Turbine blade

Abstract

A turbine blade provided with a blade wall and an insert inserted into a space formed inside the blade wall, in which an inner cavity communicating with the outside of the turbine blade is formed inside the insert, and on the outer surface of the insert, a plurality of protrusions protruding toward the inner surface of the blade wall are formed. A recovery space communicating with the outside of the turbine blade is defined between two adjacent protrusions among the plurality of protrusions, and a flow path communicating with the inner cavity and at least one cooling hole communicating with the flow path and opening so as to face the inner surface of the blade wall are formed in each of the plurality of protrusions. In at least one cross-section of the turbine blade perpendicular to the blade height direction of the turbine blade between the tip-side edge and the hub-side edge of the turbine blade, the length of at least one of the plurality of protrusions extending from the outer surface of the insert toward the inner surface of the blade wall is defined as the length of the at least one protrusion. When the length of the at least one protruding portion is L and the inner diameter of the at least one cooling hole formed in the at least one protruding portion is d, L > 5d.

Description

Technical Field

[0001] The present invention relates to a turbine blade.

[0002] This application claims the priority based on Japanese Patent Application No. 2022-189168 filed with the Japan Patent Office on November 28, 2022, and incorporates its content herein. Background Art

[0003] Patent Document 1 describes a turbine blade capable of being cooled by impingement cooling. In this turbine blade, an insert is provided in a space formed inside the blade wall. A plurality of protrusions are formed on the insert so as to protrude toward the inner surface of the blade wall, and cooling holes for ejecting a cooling medium are formed at the tips of the respective protrusions. The cooling medium ejected from the cooling holes collides with the inner surface of the blade wall, whereby the blade wall can be cooled. The cooling medium that has collided with the inner surface of the blade wall flows through a recovery space defined between adjacent protrusions and is then discharged to the outside of the turbine blade.

[0004] If a phenomenon occurs in which the cooling medium flows in a direction along the inner surface between the insert and the inner surface of the blade wall, that is, a cross flow, after the cooling medium collides with the inner surface of the blade wall, the cooling medium ejected from the cooling holes is disturbed by the cross flow, and thus the cooling efficiency of the blade wall may be reduced. In contrast, in the turbine blade described in Patent Document 1, the cross flow can be reduced by the cooling medium flowing through the recovery space after colliding with the inner surface of the blade wall.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-63997 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention

[0009] However, since the structure of the turbine blade described in Patent Document 1 is complex, the effect of reducing the cross flow may be weakened if the dimensions of each part are not specified.

[0010] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a turbine blade in which the effect of reducing the cross flow is improved.

[0011] Means for Solving the Technical Problem

[0012] To achieve the above object, the turbine blade according to the present invention includes a blade wall and an insert inserted into a space formed inside the blade wall. An internal cavity communicating with the outside of the turbine blade is formed inside the insert. A plurality of protrusions protruding toward the inner surface of the blade wall are formed on the outer surface of the insert. A recovery space communicating with the outside of the turbine blade is defined between two adjacent protrusions among the plurality of protrusions. A flow path communicating with the internal cavity is formed on each of the plurality of protrusions, and at least one cooling hole communicating with the flow path and opening in a manner facing the inner surface of the blade wall is formed. In at least one cross-section of the turbine blade perpendicular to the blade height direction between the tip side edge and the hub side edge of the turbine blade, the length of at least one of the plurality of protrusions extending from the outer surface of the insert toward the inner surface of the blade wall is defined as the length of the at least one protrusion. When the length of the at least one protrusion is set as L and the inner diameter of the at least one cooling hole formed on the at least one protrusion is set as d, L > 5d.

[0013] Advantages of the Invention

[0014] According to the turbine blade of the present invention, even without reducing the width of the flow path, the flow path cross-sectional area of the recovery space can be increased, so that the effect of reducing the cross flow can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of a gas turbine using the turbine blade according to an embodiment of the present invention.

[0016] Figure 2 is a view of the turbine blade according to an embodiment of the present invention as viewed in the direction from the pressure surface toward the suction surface.

[0017] Figure 3 is along Figure 2 section III-III.

[0018] Figure 4 is an enlarged cross-sectional view of a part of the insert of the turbine blade according to an embodiment of the present invention.

[0019] Figure 5 is a cross-sectional view for explaining the orientation of the cooling hole with respect to the inner surface of the blade wall in the turbine blade according to an embodiment of the present invention.

[0020] Figure 6 is a view showing the relative positional relationship between the flow path and the cooling hole in the protrusion of the insert of the turbine blade according to an embodiment of the present invention.

[0021] Figure 7It is a cross-sectional view showing the structure of multiple protrusions of the insert of a turbine blade according to an embodiment of the present invention.

[0022] Figure 8 It is a cross-sectional view showing the structure of multiple protrusions of the insert of a turbine blade according to an embodiment of the present invention.

[0023] Figure 9 It is a perspective view showing the structure of multiple protrusions of the insert of a turbine blade according to an embodiment of the present invention.

[0024] Figure 10 It is a diagram for explaining the effect when the arrangement of multiple cooling holes formed on multiple protrusions of the insert of a turbine blade according to an embodiment of the present invention is set to a staggered arrangement.

[0025] Figure 11 It is a diagram for explaining the effect when the arrangement of multiple cooling holes formed on multiple protrusions of the insert of a turbine blade according to an embodiment of the present invention is set to a staggered arrangement.

[0026] Figure 12 It is a diagram for explaining the effect when the arrangement of multiple cooling holes formed on multiple protrusions of the insert of a turbine blade according to an embodiment of the present invention is set to a staggered arrangement. Detailed Embodiment

[0027] Hereinafter, a turbine blade according to an embodiment of the present invention will be described with reference to the drawings. The embodiment described below represents one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention.

[0028] <Structure of a Gas Turbine Using the Turbine Blade of the Present Invention>

[0029] As Figure 1 shown, the gas turbine 1 includes: a compressor 2 for generating compressed air; a combustor 4 for generating combustion gas using the compressed air and fuel; and a turbine 6 configured to be rotationally driven by the combustion gas. In the case of the power generation gas turbine 1, a generator (not shown) is connected to the turbine 6.

[0030] The compressor 2 includes a plurality of stationary blades 16 fixed to the compressor housing 10 side and a plurality of rotating blades 18 mounted on the rotor 8. The air inhaled from the intake port 12 is sent into the compressor 2, and the air is compressed by the plurality of stationary blades 16 and the plurality of rotating blades 18, thereby becoming high-temperature and high-pressure compressed air.

[0031] Fuel and compressed air generated in compressor 2 are supplied to burner 4. After the fuel and the compressed air are mixed in burner 4, combustion occurs, thereby generating combustion gas as the working fluid of turbine 6. Inside housing 20, a plurality of burners 4 can be circumferentially arranged around the rotor.

[0032] Turbine 6 has a combustion gas flow path 28 formed inside turbine chamber 22, and includes a plurality of stationary vanes 24 and rotating blades 26 provided in combustion gas flow path 28. Stationary vanes 24 are fixed to the side of turbine chamber 22, and a plurality of stationary vanes 24 arranged along the circumference of rotor 8 constitute a stationary vane row. Also, rotating blades 26 are mounted on rotor 8, and a plurality of rotating blades 26 arranged along the circumference of rotor 8 constitute a rotating blade row. The stationary vane row and the rotating blade row are alternately arranged in the axial direction of rotor 8.

[0033] <Structure of the turbine blade of the present invention>

[0034] The turbine blade of the present invention targets both the stationary vanes 24 and the rotating blades 26 of turbine 6. Hereinafter, the turbine blade according to an embodiment of the present invention will be described as the stationary vane 24, but it can also be the rotating blade 26.

[0035] As Figure 2 shown, stationary vane 24 includes blade wall 34, and blade wall 34 extends along the direction from the hub side edge 24a of stationary vane 24 toward the tip side edge 24b, that is, along the blade height direction of stationary vane 24. An outer shroud 38 and an inner shroud 40 are respectively provided on tip side edge 24b and hub side edge 24a. Blade wall 34 has a leading edge 42 and a trailing edge 44 extending along the blade height direction, and has a pressure surface 46 and a suction surface 48 extending between leading edge 42 and trailing edge 44.

[0036] As will be described later, a space 50 is formed inside blade wall 34 (refer to Figure 3 ), and paths 37, 39 that communicate the outside of stationary vane 24 with space 50 are respectively formed on outer shroud 38 and inner shroud 40. Paths 37, 39 are not limited to the manner of being respectively formed on outer shroud 38 and inner shroud 40, and can also be formed on either outer shroud 38 or inner shroud 40. In Figure 2 , paths 37, 39 are respectively schematically drawn in a manner of each having one, but each can also have multiple or either one can have multiple. In addition, the functions of paths 37, 39 will be described later.

[0037] As Figure 3As shown, a space 50 is formed inside the blade wall 34. The space 50 can be divided into multiple spaces by the middle wall 57, such as two spaces 50a and 50b. Additionally, the space 50 can be divided into three or more spaces by two or more middle walls 57, or the space 50 can be set as one space without setting the middle wall 57. An insert 51 is inserted into the space 50. As Figure 3 illustrated, when the space 50 is divided into two spaces 50a and 50b, the insert 51 can include inserts 51a and 51b inserted into each space.

[0038] <Structure of the insert>

[0039] The inserts 51a and 51b are each formed in a shape having a longitudinal axis along the blade height direction of the stationary blade 24 (the direction perpendicular to the plane of the Figure 3 paper). An internal cavity 56 (56a, 56b) is formed inside each of them. A plurality of protrusions 52 protruding toward the inner surface 34a of the blade wall 34 are formed on the outer surfaces of the inserts 51a and 51b respectively. In each insert, the plurality of protrusions 52 extend along the blade height direction of the stationary blade 24 and are formed to be arranged at intervals in the circumferential direction centered on the longitudinal axis.

[0040] The path 37 (refer to Figure 2 ) communicates with the internal cavities 56a and 56b in the spaces 50a and 50b respectively, and the path 39 communicates with the regions between the outer surfaces of the inserts 51a and 51b in the spaces 50a and 50b and the inner surface 34a of the blade wall 34, particularly with the recovery space 53 defined between the adjacent protrusions 52 and 52 in the circumferential direction centered on the major axis direction in the spaces 50a and 50b and in each insert.

[0041] Next, the structure of the protrusion 52 will be described. Figure 4 shows a cross-sectional view of a part of the plurality of protrusions 52 provided on the insert 51a. Refer to Figure 4 The structure of the protrusion 52 described below corresponds to all or a part of the plurality of protrusions 52 provided on the other insert 51b.

[0042] A cavity, i.e., a flow path 54, communicating with the internal cavity 56a is formed inside the protrusion 52. And a cooling hole 55 communicating with the flow path 54 and opening in a manner facing the inner surface 34a of the blade wall 34 is formed on the protrusion 52. In Figure 4 , although it is depicted that one cooling hole 55 is formed in each protrusion 52, the structure is not limited to having only one cooling hole 55. As described above, since the protrusion 52 has a direction along the blade height direction of the stationary blade 24, that is, the direction perpendicular to the Figure 4extends in a direction perpendicular to the plane of the paper, and thus, for example, can be formed such that a plurality of cooling holes 55 are spaced apart from each other in this direction.

[0043] The protrusions 52 can be arranged at equal intervals to uniformly cool the entire stationary blade 24, or the interval between adjacent protrusions 52, 52 at a portion that is particularly desired to be cooled can be made smaller than the interval between adjacent protrusions 52, 52 at other portions. For example, the interval between protrusions 52, 52 arranged on the ventral side of the stationary blade 24 can be made smaller than the interval between protrusions 52, 52 arranged on the dorsal side of the stationary blade 24. Moreover, the protrusions 52 respectively arranged on the ventral side and the dorsal side of the stationary blade 24 can be arranged such that the interval between adjacent protrusions 52, 52 gradually increases from the leading edge toward the trailing edge of the stationary blade 24. Also, the number of cooling holes 55 formed on the protrusions 52 facing a portion that is particularly desired to be cooled can be made more than the number of cooling holes 55 formed on the protrusions 52 facing other portions.

[0044] For example, when it is determined through actual measurement or simulation that a specific portion becomes hot, the following can be done: the space 50 is divided into a plurality of spaces by the middle wall 57, the number of protrusions 52 formed on the insert 51 inserted into the space where the hot portion is located is made more than the number of protrusions 52 formed on the insert 51 inserted into other spaces, and the interval between adjacent protrusions 52, 52 in the former is made smaller than the interval between adjacent protrusions 52, 52 in the latter. In this case, instead of changing the number of protrusions 52, the number of cooling holes 55 in the former can be made more than the number of cooling holes 55 in the latter.

[0045] For example, when it is determined through actual measurement or simulation that the ventral side of the stationary blade 24 is hotter than the dorsal side, the number of cooling holes 55 formed on the protrusions 52 on the ventral side of the stationary blade 24 can be made more than the number of cooling holes 55 formed on the protrusions 52 on the dorsal side of the stationary blade 24. Conversely, when it is determined that the dorsal side of the stationary blade 24 is hotter than the ventral side, the number of cooling holes 55 formed on the protrusions 52 on the dorsal side of the stationary blade 24 can be made more than the number of cooling holes 55 formed on the protrusions 52 on the ventral side of the stationary blade 24.

[0046] When a plurality of cooling holes 55 are formed on each protrusion 52, the interval between adjacent cooling holes 55, 55 can be equal or different. In the case of the latter structure, for example, it can be set such that the interval between adjacent cooling holes 55, 55 gradually increases from the hub side toward the tip side, and conversely, it can also be set such that the interval between adjacent cooling holes 55, 55 gradually increases from the tip side toward the hub side.

[0047] <Cooling operation of the blade wall in the turbine blade of the present invention>

[0048] The cooling operation of the blade wall in the turbine blade of the present invention will be described. As Figure 2 shown, through path 37, a cooling medium (e.g., cooling air) is supplied from the outside of the stationary blade 24 to the inside of the blade wall 34. As Figure 3 shown, the cooling medium flows into the internal cavities 56a and 56b respectively. For example, as Figure 4 shown, the cooling medium flowing into the internal cavity 56a flows into the flow path 54, then into the cooling hole 55, and is ejected from the cooling hole 55 toward the inner surface 34a of the blade wall 34. The cooling medium ejected from the cooling hole 55 collides with the inner surface 34a of the blade wall 34, whereby the blade wall 34 is cooled. After the cooling medium collides with the inner surface 34a of the blade wall 34, it is introduced into the recovery space 53 defined between the adjacent protrusions 52, 52, and is discharged to the outside of the stationary blade 24 via path 39 (refer to Figure 2 ).

[0049] If, after the cooling medium collides with the inner surface 34a of the blade wall 34, a phenomenon occurs in which the cooling medium flows in the direction along the inner surface 34a near other cooling holes 55, i.e., a cross flow, the cooling medium ejected from the other cooling holes 55 will be disturbed by the cross flow, and thus the cooling efficiency may be reduced. In contrast, in the stationary blade 24 having the above structure, the cooling medium is introduced into the recovery space 53 after colliding with the inner surface 34a of the blade wall 34, so that the cross flow can be reduced. As a result, the possibility of a decrease in the cooling efficiency of the blade wall 34 can be suppressed.

[0050] <Function and effect of the turbine blade of the present invention>

[0051] As Figure 4 shown, preferably, the length L of the protrusion 52 extending from the outer surface of the insert 51a toward the inner surface 34a of the blade wall 34 is as long as possible. In this way, even if the width of the flow path 54 is not reduced, the flow path cross-sectional area of the recovery space 53 can be increased, so that the effect of reducing the cross flow can be improved. Specifically, it is preferable to design the length L of the protrusion 52 such that L > 5d.

[0052] Next, a structure for further improving the effect of reducing this cross flow will be described. In Figure 3On the cross-section of the space 50a shown, the area of the internal cavity 56a is set as A1, and the total area of the recovery space 53 is set as A2. The area A1 only affects the pressure loss or pressure distribution of the cooling medium flowing in the internal cavity 56a. In contrast, the area A2 not only affects the pressure loss or pressure distribution of the cooling medium flowing in the recovery space 53, but also affects the cross-flow or thermal conductivity. Therefore, the latter is a more important factor than the former. Therefore, it is preferable to increase the area A2 as much as possible. As a condition for achieving this, the above-mentioned L > 5d can be cited. However, in addition to this condition, as a further direct condition, it is preferable that A1 < A2.

[0053] <Additional structure of the insert>

[0054] Hereinafter, several additional structures that are not essential will be described for the inserts 51a and 51b, respectively. Hereinafter, the structure of the insert 51a will be described. Unless otherwise specified, the same structure can also be implemented for the insert 51b.

[0055] <Additional structure 1>

[0056] As Figure 4 shown, when the distance between the opening of the cooling hole 55 and the inner surface 34a is set as Z, it is preferable that 1 < Z / d < 5. Generally, the larger Z is, the more the area of the flow of the cooling medium that crosses the flow of the cooling medium ejected from the cooling hole 55 (the flow of the cooling medium in the axial direction of the recovery space 53 after colliding with the inner surface 34a) can be ensured. Therefore, it is considered to have a desirable effect on the cooling of the vane wall 34. However, if Z / d ≥ 5, the flow velocity of the cooling medium ejected from the cooling hole 55 will decrease during the period until it reaches the inner surface 34a, and thus the ability to cool the vane wall 34 may decrease. Therefore, the condition of Z / d < 5 is preferable. On the other hand, when Z / d ≤ 1, the pressure loss between the opening of the cooling hole 55 and the inner surface 34a becomes large, and the flow velocity of the cooling medium ejected from the cooling hole 55 will decrease. In order to ensure the pressure loss that can achieve a flow velocity suitable for cooling the vane wall 34 by the cooling medium ejected from the cooling hole 55, the condition of 1 < Z / d is preferable.

[0057] <Additional structure 2>

[0058] Preferably, the cooling hole 55 is perpendicular to the inner surface 34a of the vane wall 34. When the structure is like this, the cooling medium effectively collides with the inner surface 34a, and thus the vane wall 34 can be effectively cooled. However, the inner surface 34a is not necessarily a flat surface, and the structure in which the cooling hole 55 is perpendicular to the curved inner surface 34a may be considered unclear. Therefore, taking into account the case where the inner surface 34a is curved, as Figure 5 shown, "perpendicular" is defined as "when imagining the axis L of the cooling hole 5555 Position P where it intersects with the inner surface 34a of the blade wall 34 L When it is the virtual tangent plane IP1 tangent to the inner surface 34a above, the axis L 55 "Perpendicularly intersects with respect to the virtual tangent plane IP1". Additionally, for this purpose, it is not limited to the cooling hole 55 being strictly perpendicular to the inner surface 34a of the blade wall 34, that is, the axis L 55 Strictly perpendicularly intersecting with respect to the virtual tangent plane IP1, it can also be a structure where the cooling hole 55 is substantially perpendicular to the inner surface 34a of the blade wall 34, that is, the axis L 55 A structure where the angle formed with respect to the virtual tangent plane IP1 is within the range of 90° ± 10°. By the cooling hole 55 being substantially perpendicular to the inner surface 34a of the blade wall 34, on the leading edge side of the stationary blade 24, the plurality of protrusions 52 are arranged in a substantially radial pattern following the inner surface 34a.

[0059] <Additional structure 3>

[0060] The length of the flow path 54 in the direction in which the plurality of protrusions 52 are arranged ( Figure 4 which is the left - right direction in this case) is defined as the "width of the flow path 54". In Figure 4 this case, the width of the flow path 54 is constant in the direction in which the protrusion 52 protrudes toward the inner surface 34a ( Figure 4 which is downward in this case), but there are also structures where the width increases or decreases toward the cooling hole 55. Therefore, in the case of such a structure, when referring to the "width of the flow path 54", it is impossible to determine which part's length it is. Here, regardless of the structure of the flow path 54, when the position where the flow path 54 is connected to the cooling hole 55, that is, Figure 4 the width of the flow path 54 at the lowermost position in this case is set as b and the inner diameter of the cooling hole 55 is set as d, it is always b / d ≥ 1.2.

[0061] As described above, from the viewpoint of reducing the cross - flow, it is preferable that the flow path cross - sectional area of the recovery space 53 is large. For this purpose, on the one hand, it is necessary to reduce the width of the protrusion 52 to reduce the width of the flow path 54, and on the other hand, regarding the inner diameter d of the cooling hole 55, from the viewpoint of the ejection amount of the cooling medium, a certain size needs to be ensured. Therefore, b / d becomes a value close to 1. In contrast, in the stationary blade 24 of the present invention, b / d ≥ 1.2. To explain the function and effect of this structure, since it is related to the manufacturing method of the stationary blade 24, especially the manufacturing methods of the inserts 51a, 51b, the function and effect will be explained while explaining the manufacturing method of the stationary blade 24.

[0062] As Figure 3As shown, the stationary vane 24 is manufactured through a process of forming the vane wall 34, a process of forming the inserts 51a, 51b, and a process of combining the vane wall 34 and the inserts 51a, 51b. The forming of inserts with complex shapes such as the inserts 51a, 51b is preferably performed by AM. In the case of forming the inserts 51a, 51b by AM, in the forming of the inserts 51a, 51b, after laminating and shaping the intermediate bodies of the inserts 51a, 51b using a metallic powder material, as Figure 4 shown, cooling holes 55 are machined in the protruding portions 52 of the intermediate bodies. When laminating and shaping the intermediate bodies, temporary holes for the cooling holes 55 can be formed in the protruding portions 52 of the intermediate bodies, and the cooling holes 55 can be formed by finishing the temporary holes, or when laminating and shaping the intermediate bodies, the cooling holes 55 can be formed by machining without forming temporary holes in the protruding portions 52 of the intermediate bodies. Similar to the cooling holes 55, the temporary holes formed in the intermediate bodies have a structure that communicates with the flow path 54 and opens on the outer surface of the protruding portion 52.

[0063] Generally, the surface of a molded product formed by AM is rough, and sometimes protrusions generated by sputtering adhere to the surface. Therefore, when forming the inserts 51a, 51b by AM, deviations may occur in the width b of the flow path 54 and the inner diameter d of the cooling holes 55. The inner diameter d of the cooling holes 55 can be accurately finished by machining or finishing after AM, but due to the structure of the inserts 51a, 51b, it is difficult for tools to reach the inside (flow path 54) of the protruding portion 52, so the deviation of the width b of the flow path 54 cannot be reduced. Therefore, if the ratio b / d is made close to 1, when observing the inside (flow path 54) of the protruding portion 52 from the cooling holes 55, for example, as Figure 6 shown, it may sometimes be in a state where protrusions such as the surface 54a of the flow path 54 can be seen. And even if the deviation of the width b of the flow path 54 and the inner diameter d of the cooling holes 55 is extremely suppressed, if the ratio b / d is made close to 1, when the relative position of the cooling holes 55 and the flow path 54 is shifted during the forming of the inserts, it is likely to be in a state where the surface 54a of the flow path 54 can be seen through the cooling holes 55. If it becomes such a state, as Figure 4 shown, when cooling the vane wall 34 by causing a cooling medium to collide with the inner surface 34a, the flow of the cooling medium flowing from the flow path 54 into the cooling holes 55 will be disturbed, so the cooling efficiency of the vane wall 34 may be reduced.

[0064] In contrast, by setting the width b of the flow path 54 to be somewhat larger than the inner diameter d of the cooling hole 55, the cooling hole 55 can be accommodated within the width of the flow path 54 even when the width b of the flow path 54 deviates or the relative position of the cooling hole 55 and the flow path 54 is offset. In order to obtain such an effect, the inventors of the present invention have studied that b / d ≥ 1.2 is preferred. However, the larger the ratio b / d, the better. If the ratio b / d is too large, the effect of reducing the lateral flow will be reduced, and when the cooling medium flows from the flow path 54 to the cooling hole 55, the pressure loss caused by the contraction flow will increase. In order to minimize such adverse effects, b / d ≤ 1.5 is preferred.

[0065] In this way, when the insert to be inserted into the stationary blade 24 is molded by AM, even if the width b of the flow path 54 varies, by setting the ratio b / d of the width b of the flow path 54 to the inner diameter d of the cooling hole 55 to 1.2 or more, it is possible to reduce the possibility that when the inside of the protrusion 52 (the flow path 54) is viewed from the cooling hole 55, the surface 54a of the flow path 54 is visible through the cooling hole 55. As a result, when the blade wall 34 is cooled by causing the cooling medium to collide with the inner surface 34a, the possibility of turbulence in the flow of the cooling medium flowing from the flow path 54 into the cooling hole 55 is reduced, and thus the possibility of reduction in the cooling efficiency of the blade wall 34 can be suppressed.

[0066] <Additional Structure 4>

[0067] like Figure 7 As shown, in the cross section perpendicular to the length direction of the insert 51a (the blade height direction of the fixed blade 24), the larger the distance between the front ends of the adjacent protrusions 52, 52, the smaller the flow rate of the cooling medium per unit area, so that the blade wall 34 can be effectively cooled. When the distance between the front ends of the adjacent protrusions 52, 52 is X, and the inner diameter of the cooling hole 55 formed in the protrusion 52 is d, it is preferable that X / d≥10. However, it is not limited to the structure that X / d≥10 is satisfied in the entire insert 51a, and it may be a structure that X / d≥10 is satisfied in at least a part of the insert 51a. In the case where the insert 51a has a structure that X / d≥10 is satisfied in a part of the insert 51a, it is preferable to have the structure at a position where a lateral flow is likely to occur, for example, near the tip side edge of the fixed blade 24 or near the hub side edge.

[0068] exist Figure 7 In the embodiment, the spacing between the front ends of the adjacent protrusions 52 and 52 and the inner diameter of the cooling hole 55 are the same. For the structure with different spacing and inner diameter, refer to Figure 8This will be described below. The plurality of protrusions 52 include: a first protrusion 52a; a second protrusion 52b located adjacent to the first protrusion 52a; and a third protrusion 52c located on the side opposite to the first protrusion 52a of the second protrusion 52b and adjacent to the second protrusion 52b. Let the inner diameter of the cooling hole 55 formed in the first protrusion 52a, that is, the first cooling hole 55a, be d1, let the inner diameter of the cooling hole 55 formed in the second protrusion 52b, that is, the second cooling hole 55b, be d2, and let the inner diameter of the cooling hole 55 formed in the third protrusion 52c, that is, the third cooling hole 55c, be d3. And, let the distance between the front end of the first protrusion 52a and the front end of the second protrusion 52b be X1, and let the distance between the front end of the second protrusion 52b and the front end of the third protrusion 52c be X2. Therefore, corresponding to the relationship of X / d≥10 in Figure 7 the relationship in Figure 8 satisfies

[0069] [Equation 1]

[0070]

[0071] In this relationship, if X1 = X2 = X and d1 = d2 = d3 = d, then X / d≥10.

[0072] In addition, when two or more cooling holes 55 are formed in each protrusion 52, if the inner diameters of the cooling holes 55 formed in each protrusion 52 are the same, there is no problem in substituting the value of d (or d1, d2, d3) into the above inequality. However, when there are a plurality of cooling holes 55 with different inner diameters formed in each protrusion 52, there will be a problem of which value should be substituted. In this case, calculate the average value of the inner diameters of the plurality of cooling holes 55 formed in each protrusion 55, and substitute this average value into d of the inequality. However, the "average value" is not limited to the arithmetic mean, and the geometric mean or the median, etc. can also be used.

[0073] <Additional Structure 5>

[0074] In Figure 9 only the first protrusion 52a and the second protrusion 52b are illustratively described as the plurality of protrusions 52, but a plurality of cooling holes 55 can be formed on each of the plurality of protrusions 52 not limited to these two. The plurality of cooling holes 55 formed on each protrusion 52 are preferably arranged in a row along the axial direction of the recovery space 53. Generally, the smaller the flow velocity of the cooling medium flow (hereinafter referred to as "crosswind") that crosses the flow of the cooling medium ejected from the cooling hole 55, the higher the thermal conductivity. Therefore, the cooling blade wall 34 (refer to Figure 3The ability to improve (etc.). In order to reduce the influence of such crosswinds, if the plurality of cooling holes 55 formed on each of the protrusions 52 are arranged in a row along the axis direction of the recovery space 53, the flow of the cooling medium ejected from the cooling holes 55 at the position on the most upstream side with respect to such crosswinds interferes with the crosswind and the direction of the crosswind changes. Therefore, the interference between the flow of the cooling medium ejected from the cooling holes 55 at a position more downstream than the cooling holes 55 at the position on the most upstream side with respect to the crosswind is weakened. As a result, the ability of the cooling blade wall 34 can be improved.

[0075] Moreover, the plurality of cooling holes 55 formed on each of the plurality of protrusions 52 in a manner of being arranged in a row along the axis direction of the recovery space 53 are preferably arranged in a staggered pattern rather than a grid pattern. Here, "staggered arrangement" means that when imagining a plurality of virtual planes IP2 passing through each of the plurality of cooling holes 55 formed on the first protrusion 52a and perpendicular to the axis direction of the recovery space 53, the plurality of virtual planes IP2 respectively pass through the structure between adjacent cooling holes 55, 55 among the plurality of cooling holes 55 formed on the second protrusion 52b. On the other hand, "grid arrangement" means a structure in which the virtual plane IP2 passes through the cooling holes 55 formed on each of the adjacent protrusions.

[0076] If the arrangement of the cooling holes 55 is set to a staggered arrangement rather than a grid arrangement, the following effects are obtained. As Figure 10 shown, when focusing on two adjacent cooling holes 55, 55 of the first protrusion 52a, the region 34a2 of the inner surface 34a corresponding to the position near the center between the cooling holes 55, 55 in the axis direction A of the recovery space 53 (reference Figure 9 ) is more difficult for the cooling medium to touch than the region 34a1 of the inner surface 34a corresponding to the position of the cooling hole 55 in the axis direction A. Therefore, the cooling effect in the region 34a2 is weaker than the cooling effect in the region 34a1. That is, since the plurality of cooling holes 55 are arranged at intervals in a row, a cooling deviation is generated on the inner surface 34a in the axis direction A. In contrast, if the arrangement of the cooling holes 55 is set to a staggered arrangement, it is considered that the region 34a2 where the cooling effect of the cooling medium ejected from the cooling holes 55 of the first protrusion 52a is small and the region of the inner surface 34a facing the second protrusion 52b (reference Figure 9 ) adjacent to the first protrusion 52a where the cooling effect of the cooling medium ejected from the cooling holes 55 is considered large (the region corresponding to the region 34a1 opposite to the first protrusion 52a) become the same position in the axis direction A. Therefore, as Figure 11 shown, on the inner surface 34a, the regions 34al and 34a2 exist in a staggered manner. On the other hand, if the arrangement of the cooling holes 55 is set to a grid arrangement, then as Figure 12As shown, regions 34al and 34a2 are in the form of strips that alternate in the axial direction A. It is considered that, compared with the latter state, the time for the cooling effect through the heat transfer inner surface 34a within the blade wall 34 to become uniform is shorter in the former state. Therefore, it is considered that the cooling deviation across the entire inner surface 34a can be reduced.

[0077] The content described in each of the above embodiments can be understood as follows, for example.

[0078] [1] The turbine blades (stator blade 24 and rotor blade 26) according to one embodiment include:

[0079] A blade wall 34; and

[0080] An insert 51 inserted into a space 50 formed inside the blade wall 34,

[0081] An internal cavity 56 that is formed inside the insert 51 and communicates with the outside of the turbine blade 24 / 26,

[0082] A plurality of protrusions 52 protruding toward the inner surface 34a of the blade wall 34 are formed on the outer surface of the insert 51,

[0083] A recovery space 53 that communicates with the outside of the turbine blade 24 / 26 is defined between two adjacent protrusions 52, 52 among the plurality of protrusions 52,

[0084] On each of the plurality of protrusions 52, there are formed:

[0085] A flow path 54 that communicates with the internal cavity 56; and

[0086] At least one cooling hole 55 that communicates with the flow path 54 and opens in a manner facing the inner surface 34a of the blade wall 34,

[0087] In at least one cross-section of the turbine blade 24 / 26 that is perpendicular to the blade height direction of the turbine blade 24 / 26 between the tip-side edge 24b and the hub-side edge 24a of the turbine blade 24 / 26, the length of at least one of the plurality of protrusions 52 extending from the outer surface of the insert 51 toward the inner surface 34a of the blade wall 34 is defined as the length of the at least one protrusion 52. When the length of the at least one protrusion 52 is set as L and the inner diameter of the at least one cooling hole 55 formed on the at least one protrusion 52 is set as d, L > 5d.

[0088] For the turbine blade according to the present invention, even without reducing the width of the flow path, the flow path cross-sectional area of the recovery space can be increased, so that the effect of reducing the cross-flow can be improved.

[0089] [2] Another type of turbine blade involved is the turbine blade described in [1], where

[0090] In the at least one cross-section, when the area of the internal cavity 56 is set as A1 and the total area of the recovery spaces 53 is set as A2, A1 < A2.

[0091] According to this structure, even without reducing the width of the flow path, the flow path cross-sectional area of the recovery space can be increased, so the effect of reducing the cross flow can be improved.

[0092] [3] Yet another type of turbine blade involved is the turbine blade described in [1] or [2], where

[0093] A plurality of the cooling holes 55 are formed on each of the plurality of protruding portions 52,

[0094] On each of the plurality of protruding portions 52, the plurality of cooling holes 55 are arranged in a row along the axial direction of the recovery space 53.

[0095] According to this structure, the flow of the cooling medium ejected from the cooling hole located on the most upstream side with respect to the flow of the cooling medium (crosswind) that crosses the flow of the cooling medium ejected from the cooling hole interferes with the crosswind and the direction of the crosswind changes. Therefore, the interference between the flow of the cooling medium ejected from the cooling hole located on the more downstream side than the cooling hole on the most upstream side with respect to the crosswind is weakened. As a result, the ability to cool the blade wall can be improved.

[0096] [4] Yet another type of turbine blade involved is the turbine blade described in [3], where

[0097] The plurality of protruding portions 52 include:

[0098] A first protruding portion 52a; and

[0099] A second protruding portion 52b, located at a position adjacent to the first protruding portion 52a,

[0100] When a plurality of virtual planes IP2 perpendicular to the axial direction of the recovery space 53 are assumed to pass through each of the plurality of cooling holes 55 formed on the first protruding portion 52a, the plurality of virtual planes IP2 respectively pass between adjacent cooling holes 55, 55 among the plurality of cooling holes 55 formed on the second protruding portion 52b.

[0101] According to this structure, the cooling deviation of the entire inner surface of the blade wall can be reduced.

[0102] [5] Yet another type of turbine blade involved is the turbine blade described in any one of [1] to [4], where

[0103] The plurality of protrusions 52 include:

[0104] a first protrusion 52a;

[0105] a second protrusion 52b located adjacent to the first protrusion 52a; and

[0106] a third protrusion 52c located on the side of the second protrusion 52b opposite to the first protrusion 52a and adjacent to the second protrusion 52b,

[0107] In at least one cross-section of the turbine blade 24 / 26 perpendicular to the blade height direction between the tip side edge 24b and the hub side edge 24a of the turbine blade 24 / 26, when the inner diameter of at least one cooling hole 55 formed in the first protrusion 52a, that is, at least one first cooling hole 55a, is set as d1, the inner diameter of at least one cooling hole 55 formed in the second protrusion 52b, that is, at least one second cooling hole 55b, is set as d2, the inner diameter of at least one cooling hole 55 formed in the third protrusion 52c, that is, at least one third cooling hole 55c, is set as d3, the distance between the front end of the first protrusion 52a and the front end of the second protrusion 52b is set as X1, and the distance between the front end of the second protrusion 52b and the front end of the third protrusion 52c is set as X2, the following is satisfied

[0108] [Equation 2]

[0109]

[0110] According to this structure, in a cross-section perpendicular to the length direction of the insert, the larger the distance between the front ends of adjacent protrusions, the smaller the flow rate of the cooling medium per unit area. Therefore, the blade wall can be effectively cooled.

[0111] [6] The turbine blade according to another aspect is any one of the turbine blades described in [1] to [5], wherein

[0112] When assuming a virtual tangent plane IP1 tangent to the inner surface 34a at a position P where the axis L of the cooling hole 55 55 intersects the inner surface 34a of the blade wall 34 L the axis L 55 intersects the virtual tangent plane IP1 at an angle of 90° ± 10°.

[0113] According to this structure, the cooling hole is substantially perpendicular to the inner surface of the blade wall, and the cooling medium effectively collides with the inner surface. Therefore, the blade wall can be effectively cooled.

[0114] [7] The turbine blade involved in another method is any one of the turbine blades described in [1] to [6], wherein,

[0115] The length of the flow path 54 in the direction in which the plurality of protrusions 52 are arranged is defined as the width of the flow path 54. When the width of the flow path 54 at the position where the flow path 54 is connected to the cooling hole 55 is set as b and the inner diameter of the cooling hole 55 is set as d, b / d ≥ 1.2.

[0116] According to this structure, in the case where an insert inserted into the turbine blade is formed by AM, even if there is a deviation in the width d of the flow path, by setting the ratio b / d of the width b of the flow path to the inner diameter of the cooling hole to 1.2 or more, the possibility of the state where the surface of the flow path can be seen through the cooling hole when observing the inside (flow path) of the protrusion from the cooling hole can be reduced. Thereby, when cooling the blade wall by causing the cooling medium to collide with the inner surface, the possibility of the flow of the cooling medium flowing into the cooling hole from the flow path being disturbed is reduced, and thus the possibility of a decrease in the cooling efficiency of the blade wall can be suppressed.

[0117] [8] The turbine blade involved in another method is the turbine blade described in [7], wherein,

[0118] b / d ≤ 1.5.

[0119] If b / d is too large, the effect of reducing the cross-flow weakens, and when the cooling medium flows from the flow path to the cooling hole, the pressure loss caused by the flow constriction increases. In contrast, according to the structure described in [8], such adverse effects can be extremely suppressed.

[0120] [9] The turbine blade involved in another method is any one of the turbine blades described in [1] to [8], wherein,

[0121] In the at least one cross-section, when the distance between the opening of the cooling hole 55 facing the inner surface 34a of the blade wall 34 and the inner surface 34a is set as Z, 1 < Z / d < 5.

[0122] According to this structure, the area of the flow of the cooling medium through which the flow of the cooling medium ejected from the cooling hole crosses can be ensured, and thus, there is an expected effect on the cooling of the blade wall.

[0123] Symbol description

[0124] 24 - Fixed vane (turbine blade), 24a - Hub side edge, 24b - Tip side edge, 26 - Rotating vane (turbine blade), 34 - Blade wall, 34a - Inner surface (of the blade wall), 50 - Space, 51 - Insert, 52 - Protrusion, 52a - First protrusion, 52b - Second protrusion, 52c - Third protrusion, 53 - Recovery space, 54 - Flow path, 55 - Cooling hole, 55a - First cooling hole, 55b - Second cooling hole, 55c - Third cooling hole, IP1 - Virtual cutting plane, IP2 - Virtual plane.

Claims

1. A turbine blade, comprising: a blade wall; and an insert inserted into a space formed inside the blade wall, an internal cavity communicating with the outside of the turbine blade is formed inside the insert, a plurality of protrusions protruding toward the inner surface of the blade wall are formed on the outer surface of the insert, a recovery space communicating with the outside of the turbine blade is defined between two adjacent protrusions among the plurality of protrusions, on each of the plurality of protrusions, there are formed: a flow path communicating with the internal cavity; and at least one cooling hole communicating with the flow path and opening so as to face the inner surface of the blade wall, in at least one cross-section of the turbine blade perpendicular to the blade height direction of the turbine blade between the tip side edge and the hub side edge of the turbine blade, the length of at least one of the plurality of protrusions extending from the outer surface of the insert toward the inner surface of the blade wall is defined as the length of the at least one protrusion. When the length of the at least one protrusion is set as L and the inner diameter of the at least one cooling hole formed on the at least one protrusion is set as d, L > 5d.

2. The turbine blade according to claim 1, wherein in the at least one cross-section, when the area of the internal cavity is set as A1 and the total area of the recovery space is set as A2, A1 < A2.

3. The turbine blade according to claim 1 or 2, wherein a plurality of the cooling holes are formed on each of the plurality of protrusions, on each of the plurality of protrusions, the plurality of cooling holes are arranged in a row along the axial direction of the recovery space.

4. The turbine blade according to claim 3, wherein the plurality of protrusions include: a first protrusion; and a second protrusion located adjacent to the first protrusion, when a plurality of virtual planes passing through each of the plurality of cooling holes formed on the first protrusion and perpendicular to the axial direction of the recovery space are assumed, the plurality of virtual planes respectively pass between adjacent cooling holes among the plurality of cooling holes formed on the second protrusion.

5. The turbine blade according to claim 1 or 2, wherein the plurality of protrusions include: a first protrusion; a second protrusion located adjacent to the first protrusion; and a third protrusion located on the side opposite to the first protrusion of the second protrusion and adjacent to the second protrusion, in the at least one cross-section, when the inner diameter of the at least one cooling hole formed on the first protrusion, i.e., at least one first cooling hole, is set as d1, the inner diameter of the at least one cooling hole formed on the second protrusion, i.e., at least one second cooling hole, is set as d2, the inner diameter of the at least one cooling hole formed on the third protrusion, i.e., at least one third cooling hole, is set as d3, the distance between the front end of the first protrusion and the front end of the second protrusion is set as X1, and the distance between the front end of the second protrusion and the front end of the third protrusion is set as X2, the following is satisfied [Equation 1] 6. The turbine blade according to claim 1 or 2, wherein, when a virtual tangent plane tangent to the inner surface is envisioned at a position where the axis of the cooling hole intersects the inner surface of the blade wall, the axis intersects the virtual tangent plane at an angle of 90° ± 10°.

7. The turbine blade according to claim 1 or 2, wherein, the length of the flow path in the direction in which the plurality of protrusions are arranged is defined as the width of the flow path, and when the width of the flow path at a position where the flow path is connected to the cooling hole is b and the inner diameter of the cooling hole is d, b / d ≥ 1.

2.

8. The turbine blade according to claim 7, wherein, b / d ≤ 1.

5.

9. The turbine blade according to claim 1 or 2, wherein, in the at least one cross section, when the distance between the opening of the cooling hole facing the inner surface of the blade wall and the inner surface is Z, 1 < Z / d < 5.

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