Turbine blades

Abstract

This turbine blade comprises a blade wall and an insert inserted in a space formed inside the blade wall. Inside the insert, an inner cavity communicating with the outside of the turbine blade is formed. On the outer surface of the insert, a plurality of projections projecting toward the inner surface of the blade wall are formed. Between two adjacent projections among the plurality of projections, a collection space communicating with the outside of the turbine blade is defined. Formed in each of the plurality of projections are a flow path communicating with the inner cavity, and at least one cooling hole that is open so as to communicate with the flow path and face the inner surface of the blade wall. On at least one cross section of the turbine blade vertical to the blade height direction of the turbine blade between the tip-side edge and the hub-side edge of the turbine blade, given that the length of at least one projection is defined as the length of at least one projection among the plurality of projections extending from the outer surface of the insert toward the inner surface of the blade wall, that the length of at least one projection is L, and that the inner diameter of at least one cooling hole formed in at least one projection is d, L > 5d is satisfied.

Description

[Technical Field]

[0001] The present disclosure relates to turbine blades. This application claims priority based on Japanese Patent Application No. 2022-189168, filed with the Japan Patent Office on November 28, 2022, the contents of which are incorporated herein by reference. [Background technology]

[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 a blade wall, and the insert is formed with multiple protrusions that protrude toward the inner surface of the blade wall, and a cooling hole for ejecting a cooling medium is formed at the tip of each protrusion. The cooling medium ejected from the cooling holes collides with the inner surface of the blade wall, thereby cooling the blade wall. The cooling medium that collides 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] If a crossflow occurs, in which the coolant flows along the inner surface between the insert and the inner surface of the blade wall after colliding with the inner surface of the blade wall, the crossflow may interfere with the coolant ejected from the cooling holes, reducing the cooling efficiency of the blade wall. In contrast, the turbine blade described in Patent Document 1 reduces the crossflow by having the coolant flow through a recovery space after colliding with the inner surface of the blade wall. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-63997 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the turbine blade described in Patent Document 1 has a complex configuration, unless the dimensions of each portion are specified, the effect of reducing cross flow may be diminished.

[0006] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a turbine blade that has an improved effect of reducing crossflow. [Means for solving the problem]

[0007] In order to achieve the above object, the present disclosure provides a turbine blade including 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, and a projection on the outer surface of the insert projects toward the inner surface of the blade wall. and extending along the blade height direction of the turbine blade. a plurality of protrusions are formed, and 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 plurality of protrusions is formed with a flow path communicating with the internal cavity and at least one cooling hole communicating with the flow path and opening to face the inner surface of the blade wall; the length of at least one of the plurality of protrusions is defined as the length of the at least one protrusion extending from the outer surface of the insert toward 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; and where L is the length of the at least one protrusion and d is an inner diameter of the at least one cooling hole formed in the at least one protrusion, L>5d. [Effects of the Invention]

[0008] According to the turbine blade of the present disclosure, the cross-sectional area of ​​the flow passage of the recovery space can be increased without reducing the width of the flow passage, thereby enhancing the effect of reducing cross-flow. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a schematic configuration diagram of a gas turbine using a turbine blade according to an embodiment of the present disclosure. [Figure 2] FIG. 1 illustrates a turbine blade viewed from the pressure side toward the suction side according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is an enlarged cross-sectional view of a portion of a turbine blade insert according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a cross-sectional view illustrating the orientation of cooling holes relative to the inner surface of a blade wall in a turbine blade according to an embodiment of the present disclosure. [Figure 6] FIG. 2 illustrates the relative positions of flow passages and cooling holes in a protrusion of an insert of a turbine blade according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a cross-sectional view illustrating the configuration of multiple protrusions of an insert for a turbine blade according to an embodiment of the present disclosure. [Figure 8] FIG. 2 is a cross-sectional view illustrating the configuration of multiple protrusions of an insert for a turbine blade according to an embodiment of the present disclosure. [Figure 9] FIG. 2 is a perspective view illustrating the configuration of multiple protrusions of an insert for a turbine blade according to an embodiment of the present disclosure. [Figure 10] 10A and 10B are diagrams for explaining the effects of staggering the arrangement of a plurality of cooling holes formed in a plurality of protrusions of an insert of a turbine blade according to an embodiment of the present disclosure. [Figure 11] 10A and 10B are diagrams for explaining the effects of staggering the arrangement of a plurality of cooling holes formed in a plurality of protrusions of an insert of a turbine blade according to an embodiment of the present disclosure. [Figure 12] 10A and 10B are diagrams for explaining the effects of staggering the arrangement of a plurality of cooling holes formed in a plurality of protrusions of an insert of a turbine blade according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0016] Hereinafter, a turbine blade according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment described below shows one aspect of the present disclosure, but does not limit the present disclosure and can be modified as desired within the scope of the technical concept of the present disclosure.

[0011] <Configuration of gas turbine using turbine blades according to the present disclosure> 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 a gas turbine 1 for power generation, a generator (not shown) is connected to the turbine 6.

[0012] The compressor 2 includes a plurality of stator vanes 16 fixed to the compressor casing 10 side and a plurality of moving blades 18 attached to the rotor 8. Air taken in from an air intake 12 is sent to the compressor 2, and this air is compressed as it passes through the plurality of stator vanes 16 and the plurality of moving blades 18, becoming high-temperature, high-pressure compressed air.

[0013] The combustor 4 is supplied with fuel and compressed air generated by the compressor 2, and the fuel and compressed air are mixed in the combustor 4 and then combusted to generate combustion gas, which is the working fluid of the turbine 6. A plurality of combustors 4 may be arranged in the casing 20 in the circumferential direction around the rotor.

[0014] The turbine 6 has a combustion gas flow path 28 formed in the turbine casing 22 and includes a plurality of stator vanes 24 and rotor blades 26 provided in the combustion gas flow path 28. The stator vanes 24 are fixed to the turbine casing 22 side, and the plurality of stator vanes 24 arranged along the circumferential direction of the rotor 8 constitute a stator vane row. The rotor blades 26 are attached to the rotor 8, and the plurality of rotor blades 26 arranged along the circumferential direction of the rotor 8 constitute a rotor blade row. The stator vane rows and rotor blade rows are arranged alternately in the axial direction of the rotor 8.

[0015] <Configuration of turbine blade according to the present disclosure> The turbine blades of the present disclosure are intended to be both the stationary blades 24 and the moving blades 26 of the turbine 6. In the following, the turbine blades according to one embodiment of the present disclosure will be described as the stationary blades 24, but they may also be the moving blades 26.

[0016] 2, the stator vane 24 has a blade wall 34 that extends in a direction from the hub side edge 24a toward the tip side edge 24b of the stator vane 24, i.e., in the blade height direction of the stator vane 24, and an outer shroud 38 and an inner shroud 40 are provided at the tip side edge 24b and the hub side edge 24a, respectively. The blade wall 34 has a leading edge 42 and a trailing edge 44 that extend along the blade height direction, and has a pressure surface 46 and a suction surface 48 that extend between the leading edge 42 and the trailing edge 44.

[0017] As will be described later, a space 50 (see FIG. 3) is formed inside the blade wall 34, and paths 37, 39 that communicate the outside of the stator blade 24 with the space 50 are formed in the outer shroud 38 and the inner shroud 40, respectively. The paths 37, 39 are not limited to being formed in the outer shroud 38 and the inner shroud 40, respectively, and may be formed in either the outer shroud 38 or the inner shroud 40. Although FIG. 2 schematically illustrates one path each of the paths 37, 39, a plurality of paths may be provided for each of the paths 37, 39, or a plurality of paths for either one of the paths may be provided. The roles of the paths 37, 39 will be described later.

[0018] As shown in FIG. 3, a space 50 is formed inside the wing wall 34. The space 50 may be divided into a plurality of spaces, for example, two spaces 50a and 50b, by a middle wall 57. The space 50 may be divided into three or more spaces by two or more middle walls 57, or the space 50 may be a single space without providing a middle wall 57. An insert 51 is inserted into the space 50. As shown in FIG. 3 as an example, when the space 50 is divided into two spaces 50a and 50b, the insert 51 may include inserts 51a and 51b inserted into each space.

[0019] <Insert configuration> Each of the inserts 51a and 51b has a shape having a longitudinal axis along the blade height direction of the stator blade 24 (a direction perpendicular to the paper surface of FIG. 3), and has an internal cavity 56 (56a, 56b) therein. ) A plurality of protrusions 52 are formed on the outer surface of each of the inserts 51a, 51b, protruding toward the inner surface 34a of the blade wall 34. In each insert, the plurality of protrusions 52 extend along the blade height direction of the stator vane 24 and are formed to be spaced apart in the circumferential direction around the longitudinal axis.

[0020] The passage 37 (see Figure 2) is connected to each of the internal cavities 56a, 56b in the spaces 50a, 50b, and the passage 39 is connected to the region between the outer surface of each of the inserts 51a, 51b in the spaces 50a, 50b and the inner surface 34a of the wing wall 34, particularly in the spaces 50a, 50b, with the recovery space 53 defined between adjacent protrusions 52, 52 in the circumferential direction of each insert, centered on the longitudinal axis direction.

[0021] Next, the configuration of the protrusions 52 will be described. Fig. 4 shows a cross-sectional view of some of the multiple protrusions 52 provided on the insert 51a. The configuration of the protrusions 52 described below with reference to Fig. 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 that communicates with the internal cavity 56a, is formed inside the protrusion 52. The protrusion 52 also has a cooling hole 55 that communicates with the flow path 54 and opens to face the inner surface 34a of the blade wall 34. While FIG. 4 illustrates one cooling hole 55 being formed in each protrusion 52, the present invention is not limited to a configuration in which only one cooling hole 55 is formed. As described above, the protrusion 52 has a shape that extends along the blade height direction of the stator blade 24, i.e., along the direction perpendicular to the paper surface of FIG. 4, and therefore, for example, a plurality of cooling holes 55 may be formed at intervals from one another along this direction.

[0023] The protrusions 52 may be arranged at equal intervals to uniformly cool the entire stator blade 24, or the interval between adjacent protrusions 52, 52 at a location where cooling is particularly desired may be smaller than the interval between adjacent protrusions 52, 52 at other locations. For example, the interval between the protrusions 52, 52 arranged on the pressure side of the stator blade 24 may be smaller than the interval between the protrusions 52, 52 arranged on the suction side of the stator blade 24. Furthermore, the protrusions 52 arranged on each of the pressure side and suction side of the stator blade 24 may be arranged so that the interval between adjacent protrusions 52, 52 gradually increases from the leading edge to the trailing edge of the stator blade 24. Furthermore, the number of cooling holes 55 formed in the protrusions 52 facing the location where cooling is particularly desired may be greater than the number of cooling holes 55 formed in the protrusions 52 facing other locations.

[0024] For example, if it is found by actual measurement or simulation that a particular location becomes hot, the space 50 may be divided into multiple spaces by middle walls 57, and the number of protrusions 52 formed on the insert 51 inserted in the space where the hot location exists may be made larger than the number of protrusions 52 formed on the insert 51 inserted in the other spaces, so that the spacing between adjacent protrusions 52 in the former space is smaller than the spacing between adjacent protrusions 52 in the latter space. In this case, instead of changing the number of protrusions 52, the number of cooling holes 55 in the former space may be made larger than the number of cooling holes 55 in the latter space.

[0025] For example, if it is found by actual measurements or simulations that the ventral side of the stator blade 24 will be hotter than the suction side, the number of cooling holes 55 formed in the protruding portion 52 on the ventral side of the stator blade 24 may be made larger than the number of cooling holes 55 formed in the protruding portion 52 on the suction side of the stator blade 24. Conversely, if it is found that the suction side of the stator blade 24 will be hotter than the ventral side, the number of cooling holes 55 formed in the protruding portion 52 on the suction side of the stator blade 24 may be made larger than the number of cooling holes 55 formed in the protruding portion 52 on the ventral side of the stator blade 24.

[0026] When multiple cooling holes 55 are formed in each protrusion 52, the spacing between adjacent cooling holes 55 may be equal or different. In the latter configuration, for example, the spacing between adjacent cooling holes 55 may gradually increase from the hub side toward the tip side, or conversely, the spacing between adjacent cooling holes 55 may gradually increase from the tip side toward the hub side.

[0027] <Cooling Operation of Blade Wall in Turbine Blade of the Present Disclosure> The cooling operation of the blade wall in the turbine blade of the present disclosure will be described. As shown in FIG. 2, a cooling medium (e.g., cooling air) is supplied from the outside of the stator blade 24 to the inside of the blade wall 34 via a path 37. As shown in FIG. 3, the cooling medium flows into each of the internal cavities 56a and 56b. For example, the cooling medium that flows into the internal cavity 56a flows into the flow passage 54, then flows into the cooling holes 55, and is ejected from the cooling holes 55 toward the inner surface 34a of the blade wall 34, as shown in FIG. 4. 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 is discharged to the outside of the stator blade 24 via a path 39 (see FIG. 2).

[0028] If a crossflow occurs, in which the cooling medium flows along the inner surface 34a in the vicinity of other cooling holes 55 after colliding with the inner surface 34a of the blade wall 34, the cooling medium ejected from the other cooling holes 55 may be interfered with by the crossflow, resulting in a decrease in cooling efficiency. 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, thereby reducing the crossflow and, as a result, reducing the risk of a decrease in the cooling efficiency of the blade wall 34.

[0029] <Actions and Effects of the Turbine Blades Disclosed Herein> As shown in FIG. 4, it is preferable that the length L of the protrusion 52 extending from the outer surface of the insert 51a toward the inner surface 34a of the wing wall 34 is 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 flow path of the recovery space 53 can be increased, so that the reduction effect of cross flow can be enhanced. Specifically, it is preferable to design the length L of the protrusion 52 such that L > 5d.

[0030] 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, the above-mentioned L > 5d can be cited. In addition to this condition, as a more direct condition, it is preferable that A1 < A2.

[0031] <Additional configuration of the insert> Hereinafter, several additional configurations that are not essential for each of the inserts 51a and 51b will be described. Hereinafter, the configuration of the insert 51a will be described, but unless otherwise specified, the same configuration is possible for the insert 51b.

[0032] <Additional configuration 1> 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 crossing 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 wing wall 34. However, when Z / d ≥ 5, the flow velocity of the cooling medium ejected from the cooling hole 55 decreases before reaching the inner surface 34a, and there is a possibility that the ability to cool the wing wall 34 decreases. 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 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 realize a flow velocity suitable for cooling the wing wall 34 by the cooling medium ejected from the cooling hole 55, the condition of 1 < Z / d is preferable.

[0033] <Additional Configuration 2> It is preferable that the cooling hole 55 is perpendicular to the inner surface 34a of the wing wall 34. With such a configuration, the cooling medium collides with the inner surface 34a efficiently, so the wing wall 34 can be cooled efficiently. However, the inner surface 34a is not necessarily a flat surface, and there may be a possibility that the configuration in which the cooling hole 55 is perpendicular to the curved inner surface 34a is considered unclear. Therefore, considering the case where the inner surface 34a is curved, as shown in FIG. 5, "perpendicular" is defined as "the axis L 55 of the cooling hole 55 intersects the inner surface 34a of the wing wall 34 at the position P L and touches the virtual tangent plane IP1 contacting the inner surface 34a at that position, the axis L 55 intersects the virtual tangent plane IP1 perpendicularly". In addition, for this purpose, it is not limited to the case where the cooling hole 55 is exactly perpendicular to the inner surface 34a of the wing wall 34, that is, the axis L 55 intersects the virtual tangent plane IP1 exactly perpendicularly, but a configuration in which the cooling hole 55 is substantially perpendicular to the inner surface 34a of the wing wall 34, that is, the axis L 55The angle formed by the cooling holes 55 may be within a range of 90°±10°. Since the cooling holes 55 are substantially perpendicular to the inner surface 34a of the blade wall 34, the multiple protrusions 52 are arranged substantially radially on the leading edge side of the stator blade 24, following the inner surface 34a.

[0034] <Additional Configuration 3> The length of the flow passage 54 in the direction in which the multiple protrusions 52 are arranged (the left-right direction in FIG. 4 ) is defined as the "width of the flow passage 54." In FIG. 4 , the width of the flow passage 54 is constant in the direction protruding toward the inner surface 34a of the protrusion 52 (downward in FIG. 4 ). However, there are configurations in which the width increases or decreases toward the cooling hole 55. In such configurations, the "width of the flow passage 54" does not specify the length. Therefore, regardless of the configuration of the flow passage 54, if the width of the flow passage 54 at the position where the flow passage 54 connects to the cooling hole 55, i.e., the lowest position in FIG. 4 , is defined as b and the inner diameter of the cooling hole 55 is defined as d, then b / d≧1.2.

[0035] As described above, from the viewpoint of reducing the cross-flow, it is preferable that the cross-sectional area of ​​the flow passage of the recovery space 53 is large. 2 While it is necessary to reduce the width of the cooling hole 55, and therefore the width of the flow passage 54, it is necessary to ensure a certain degree of size for the inner diameter d of the cooling hole 55 from the viewpoint of the amount of coolant ejected, and therefore the ratio b / d is close to 1. In contrast, in the stator vane 24 of the present disclosure, b / d≧1.2. In order to explain the effects of this configuration, the effects will be explained while explaining the manufacturing method of the stator vane 24, particularly the manufacturing method of the inserts 51a, 51b.

[0036] As shown in Fig. 3, the vane 24 is manufactured by molding the blade wall 34, molding the inserts 51a and 51b, and combining the blade wall 34 and the inserts 51a and 51b. The shape isAM is preferred. When the inserts 51a, 51b are molded by AM, intermediates of the inserts 51a, 51b are additively manufactured using a metal powder material, and then the cooling holes 55 are machined in the protruding portions 52 of the intermediates as shown in FIG. 4. Temporary holes for the cooling holes 55 may be formed in the protruding portions 52 of the intermediates when additively manufacturing the intermediates, and the cooling holes 55 may be formed by finish-machining the temporary holes. Alternatively, the cooling holes may be formed by machining without forming temporary holes in the protruding portions 52 of the intermediates when additively manufacturing the intermediates. The temporary holes formed in the intermediates, like the cooling holes 55, are configured to communicate with the flow paths 54 and open on the outer surfaces of the protruding portions 52.

[0037] Generally, products molded by AM have rough surfaces, and protrusions due to spattering may adhere to the surface. For this reason, when inserts 51a and 51b are molded by AM, variations can occur in the width b of the flow passage 54 and the inner diameter d of the cooling hole 55. Although the inner diameter d of the cooling hole 55 can be precisely finished by machining or finishing after AM, the structure of the inserts 51a and 51b makes it difficult for tools to access the inside of the protrusion 52 (flow passage 54), making it impossible to reduce the variation in the width b of the flow passage 54. Therefore, when the ratio b / d approaches 1, protrusions or the like may be visible on the surface 54a of the flow passage 54 when viewing the inside of the protrusion 52 (flow passage 54) from the cooling hole 55, as shown in FIG. 6, for example. Furthermore, even if variations in the width b of the flow passage 54 and the inner diameter d of the cooling hole 55 are minimized, if the ratio b / d is set close to 1, if the relative positions of the cooling hole 55 and the flow passage 54 are misaligned during molding of the insert, the surface 54a of the flow passage 54 is likely to be visible through the cooling hole 55. In this state, as shown in Fig. 4, when the blade wall 34 is cooled by colliding the coolant with the inner surface 34a, the flow of the coolant flowing from the flow passage 54 into the cooling hole 55 is disturbed, which may reduce the cooling efficiency of the blade wall 34.

[0038] In contrast, by making the width b of the flow passage 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 passage 54 or if the relative positions of the cooling hole 55 and the flow passage 54 are shifted, the cooling hole 55 will fit within the width of the flow passage 54. Investigating the ratio b / d≧1.2, the inventors of the present disclosure have concluded that in order to achieve such an effect, it is preferable that the ratio b / d is greater than or equal to 1.2. However, it is not necessarily the case that a larger ratio b / d is better; if the ratio b / d is too large, the effect of reducing cross-flow will be reduced, and pressure loss due to contraction will increase when the coolant flows from the flow passage 54 to the cooling hole 55. To minimize such adverse effects, it is preferable that the ratio b / d is less than or equal to 1.5.

[0039] In this way, even if there is variation in the width b of the flow passage 54 when the insert to be inserted into the stator blade 24 is molded by AM, by setting the ratio b / d of the width b of the flow passage 54 to the inner diameter d of the cooling hole 55 to be 1.2 or more, it is possible to reduce the possibility that the surface 54a of the flow passage 54 will be visible through the cooling hole 55 when the inside of the protrusion 52 (flow passage 54) is viewed from the cooling hole 55. This reduces the possibility of turbulence in the flow of the cooling medium flowing from the flow passage 54 into the cooling hole 55 when the blade wall 34 is cooled by colliding the cooling medium with the inner surface 34a, and therefore reduces the risk of a decrease in the cooling efficiency of the blade wall 34.

[0040] <Additional Configuration 4> As shown in FIG. 7 , in a cross section perpendicular to the longitudinal direction of the insert 51a (the blade height direction of the stator vane 24), the greater the pitch between the tips of adjacent protrusions 52, 52, the smaller the flow rate of the coolant per unit area, thereby enabling more efficient cooling of the blade wall 34. If the pitch between 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, then it is preferable that X / d≧10. However, the configuration is not limited to one in which X / d≧10 is satisfied over the entire insert 51a, and it may be one in which X / d≧10 is satisfied over at least a portion of the insert 51a. When the insert 51a has a configuration in which X / d≧10 is satisfied over a portion of the insert 51a, it is preferable that this configuration be present in an area where crossflow is likely to occur, such as near the tip edge or hub edge of the stator vane 24.

[0041] 7 shows a configuration in which the pitch of the tips of adjacent protrusions 52, 52 and the inner diameters of the cooling holes 55 are all the same, but a configuration in which these are different will be described with reference to FIG. 8. The multiple protrusions 52 include a first protrusion 52a, a second protrusion 52b located adjacent to the first protrusion 52a, and a third protrusion 52c located adjacent to the second protrusion 52b on the opposite side of the second protrusion 52b from the first 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, 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. Then, the relationship in FIG. 8, which corresponds to the relationship X / d≧10 in FIG. 7, is

number

[0042] In addition, when two or more cooling holes 55 are formed in each protrusion 52, and the cooling holes 55 formed in each protrusion 52 all have the same inner diameter, there is no particular problem with the value substituted for d (or d1, d2, d3) in the above inequality. However, when 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 a case, the average value of the inner diameters of the multiple cooling holes 55 formed in each protrusion 55 can be calculated and this average value can be substituted for d in the inequality. However, the "average" is not limited to the arithmetic mean, and the geometric mean, median, etc. can also be used.

[0043] <Additional Configuration 5> 9 illustrates only the first protrusion 52a and the second protrusion 52b as examples of the plurality of protrusions 52, but the plurality of protrusions 52 is not limited to these two, and each of the plurality of protrusions 52 may have a plurality of cooling holes 55 formed therein. The plurality of cooling holes 55 formed in each protrusion 52 are preferably arranged in a row along the axial direction of the recovery space 53. In general, the smaller the flow velocity of the cooling medium that crosses the flow of the cooling medium ejected from the cooling holes 55 (hereinafter referred to as "crosswind"), the higher the heat transfer coefficient, and therefore the better the ability to cool the blade wall 34 (see FIG. 3, etc.). In order to reduce the effect of such crosswinds, if the multiple cooling holes 55 formed in each protrusion 52 are aligned in a row along the axial direction of the recovery space 53, the direction of the crosswind will change due to interference between the flow of cooling medium ejected from the cooling hole 55 located most upstream with respect to the crosswind, thereby weakening the interference between the crosswind and the flow of cooling medium ejected from the cooling holes 55 located downstream of the cooling hole 55 located most upstream with respect to the crosswind. As a result, the ability to cool the blade 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 arranged in a staggered arrangement rather than a lattice arrangement. Here, the "staggered arrangement" refers to a configuration in which, assuming multiple imaginary 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, each of the multiple imaginary 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, the "lattice arrangement" refers to a configuration in which the imaginary plane IP2 passes through the cooling holes 55 formed in each of the adjacent protrusions.

[0045] Arranging the cooling holes 55 in a staggered arrangement rather than a grid arrangement has the following effect. As shown in Fig. 10, when focusing on two adjacent cooling holes 55, 55 of the first protrusion 52a, the cooling medium is less likely to reach a region 34a2 of the inner surface 34a corresponding to a position near the center between the cooling holes 55, 55 in the axial direction A of the recovery space 53 (see Fig. 9) than a region 34a1 of the inner surface 34a corresponding to the position of the cooling hole 55 in the axial direction A, and therefore the cooling effect in the region 34a2 is smaller than the cooling effect in the region 34a1. In other words, because the multiple cooling holes 55 are arranged in a row with intervals between them, uneven cooling occurs on the inner surface 34a in the axial direction A. In contrast, when the cooling holes 55 are arranged in a staggered pattern, the region 34a2 where the cooling effect of the cooling medium ejected from the cooling holes 55 of the first protrusion 52a is thought to be small and the region of the inner surface 34a facing the second protrusion 52b (see FIG. 9) adjacent to the first protrusion 52a where the cooling effect of the cooling medium ejected from the cooling holes 55 is thought to be large (the region corresponding to the region 34a1 for the first protrusion 52a) are at the same position in the axial direction A. As a result, as shown in FIG. 11, the regions 34a1 and 34a2 are present in a staggered pattern on the inner surface 34a. On the other hand, when the cooling holes 55 are arranged in a lattice pattern, as shown in FIG. 12, the regions 34a1 and 34a2 are present in a striped pattern where they alternate in the axial direction A. In the shapeIt is considered that the time required for the cooling effect of the inner surface 34a to become uniform due to heat conduction within the blade wall 34 is shorter in the former state than in the latter state, and therefore it is considered that uneven cooling of the entire 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 aspect includes: wing walls (34); an insert (51) inserted into a space (50) formed inside the wing wall (34); A turbine blade (a stationary blade 24 and a moving blade 26) comprising: The insert (51) has an internal cavity (56) formed therein that communicates with the exterior of the turbine blade (24 / 26), 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), a recovery space (53) communicating with the outside of the turbine blade (24 / 26) is defined between two adjacent protrusions (52, 52) among the plurality of protrusions (52); Each of the plurality of protrusions (52) has: a flow passage (54) communicating with the internal cavity (56); at least one cooling hole (55) communicating with the flow path (54) and opening to face the inner surface (34a) of the blade wall (34); is formed, 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 tip side edge (24b) and the hub side edge (24a) of the turbine blade (24 / 26), the length of at least one of the multiple 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), and 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, so that L > 5d.

[0048] According to the turbine blade of the present disclosure, the cross-sectional area of ​​the flow passage of the recovery space can be increased without reducing the width of the flow passage, thereby enhancing the effect of reducing cross-flow.

[0049] [2] A turbine blade according to another aspect is the turbine blade according to [1], In the at least one cross section, the area of ​​the internal cavity (56) is A1, and the total area of ​​the recovery space (53) is A2. <A2である。

[0050] According to 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.

[0051] [3] A turbine blade according to yet another embodiment is the turbine blade according to [1] or [2], A plurality of the cooling holes (55) are formed in each of the plurality of protrusions (52), The cooling holes (55) in each of the protrusions (52) are arranged in a row along the axial direction of the recovery space (53).

[0052] With this configuration, the direction of the crosswind changes due to interference between the cooling medium flow (crosswind) that crosses the cooling medium flow ejected from the cooling holes located most upstream, and therefore interference between the cooling medium flow ejected from the cooling holes located downstream of the cooling hole located most upstream with respect to the crosswind is reduced, thereby improving the ability to cool the blade wall.

[0053] [4] A turbine blade according to yet another embodiment is the turbine blade according to [3], The plurality of protrusions (52) are a first protrusion (52a); a second protrusion (52b) located adjacent to the first protrusion (52a); Equipped with If we imagine multiple imaginary 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), each of the multiple imaginary planes (IP2) passes between adjacent cooling holes (55, 55) among the multiple cooling holes (55) formed in the second protrusion (52b).

[0054] With this configuration, it is possible to reduce uneven cooling of the entire inner surface of the blade wall.

[0055] [5] A turbine blade according to yet another embodiment is the turbine blade according to any one of [1] to [4], The plurality of protrusions (52) are a first protrusion (52a); a second protrusion (52b) located adjacent to the first protrusion (52a); a third protrusion (52c) located adjacent to the second protrusion (52b) on the opposite side of the first protrusion (52a) with respect 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 tip side edge (24b) and the hub side edge (24a), an inner diameter of at least one first cooling hole (55a) which is the at least one cooling hole (55) formed in the first protruding portion (52a) is defined as d1, and an inner diameter of at least one first cooling hole (55a) which is the at least one cooling hole (55) formed in the second protruding portion (52b) is defined as d2. Let d2 be the inner diameter of at least one second cooling hole (55b) that is a cooling hole (55), d3 be the inner diameter of at least one third cooling hole (55c) that is the at least one cooling hole (55) formed in the third protruding portion (52c), X1 be the pitch between the tip of the first protruding portion (52a) and the tip of the second protruding portion (52b), and X2 be the pitch between the tip of the second protruding portion (52b) and the tip of the third protruding portion (52c),

number

[0056] With this configuration, the greater the pitch between the tips of adjacent protrusions in a cross section perpendicular to the longitudinal direction of the insert, the smaller the flow rate of cooling medium per unit area, making it possible to efficiently cool the blade wall.

[0057] [6] A turbine blade according to yet another embodiment is the turbine blade according to any one of [1] to [5], The axis (L 55 ) intersects with the inner surface (34a) of the wing wall (34) (P L ) and the inner surface (34a) is in contact with the axis (L 55 ) intersects with the imaginary tangent plane (IP1) at an angle of 90°±10°.

[0058] With this configuration, the cooling holes are substantially perpendicular to the inner surface of the blade wall, and the cooling medium collides efficiently with the inner surface, thereby enabling the blade wall to be cooled efficiently.

[0059] [7] A turbine blade according to yet another embodiment is the turbine blade according to any one of [1] to [6], The length of the flow path (54) in the direction in which the multiple protrusions (52) are arranged is defined as the width of the flow path (54), the width of the flow path (54) at the position where the flow path (54) is connected to the cooling hole (55) is defined as b, and the inner diameter of the cooling hole (55) is defined as d, where b / d≧1.2.

[0060] With this configuration, even if there is variation in the flow path width d when the insert to be inserted into the turbine blade is molded by AM, by setting the ratio b / d of the flow path width b to the cooling hole inner diameter to be 1.2 or more, it is possible to reduce the possibility that the surface of the flow path will be visible through the cooling hole when looking at the inside of the protrusion (flow path) from the cooling hole. This reduces the possibility of turbulence in the flow of the cooling medium flowing from the flow path into the cooling hole when the blade wall is cooled by colliding the cooling medium with the inner surface, thereby minimizing the risk of a decrease in the cooling efficiency of the blade wall.

[0061] [8] A turbine blade according to another aspect is the turbine blade according to [7], b / d≦1.5.

[0062] If the ratio b / d is too large, the effect of reducing cross-flow will be reduced, and the pressure loss due to contraction will increase when the coolant flows from the flow passage to the cooling hole. In contrast, the configuration described in [2] can minimize these adverse effects.

[0063] [9] A turbine blade according to yet another embodiment is the turbine blade according to any one of [1] to [8], In the at least one cross section, when a distance between an opening of the cooling hole (55) facing the inner surface (34a) of the blade wall (34) and the inner surface (34a) is Z, 1 <Z / d<5である。

[0064] This configuration provides a desirable effect on the cooling of the blade wall, since it ensures a cooling medium flow area that crosses the flow of cooling medium ejected from the cooling holes. [Explanation of symbols]

[0065] 24 Stationary blade (turbine blade) 24a Hub side edge 24b Chip side edge 26 Moving blades (turbine blades) 34 Wing wall 34a (Wing wall) inner surface 50 space 51 Insert 52 Protrusion 52a 1st protrusion 52b Second protrusion 52c 3rd protrusion 53 Recovery Space 54 Flow path 55 Cooling hole 55a 1st cooling hole 55b 2nd cooling hole 55c 3rd cooling hole IP1 virtual tangent plane IP2 Virtual Plane

Claims

1. Wing walls and an insert inserted into a space formed inside the wing wall; A turbine blade comprising: an internal cavity formed inside the insert and communicating with the exterior of the turbine blade; a plurality of protrusions are formed on an outer surface of the insert, the protrusions protruding toward an inner surface of the blade wall and extending along a blade height direction of the turbine blade; 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 plurality of protrusions has a flow path communicating with the internal cavity; at least one cooling hole communicating with the flow passage and opening to face the inner surface of the blade wall; is formed, a turbine blade, wherein L>5d is satisfied, where L is defined as a length of at least one of the plurality of protrusions extending from an outer surface of the insert toward an inner surface of the blade wall in at least one cross section of the turbine blade perpendicular to a blade height direction of the turbine blade between a tip side edge and a hub side edge of the turbine blade, and d is an inner diameter of the at least one cooling hole formed in the at least one protrusion.

2. In the at least one cross section, the area of ​​the internal cavity is A １ The total area of ​​the recovery space is A ２ Then, A １ <A ２ The turbine blade of claim 1 , wherein:

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

4. The plurality of protrusions are A first protrusion; a second protrusion located adjacent to the first protrusion; Equipped with 4. The turbine blade according to claim 3, wherein when imaginary planes are assumed that pass through each of the plurality of cooling holes formed in the first protruding portion and are perpendicular to the axial direction of the recovery space, each of the plurality of imaginary planes passes between adjacent cooling holes among the plurality of cooling holes formed in the second protruding portion.

5. The plurality of protrusions are A first protrusion; a second protrusion located adjacent to the first protrusion; a third protrusion located adjacent to the second protrusion on the opposite side of the first protrusion with respect to the second protrusion; Equipped with In the at least one cross section, the inner diameter of the at least one first cooling hole formed in the first protrusion is defined as d １ and the inner diameter of the at least one second cooling hole formed in the second protrusion is d ２ and 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 and the pitch between the tip of the first protrusion and the tip of the second protrusion is X １ and the pitch between the tip of the second protrusion and the tip of the third protrusion is X ２ Then, [Equation 1] The turbine blade according to claim 1 or 2, wherein

6. 3. The turbine blade according to claim 1, wherein, when an imaginary tangent plane is assumed to be tangent to the inner surface of the blade wall at a position where the axis of the cooling hole intersects with the inner surface, the axis intersects with the imaginary tangent plane at an angle of 90°±10° with respect to the imaginary tangent plane.

7. 3. The turbine blade according to claim 1, wherein a length of the flow passage in a direction in which the plurality of protrusions are arranged is defined as a width of the flow passage, a width of the flow passage at a position where the flow passage is connected to the cooling hole is defined as b, and an inner diameter of the cooling hole is defined as d, and b / d≧1.2 is satisfied.

8. The turbine blade of claim 7, wherein b / d≦1.

5.

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

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