbine of any one of claims 11 to 16, wherein the airfoil further comprises a tip plate connected to the suction side and the pressure side, the tip plate being disposed outwardly and comprising a blocked plate having no openings. [Item 18] The cooling passage has a flow extension portion protruding into the cooling passage and connected to the discharge hole, Item 18. The turbine of item 17, wherein the flow extensions include a top extension that projects at an angle relative to an inner surface of the tip plate and a side extension that projects at an angle relative to the pressure surface. [Item 19] A gas turbine including a compressor that compresses air flowing in from the outside, a combustor that mixes the compressed air compressed by the compressor with fuel and burns the mixture, and a turbine including a plurality of turbine blades that are rotated by combustion gas combusted in the combustor, the plurality of turbine blades are shaped like an airfoil and include an airfoil having an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil includes a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole extending from the inside to the outside at an angle toward tips of the plurality of turbine blades, A gas turbine having a plurality of cooling holes formed in the turbine blade for discharging cooling air, the discharge hole being located outside the plurality of cooling holes and having a larger diameter. [Item 20] A gas turbine including a compressor that compresses air flowing in from the outside, a combustor that mixes the compressed air compressed by the compressor with fuel and burns the mixture, and a turbine including a plurality of turbine blades that are rotated by combustion gas combusted in the combustor, the plurality of turbine blades are shaped like an airfoil and include an airfoil having an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil includes a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole extending from the inside to the outside at an angle toward tips of the plurality of turbine blades, The exhaust hole includes a compression passage having an inner diameter gradually decreasing toward an outer side, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter. [Explanation of symbols]

[0103] 1000: Gas turbine 1100: Compressor 1130: Compressor blade 1140: Vane 1150: Housing 1170: Torque tube 1200: Combustor 1300: Turbine 1310:Rotor disc 1400, 2400, 3400: Turbine blades 1410, 2410, 3410: Airfoil 1420: Platform section 1425: Root 1430, 2430, 3430: Chip plate 1460, 2460, 3460: Discharge hole 2470: Flow extension part 2480: Flow guide section 3480: Cooling Hall

Claims

1. an airfoil having an airfoil shape and having an inlet surface and a pressure surface; a platform portion coupled to a lower portion of the airfoil; and a root portion protruding downward from the platform portion and coupled to a rotor disk, The airfoil includes a cooling passage formed therein, and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, The exhaust hole extends from the inside to the outside at an angle toward the tip of the turbine blade, The discharge hole includes a compression passage having an inner diameter gradually decreasing toward an outer side, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter. The exhaust holes are formed to extend parallel to the rotation direction of the turbine blade in a cross section, or extend from the inside to the outside at an angle toward the leading edge of the turbine blade.

2. The turbine blade according to claim 1 , wherein the exhaust holes are formed only on the pressure surface.

3. The turbine blade according to claim 1 or 2, wherein an inclination angle of the exhaust hole with respect to a plane perpendicular to a height direction of the turbine blade is 5 degrees to 15 degrees, or 35 degrees to 45 degrees.

4. 4. The turbine blade according to claim 1, wherein the airfoil further comprises a tip plate connected to the suction surface and the pressure surface, the tip plate being disposed outwardly and consisting of a closed plate having no openings.

5. The cooling passage has a flow extension portion protruding into the cooling passage and connected to the discharge hole, The turbine blade of claim 4 , wherein the flow extensions include a top extension that projects at an angle relative to an inner surface of the tip plate and a side extension that projects at an angle relative to the pressure face.

6. The cooling passage includes a flow guide portion protruding into the cooling passage and connected to the discharge hole.

5. The turbine blade of claim 4, wherein the flow guide portion includes a first guide portion having a curved surface protruding from the lower surface of the tip plate and the suction surface and connected to the discharge hole, and a second guide portion protruding from the pressure surface and connected to the discharge hole.

7. an injection ratio is calculated by multiplying the discharge speed of air discharged from the inside of the turbine blade to the outside by the density of the air and dividing the product by the product of the speed of combustion gas passing through the outer surface of the turbine blade by the density of the gas; The turbine blade according to any one of claims 1 to 6, wherein an injection ratio between the air discharged through the exhaust holes and the gas passing through the turbine blade is 4 to 10.

8. A turbine including a rotatable rotor disk and a plurality of turbine blades disposed on the rotor disk, the plurality of turbine blades are shaped like an airfoil and include an airfoil having an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil includes a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole extending from the inside to the outside at an angle toward tips of the plurality of turbine blades, The discharge hole includes a compression passage having an inner diameter gradually decreasing toward an outer side, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter. The exhaust holes are formed to extend parallel to the rotation direction of the turbine blades in a cross section, or extend from the inside to the outside at an angle toward the leading edges of the turbine blades.

9. The turbine according to claim 8 , wherein the exhaust holes are formed only on the pressure surface out of the suction surface and the pressure surface.

10. The turbine according to claim 8 or 9, wherein an inclination angle of the exhaust hole with respect to a plane perpendicular to a height direction of the turbine blades is between 5 degrees and 15 degrees, or between 35 degrees and 45 degrees.

11. 11. The turbine of claim 8, wherein the airfoil further comprises a tip plate connected to the suction surface and the pressure surface, the tip plate being disposed outwardly and comprising a blocked plate having no openings.

12. The cooling passage has a flow extension portion protruding into the cooling passage and connected to the discharge hole, The turbine of claim 11 , wherein the flow extensions include a top extension that projects at an angle relative to an inner surface of the tip plate and a side extension that projects at an angle relative to the pressure surface.

13. A gas turbine including a compressor that compresses air flowing in from the outside, a combustor that mixes the compressed air compressed by the compressor with fuel and burns the mixture, and a turbine including a plurality of turbine blades that are rotated by combustion gas combusted in the combustor, the plurality of turbine blades are shaped like an airfoil and include an airfoil having an inlet surface and a pressure surface, a platform portion coupled to a lower portion of the airfoil, and a root portion protruding downward from the platform portion and coupled to a rotor disk, the airfoil includes a cooling passage formed therein and an exhaust hole connected to an upper portion of the cooling passage to exhaust cooling air, the exhaust hole extending from the inside to the outside at an angle toward tips of the plurality of turbine blades, The discharge hole includes a compression passage having an inner diameter gradually decreasing toward an outer side, and a guide passage extending from the compression passage to the pressure surface and having a uniform inner diameter. The exhaust hole is formed to extend parallel to a rotation direction of the turbine blades in a cross section, or extends from the inside to the outside at an angle toward the leading edges of the turbine blades.

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