TURBINE SHAFTS AND GAS TURBINE

Abstract

A turbine blade (30) comprising: a flow profile section (34) extending in a blade height direction and having a pressure surface (46, 46A) and a suction surface (48, 48A), each of which extends between a leading edge (42, 42A) and a trailing edge (44, 44A); a cover section (52) arranged at an outer end face of the flow profile section (34); a rounding section (40) formed by a curved surface (40a) and connected to an end section of the cover section (52) on one side of the flow profile section (34); at least one first cooling hole (60, 60a-60i) extending along the blade height direction within the flow profile section (34); and at least one cooling cavity (70) arranged at least partially within the cover section (52) and connected to with at least one first cooling hole (60, 60a-60i),and a second cooling hole (62) connected to the at least one cooling cavity (70) and open to a surface of the cover section (52), wherein the flow profile section (34) has a reference flow profile (34A) in which a maximum blade thickness at a reference position (PA) in the blade height direction is minimal, wherein the at least one cooling cavity (70) comprises a cavity (72) extending such that it overlaps the fillet section (40) in the blade height direction, wherein in a cross-section enclosing the cavity (72) perpendicular to the blade height direction, the cavity (72) extends inside and outside a first region where a contour of the reference flow profile (34A) is projected onto the cross-section in the blade height direction, and wherein the cavity (72) has: a bottom surface (76),which extends along a direction perpendicular to the blade height direction; and an inner wall surface (78) which extends along the blade height direction into an extension area (Ra1, Rb1) into which the rounding section (40) extends, and which is connected to the bottom surface (76) in an area, viewed from the blade height direction, outside the first area at the cross-section.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a turbine blade and a gas turbine. BACKGROUND

[0002] A turbine blade that has a cooling cavity at one end section of the blade can be used as a turbine blade for a gas turbine or the like.

[0003] For example, patent document 1 discloses a turbine blade for a gas turbine comprising a flow profile section and an outer end cover with a plurality of radial cooling holes extending through the flow profile section and an enlarged inner section (cavity) arranged within the outer end cover and connected to the radial cooling holes. A cooling medium supplied to the radial cooling holes flows through the radial cooling holes, is introduced into the enlarged inner section within the outer end cover, and then exits the turbine blade. In this way, the flow profile section and the outer end cover of the turbine blade are cooled. Citation list for patent literature

[0004] Patent Document 1: JP2000-297604A SUMMARY Problems to be solved

[0005] When a turbine rotor rotates, a centrifugal load acts on a rotating blade (runner or rotor blade) of a gas turbine. If a large centrifugal load acts on a turbine blade, its service life can be shortened, so the centrifugal load acting on the turbine blade must be reduced.

[0006] In view of the foregoing, an object of at least one embodiment of the present invention is to provide a turbine blade and a gas turbine, wherein a centrifugal load acting on the turbine blade can be reduced. Problem solving

[0007] A turbine blade according to at least one embodiment of the present invention comprises: a flow profile section extending in a blade height direction and having a pressure surface and a suction surface, each extending between a leading edge and a trailing edge; a cover section arranged at an outer end face of the flow profile section; a fillet section formed by a curved surface and connected to an end section of the cover section on one side of the flow profile section; at least one first cooling hole extending along the blade height direction within the flow profile section; at least one cooling cavity arranged at least partially within the cover section and connected to the at least one first cooling hole; and a second cooling hole.which is connected to the at least one cooling cavity and is open to a surface of the cover section. The flow profile section has a reference flow profile in which the maximum blade thickness at a reference position in the blade height direction is minimal. The at least one cooling cavity comprises a cavity that extends such that it overlaps the fillet section in the blade height direction. In a cross-section enclosing the cavity perpendicular to the blade height direction, the cavity extends inside and outside a region where a contour of the reference flow profile is projected onto the cross-section in the blade height direction.

[0008] A gas turbine according to at least one embodiment of the present invention comprises: the turbine blade described above and a combustion chamber for generating a combustion gas which flows through a combustion gas passage provided with the turbine blade. Beneficial effects

[0009] At least one embodiment of the present invention provides a turbine blade and a gas turbine, wherein a centrifugal load acting on the turbine blade can be reduced. List of characters Fig. Figure 1 is a schematic configuration representation of a gas turbine in which a turbine blade according to one embodiment is used. Fig. Figure 2 is a schematic representation of a turbine blade (runner or rotor blade) according to one embodiment, viewed in a direction from the suction surface to the pressure surface. Fig. 3 is a representation of the in Fig. 2 turbine blade shown when viewed in the blade height direction along line AA of Fig. 2. Fig. Figure 4 is a schematic cross-sectional view along line BB of Fig. 3. Fig. Figure 5 is a schematic representation of a cavity according to one embodiment when viewed in the blade height direction. Fig. Figure 6 is a schematic cross-sectional view of a turbine blade comprising a cavity according to one embodiment. Fig. Figure 7 is a schematic cross-sectional view of a turbine blade comprising a cavity according to one embodiment. Fig. Figure 8 is a schematic cross-sectional view of a turbine blade comprising a cavity according to one embodiment. Fig. Figure 9 is a schematic cross-sectional view of a turbine blade comprising a cavity according to one embodiment. Fig. Figure 10 is a diagram of a turbine blade comprising a cavity according to one embodiment. DETAILED DESCRIPTION

[0010] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, unless specifically stated otherwise, it is intended that dimensions, materials, shapes, relative positions, and the like of components described in the present embodiments are to be understood as illustrative only and not as limiting the scope of the present invention. (Gas turbine configuration)

[0011] First, a gas turbine is described to which a turbine blade is attached according to some embodiments.

[0012] Fig. Figure 1 is a schematic configuration representation of a gas turbine in which a turbine blade according to one embodiment is used. As in Fig. Figure 1 shows that the gas turbine 1 comprises a compressor 2 for generating compressed air, a combustion chamber 4 for generating combustion gas from the compressed air and fuel, and a turbine 6 configured to be set in rotation by the combustion gas. In the case of the gas turbine 1 for power generation, a generator (not shown) is connected to the turbine 6.

[0013] The compressor 2 comprises a plurality of guide vanes (stator blades) 16, which are attached to a compressor housing 10, and a plurality of impeller blades (rotor blades) 18, which are mounted on a rotor 8 such that they are arranged alternately with the guide vanes 16. Air is supplied to the compressor 2, which is drawn in through an air inlet 12. The air flows through the plurality of guide vanes 16 and the plurality of impeller blades 18 and is compressed into compressed air at high temperature and high pressure.

[0014] Combustion chamber 4 is supplied with fuel and the compressed air generated in compressor 2. Combustion chamber 4 mixes the fuel and compressed air and burns the mixture to produce a combustion gas that serves as the working fluid for turbine 6. As described in Fig. As shown in Figure 1, a plurality of combustion chambers 4 can be arranged along the circumferential direction around the rotor inside a housing 20.

[0015] The turbine 6 has a combustion gas passage 28, which is formed inside a turbine housing 22 and comprises a plurality of guide vanes (stator blades) 24 and a plurality of rotor blades 26 arranged in the combustion gas passage 28. The guide vanes 24 are attached to the turbine housing 22, and a set of guide vanes 24 arranged along the circumferential direction of the rotor 8 forms a guide vane assembly. Furthermore, the rotor blades 26 are mounted on the rotor 8, and a set of rotor blades 26 arranged along the circumferential direction of the rotor 8 forms a rotor blade assembly. The guide vane assemblies and the rotor blade assemblies are arranged alternately in the axial direction of the rotor 8.

[0016] In the turbine 6, the rotor 8 is driven rotationally when the combustion gas introduced from the combustion chamber 4 into the combustion gas passage 28 flows through the plurality of guide vanes 24 and the plurality of rotor blades 26. This drives the generator connected to the rotor 8 to produce power. The combustion gas that has driven the turbine 6 is discharged to an outside via an exhaust chamber 29.

[0017] In some embodiments, at least one of the rotor blade 26 or the guide blade 24 of the turbine 6 is a turbine blade 30 as described below. (configuration of the turbine blade)

[0018] The turbine blade 30 according to some embodiments will now be described in more detail. Fig. Figure 2 is a schematic representation of a turbine blade 30 (rotor blade 26) according to an embodiment, viewed in a direction from the suction surface to the pressure surface (direction along the rotor circumferential direction). Fig. 3 is a representation of the in Fig. 2 turbine blade 30 shown when viewed in the blade height direction along line AA of Fig. 2. Fig. Figure 4 is a schematic cross-sectional view along line BB of Fig. 3. Fig. Figure 10 is a representation of the turbine blade 30 according to another embodiment, which differs from Fig. 4 differs and the cross-section along line BB of Fig. 3 corresponds to. In Fig. 2 is a closure (described later, see Fig. 4) not shown for closing the opening of the cavity.

[0019] As in the Fig. 2 to Fig. Figure 4 shows that, according to one embodiment, the turbine blade 30 (rotor blade 26) comprises a platform 32, a flow profile section 34, a blade root section 36 connected to the platform 32, a cover section 52 arranged at the outer end of the flow profile section 34, and a rounding section 40 connected to the cover section 52. Furthermore, the turbine blade 30 comprises a rib 54 to reduce fluid discharge at the outer end section of the turbine blade 30.

[0020] The airfoil section 34 extends in the blade height direction (span direction), has a base end section 38 and an outer end section 39, both of which are end sections in the blade height direction, and is connected to the platform 32 at the base end section 38. Furthermore, the airfoil section 34 has a leading edge 42 and a trailing edge 44 extending along the blade height direction, and a pressure surface 46 and a suction surface 48 extending between the leading edge 42 and the trailing edge 44. The airfoil section 34 may have a shape that is twisted in the blade height direction with respect to the distance from the base end section 38 to the outer end section 39.

[0021] The blade root section 36 is located on the side of the platform 32 opposite the flow profile section 34 in the blade height direction. The blade root section 36 comprises an engagement section with an uneven shape. The engagement section engages with a blade groove in a rotor disk (not shown) that rotates with the rotor 8, so that the turbine blade 30 is attached to the rotor 8 of the turbine 6.

[0022] When the turbine blade 30 is attached to the rotor 8, the blade height direction lies along the radial direction of the turbine 6. In other words, the blade height direction of the turbine blade 30 essentially coincides with the radial direction of the turbine 6.

[0023] As in Fig. 2 or Fig. As shown in Figure 4, the rounding section 40 is formed by a curved surface 40a and is connected to an end section of the airfoil section 34 adjacent to the cover section 52. The rounding section 40 can be connected to a flat surface 52a of the cover section 52, which extends along the direction perpendicular to the blade height. The rounding section 40, formed by the curved surface 40a, can relieve the stress concentration at the connection between the cover section 52 and the airfoil section 34.

[0024] Here, the position where the maximum blade thickness of the flow profile section 34 is minimum in the blade height direction is used as a reference position P. Adefined, and the flow profile of the flow profile section 34 at the reference position is defined as a reference flow profile 34A. In other words, the flow profile section 34 has the reference flow profile 34A, where the maximum blade thickness at the reference position P A is minimal in the blade height direction. The reference position P A essentially corresponds to the initial position of the rounding section in a direction from the base end section 38 to the outer end section 39 in the blade height direction.

[0025] In Fig. Figure 3 shows the airfoil profile 34A, projected in the blade height direction onto a plane perpendicular to the blade height direction, as represented by the dashed line. The airfoil profile 34A has a leading edge 42A, a trailing edge 44A, a pressure surface 46A, and a suction surface 48A. The direction connecting the leading edge 42A and the trailing edge 44A of the reference airfoil profile 34A is the chord direction of the reference airfoil profile 34A. Fig. Figure 3 also shows a curve Lc A of the reference flow profile 34A. In the following, the leading edge 42A, the trailing edge 44A, the pressure surface 46A and the suction surface 48A of the reference flow profile 34A are simply referred to as the leading edge 42A, the trailing edge 44A, the pressure surface 46A and the suction surface 48A.

[0026] The cover section 52 is attached to the outer end section 39 of the flow profile section 34 via the rounded section 40. As shown in Fig. Figure 3 shows that the cover section 52 has an upstream end surface 66, which is located on the upstream side, and a downstream end surface 67, which is located on the downstream side of a fluid (combustion gas) that passes through the combustion gas passage 28 (see Figure 3). Fig. 1) of the turbine 6. Furthermore, the cover section 52 has a first contact surface 68 located on the side of the leading edge 42A of the reference flow profile 34A, and a second contact surface 69 located on the side of the trailing edge 44A of the reference flow profile 34A. The first contact surface 68 and the second contact surface 69 extend along the blade height direction and, when viewed in the blade height direction, extend in a direction that intersects the circumferential and / or axial direction of the rotor 8 (hereinafter also referred to simply as the circumferential direction or axial direction).

[0027] The contact surfaces (first contact surface 68 and second contact surface 69) of the cover section 52 are arranged such that they face the cover sections 52 of adjacent turbine blades 30. In particular, the first contact surface 68 of the cover section 52 of one turbine blade 30 faces the second contact surface 69 of the cover section 52 of another turbine blade 30 adjacent to the first turbine blade 30 and can bear against it. Furthermore, the second contact surface 69 of the cover section 52 of one turbine blade 30 faces the first contact surface 68 of the cover section 52 of another turbine blade 30 adjacent to the first turbine blade 30 and can bear against it. This restricts the movement of the turbine blade 30 in the circumferential and / or axial direction.

[0028] The rib 54 projects from the cover section 52 to the outer edge of the blade and extends along the circumferential direction. The ribs 54 of several turbine blades 30, arranged in the circumferential direction, form an annular sealing section.

[0029] The turbine blade 30 further comprises a plurality of first cooling holes 60 (60a to 60i), at least one cooling cavity 70 (70A,70B) and a plurality of second cooling holes 62.

[0030] Each of the first cooling holes 60 extends along the blade height direction within the airfoil section 34. Typically, the first cooling holes 60 are arranged along the curvature line of the airfoil section 34. The cooling cavity 70 is located at least partially within the cover section 52 and is connected to at least one first cooling hole 60. Each of the second cooling holes 62 is connected to the cooling cavity 70 and is open to a surface of the cover section 52. The second cooling hole 62 can open to an outer blade end surface 52b (see Fig. 4) of the cover section 52 or to the upstream end surface 66 or the downstream end surface 67.

[0031] The open end section of the cooling cavity 70 at the outer end of the blade in the blade height direction is provided with a closure 74 for closing the open end section. This prevents fluid from escaping into the cooling cavity 70 through the open end section.

[0032] The closure 74 can be plate-shaped. The closure 74 can be inserted into a recess provided in the outer end surface 52b of the cover section 52 along the contour of the cooling cavity 70, as for example in Fig. Figure 4 shows that the surface of the closure 74 and the blade-outer end surface 52b of the cover section 52 can be flush with each other. Alternatively, the closure 74 can be inserted into a recess provided in a padding portion 75, which is arranged on the blade-outer end surface 52b along the contour of the cooling cavity 70, as shown, for example, in Fig. 10 shown. Alternatively, the closure 74 can be inserted into a recess in the inner wall surface (side wall surface) 78 of the cooling cavity 70, although this is not explicitly shown.

[0033] During the Fig. 2 to Fig. In the exemplary embodiment shown in Figure 4, the at least one cooling cavity 70 comprises a front-edge-side cavity 70A and a rear-edge-side cavity 70B, which is located on the side of the rear edge (44A) of the front-edge-side cavity 70A in the chordal direction (see Figure 4). Fig. 3) of the flow profile section 34 at the reference position P A (i.e., reference flow profile 34A) is arranged.

[0034] The leading-edge cavity 70A is connected to a plurality of first cooling holes 60a to 60e. The first cooling holes 60a, 60b, 60c, 60d, 60e are arranged in this order from the leading edge 42A to the trailing edge 44A along the curve Lc. AThe trailing-edge cavity 70B is connected to a plurality of first cooling holes 60f to 60i. The first cooling holes 60f, 60g, 60h, 60i are arranged in this order from the leading edge 42A to the trailing edge 44A along the line of curvature LCA.

[0035] During the Fig. 2 to Fig. In the exemplary embodiment shown in Figure 4, the first cooling hole 60 is open to a bottom surface 76 of the cooling cavity 70. Furthermore, the second cooling hole 62 is open to an inner wall surface (side wall surface) 78 of the cooling cavity 70.

[0036] The multitude of first cooling holes 60 are supplied with a cooling fluid (e.g., air) through an inlet opening 58, which is open to a terminal section of the blade root section 36 of the turbine blade 30. The cooling fluid supplied to the first cooling holes 60 flows through them to the outer edge of the blade, passes through the first cooling holes 60, and is then retained in the cooling cavity 70. The cooling fluid in the cooling cavity 70 flows through the second cooling holes 62 and is discharged from the turbine blade 30 through openings 63 in the surface of the cover section 52. Since the cooling fluid flows within the turbine blade 30, the turbine blade 30, including the flow profile section 34 and the cover section 52, is cooled.

[0037] In some embodiments, at least one cooling cavity 70 is a cavity 72 as described below. In particular, the cavity 72 extends such that it overlaps the rounding section 40 in the blade height direction, and in a cross-section enclosing the cavity 72 perpendicular to the blade height direction, the cavity 72 extends inside and outside a region where the contour of the reference flow profile section 34A is projected onto the cross-section in the blade height direction (the region shown in Fig. 3 is shown as the reference flow profile 34A).

[0038] The turbine blade 30 can have the cross-section described above (the cross-section in which the cavity 72 extends inside and outside the projection area of ​​the contour of the reference flow profile 34A) in at least one position within the extent of the cavity 72 in the blade height direction. For example, the turbine blade 30 can have the cross-section described above over a region of not less than 30% or not less than 50% of the extent of the cavity 72 in the blade height direction.

[0039] At the in Fig. 2 to Fig. In the exemplary embodiment shown in Figure 4, the front edge-side cavity 70A and the rear edge-side cavity 70B are the cavities 72 described above.

[0040] For example, as in Fig. As shown in Figure 4, on the side of the pressure surface 46, the rounding section 40 extends within the region Ra1 in the blade height direction and within the region Ra2 in the blade thickness direction. On the side of the suction surface 48, the rounding section 40 extends within the region Rb1 in the blade height direction and within the region Rb2 in the blade thickness direction. Furthermore, the cavity 72 is arranged such that, in the blade height direction, it at least partially overlaps the extension region Ra1 of the rounding section 40 on the side of the pressure surface 46 and the extension region Rb1 of the rounding section 40 on the side of the suction surface 48.

[0041] Furthermore, the cavity comprises 72, as shown in Fig. 3 shows, when viewed in the blade height direction, an inner section (in Fig. 3 the dot-filled section of cavity 72), which extends within the contour of reference flow profile 34A, and an outer section (in Fig. 3 the section of cavity 72 not filled with dots, which extends outside the reference flow profile 34.

[0042] According to the embodiment described above, the cavity 72 (leading-edge cavity 70A and trailing-edge cavity 70B) is arranged in the outer end section of the turbine blade 30, which includes the cover section 52. The depth of the cavity 72 extends to the rounded section 40 in the blade height direction. In a cross-section perpendicular to the blade height direction, the cavity 72 extends both inside and outside the projection area of ​​the contour of the reference flow profile 34A (i.e., it projects from the inside of the contour of the reference flow profile 34A). Thus, since the outer end section of the turbine blade 30, including the cover 52, is provided with a cavity 72 that is large both in and from the blade height direction, the weight of the outer end section can be effectively reduced.In this way, the centrifugal load acting on the turbine blade 30 can be effectively reduced and the shortening of the service life of the turbine blade 30 can be prevented.

[0043] Furthermore, according to the embodiment described above, since the depth of the cavity 72 extends to the rounding section 40 in the blade height direction, the rounding section 40 can be effectively cooled. Consequently, the reduction in the service life of the turbine blade 30 can be effectively prevented.

[0044] In some embodiments, the [element] is located on the side of the front edge 42 in the chord direction (see Fig. 3) the cavity 72 arranged below the plurality of cooling cavities 70 of the reference flow profile 34A extends from the projection area of ​​the contour of the reference flow profile 34A to the side of the blade surface 48 of the flow profile section 34 in a cross-section perpendicular to the blade height direction. For example, the outer section of the leading-edge cavity 70A (the section extending outside the reference flow profile 34), as shown in Fig. Figure 3 shows, when viewed in the blade height direction, an outer section 102 on the suction surface side, which protrudes towards the side of the suction surface 48 of the flow profile section 34 (reference flow profile).

[0045] On the leading edge 42 side, the cover section 52 typically has a relatively large mass on the side of the suction surface 48, which causes the center of gravity of the cover section 52 to be offset towards the side of the suction surface 48. According to the embodiment described above, the center of gravity of the cover section 52 on the leading edge 42 side can therefore be brought closer to the central section of the cover section 52 in the turbine axial direction, since the contour of the leading-edge-side cavity 70A projects from the projection area of ​​the reference flow profile 34A to the side of the suction surface 48 in a cross-section perpendicular to the blade height direction.By adjusting the position of the center of gravity in this way, the centrifugal load acting on the turbine blade 30 can be effectively reduced, while the stress balance between the side of the pressure surface 46 and the side of the suction surface 48 of the turbine blade 30 is adjusted.

[0046] In some embodiments, the [element] is located on the side of the trailing edge 44 in the chord direction (see Fig. 3) the cavity 72 arranged of the reference flow profile 34A below the plurality of cooling cavities 70 from the projection area of ​​the contour of the reference flow profile 34A to the side of the pressure surface 46 of the flow profile section 34 in a cross-section perpendicular to the blade height direction. For example, as shown in Fig. Figure 3 shows the outer section of the trailing edge cavity 70B (the section which extends outside the reference flow profile 34) when viewed in the blade height direction as a pressure surface-side outer section 104 which projects to the side of the pressure surface 46 of the flow profile section 34 (reference flow profile).

[0047] On the trailing edge 44 side, the cover section 52 typically has a relatively large mass on the side of the pressure surface 46, which causes the center of gravity of the cover section 52 to be offset towards that side of the pressure surface 46. According to this embodiment, the center of gravity of the cover section 52 on the trailing edge 44 side can therefore be brought closer to the central section of the cover section 52 in the turbine axial direction, since the contour of the trailing edge-side cavity 70B projects from the projection area of ​​the reference flow profile 34A to the side of the pressure surface 46 in a cross-section perpendicular to the blade height direction.By adjusting the position of the center of gravity in this way, the centrifugal force acting on the turbine blade 30 can be effectively reduced, while at the same time the stress balance between the side of the pressure surface 46 and the side of the suction surface 48 of the turbine blade 30 is adjusted.

[0048] Fig. Figure 5 is a schematic representation of the cavity 72 (in this example the trailing edge cavity 70B) according to an embodiment when viewed in the blade height direction. Fig. 6 to Fig. Figure 8 each represents a schematic cross-sectional view of the turbine blade 30, which includes the cavity 72 according to one embodiment, in a plane that includes the blade height direction and a first direction or a second direction, which will be described later.

[0049] The following describes features of the turbine blade 30 according to some embodiments with reference to the figures ( Fig. 5 to Fig. 8) of the rear-edge cavity 70B is described as an example of the cavity 72, but the same description applies to the case of the rear-edge cavity 70A.

[0050] As in the Fig. 3 to Fig. Figure 8 shows the first cooling holes 60f to 60i, which are connected to the trailing edge cavity 70B, along the line of curvature (see Fig. 3) of the flow profile section 34 and are open to the bottom surface 76 of the trailing edge cavity 70B.

[0051] In some embodiments, when viewed in the blade height direction on a straight line L1, which is the center point (Pf,Pi) of the openings of two first cooling holes 60 (in Fig. 5, first cooling holes 60f,60i) at both ends in one direction along the line of curvature, a distance (W L or W T) between the inner wall surface 78 of the cavity 72 and the center point (Pf,Pi) of the opening of at least one of the two first cooling holes 60f,60i, is 0.8 times or more of a distance W1 between the centers of the two first cooling holes 60f,60i. In this case, the number of first cooling holes 60 open to the bottom surface 76 of the cavity 72 can be three or more.

[0052] When viewed in the blade height direction, a first direction is defined as the direction of the straight line L1, which connects the centers (Pf,Pi) of the openings of two first cooling holes 60f, 60i at both ends in the direction along the line of curvature under the plurality of first cooling holes 60f to 60i. Two points of intersection between the inner wall surface 78 of the cavity 72 and the straight line L1 in the first direction comprise a point of intersection P. Lon the side of the front edge 42 and an intersection point P T on the side of the trailing edge 44.

[0053] The distance W L is a distance W L on the straight line L1 between the intersection point P L on the side of the leading edge 42 and the first cooling hole 60f, which is located closer to the leading edge 42 than the two first cooling holes 60f, 60i. The distance W T is a distance W T on the straight line L1 between the intersection point P T on the side of the trailing edge 44 and the first cooling hole 60i, which is located closer to the trailing edge 44 than the two first cooling holes 60f, 60i.

[0054] Since the position and size (diameter, etc.) of the first cooling hole 60 are limited by the flow profile section 34, the size of the area where the openings of the first cooling holes 60 are located (i.e., the distance W1 between the centers of the first cooling holes 60f, 60i at both ends) is largely determined in accordance with the flow profile (e.g., reference flow profile 34A) at the blade tip section when viewed in the blade height direction. In this respect, a large cavity 72 is provided in the embodiment described above, such that the distance W L or W TThe distance between the inner wall surface 78 of the cavity 72 and the opening of one of the first cooling holes 60f, 60i at both ends, in the direction along the line of curvature, is 0.8 times or more the distance W1 between the centers of the openings of the first cooling holes 60f, 60i when viewed in the blade height direction. In this way, the weight of the outer end section of the turbine blade 30, including the cover section 52, can be effectively reduced, and the centrifugal load acting on the turbine blade 30 can be effectively reduced.

[0055] In some embodiments, when viewed in the blade height direction on a straight line that includes the centers of the openings of two first cooling holes closest to the leading edge 42A or the trailing edge 44A, the reference position P A Among the numerous initial cooling holes, 60 are connected by a distance (W L or W T) between the inner wall surface 78 of the cavity 72 and the center point of the opening of the first cooling hole 60, which is the front edge 42A or the rear edge 44A at the reference position P A among the multitude of first cooling holes 60, is closest, which is 1.5 times or more a distance (W2 or W3) between the centers of the openings of the two first cooling holes 60.

[0056] In one embodiment, for example as in Fig. As shown in Figure 5, when viewed in the blade height direction on a straight line L2 connecting the centers (Ph,Pi) of openings of two first cooling holes 60h, 60i, which are closest to the trailing edge 44A of the plurality of first cooling holes 60, a distance W can be determined. Tbetween the inner wall surface 78 of the cavity 72 and the first cooling hole 60i that is closest to the trailing edge 44A, shall be 1.5 times or more a distance W2 between the centers of the openings of the two first cooling holes 60h,60i.

[0057] Alternatively, in one embodiment, when considering the blade height direction along a straight line (in Fig. 5 the same line as the straight line L2), which connects the centers (Pf,Pg) of openings of two first cooling holes 60f,60g which are closest among the multitude of first cooling holes 60 to the trailing edge 44A, a distance W L between the inner wall surface 78 of the cavity 72 and the first cooling hole 60f that is closest to the leading edge 42A, 1.5 times or more a distance W3 (see Fig. 5) between the centers of the openings of the first two cooling holes shall be 60f, 60g.

[0058] When viewed in the blade height direction, a second direction of the straight line (i.e., the straight line L2) connecting the centers of the openings of two first cooling holes (first cooling holes 60f, 60g or first cooling holes 60h, 60i) that are closest to the leading edge 42A or the trailing edge 44A among the plurality of first cooling holes 60f to 60i is defined. Two points of intersection between the inner wall surface 78 of the cavity 72 and the straight line L2 in the second direction comprise a point of intersection P. L on the side of the front edge 42 and an intersection point P T on the side of the trailing edge 44. At the in Fig. In the embodiment shown in section 5, the first direction and the second direction are the same direction.

[0059] Since the position and size (diameter, etc.) of the first cooling hole 60 are limited by the flow profile section 34, the distance W2 or W3 between the centers of two first cooling holes 60 (first cooling holes 60f, 60g or first cooling holes 60h, 60i) near the leading edge 42A or the trailing edge 44A, when viewed in the blade height direction, is largely determined in accordance with the flow profile at the blade tip section. In this respect, a large cavity 72 is provided in the embodiment described above, so that the distance W L or W TThe distance between the inner wall surface 78 of the cavity 72 and the opening of one of the first cooling holes 60 (first cooling holes 60f, 60g or first cooling holes 60h, 60i), which are located adjacent to the leading edge 42A or the trailing edge 44A in the direction along the line of curvature, is, when viewed in the blade height direction, 1.5 times or more the distance W2 or W3 between the centers of the openings of these first cooling holes 60. Thus, the weight of the outer end of the turbine blade 30, including the cover section 52, can be effectively reduced, and the centrifugal load acting on the turbine blade 30 can be effectively reduced.

[0060] As in Fig. 6 to Fig. Figure 8 shows that in a cross-section including the blade height direction and the first direction or the second direction, the bottom surface 76 of the cavity 72 extends along the direction perpendicular to the blade height direction, and the inner wall surface 78 of the cavity 72 extends along the blade height direction.

[0061] In some embodiments, such as in Fig. 7 or Fig. As shown in Figure 8, the bottom surface 76 of the cavity 72 can run obliquely to the direction perpendicular to the blade height direction or can at least partially be formed by a curved surface.

[0062] Furthermore, in some embodiments, such as in Fig. 7 or Fig. As shown in Figure 8, the inner wall surface 78 of the cavity 72 may be inclined to the blade height direction or at least partially formed by a curved surface. For example, in a cross-section enclosing the blade height direction and the first direction or the second direction, a section of the surface forming the cavity 72 may be formed where the angle θ (see Figure 8) is inclined to the blade height direction and the first direction or the second direction. Fig. 7) between the surface and the blade height direction or the angle θ (see Fig. 8) between the tangent L3 at the surface and the blade height direction is 45 degrees or less than the inner wall surface 78. As described above, the distance between the opening center of the first cooling hole 60 and the inner wall surface 78 is the distance between the opening center of the first cooling hole 60 and the position of the inner wall surface 78 closest to the first cooling hole 60 when the inner wall surface 78 of the cavity 72 is inclined to the blade height direction or is at least partially formed by a curved surface.

[0063] Fig. Figure 9 is a schematic cross-sectional view of the turbine blade 30 including the cavity 72 according to an embodiment in a plane that shows the blade height direction and the chord direction at the reference position P. A includes.

[0064] In some embodiments, a cross-section is taken that defines the blade height direction and the chord direction at the reference position P. A includes the depth D (see Fig. 9) of the cavity 72 in the blade height direction from the leading edge 42A to the trailing edge 44A in the chord direction of the flow profile section 34 at the reference position P A (the chord direction of the reference flow profile 34A). Alternatively, in some embodiments, in a cross-section that defines the blade height direction and the chord direction at the reference position P, the angle of rotation increases. A includes the depth D (see Fig. 9) of the cavity 72 in the blade height direction from upstream to downstream in the axial direction of the rotor 8 of the turbine 6.

[0065] If a point moves from a point on the front edge to a point on the back edge in the chord direction at the reference position P AWhen it moves, it moves in the axial direction from upstream to downstream. Therefore, "the depth increases from the leading edge 42A to the trailing edge 44A" and "the depth increases from upstream to downstream in the axial direction" are essentially synonymous.

[0066] In the exemplary case in Fig. In the embodiment shown in Figure 9, the depth D of the cavity 72 in the blade height direction is measured from the leading edge 42A to the trailing edge 44A in the chord direction of the flow profile section 34 at the reference position P, both with respect to the leading-edge cavity 70A and the trailing-edge cavity 70B. A (the chord direction of the reference flow profile 34A).

[0067] According to the embodiment described above, the weight of the outer end section of the turbine blade 30, including the cover section 52, can be effectively reduced because the depth D of the cavity 72 increases in the blade height direction towards the trailing edge 44A (or downstream). For example, in a turbine blade 30 whose dimensions increase in the blade height direction from the leading edge 42 to the trailing edge 44, the weight of the outer end section of the turbine blade 30 can be effectively reduced if the cavity 72 is deeper on the side of the trailing edge 44, by utilizing the blade height of the section on the side of the trailing edge 44. In this way, the centrifugal load acting on the turbine blade 30 can be effectively reduced.

[0068] In some embodiments, for example as in Fig. As shown in Figure 3, when viewed in the blade height direction, the extended line of the contact surface (first contact surface 68 or second contact surface 69) of the cover section 52 runs through the cavity 72. In the exemplary embodiment in Fig. 3. The extended line L4 of the first surface 68, when viewed in the blade height direction, runs through the leading-edge cavity 70A. Furthermore, in the Fig. In the embodiment shown in Figure 3, when viewed in the blade height direction, the extended line L5 of the second contact surface 69 passes through the cavity 70B on the trailing edge.

[0069] The contact surface (first contact surface 68 or second contact surface 69) is located at the circumferential end section of the cover section 52, and when viewed in the blade height direction, the extended line (L4 or L5) of the contact surface generally passes through the circumferential end section of the cover section 52. Since, in the aforementioned embodiment, the extended line (L4 or L5) of the contact surface passes through the cavity 72, the cavity 72 extends circumferentially to the end section of the cover section 52 when viewed in the blade height direction. Thus, according to the aforementioned embodiment, because the outer end section of the turbine blade 30, including the cover section 52, is provided with a large cavity 72 that extends to the circumferential end section, the weight of the outer end section can be effectively reduced.Therefore, the centrifugal load acting on the turbine blade 30 can be effectively reduced and the shortening of the service life of the turbine blade 30 can be prevented.

[0070] In some embodiments, the second cooling hole 62 is connected to a section of the cavity 72 that is located outside the area where the contour of the reference flow profile 34A in the blade height direction is projected onto a cross-section perpendicular to the blade height direction (i.e., the outer section described above).

[0071] For example, in the Fig. 3 and Fig. In the exemplary embodiment shown in Figure 4, the second cooling hole 62, connected to the leading-edge cavity 70A, is connected to the suction-surface-side outer section 102 of the leading-edge cavity 70A, which, when viewed in the blade height direction, projects towards the side of the suction surface 48 of the flow profile section 34 (reference flow profile). In the Fig. 3 and Fig. In the exemplary embodiment shown in Figure 4, the second cooling hole 62, which is connected to the trailing-side cavity 70B, is connected to the pressure-surface-side outer section 104 of the trailing-side cavity 70B, which, when viewed in the blade height direction, protrudes towards the side of the pressure surface 46 of the flow profile section 34 (reference flow profile).

[0072] On the side (side of the pressure surface 46 or side of the suction surface 48) where the cavity 72 projects from the projection area of ​​the reference flow profile 34A on the cross-section described above when viewed in the blade height direction, the fillet section 40 is generally relatively large, or the width of the cover section 52 (e.g., the width in the direction perpendicular to the chord direction of the reference flow profile 34A) is relatively large. In accordance with the embodiment described above, the cover section 52 and the fillet section 40 can be effectively cooled because the second cooling hole 62 is connected to the section that projects from the projection area of ​​the reference flow profile 34A on the cross-section described above when viewed in the blade height direction.

[0073] In some embodiments, such as in Fig. 3 and Fig. As shown in Figure 4, the second cooling hole 62 extends on both sides of the rib 54, so that when viewed in the blade height direction it runs over the rib 54.

[0074] Since in the embodiment described above a relatively long second cooling hole 62 is arranged such that, when viewed in the blade height direction, it runs over the rib 54 and extends on both sides of the rib 54, the cover section 52 and the rounding section 40 can be effectively cooled.

[0075] In some embodiments, for example as in Fig. As shown in Figure 4, the second cooling hole 62 extends such that it at least partially overlaps the rounded section 40 in the blade height direction. In the Fig.In the exemplary embodiment shown in Figure 4, the second cooling hole 62 extends in the blade height direction such that it at least partially overlaps the extent Ra1 of the rounded section 40 on the side of the pressure surface 46. Furthermore, the second cooling hole 62 extends such that it at least partially overlaps the extent Rb1 of the rounded section 40 on the side of the suction surface 48.

[0076] Since, in the embodiment described above, the second cooling hole 62 is arranged such that it at least partially overlaps the rounding section 40 in the blade height direction, the rounding section 40 can be effectively cooled by supplying a cooling fluid to the second cooling hole 62.

[0077] The content described in the above embodiments is to be understood, for example, as follows.

[0078] (1) A turbine blade (30) according to at least one embodiment of the present invention comprises: a flow profile section (34) extending in a blade height direction and having a pressure surface (46) and a suction surface (48), each of which extends between a leading edge (42) and a trailing edge (44); a cover section (52) arranged at an outer end face of the flow profile section; a rounding section (40) formed by a curved surface (40a) and connected to an end section of the cover section on one side of the flow profile section; at least one first cooling hole (60) extending along the blade height direction within the flow profile section; and at least one cooling cavity (70) arranged at least partially within the cover section and connected to the at least one first cooling hole.and a second cooling hole (62) connected to the at least one cooling cavity and open to a surface of the cover section. The flow profile section has a reference flow profile (34A) in which a maximum blade thickness at a reference position (PA) in the blade height direction is minimal. The at least one cooling cavity includes a cavity (72) extending such that it overlaps the fillet section in the blade height direction. In a cross-section enclosing the cavity perpendicular to the blade height direction, the cavity (72) extends inside and outside a region where a contour of the reference flow profile is projected onto the cross-section in the blade height direction.

[0079] According to the configuration above (1), a cavity is provided in the outer end section of the turbine blade, which includes the cover section.

[0080] The depth of the cavity extends to the radius in the blade height direction. In a cross-section perpendicular to the blade height direction, the cavity extends both inside and outside the projection area of ​​the reference flow profile contour (i.e., it projects from the inside of the reference flow profile contour). Since the outer end section of the turbine blade, which includes the cover section, has a large cavity in the blade height direction when viewed along the blade height, the weight of the outer end section can be effectively reduced. This effectively reduces the centrifugal load acting on the turbine blade and prevents a reduction in the blade's service life.

[0081] (2) In some embodiments of the above configuration (1), the at least one cooling cavity comprises: a leading-edge cavity (70A) as cavity (72), and a trailing-edge cavity (70B) located on a trailing-edge side of the leading-edge cavity in a chordal direction of the airfoil section at the reference position (P A ) is arranged. In the cross-section, the leading-edge cavity projects from the area to a suction surface side of the flow profile section.

[0082] On the leading edge side, the cover section typically has a relatively large mass on the suction surface side, which shifts the center of gravity of the cover section towards the suction surface side. According to the configuration (2) above, the center of gravity of the cover section on the leading edge side can be brought closer to the central section of the cover section in the turbine axial direction because the contour of the leading-edge cavity in the cross-section described above projects from the projection area of ​​the reference flow profile towards the suction surface side. By adjusting the position of the center of gravity in this way, the centrifugal load acting on the turbine blade can be effectively reduced while simultaneously maintaining the stress equilibrium between the pressure surface side and the suction surface side of the turbine blade.

[0083] (3) In some embodiments of the above configuration (1) or (2), the at least one cooling cavity comprises: a leading-edge cavity (70A), and a trailing-edge cavity (70B), such as the cavity (72), which is arranged on a trailing-edge side of the leading-edge cavity in a chordal direction of the airfoil section at the reference position. In cross-section, the trailing-edge cavity projects from the area to a pressure surface side of the airfoil section.

[0084] On the trailing edge side, the cover section typically has a relatively large mass on the pressure surface side, which causes the center of gravity of the cover section to be offset towards the pressure surface. In this respect, according to the configuration (3) above, since the contour of the trailing edge cavity projects from the projection area of ​​the reference flow profile to the pressure surface side in the cross-section described above, the center of gravity of the cover section on the trailing edge side can be brought closer to the central section of the cover section in the axial direction of the turbine. By adjusting the position of the center of gravity in this way, the centrifugal load acting on the turbine blade can be effectively reduced while simultaneously establishing the stress equilibrium between the pressure surface side and the suction surface side of the turbine blade.

[0085] (4) In some embodiments in one of the above configurations (1) to (3), the at least one first cooling hole (60) comprises a plurality of first cooling holes arranged along a line of curvature of the airfoil section (34) and open to a bottom surface (76) of the cavity. When considering the cavity in the blade height direction along a straight line (L1) connecting the centers of openings of two first cooling holes (e.g., first cooling holes 60f, 60i) at both ends in a direction along the line of curvature under the plurality of first cooling holes, a distance (W) is L or W T ) between an inner wall surface (78) of the cavity and the center point of the opening of at least one of the two first cooling holes, 0.8 times or more a distance (W1) between the centers of the two first cooling holes.

[0086] Since the position and size (diameter, etc.) of the first cooling hole are limited by the flow profile, the size of the area where the openings of the first cooling holes are located (i.e., the distance between the centers of the first cooling holes at both ends) is largely determined in accordance with the blade tip section when viewed in the blade height direction. According to the configuration (4) above, a large cavity is provided such that the distance between the inner wall surface of the cavity and the center of the opening of one of the first cooling holes at both ends, in the direction along the line of curvature, is 0.8 times or more the distance between the centers of the openings of the first cooling holes at both ends when viewed in the blade height direction.In this way, the weight of the outer end section of the turbine blade, which includes the cover section, can be effectively reduced, and the centrifugal load acting on the turbine blade can be effectively reduced.

[0087] (5) In some embodiments in one of the above configurations (1) to (4), the at least one first cooling hole (60) comprises a plurality of first cooling holes arranged along a curve of the airfoil section (34) and open to a bottom surface (76) of the cavity. When considering the cavity in the blade height direction along a straight line (L2) connecting the centers of openings of two first cooling holes (e.g., first cooling holes 60h, 60i) that are closest to the leading edge or the trailing edge (e.g., trailing edge 44) at the reference position under the plurality of first cooling holes, a distance (W) is L or W T) between an inner wall surface of the cavity and the center point of the opening of the first cooling hole (e.g. first cooling hole 60i) that is closest to the front edge or the rear edge at the reference position among the plurality of first cooling holes, 1.5 times or more a distance (e.g. W3) between the centers of the openings of the two first cooling holes.

[0088] Since the position and size (diameter, etc.) of the first cooling hole are limited by the flow profile, the distance between the centers of any two first cooling holes adjacent to the leading or trailing edge when viewed in the blade height direction is largely determined in accordance with the flow profile at the blade tip section. According to the configuration (5) above, a large cavity is provided such that the distance between the inner wall surface of the cavity and the center of the opening of one of the two first cooling holes adjacent to the leading or trailing edge in the direction along the line of curvature, when viewed in the blade height direction, is 1.5 times or more the distance between the centers of the openings of the two first cooling holes.In this way, the weight of the outer end section of the turbine blade, including the cover section, can be effectively reduced, and the centrifugal load acting on the turbine blade can be effectively reduced.

[0089] (6) In some embodiments, in one of the above configurations (1) to (5), the depth (D) of the cavity in the blade height direction from the leading edge (42) to the trailing edge (44) increases in a chordal direction of the airfoil section at the reference position.

[0090] According to the configuration above (6), since the depth of the cavity increases in the blade height direction towards the trailing edge, the weight of the outer end section of the turbine blade, including the cover section, can be effectively reduced. For example, in a turbine blade whose dimension increases in the blade height direction from the leading edge to the trailing edge, the weight of the outer end section of the turbine blade can be effectively reduced if the cavity on the trailing edge side is made deeper by utilizing the blade height of the trailing edge section. In this way, the centrifugal load acting on the turbine blade can be effectively reduced.

[0091] (7) In some embodiments in one of the above configurations (1) to (6) the cover section (52) has a contact surface (e.g. a first contact surface (68) or a second contact surface (69)) which extends along the blade height direction and faces a cover section of one of the turbine blades adjacent to the turbine blade, and an extended line (L4 or L5) of the contact surface passes through the cavity when viewed in the blade height direction.

[0092] The contact surface is located at the circumferential end section of the cover section, and when viewed in the blade height direction, the extended line of the contact surface passes through the circumferential end section of the cover section. Since the extended line of the contact surface passes through the cavity, the cavity in the above configuration (7) extends to the end section of the cover section when viewed in the blade height direction. According to the above configuration (7), the weight of the outer end section can be effectively reduced because the outer end section of the turbine blade, which includes the cover section, is provided with a large cavity that extends to the circumferential end section. Thus, the centrifugal load acting on the turbine blade can be effectively reduced, and a reduction in the service life of the turbine blade can be prevented.

[0093] (8) In some embodiments in one of the above configurations (1) to (7) the second cooling hole (62) is connected to a section (e.g. suction surface outer section 102 or pressure surface outer section 104) of the cavity (72) which, when viewed in the blade height direction, lies outside the area.

[0094] On the side (leading edge side or suction surface side) where the cavity projects from the projection area of ​​the reference flow profile onto the cross-section described above when viewed in the blade height direction, the fillet section is generally relatively large or the width of the cover section is relatively large. According to the configuration (8) above, the cover section and the fillet section can be effectively cooled because the second cooling hole is connected to the section that projects from the projection area of ​​the reference flow profile onto the cross-section described above when viewed in the blade height direction.

[0095] (9) In some embodiments in one of the above configurations (1) to (8), the turbine blade further comprises a rib (54) that projects from the cover section to the outer end of the blade and extends along a circumferential direction. The second cooling hole (62) extends on both sides of the rib, so that, when viewed in the blade height direction, it extends over the rib.

[0096] According to the configuration above (9), the cover section and the rounding section can be effectively cooled, since a relatively long second cooling hole is arranged such that, when viewed in the blade height direction, it runs over the rib and extends on both sides of the rib.

[0097] (10) In some embodiments in one of the above configurations (1) to (9) the second cooling hole (62) extends such that it at least partially overlaps the rounding section (40) in the blade height direction.

[0098] According to the above configuration (10), the rounding section can be effectively cooled because the second cooling hole is arranged to at least partially overlap the rounding section in the blade height direction.

[0099] (11) A gas turbine (1) according to at least one embodiment of the present invention comprises: the turbine blade (24, 26, 30) described in one of the aforementioned embodiments (1) to (10), and a combustion chamber (4) for generating a combustion gas which flows through combustion gas passage (28) provided with the turbine blade.

[0100] According to the configuration (11) above, a cavity is provided in the outer end section of the turbine blade, which includes the cover section. The depth of the cavity extends to the radius in the blade height direction. In a cross-section perpendicular to the blade height direction, the cavity extends both inside and outside the projection area of ​​the reference flow profile contour (i.e., it extends such that it projects from the inside of the reference flow profile contour). Thus, since the outer end section of the turbine blade, which includes the cover section, is provided with the large cavity when viewed in the blade height direction, the weight of the outer end section can be effectively reduced. In this way, the centrifugal load acting on the turbine blade can be effectively reduced, preventing a reduction in the turbine blade's service life.

[0101] Embodiments of the present invention have been described in detail above, but the present invention is not limited thereto, and various changes and modifications can be implemented.

[0102] Furthermore, in the present description, an expression of a relative or absolute arrangement such as "in a direction", "along a direction", "parallel", "orthogonal", "centered", "concentric" and "coaxial" is not to be interpreted as indicating only the arrangement in a strictly literal sense, but also includes a state in which the arrangement is offset relative to a tolerance or by an angle or a distance, whereby the same function can be achieved.

[0103] For example, an expression for an identical state such as "equal", "corresponding" and "uniform" is not to be understood as indicating only the state in which the characteristic is strictly identical, but also includes a state in which there is a tolerance or a difference with which the same function can still be achieved.

[0104] Furthermore, a shape such as a square shape or a cylindrical shape does not only refer to the geometrically strict shape, but also includes a shape with irregularities or chamfered corners within the area in which the same effect can be achieved.

[0105] On the other hand, expressions such as "comprise", "exhibit" and "have" should not be understood as excluding other components. Reference symbol list 1 gas turbine 2 compressors 4 Combustion chamber 6 Turbine 8 Rotor 10 compressor housings 12 Air intake 16 Guide vane (stator vane) 18 Running blade (rotor blade) 20 cases 22 turbine housings 24 guide vanes 26 Running blade 28 Combustion gas passage 29 Exhaust chamber 30 turbine blades 32 platform 34 Flow profile section 34A Reference flow profile 36 Shovel foot section 38 Base end section 39 Outer end section 40 Rounding section 40a curved surface 42 Front edge 42A Leading edge 44 trailing edge 44A Trailing edge 46 printing surface 46A Print surface 48 Suction surface 48A Suction surface 52 Cover section 52a flat surface 52b outer end surface of the blade 54th rib 58 Inlet opening 60,60a to 60i first cooling hole 62 second cooling hole 63 Opening 66 upstream end surface 67 downstream end surface 68 first plant surface 69 second plant surface 70 Cooling cavity 70A Front edge cavity 70B rear edge cavity 72 Cavity 74 Closure 76 Soil surface 78 inner wall surface 102 suction surface outer section 104 outer section on the printed surface LcA Curvature Line PA Reference Position Ra1 Scope area Rb1 Scope QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2000297604 A

[0004]

Claims

[1] A turbine blade with: an airfoil section extending in a blade height direction and having a pressure surface and a suction surface, each of which extends between a leading edge and a trailing edge, a cover section arranged on a blade outer end side of the airfoil section, a fillet portion formed by a curved surface and connected to an end portion of the cover portion on one side of the airfoil portion, at least one first cooling hole extending along the blade height direction within the airfoil section, at least one cooling cavity which is arranged at least partially within the cover portion and is in communication with the at least one first cooling hole, and a second cooling hole connected to the at least one cooling cavity and open to a surface of the cover portion, wherein the airfoil section has a reference airfoil in which a maximum blade thickness is minimal at a reference position in the blade height direction, wherein the at least one cooling cavity comprises a cavity extending to overlap the fillet portion in the blade height direction, and wherein in a cross-section enclosing the cavity perpendicular to the blade height direction, the cavity extends inside and outside a region where a contour of the reference flow profile is projected onto the cross-section in the blade height direction. [2] The turbine blade according to claim 1, wherein the at least one cooling cavity comprises: a leading edge cavity as the cavity, and a trailing edge side cavity disposed on a trailing edge side of the leading edge side cavity in a chord direction of the airfoil portion at the reference position, and wherein, in the cross section, the leading edge side cavity protrudes from the region to a suction surface side of the airfoil portion. [3] The turbine blade according to claim 1 or 2, wherein the at least one cooling cavity comprises: a leading edge cavity, and a trailing edge side cavity as the cavity disposed on a trailing edge side of the leading edge side cavity in a chord direction of the airfoil portion at the reference position, and wherein, in the cross section, the trailing edge side cavity protrudes from the region to a pressure surface side of the airfoil portion. [4] The turbine blade according to one of claims 1 to 3, wherein the at least one first cooling hole comprises a plurality of the first cooling holes arranged along a curvature line of the airfoil section and open to a bottom surface of the cavity, and wherein, when viewing the cavity in the blade height direction, on a straight line connecting the centers of openings of two first cooling holes at both ends in a direction along the curvature line among the plurality of first cooling holes, a distance between an inner wall surface of the cavity and the center of the opening of at least one of the two first cooling holes is 0.8 times or more of a distance between the centers of the two first cooling holes. [5] The turbine blade according to any one of claims 1 to 4, wherein the at least one first cooling hole comprises a plurality of first cooling holes arranged along a curvature line of the airfoil section and open to a bottom surface of the cavity, and wherein, when viewing the cavity in the blade height direction, on a straight line connecting the centers of openings of two first cooling holes closest to the leading edge or the trailing edge at the reference position among the plurality of first cooling holes, a distance between an inner wall surface of the cavity and the center of the opening of the first cooling hole closest to the leading edge or the trailing edge at the reference position among the plurality of first cooling holes is 1.5 times or more of a distance between the centers of the openings of the two first cooling holes. [6] The turbine blade according to any one of claims 1 to 5, wherein a depth of the cavity increases in the blade height direction from the leading edge to the trailing edge in a chord direction of the airfoil section at the reference position. [7] The turbine blade according to one of claims 1 to 6, wherein the cover portion has a contact surface extending along the blade height direction and facing a cover portion of a turbine blade adjacent to the turbine blade, and where, when viewed in the blade height direction, an extended line of the contact surface passes through the cavity. [8] The turbine blade according to any one of claims 1 to 7, wherein the second cooling hole is connected to a portion of the cavity which is outside the area when viewed in the blade height direction. [9] The turbine blade according to any one of claims 1 to 8, further comprising a rib projecting from the cover portion to the blade outer end side and extending along a circumferential direction, wherein the second cooling hole extends on both sides of the rib so as to extend over the rib when viewed in the blade height direction. [10] The turbine blade according to any one of claims 1 to 9, wherein the second cooling hole extends to at least partially overlap the fillet portion in the blade height direction. [11] A gas turbine with: the turbine blade according to one of claims 1 to 10, and a combustion chamber for producing a combustion gas which flows through a combustion gas passage provided with the turbine blade.