Turbine blade and method for manufacturing the turbine blade.

Abstract

This turbine blade comprises: a blade wall; and an insert inserted in a space formed inside the blade wall. An internal cavity that is in communication with the outside of the turbine blade is formed inside the insert, and a plurality of protrusions protruding toward the inner surface of the blade wall are formed on the outer surface of the insert. Between two adjacent protrusions among the plurality of protrusions, a recovery space that is in communication with the outside of the turbine blade is defined. Each of the plurality of protrusions has formed therein a flow channel which is in communication with the internal cavity and at least one cooling hole which is in communication with the flow channel and which is opened so as to face the inner surface of the blade wall. When the length of the flow channel in a direction in which the plurality of protrusions are arrayed side by side is defined as the width of the flow channel, the width of the flow channel at a position where the flow channel is connected to the cooling hole is denoted by b, and the inner diameter of the cooling hole is denoted by d, b / d≥1.2 is satisfied.

Description

【Technical Field】 【0001】 The present disclosure relates to a turbine blade and a method for manufacturing the same. This application claims priority based on Japanese Patent Application No. 2022-189158 filed with the Japan Patent Office on November 28, 2022, and incorporates the content herein by reference. 【Background Art】 【0002】 Patent Document 1 describes a turbine blade that can be cooled by impingement cooling. In this turbine blade, an insert is provided in a space formed inside the blade wall, and the insert has a plurality of protrusions formed so as to protrude toward the inner surface of the blade wall. Cooling holes for ejecting a cooling medium are formed at the tips of the respective protrusions. By the cooling medium ejected from the cooling holes colliding with the inner surface of the blade wall, 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. 【0003】 When 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 after the cooling medium collides with the inner surface of the blade wall, that is, cross-flow occurs, the cooling medium ejected from the cooling holes may be interfered by the cross-flow, resulting in a possible reduction in the cooling efficiency of the blade wall. On the other hand, 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. From the perspective of reducing cross-flow, it is preferable that the flow path cross-sectional area of the recovery space is larger. The larger the flow path cross-sectional area of the recovery space, the smaller the width of each protrusion, that is, the width of the flow path of the cooling medium formed inside each protrusion and communicating with the cooling holes. Therefore, from the perspective of reducing cross-flow, it is preferable to make the ratio b / d of the width b of the flow path to the inner diameter d of the cooling hole close to 1. 【Prior Art Documents】 【Patent Documents】 【0004】 [Patent Document 1] Japanese Patent Publication No. 2015-63997 [Overview of the project] [Problems that the invention aims to solve] 【0005】 Because inserts with multiple protrusions have a complex shape, additive manufacturing (AM) is a possible method for forming the inserts. Products formed by AM have rough surfaces, and sputtered protrusions may adhere to the surface, which can cause variations in the width b of the flow channels and the inner diameter d of the cooling holes. While the inner diameter d of the cooling holes can be precisely finished by machining and finishing after AM, the structure of the insert makes it difficult to access the inside of the protrusions (flow channels) with tools, so it is not possible to reduce variations in the width b of the flow channels. Consequently, if the ratio b / d approaches 1, when looking at the inside of the protrusions (flow channels) from the cooling holes, protrusions on the surface of the flow channels will be visible, disrupting the flow of the cooling medium from the flow channels into the cooling holes, which may reduce the cooling efficiency of the wing walls. 【0006】 In view of the circumstances described above, at least one embodiment of the present disclosure aims to provide a turbine blade capable of suppressing the risk of reduced cooling efficiency of the blade wall and a method for manufacturing the turbine blade. [Means for solving the problem] 【0007】 To achieve the above objective, the turbine blade according to the present disclosure comprises a blade wall and an insert inserted into a space formed inside the blade wall, wherein an internal cavity communicating with the outside of the turbine blade is formed inside the insert, a plurality of protrusions are formed on the outer surface of the insert projecting toward the inner surface of the blade wall, a recovery space communicating with the outside of the turbine blade is defined between two adjacent protrusions, each of the plurality of protrusions has a flow path communicating with the internal cavity and at least one cooling hole communicating with the flow path and opening toward the inner surface of the blade wall, the length of the flow path in the direction in which the plurality of protrusions are aligned is defined as the width of the flow path, the width of the flow path at the position where the flow path is connected to the cooling hole is denoted as b, and the inner diameter of the cooling hole is denoted as d. 1.2 ≤ b / d ≤ 1.5 That is the case. [Effects of the Invention] 【0008】 According to the turbine blade of this disclosure, even if there is variation in the width d of the flow path when the insert inserted into the turbine blade is molded by additive manufacturing, 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 surface of the flow path being visible through the cooling hole when looking at the inside of the protruding part (flow path) from the cooling hole can be reduced. As a result, when cooling the blade wall by causing the cooling medium to collide with the inner surface, the possibility of turbulence in the flow of the cooling medium flowing from the flow path into the cooling hole can be reduced, thereby suppressing the risk of a decrease in the cooling efficiency of the blade wall. [Brief explanation of the drawing] 【0009】 [Figure 1] This is a schematic diagram of a gas turbine using turbine blades according to one embodiment of the present disclosure. [Figure 2] This is a view of a turbine blade according to one embodiment of the present disclosure, as seen in the direction from the pressure surface toward the negative pressure surface. [Figure 3] This is a cross-sectional view along line III-III in Figure 2. [Figure 4]This is an enlarged cross-sectional view of a portion of a turbine blade insert according to one embodiment of the present disclosure. [Figure 5] This figure shows the relative positional relationship between the flow path and the cooling hole in the protruding portion of a turbine blade insert according to one embodiment of the present disclosure. [Figure 6] This is a cross-sectional view illustrating the orientation of the cooling holes relative to the inner surface of the blade wall in a turbine blade according to one embodiment of the present disclosure. [Figure 7] This is a cross-sectional view illustrating the configuration of multiple protrusions of a turbine blade insert according to one embodiment of the present disclosure. [Figure 8] This is a cross-sectional view illustrating the configuration of multiple protrusions of a turbine blade insert according to one embodiment of the present disclosure. [Figure 9] This is a perspective view illustrating the configuration of multiple protrusions of a turbine blade insert according to one embodiment of the present disclosure. [Figure 10] This figure illustrates the effects of arranging multiple cooling holes formed in multiple protrusions of a turbine blade insert according to one embodiment of the present disclosure in a staggered arrangement. [Figure 11] This figure illustrates the effects of arranging multiple cooling holes formed in multiple protrusions of a turbine blade insert according to one embodiment of the present disclosure in a staggered arrangement. [Figure 12] This figure illustrates the effects of arranging multiple cooling holes formed in multiple protrusions of a turbine blade insert according to one embodiment of the present disclosure in a staggered arrangement. [Modes for carrying out the invention] 【0010】 The turbine blades according to embodiments of this disclosure will be described below with reference to the drawings. The embodiments described below represent one aspect of this disclosure and are not limiting, and can be modified at will within the scope of the technical idea of ​​this disclosure. 【0011】 <Configuration of a gas turbine using the turbine blades of this disclosure> As shown in FIG. 1, 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 gas turbine 1 for power generation, a generator (not shown) is connected to the turbine 6. 【0012】 The compressor 2 includes a plurality of stationary blades 16 fixed to the compressor casing 10 side and a plurality of rotating blades 18 attached to the rotor 8. Air taken in from the air inlet 12 is sent to the compressor 2, and this air is compressed by passing through the plurality of stationary blades 16 and the plurality of rotating blades 18 to become high-temperature and high-pressure compressed air. 【0013】 Fuel and the compressed air generated by the compressor 2 are supplied to the combustor 4. In the combustor 4, the fuel and the compressed air are mixed and then burned to generate combustion gas, which is the working fluid of the turbine 6. A plurality of combustors 4 may be arranged along the circumferential direction around the rotor within the casing 20. 【0014】 The turbine 6 has a combustion gas flow path 28 formed within the turbine casing 22 and includes a plurality of stationary blades 24 and rotating blades 26 provided in the combustion gas flow path 28. The stationary blades 24 are fixed to the turbine casing 22 side, and the plurality of stationary blades 24 arranged along the circumferential direction of the rotor 8 constitute a stationary blade row. The rotating blades 26 are attached to the rotor 8, and the plurality of rotating blades 26 arranged along the circumferential direction of the rotor 8 constitute a rotating blade row. The stationary blade row and the rotating blade row are alternately arranged in the axial direction of the rotor 8. 【0015】 <Configuration of Turbine Blades of the Present Disclosure> The turbine blades of the present disclosure target both the stationary blades 24 and the rotating blades 26 of the turbine 6. Hereinafter, the turbine blades according to an embodiment of the present disclosure will be described as the stationary blades 24, but they may also be the rotating blades 26. 【0016】 As shown in Figure 2, the stator vane 24 is provided with a wing wall 34, which extends in the direction from the hub side edge 24a to the tip side edge 24b of the stator vane 24, i.e., in the direction of the wing height of the stator vane 24, and an outer shroud 38 and an inner shroud 40 are provided on the tip side edge 24b and the hub side edge 24a, respectively. The wing wall 34 has a leading edge 42 and a trailing edge 44 that extend along the direction of the wing height, and also has a pressure surface 46 and a negative pressure surface 48 that extend between the leading edge 42 and the trailing edge 44. 【0017】 As will be described later, a space 50 (see Figure 3) is formed inside the wing wall 34, and paths 37 and 39 are formed in the outer shroud 38 and the inner shroud 40, respectively, that connect the outside of the stator vane 24 to the space 50. The paths 37 and 39 are not limited to being formed in the outer shroud 38 and the inner shroud 40, but may be formed in either the outer shroud 38 or the inner shroud 40. In Figure 2, one path 37 and 39 are schematically shown, but multiple paths of either or each may be provided. The roles of paths 37 and 39 will be described later. 【0018】 As shown in Figure 3, a space 50 is formed inside the wing wall 34. The space 50 may be divided into multiple spaces, for example, two spaces 50a and 50b, by an intermediate wall 57. Alternatively, the space 50 may be divided into three or more spaces by two or more intermediate walls 57, or the space 50 may be a single space without intermediate walls 57. An insert 51 is inserted into the space 50. As illustrated in Figure 3, if the space 50 is divided into two spaces 50a and 50b, the insert 51 may consist of inserts 51a and 51b inserted into each space. 【0019】 <Insert Configuration> Each insert 51a and 51b has a shape with a longitudinal axis aligned with the wing height direction of the stator vane 24 (the direction perpendicular to the plane of the paper in Figure 3), and each has an internal cavity 56 (56a, 56b) formed inside. Multiple protrusions 52 are formed on the outer surface of each insert 51a and 51b, projecting toward the inner surface 34a of the wing wall 34. In each insert, the multiple protrusions 52 extend along the wing height direction of the stator vane 24 and are formed to be spaced apart in the circumferential direction around the longitudinal axis. 【0020】 The path 37 (see Figure 2) communicates with the internal cavities 56a and 56b in spaces 50a and 50b, respectively, and the path 39 communicates with the region between the outer surfaces of the inserts 51a and 51b in spaces 50a and 50b and the inner surface 34a of the wing wall 34, and in particular in spaces 50a and 50b, with the recovery space 53 defined between adjacent protrusions 52 and 52 in the circumferential direction centered on the longitudinal axis of each insert. 【0021】 Next, the configuration of the protrusion 52 will be described. Figure 4 shows a cross-sectional view of some of the multiple protrusions 52 provided on the insert 51a. The configuration of the protrusion 52 described below with reference to Figure 4 also applies to all or some of the multiple protrusions 52 provided on the other insert 51b. 【0022】 A flow path 54, which is a cavity communicating with the internal cavity 56a, is formed inside the protruding portion 52. A cooling hole 55 is also formed in the protruding portion 52, which communicates with the flow path 54 and opens to face the inner surface 34a of the wing wall 34. Figure 4 depicts each protruding portion 52 as having one cooling hole 55, but the configuration is not limited to having only one cooling hole 55. As described above, the protruding portion 52 has a shape that extends along the wing height direction of the stator vane 24, that is, along the direction perpendicular to the plane of the paper in Figure 4, so for example, multiple cooling holes 55 may be formed along this direction at intervals from one another. 【0023】 The length of the flow path 54 in the direction in which the multiple protrusions 52 are aligned (left-right direction in Figure 4) is defined as the "width of the flow path 54". In Figure 4, the width of the flow path 54 is constant in the direction in which it protrudes toward the inner surface 34a of the protrusion 52 (downward in Figure 4). However, there are configurations in which the width increases or decreases toward the cooling hole 55, so in such configurations, it is not possible to specify which length the "width of the flow path 54" refers to. Therefore, regardless of the configuration of the flow path 54, if we let b be the width of the flow path 54 at the position where the flow path 54 is connected to the cooling hole 55, that is, at the lowest position in Figure 4, and let d be the inner diameter of the cooling hole 55, then b / d ≥ 1.2. 【0024】 The protrusions 52 may be arranged at equal intervals to evenly cool the entire stator vane 24, or the spacing between adjacent protrusions 52, 52 in areas that require particular cooling may be smaller than the spacing between adjacent protrusions 52, 52 in other areas. For example, the spacing between protrusions 52, 52 located on the ventral side of the stator vane 24 may be smaller than the spacing between protrusions 52, 52 located on the dorsal side of the stator vane 24. Furthermore, the protrusions 52 located on the ventral and dorsal sides of the stator vane 24 may be arranged such that the spacing between adjacent protrusions 52, 52 gradually increases from the leading edge to the trailing edge of the stator vane 24. In addition, the number of cooling holes 55 formed in the protrusions 52 facing areas that require particular cooling may be greater than the number of cooling holes 55 formed in the protrusions 52 facing other areas. 【0025】 For example, if it is found through actual measurements or simulations that a particular area becomes hot, the space 50 may be divided into multiple spaces by the middle wall 57, and the number of protrusions 52 formed on the insert 51 inserted into the space where the hot area exists may be made greater than the number of protrusions 52 formed on the insert 51 inserted into the other spaces, so that the spacing between adjacent protrusions 52, 52 in the former is smaller than the spacing 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 may be made greater than the number of cooling holes 55 in the latter. 【0026】 For example, if it is found through actual measurements or simulations that the ventral side of the stator vane 24 becomes hotter than the dorsal side, the number of cooling holes 55 formed in the ventral projection 52 of the stator vane 24 may be greater than the number of cooling holes 55 formed in the dorsal projection 52 of the stator vane 24. Conversely, if it is found that the dorsal side of the stator vane 24 becomes hotter than the ventral side, the number of cooling holes 55 formed in the dorsal projection 52 of the stator vane 24 may be greater than the number of cooling holes 55 formed in the ventral projection 52 of the stator vane 24. 【0027】 When multiple cooling holes 55 are formed in each protrusion 52, the spacing between adjacent cooling holes 55, 55 may be equal or different. In the latter configuration, for example, the spacing between adjacent cooling holes 55, 55 may gradually increase from the hub side toward the chip side, or conversely, the spacing between adjacent cooling holes 55, 55 may gradually increase from the chip side toward the hub side. 【0028】 <Cooling operation of the blade wall in the turbine blade of this disclosure> The cooling operation of the blade wall in the turbine blade of this disclosure will now be described. As shown in Figure 2, a cooling medium (e.g., cooling air) is supplied to the inside of the blade wall 34 from outside the stator blade 24 via path 37. As shown in Figure 3, the cooling medium flows into the internal cavities 56a and 56b, respectively. For example, the cooling medium that flows into the internal cavity 56a flows into the flow path 54, as shown in Figure 4, and then into the cooling holes 55, from which it is ejected toward the inner surface 34a of the blade wall 34. The cooling medium ejected from the cooling holes 55 collides with the inner surface 34a of the blade wall 34, thereby cooling the blade wall 34. After colliding with the inner surface 34a of the blade wall 34, the cooling medium is introduced into a recovery space 53 defined between adjacent protrusions 52, 52 and discharged to the outside of the stator blade 24 via path 39 (see Figure 2). 【0029】 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 along the inner surface 34a in the vicinity of other cooling holes 55, i.e., cross-flow, the cooling medium ejected from the other cooling holes 55 may interfere with the cooling efficiency due to the cross-flow. In contrast, in the stator vane 24 having the above-described configuration, the cooling medium is introduced into the recovery space 53 after colliding with the inner surface 34a of the blade wall 34, so that cross-flow can be reduced, and as a result, the risk of a decrease in the cooling efficiency of the blade wall 34 can be suppressed. 【0030】 <Effects of the turbine blades of this disclosure> From the viewpoint of reducing cross-flow, a larger flow path cross-sectional area of ​​the recovery space 53 is preferable. To achieve this, it is necessary to reduce the width of the protrusion 53, and therefore the width of the flow path 54. On the other hand, the inner diameter d of the cooling hole 55 needs to be of a certain size from the viewpoint of the amount of cooling medium ejected, so the ratio b / d becomes a value close to 1. In contrast, in the stator vane 24 of this disclosure, b / d ≥ 1.2. In order to explain the effects of this configuration, it is necessary to explain the manufacturing method of the stator vane 24, in particular the manufacturing method of the inserts 51a and 51b, so the effects will be explained while explaining the manufacturing method of the stator vane 24. 【0031】 As shown in Figure 3, the stator vane 24 is manufactured by forming the wing wall 34, forming the inserts 51a and 51b, and combining the wing wall 34 and the inserts 51a and 51b. AM is preferred for forming inserts with complex shapes such as inserts 51a and 51b. When forming inserts 51a and 51b by AM, the intermediate bodies of inserts 51a and 51b are additively fabricated using metallic powder material, and then cooling holes 55 are machined into the protruding portions 52 of the intermediate bodies as shown in Figure 4. When additively fabricating the intermediate bodies, temporary holes for the cooling holes 55 may be formed in the protruding portions 52 of the intermediate bodies, and the cooling holes 55 may be formed by finishing the temporary holes, or the cooling holes may be formed by machining without forming temporary holes in the protruding portions 52 of the intermediate bodies when additively fabricating the intermediate bodies. The temporary holes formed in the intermediate body, like the cooling holes 55, are configured to communicate with the flow path 54 and to open on the outer surface of the protruding portion 52. 【0032】 Generally, AM-molded products have rough surfaces, and sputtered protrusions may adhere to the surface. Therefore, when inserts 51a and 51b are molded by AM, variations may occur in the width b of the flow path 54 and the inner diameter d of the cooling hole 55. While the inner diameter d of the cooling hole 55 can be precisely finished by machining or finishing after AM, due to the structure of inserts 51a and 51b, it is difficult to access the inside of the protruding portion 52 (flow path 54) with a tool, making it impossible to reduce variations in the width b of the flow path 54. Consequently, when the ratio b / d approaches 1, when looking into the inside of the protruding portion 52 (flow path 54) from the cooling hole 55, protrusions on the surface 54a of the flow path 54 may be visible, as shown in Figure 5, for example. Furthermore, even if variations in the width b of the flow path 54 and the inner diameter d of the cooling hole 55 are minimized, if the ratio b / d approaches 1, the surface 54a of the flow path 54 is more likely to become visible through the cooling hole 55 if the relative positions of the cooling hole 55 and the flow path 54 are misaligned during insert molding. In such a state, as shown in Figure 4, when cooling the wing wall 34 by causing the cooling medium to collide with the inner surface 34a, the flow of the cooling medium flowing from the flow path 54 into the cooling hole 55 is disturbed, which may reduce the cooling efficiency of the wing wall 34. 【0033】 In contrast, by making the width b of the flow path 54 somewhat larger than the inner diameter d of the cooling hole 55, even if there is variation in the width b of the flow path 54, or if the relative position of the cooling hole 55 and the flow path 54 is shifted, the cooling hole 55 will be able to fit within the width of the flow path 54. In order to obtain such effects, the inventors of this disclosure have found that it is preferable for b / d ≥ 1.2. However, a larger ratio b / d is not necessarily better, as making the ratio b / d too large reduces the effect of reducing crossflow, and also increases the pressure loss due to flow contraction when the cooling medium flows from the flow path 54 to the cooling hole 55. In order to suppress such adverse effects as much as possible, it is preferable for b / d ≤ 1.5. 【0034】 Thus, even if there is variation in the width b of the flow path 54 when the insert inserted into the stator vane 24 is molded by AM, 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, the possibility that the surface 54a of the flow path 54 will be visible through the cooling hole 55 when looking at the inside of the protrusion 52 (flow path 54) from the cooling hole 55 can be reduced. As a result, when cooling the wing wall 34 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 can be reduced, thereby suppressing the risk of a decrease in the cooling efficiency of the wing wall 34. 【0035】 <Additional configuration for inserts> Below, we describe some optional additional configurations for inserts 51a and 51b. The following describes the configuration of insert 51a, but unless otherwise specified, a similar configuration is possible for insert 51b. 【0036】 <Additional Configuration 1> As shown in Figure 4, it is preferable that the cooling holes 55 are perpendicular to the inner surface 34a of the wing wall 34. With this configuration, the cooling medium efficiently collides with the inner surface 34a, so the wing wall 34 can be efficiently cooled. However, the inner surface 34a is not necessarily a flat surface, and it may be unclear whether the configuration in which the cooling holes 55 are perpendicular to a curved inner surface 34a is correct. For this reason, taking into consideration the case where the inner surface 34a is curved, as shown in Figure 6, "perpendicular" is defined as "axis L of the cooling holes 55". 55 Position P where it intersects the inner surface 34a of the wing wall 34. L Assuming a virtual tangent plane IP1 that is in contact with the inner surface 34a, the axis L 55 It is defined as "intersecting perpendicularly to the virtual tangent plane IP1". Furthermore, for this purpose, the cooling holes 55 must be strictly perpendicular to the inner surface 34a of the wing wall 34, that is, the axis L 55 This is not limited to the configuration in which the cooling holes 55 intersect the virtual tangent plane IP1 strictly perpendicularly, but rather the configuration in which the cooling holes 55 are almost perpendicular to the inner surface 34a of the wing wall 34, that is, the axis L with respect to the virtual tangent plane IP1.55 It may also be configured such that the angle formed by is within the range of 90° ± 10°. Since the cooling holes 55 are 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 substantially radially following the inner surface 34a. 【0037】 <Additional Configuration 2> As shown in FIG. 4, 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 preferably as long as possible. By doing so, even if the width of the flow path 54 is not reduced, the cross-sectional area of the recovery space 53 can be increased, so that the effect of reducing cross-flow can be enhanced. Specifically, it is preferable to design the length L of the protrusion 52 such that L > 5d. 【0038】 Next, a configuration for further enhancing such a cross-flow reduction effect will be described. In the cross-section of the space 50a shown in FIG. 3, let the area of the internal cavity 56a be A1 and the total area of the recovery space 53 be A2. The area A1 only affects the pressure loss and pressure distribution of the cooling medium flowing through the internal cavity 56a, while the area A2, in addition to affecting the pressure loss and pressure distribution of the cooling medium flowing through the recovery space 53, also affects the cross-flow and heat transfer coefficient. Therefore, the latter is a more important factor than the former. For this reason, it is preferable to make the area A2 as large as possible. As a condition for realizing this, L > 5d described above can be cited. In addition to this condition, as a more direct condition, it is preferable that A1 < A2. 【0039】 <Additional Configuration 3> As shown in FIG. 4, when the distance between the opening of the cooling hole 55 and the inner surface 34a is 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 across the flow of the cooling medium ejected from the cooling hole 55 (the flow of the cooling medium along the axial direction of the recovery space 53 after colliding with the inner surface 34a) can be ensured, which is considered to have a desirable effect on the cooling of the vane wall 34. However, when Z / d ≥ 5, the flow velocity of the cooling medium decreases before it reaches the inner surface 34a after being ejected from the cooling hole 55, and there is a risk that the ability to cool the vane wall 34 decreases. For this reason, 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 increases, and the flow velocity of the cooling medium ejected from the cooling hole 55 decreases. In order to ensure a 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. 【0040】 <Additional Configuration 4> As shown in FIG. 7, in a cross section perpendicular to the length direction of the insert 51a (the vane height direction of the stator vane 24), the larger the pitch of the tips of adjacent protrusions 52, 52 is, the smaller the flow rate of the cooling medium per unit area becomes, so that the vane wall 34 can be efficiently cooled. When the pitch of the tips of 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 a configuration in which X / d ≥ 10 holds for the entire insert 51a, and a configuration in which X / d ≥ 10 holds for at least a part of the insert 51a may be used. When the insert 51a has a configuration in which X / d ≥ 10 holds for a part of the insert 51a, cross-flow is likely to occur. For example, it is preferable to have this configuration near the tip side edge or the hub side edge of the stator vane 24. 【0041】 In Figure 7, the pitch of the tips of adjacent protrusions 52, 52 and the inner diameter of the cooling holes 55 were all the same. However, a configuration in which these are different will be explained with reference to Figure 8. The multiple protrusions 52 include a first protrusion 52a, a second protrusion 52b located next to the first protrusion 52a, and a third protrusion 52c located next to the second protrusion 52b on the opposite side of the second protrusion 52a. The inner diameter of the first cooling hole 55a, which is a cooling hole 55 formed in the first protrusion 52a, is d1, the inner diameter of the second cooling hole 55b, which is a cooling hole 55 formed in the second protrusion 52b, is d2, and the inner diameter of the third cooling hole 55c, which is a cooling hole 55 formed in the third protrusion 52c, is d3. Furthermore, let X1 be the pitch between the tip of the first protrusion 52a and the tip of the second protrusion 52b, and let X2 be the pitch between the tip of the second protrusion 52b and the tip of the third protrusion 52c. Then, the relationship in Figure 8, which corresponds to the relationship X / d≧10 in Figure 7, is: 【number】 This is the result. In this relationship, if X1=X2=X and d1=d2=d3=d, then X / d≧10. 【0042】 Furthermore, if two or more cooling holes 55 are formed in each protrusion 52, and the inner diameters of all the cooling holes 55 formed in each protrusion 52 are the same, there is no particular problem in substituting the value to d (or d1, d2, d3) in the above inequality. However, if multiple cooling holes 55 with different inner diameters are formed in each protrusion 52, the question arises as to which value should be substituted. In such cases, the average value of the inner diameters of the multiple cooling holes 55 formed in each protrusion 55 should be calculated and that average value should be substituted into d in the inequality. However, the "average value" is not limited to the arithmetic mean; the geometric mean or median may also be used. 【0043】 <Additional Configuration 5> Figure 9 shows only the first protrusion 52a and the second protrusion 52b as examples of multiple protrusions 52, but multiple cooling holes 55 may be formed in each of multiple protrusions 52, not limited to these two. Preferably, the multiple cooling holes 55 formed in each protrusion 52 are arranged in a line along the axial direction of the recovery space 53. In general, the smaller the flow velocity of the flow of cooling medium that crosses the flow of cooling medium ejected from the cooling holes 55 (hereinafter referred to as "crosswind"), the higher the heat transfer coefficient, and thus the ability to cool the blade wall 34 (see Figure 3, etc.) is improved. To reduce the effects of such crosswinds, arranging the multiple cooling holes 55 formed in each protrusion 52 in a line along the axial direction of the recovery space 53 causes the flow of the cooling medium ejected from the cooling hole 55 located furthest upstream to the crosswind to interfere with the crosswind, thereby changing the direction of the crosswind. As a result, the interference between the flow of the cooling medium ejected from the cooling holes 55 located downstream of the cooling hole 55 located furthest upstream to the crosswind and the crosswind is weakened. Consequently, the ability to cool the wing wall 34 can be improved. 【0044】 Furthermore, it is preferable that the multiple cooling holes 55 formed in each of the multiple protrusions 52 so as to be arranged in a line along the axial direction of the recovery space 53 be in a staggered arrangement rather than a grid arrangement. Here, "staggered arrangement" means that if we assume multiple virtual planes IP2 that pass through each of the multiple cooling holes 55 formed in the first protrusion 52a and are perpendicular to the axial direction of the recovery space 53, then each of the multiple virtual planes IP2 passes between adjacent cooling holes 55, 55 among the multiple cooling holes 55 formed in the second protrusion 52b. On the other hand, "grid arrangement" means that the virtual planes IP2 pass through the cooling holes 55 formed in each of the adjacent protrusions. 【0045】 If the arrangement of the cooling holes 55 is changed from a grid arrangement to a staggered arrangement, the following effects occur. As shown in Figure 10, 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 axial direction A of the recovery space 53 (see Figure 9) is less likely to be contacted by the cooling medium than the region 34a1 of the inner surface 34a corresponding to the position of the cooling hole 55 in the axial direction A. Therefore, the cooling effect in region 34a2 is smaller than the cooling effect in region 34a1. In other words, because multiple cooling holes 55 are arranged in a line with spacing between them, uneven cooling occurs on the inner surface 34a in the axial direction A. In contrast, if the arrangement of the cooling holes 55 is staggered, the region 34a2, in which the cooling effect of the cooling medium ejected from the cooling holes 55 of the first protrusion 52a is considered to be small, and the region of the inner surface 34a facing the second protrusion 52b (see Figure 9) adjacent to the first protrusion 52a, in which the cooling effect of the cooling medium ejected from the cooling holes 55 is considered to be large (the region corresponding to region 34a1 for the first protrusion 52a), are in the same position in the axial direction A. As a result, as shown in Figure 11, regions 34a1 and 34a2 exist in a staggered pattern on the inner surface 34a. On the other hand, if the arrangement of the cooling holes 55 is grid-like, as shown in Figure 12, regions 34a1 and 34a2 exist alternately in a striped pattern in the axial direction A. In the former state, the time required for the cooling effect on the inner surface 34a to become uniform due to heat conduction within the wing wall 34 is considered to be shorter than in the latter state, so it is considered that the overall cooling unevenness of the inner surface 34a can be reduced. 【0046】 The contents described in each of the above embodiments can be understood, for example, as follows: 【0047】 [1] A turbine blade according to one embodiment is: Wing wall (34) and, The insert (51) is inserted into the space (50) formed inside the wing wall (34) and A turbine blade (stator blade 24 and rotor blade 26) comprising, An internal cavity (56) is formed inside the insert (51) that communicates with the outside of the turbine blade (24 / 26). Multiple protrusions (52) are formed on the outer surface of the insert (51) that project toward the inner surface (34a) of the wing wall (34). Between two adjacent protrusions (52, 52) of the plurality of protrusions (52), a recovery space (53) is defined that communicates with the outside of the turbine blade (24 / 26). Each of the aforementioned multiple protrusions (52) has, A flow path (54) that communicates with the internal cavity (56), At least one cooling hole (55) that communicates with the flow path (54) and opens so as to face the inner surface (34a) of the wing wall (34) and Formed, If we define the length of the flow path (54) in the direction in which the plurality of protrusions (52) are aligned as the width of the flow path (54), and let b be the width of the flow path (54) at the position where the flow path (54) is connected to the cooling hole (55), and let d be the inner diameter of the cooling hole (55), then b / d ≥ 1.2. 【0048】 According to the turbine blade of this disclosure, even if there is variation in the width d of the flow path when the insert inserted into the turbine blade is molded by additive manufacturing, 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 surface of the flow path being visible through the cooling hole when looking at the inside of the protruding part (flow path) from the cooling hole can be reduced. As a result, when cooling the blade wall by causing the cooling medium to collide with the inner surface, the possibility of turbulence in the flow of the cooling medium flowing from the flow path into the cooling hole can be reduced, thereby suppressing the risk of a decrease in the cooling efficiency of the blade wall. 【0049】 [2] A turbine blade according to another embodiment is the turbine blade of [1], b / d ≤ 1.5. 【0050】 If the ratio b / d is made too large, the effect of reducing crossflow decreases, and the pressure loss due to flow contraction increases when the cooling medium flows from the flow path to the cooling hole. In contrast, a configuration like that shown in [2] can suppress these adverse effects as much as possible. 【0051】 [3] A turbine blade in yet another embodiment is a turbine blade of [1] or [2], The axis (L) of the cooling hole (55) 55 The position (P) where the ) intersects the inner surface (34a) of the wing wall (34). L Assuming a virtual tangent plane (IP1) that is in contact with the inner surface (34a) in the above, the axis (L 55 The lines intersect the virtual tangent plane (IP1) at an angle of 90° ± 10°. 【0052】 With this configuration, the cooling holes are almost perpendicular to the inner surface of the wing wall, and the cooling medium efficiently collides with the inner surface, thus efficiently cooling the wing wall. 【0053】 [4] A turbine blade according to yet another embodiment is a turbine blade according to any of [1] to [3], The plurality of protrusions (52) are, First protrusion (52a), The second protrusion (52b) is located next to the first protrusion (52a), The third protrusion (52c) is located on the opposite side of the first protrusion (52a) from the second protrusion (52b) and is adjacent to the second protrusion (52b). Equipped with, In at least one cross-section of the turbine blade (24 / 26) perpendicular to the blade height direction of the turbine blade (24 / 26) between the turbine blade (24 / 26), the tip side edge (24b), and the hub side edge (24a), the inner diameter of at least one first cooling hole (55a), which is the at least one cooling hole (55) formed in the first projection (52a), is d1, and the at least one formed in the second projection (52b) If the inner diameter of at least one second cooling hole (55b), which is a cooling hole (55), is d2, and the inner diameter of at least one third cooling hole (55c), which is a cooling hole (55), formed in the third protrusion (52c), is d3, and the pitch between the tip of the first protrusion (52a) and the tip of the second protrusion (52b) is X1, and the pitch between the tip of the second protrusion (52b) and the tip of the third protrusion (52c) is X2, 【number】 That is the case. 【0054】 With this configuration, in a cross-section perpendicular to the length of the insert, the larger the pitch between the tips of adjacent protrusions, the lower the flow rate of the cooling medium per unit area, thus enabling efficient cooling of the wing wall. 【0055】 [5] A turbine blade according to yet another embodiment is a turbine blade according to any of [1] to [4], In the above-mentioned cross-section, 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 wing wall (34) is defined as the length of the at least one protrusion (52), and if the length of the at least one protrusion (52) is L, and the inner diameter of the at least one cooling hole (55) formed in the at least one protrusion (52) is d, then L > 5d. 【0056】 With this configuration, the cross-sectional area of ​​the recovery space can be increased without reducing the width of the flow path, thereby enhancing the effect of reducing cross-flow. 【0057】 [6] A turbine blade according to yet another embodiment is the turbine blade of [5], In the above-mentioned cross-section, if the area of ​​the internal cavity (56) is A1 and the total area of ​​the recovery space (53) is A2, then A1 <A2である。 【0058】 With this configuration, the cross-sectional area of ​​the recovery space can be increased without reducing the width of the flow path, thereby enhancing the effect of reducing cross-flow. 【0059】 [7] A turbine blade according to yet another embodiment is a turbine blade according to any of [1] to [6], Each of the plurality of protrusions (52) has a plurality of cooling holes (55) formed therein. In each of the plurality of protrusions (52), the plurality of cooling holes (55) are arranged in a line along the axial direction of the recovery space (53). 【0060】 With this configuration, the flow of cooling medium ejected from the cooling holes interferes with the flow of cooling medium crossing the flow of cooling medium (crosswind), causing the direction of the crosswind to change. As a result, the interference between the flow of cooling medium ejected from cooling holes located downstream of the upstream cooling hole and the crosswind is weakened. Consequently, the ability to cool the wing wall can be improved. 【0061】 [8] A turbine blade according to yet another embodiment is the turbine blade of [7], The plurality of protrusions (52) are, First protrusion (52a), The second protrusion (52b) located next to the first protrusion (52a) and Equipped with, Assuming a plurality of virtual planes (IP2) that pass through each of the plurality of cooling holes (55) formed in the first protrusion (52a) and are perpendicular to the axial direction of the recovery space (53), each of the plurality of virtual planes (IP2) passes between adjacent cooling holes (55, 55) among the plurality of cooling holes (55) formed in the second protrusion (52b). 【0062】 This configuration makes it possible to reduce uneven cooling across the entire inner surface of the wing wall. 【0063】 [9] A turbine blade according to yet another embodiment is a turbine blade of any of [1] to [8], In at least one cross-section, if Z is the distance between the opening of the cooling hole (55) facing the inner surface (34a) of the wing wall (34) and the inner surface (34a), then 1 <Z / d<5である。 【0064】 This configuration ensures that there is sufficient surface area for the flow of the cooling medium across the flow of the cooling medium ejected from the cooling holes, which has a desirable effect on the cooling of the wing wall. 【0065】

[10] A method for manufacturing a turbine blade according to one embodiment is: A method for manufacturing any of the turbine blades (24 / 26) of [1] to [9], The steps include forming the wing wall (34), The steps include molding the insert (51), The steps of combining the wing wall (34) and the insert (51) Includes, The step of molding the insert (51) is as follows: The steps include: additively fabricating an intermediate of the insert (51) using a metallic powder material; The steps include machining the cooling holes (55) on the protruding portion of the intermediate body, Includes. 【0066】 According to the method for manufacturing turbine blades of this disclosure, even inserts having complex shapes can be molded. 【0067】

[11] A method for manufacturing a turbine blade according to another embodiment is a method for manufacturing the turbine blade of

[10] , In the step of additively manufacturing the intermediate body, a temporary hole for the cooling hole (55) is formed in the protruding portion of the intermediate body, and the cooling hole (55) is formed by finishing the temporary hole in the step of machining the cooling hole (55). 【0068】 This method allows for precise finishing of the inner diameter of the cooling holes. 【0069】

[12] A further embodiment of a method for manufacturing a turbine blade is a method for manufacturing the turbine blade of

[10] , In the step of additively fabricating the intermediate body, no holes communicating with the flow channel (54) are formed in the protruding portion of the intermediate body, and the cooling holes (55) are formed in the step of machining the cooling holes (55). 【0070】 This method allows for precise finishing of the inner diameter of the cooling holes. [Explanation of Symbols] 【0071】 24. Stator vanes (turbine blades) 24a Hub side edge 24b Chip side edge 26. Turbine blades 34 Wing wall 34a Inner surface (of the wing wall) 50 space 51 Inserts 52 Protrusion 52a 1st protrusion 52b Second protrusion 52c 3rd protrusion 53. Recovery Space 54 Flow channels 55 Cooling hole 55a 1st cooling hole 55b 2nd cooling hole 55c 3rd cooling hole IP1 virtual tangent plane IP2 Virtual Plane

Claims

[Claim 1] Wing wall and, An insert inserted into the space formed inside the wing wall and A turbine blade equipped with, An internal cavity is formed inside the insert, which communicates with the outside of the turbine blade. The outer surface of the insert has a plurality of protrusions that project toward the inner surface of the wing wall. A recovery space communicating with the outside of the turbine blade is defined between two adjacent protrusions among the plurality of protrusions. Each of the aforementioned multiple protrusions has, A flow path communicating with the aforementioned internal cavity, At least one cooling hole that communicates with the aforementioned flow path and opens so as to face the inner surface of the wing wall Formed, A turbine blade in which the length of the flow path in the direction in which the plurality of protrusions are aligned is defined as the width of the flow path, the width of the flow path at the position where the flow path is connected to the cooling hole is denoted as b, and the inner diameter of the cooling hole is denoted as d, such that 1.2 ≤ b / d ≤ 1.

5. [Claim 2] Assuming a virtual tangent plane that contacts the inner surface at the 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°, according to claim 1. [Claim 3] The plurality of protrusions are, First protruding portion and A second protrusion located next to the first protrusion, A third protrusion located on the opposite side of the first protrusion from the second protrusion and adjacent to the second protrusion, Equipped with, In at least one cross-section of the turbine blade perpendicular to the blade height direction between the turbine blade, the tip edge, and the hub edge, the inner diameter of at least one first cooling hole, which is the at least one cooling hole formed in the first projection, is d １ The inner diameter of the at least one second cooling hole, which is the at least one cooling hole formed in the second protrusion, is d. ２ The inner diameter of the at least one third cooling hole, which is the at least one cooling hole formed in the third protrusion, is d. ３ The pitch between the tip of the first protrusion and the tip of the second protrusion is set to X １ The pitch between the tip of the second protrusion and the tip of the third protrusion is set to X ２ So, [Math 1] The turbine blade according to claim 1 or 2. [Claim 4] The turbine blade according to claim 3, wherein in the at least one cross-section, 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, L is defined as the length of the at least one protrusion, and d is defined as the inner diameter of the at least one cooling hole formed in the at least one protrusion, such that L > 5d. [Claim 5] In at least one of the cross-sections, let the area of the internal cavity be A １ and let the total area of the recovery spaces be A ２ Then, A １ < A ２ The turbine blade according to claim 4, wherein this is the case [Claim 6] Each of the aforementioned multiple protrusions has a plurality of cooling holes formed therein. The turbine blade according to claim 1 or 2, wherein in each of the plurality of protrusions, the plurality of cooling holes are arranged in a row along the axial direction of the recovery space. [Claim 7] The plurality of protrusions are, First protruding portion and The second protrusion located next to the first protrusion and Equipped with, The turbine blade according to claim 6, wherein, assuming a plurality of virtual planes that pass through each of the plurality of cooling holes formed in the first protrusion and are perpendicular to the axial direction of the recovery space, each of the plurality of virtual planes passes between adjacent cooling holes among the plurality of cooling holes formed in the second protrusion. [Claim 8] The turbine blade according to claim 1 or 2, wherein in at least one cross-section, if Z is the distance between the opening of the cooling hole facing the inner surface of the blade wall and the inner surface, then 1 < Z / d < 5. [Claim 9] A method for manufacturing a turbine blade according to claim 1 or 2, The steps include forming the wing wall, The steps include molding the insert, The step of combining the wing wall and the insert. Includes, The step of molding the insert is: The steps include: additively fabricating an intermediate for the insert using a metallic powder material; The steps include machining the cooling holes in the protruding portion of the intermediate body. A method for manufacturing turbine blades, including the process described above. [Claim 10] A method for manufacturing a turbine blade according to claim 9, wherein in the step of additively fabricating the intermediate, temporary holes for the cooling holes are formed in the protruding portion of the intermediate, and the cooling holes are formed by finishing the temporary holes in the step of machining the cooling holes. [Claim 11] A method for manufacturing a turbine blade according to claim 9, wherein in the step of additively fabricating the intermediate, no holes communicating with the flow path are formed in the protruding portion of the intermediate, and the cooling holes are formed in the step of machining the cooling holes.

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