Improved turbine rotor assembly

Abstract

The invention is entitled "Improved Turbomachine Rotor Assembly". A rotor assembly (300) is disclosed that includes a rotor (34) having a dovetail slot (36). The dovetail slot (36) includes a plurality of recesses (44) and a first radially innermost surface (210). A rotor blade (20) includes an airfoil (22) extending radially outward from a platform (31) and a dovetail (32) extending radially inward from the platform (31). The dovetail (32) includes a plurality of projections (40) extending in opposite directions received by the plurality of recesses (44) of the dovetail slot (36). A second radially innermost surface (46) defines a channel (33) from a leading edge surface (25) to a trailing edge surface (27). A shim (52) is positioned within the channel (33) and between the first radially innermost surface (210) of the dovetail slot (36) and the second radially innermost surface (46) of the dovetail (32). The shim (52) extends radially at least partially along both the leading edge surface (25) and the trailing edge surface (27) to secure the rotor blade (20) within the dovetail slot (36) during various operating conditions of a turbomachine.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to turbomachinery. In particular, the present disclosure relates to the support and / or retention of rotor blades in turbomachinery. BACKGROUND

[0002] Turbomachinery, such as steam turbines, generally include a static nozzle assembly that directs a flow of working fluid into rotor blades connected to a rotating rotor. The nozzle configuration, including a plurality of nozzles or "airfoils," is sometimes referred to as a "diaphragm" or "nozzle assembly stage." Each rotor blade includes a base having a dovetail that is sized to fit within a corresponding dovetail slot in the rotor. Many last stage rotor blades have significant length and have significant weight. During low speed operation or "turning gear" operation, the blades are able to move within the dovetail slots in which they are retained. This undesirable movement can result in significant wear to the blades and / or the rotor dovetail slots. In many cases, the wear to the blades and dovetail slots can result in an outage, require repair, and result in undesirable costs.

[0003] However, during rotor assembly, some movement ("laying out") of the rotor blades is required in order to facilitate assembly of the rotor blades. The rotor blades have outer shroud ends, and these ends often have interlocking features. During row assembly, the rotor blades must pass by one another. The rotor blades can also overlap with the airfoils, such that if there is not sufficient movement, it can be difficult, if not impossible, to assemble the last rotor blade in the row.

[0004] Accordingly, there is a need in the art for an improved system and method for rotor blade installation. In particular, there is a need for an improved system and method for rotor blade installation that allows for sufficient clearance during assembly, while maintaining proper retention of the rotor blades during turbomachinery operation. SUMMARY

[0005] Aspects and advantages of the rotor assembly, turbomachinery, and method of installing a plurality of rotor blades in a rotor assembly of the present invention according to the present disclosure will be set forth in part in the following Description, or can be obvious from the Description, or can be learned by practice of the technology.

[0006] According to one embodiment, a rotor assembly is provided. The rotor assembly includes a rotor having a dovetail slot. The dovetail slot includes a plurality of recesses and a first radially innermost surface. The rotor assembly also includes a shim and a rotor blade having a platform. An airfoil extends radially outward from the platform, and a dovetail extends radially inward from the platform. The dovetail includes a plurality of protrusions extending in opposite directions and received by the plurality of recesses of the dovetail slot. The dovetail also includes a leading edge surface, a trailing edge surface, and a second radially innermost surface. The dovetail further includes a groove defined along the second radially innermost surface from the leading edge surface to the trailing edge surface. The shim is positioned within the groove and between the first radially innermost surface of the dovetail slot and the second radially innermost surface of the dovetail. The shim extends radially at least partially along both the leading edge surface and the trailing edge surface.

[0007] According to another embodiment, a turbomachine is provided. The turbomachine includes at least one turbine section, a rotor shaft extending axially through the at least one turbine section, and a rotor assembly coupled to the rotor shaft. The rotor assembly includes a rotor having a dovetail slot. The dovetail slot includes a plurality of recesses and a first radially innermost surface. The rotor assembly also includes a shim and a rotor blade having a platform. An airfoil extends radially outward from the platform, and a dovetail extends radially inward from the platform. The dovetail includes a plurality of protrusions extending in opposite directions and received by the plurality of recesses of the dovetail slot. The dovetail includes a leading edge surface, a trailing edge surface, and a second radially innermost surface. The dovetail further includes a groove defined along the second radially innermost surface from the leading edge surface to the trailing edge surface. The shim is positioned within the groove and between the first radially innermost surface of the dovetail slot and the second radially innermost surface of the dovetail. The shim extends radially at least partially along both the leading edge surface and the trailing edge surface.

[0008] According to yet another embodiment, a method of installing a plurality of rotor blades in a rotor assembly is provided. The method includes machining a first reentrant corner and a second reentrant corner onto a dovetail of each rotor blade of the plurality of rotor blades. The first reentrant corner is defined at an intersection between a leading edge surface of the dovetail and a radially innermost surface of the dovetail. The second reentrant corner is defined at an intersection between a trailing edge surface of the dovetail and the radially innermost surface of the dovetail. The method also includes joining the dovetail of each rotor blade into a corresponding dovetail slot defined within a rotor. A groove is defined between the radially innermost surface of the dovetail and a radially innermost surface of the dovetail slot. The method further includes inserting a shim into the groove until a first end of the shim extends axially beyond the trailing edge surface and a second end of the shim extends axially beyond the leading edge surface. The method also includes bending the first end of the shim around the second reentrant corner and bending the second end of the shim around the first reentrant corner.

[0009] These and other features, aspects, and advantages of the rotor assembly, turbomachine, and method of installing a plurality of rotor blades in a rotor assembly of the present technology will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the technology and serve to explain the principles of the technology. BRIEF DESCRIPTION OF DRAWINGS

[0010] A complete and enabling disclosure of the rotor assembly, turbomachine, and method of installing a plurality of rotor blades in a rotor assembly of the present technology, including the best mode of making and using the systems and methods of the present technology, is set forth in this specification with reference to the accompanying drawings, in which:

[0011] Figure 1 is a schematic illustration of a turbomachine according to embodiments of the present disclosure;

[0012] Figure 2 shows a rotor blade according to embodiments of the present disclosure;

[0013] Figure 3 shows a magnified perspective view of a rotor blade dovetail according to embodiments of the present disclosure;

[0014] Figure 4 shows a magnified perspective view of a rotor blade dovetail according to embodiments of the present disclosure;

[0015] Figure 5 shows a magnified perspective view of a rotor blade dovetail according to embodiments of the present disclosure;

[0016] Figure 6 shows a magnified perspective view of a rotor according to embodiments of the present disclosure, showing dovetail slots separate from the rotor blade dovetails;

[0017] Figure 7 shows a perspective view of a shim according to embodiments of the present disclosure;

[0018] Figure 8 shows a magnified perspective view of a shim according to embodiments of the present disclosure;

[0019] Figure 9 shows a cutaway view of a rotor blade engaged with a rotor according to embodiments of the present disclosure;

[0020] Figure 10 shows a radially outward-facing perspective view of an axial retention member positioned relative to a rotor (not including rotor blades) according to embodiments of the present disclosure;

[0021] Figure 11 shows a blown-out perspective view of a rotor blade dovetail and shim according to embodiments of the present disclosure;

[0022] Figure 12 A blowout perspective view of a rotor blade dovetail, shim, and sectioned rotor is shown in accordance with an embodiment of the present disclosure;

[0023] Figure 13 A simplified cross-sectional view of a trench is shown in accordance with an embodiment of the present disclosure;

[0024] Figure 14 A cross-sectional view of a shim is shown in accordance with an embodiment of the present disclosure;

[0025] Figure 15 A cross-sectional view of a rotor assembly is shown in accordance with an embodiment of the present disclosure;

[0026] Figure 16 A cross-sectional view of a rotor assembly is shown in accordance with an embodiment of the present disclosure; and

[0027] Figure 17 is a flowchart showing a method in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] Reference will now be made in detail to embodiments of the rotor assembly, turbomachine, and method of installing a plurality of rotor blades in a rotor assembly of the present application, examples of which are illustrated in the accompanying drawings. Every effort has been made to accurately describe the present technology in the language and manner intended to convey its principles and aspects. No limitation of the scope of the technology claimed is intended by the description appended hereto. Instead, this description is made for the purposes of illustrating the present technology so that it will be understood by those skilled in the art. It will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the technology. For example, features illustrated or described as part of one embodiment, can be used with another embodiment to yield still a further embodiment. It is, therefore, to be understood that it is the claims that are accorded the scope of protection, not the descriptions accompanying them. The present disclosure is intended to cover and embrace all suitable modifications and changes in, or to, the present technology.

[0029] The DETAILED DESCRIPTION uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the present application. As used herein, the terms "first", "second", and "third" can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0030] As used herein, the terms “upstream” (or “upward”) and “downstream” (or “downward”) refer to the relative directions of fluid flow within a fluid passage. For example, “upstream” refers to the direction from which fluid flows, and “downstream” refers to the direction towards which fluid flows. The term “radial” refers to a relative direction substantially perpendicular to the axial centerline of a particular component, the term “axial” refers to a relative direction substantially parallel and / or coaxially aligned with the axial centerline of a particular component, and the term “circumferential” refers to a relative direction extending around the axial centerline of a particular component.

[0031] Approximate terms, such as “generally,” “substantially,” “approximately,” or “about,” include values ​​that are greater than or less than ten percent of the specified value. When used in the context of angles or directions, such terms include values ​​that are greater than or less than ten degrees of the angle or direction. For example, “generally vertical” includes directions within ten degrees of vertical in any direction (e.g., clockwise or counterclockwise).

[0032] Now refer to the attached diagram, Figure 1 A schematic diagram of an exemplary counter-flow steam turbine 100 is shown. Although an exemplary steam turbine has been shown and described herein, this disclosure is not limited to this embodiment or the steam turbine unless otherwise specified in the claims. For example, the invention described herein can be used with any type of turbine, including but not limited to industrial or land-based gas turbines, aircraft gas turbines, or marine gas turbines. Figure 1 As shown, the steam turbine 100 may define an axial direction A and a circumferential direction C extending around the axial direction A. The steam turbine 100 may also define a radial direction R perpendicular to the axial direction A.

[0033] like Figure 1 As shown, the steam turbine 100 may include a first low-pressure (LP) section 105 and a second LP section 110. Each LP section 105 and 110 may include multiple diaphragm stages ( Figure 1 (Not shown in the diagram). In one embodiment, each LP segment 105 and 110 may include eight or more stages arranged adjacent to each other in the axial direction A. The last four stages or “edge stages” in the axial direction A are referred to as stages L0, L1, L2, and L3. The rotor blades of stage L3 are the smallest in the radial direction R, and the rotor blades in the remaining edge stages L2, L1, and L0 have progressively larger dimensions in the radial direction R in the axial direction A.

[0034] The L3 stage is the first stage in the rim stage in the axial direction A and is the smallest in the radial direction R of the rim stage. The L2 stage is the third to last stage and is the next stage in the axial direction A. The LI stage is the second to last stage of the four rim stages. The L0 stage is the last stage and is the largest in the radial direction R. It should be appreciated that the four stages are described as an example only, and the LP sections 105 and 110 can have more or less than four rim stages.

[0035] The rotor shaft 115 can extend through the LP sections 105 and 110. Each LP section 105 and 110 can include a nozzle 120 and 125, respectively. A single outer casing or shell 130 can be split into an upper half section 135 and a lower half section 140, respectively, along a horizontal plane and axially. The single outer casing or shell 130 can span both LP sections 105 and 110. A central section 145 of the shell 130 includes a low pressure steam inlet 150. Within the outer casing or shell 130, the LP sections 105 and 110 are arranged in a single bearing span supported by journal bearings 155 and 160. A splitter 165 extends between the LP sections 105 and 110.

[0036] During operation, the low pressure steam inlet 150 receives low pressure / intermediate temperature steam 170 from a source, such as but not limited to a high pressure (HP) turbine or an intermediate pressure (IP) turbine, through a cross-over pipe (not shown). The steam 170 is directed through the inlet 150, where the splitter 165 splits the steam flow into two opposing flow paths 175 and 180. More specifically, in the example embodiment, the steam 170 is directed through the LP sections 105 and 110, where work is extracted from the steam to rotate the rotor shaft 115. The steam exits the LP sections 105 and 110, where the steam is directed for further processing (e.g., directed to a condenser).

[0037] It should be noted that, as will be appreciated by one of ordinary skill in the art, although the example embodiment is described with respect to a reverse flow LP turbine, the systems and methods of the present disclosure are not limited to use with only LP turbines, but can be used with any reverse flow turbine, including but not limited to IP turbines and / or HP turbines. Furthermore, the systems and methods of the present disclosure are not limited to use with only reverse flow turbines, but can also be used with other turbine types (e.g., single flow steam turbines). Figure 1 A reverse flow LP turbine is shown, but the systems and methods of the present disclosure are not limited to use with only LP turbines, but can be used with any reverse flow turbine, including but not limited to IP turbines and / or HP turbines. Furthermore, the systems and methods of the present disclosure are not limited to use with only reverse flow turbines, but can also be used with other turbine types (e.g., single flow steam turbines).

[0038] Figure 2A schematic perspective view of a steam turbine rotor blade 20 (e.g., within L1 or L0 levels) according to various embodiments of the present disclosure is shown. As shown, the steam turbine rotor blade 20 may include a blade or airfoil 22 having a leading edge 35, a trailing edge 37, a radially outer first end 24, and a radially inner second end 26 opposite to the first end 24. The first end 24 of the airfoil 22 may include a tip 28, which in some embodiments may be coupled to a shroud (not shown). At the second end 26 of the airfoil 22 is a base 30, which includes a dovetail tenon 32 for engagement with a corresponding dovetail groove 36 in the rotor 34. Figure 6 They combine and complement each other.

[0039] The rotor blade 20 may also include a platform 31 generally surrounding the dovetail 32 and the airfoil 22. Typically, the platform may be located at the junction or transition between the airfoil 22 and the dovetail 32, and may extend outward in generally axial and tangential directions, as shown. In various embodiments, the airfoil 22 may extend radially outward from the platform 31, and the dovetail 32 may extend radially inward from the platform 31. In many embodiments, the platform 31 typically serves as a radially inward flow boundary for the working fluid flowing through the steam path.

[0040] like Figure 2 As shown, the groove or tapered groove 33 may extend along the radially inner portion of the dovetail tenon 32. The dovetail tenon 32 may extend between a leading edge face 25 radially inward from the leading edge 35 and a trailing edge face 27 radially inward from the trailing edge 37. The trailing edge face 27 may include a retaining feature 54, as discussed further herein.

[0041] In some embodiments, the tapered groove 33 may be deeper near the leading edge face 25 (i.e., deeper radially into the dovetail tenon), and the depth of the groove 33 gradually decreases as it extends along the dovetail tenon 32 to the trailing edge face 27. As a non-limiting example, the depth of the tapered groove 33 near the leading edge face 25 may be about 0.30 inches, and the depth of the groove 33 near the trailing edge face 27 may be about 0.12 inches. In other embodiments, the depth of the tapered groove 33 near the leading edge face 25 may be between about 0.20 inches and about 0.40 inches. Similarly, in some embodiments, the depth of the groove 33 near the trailing edge face may be between about 0.08 inches and about 0.16 inches.

[0042] Figure 3An enlarged perspective view of a portion of a steam turbine rotor blade 20 is shown. As shown, the dovetail joint 32 may include a body 38, a plurality of protrusions 40 extending in opposite directions from the body 38, a radially innermost surface 46, and a tapered groove 33 extending along the length of the dovetail joint 32 within the radially innermost surface 46. The protrusions 40 are sized to correspond to the dovetail grooves 36. Figure 12 The multiple recesses 44 in the groove are complementary. In several embodiments, the tapered groove 33 opens at the innermost radial surface 46, and its dimensions are set to engage the gasket 52. Figure 7 ,by Figure 12 (As shown). The tapered groove 33 extends along the entire radial innermost surface 46 of the body 38. In various embodiments, the body 38 includes a spherical segment 48 for complementing one of the plurality of recesses 44 in the dovetail groove 36.

[0043] Figure 4 An enlarged perspective view of the leading edge surface 25 of the dovetail tenon 32 according to an embodiment of this disclosure is shown. Similarly, Figure 5 An enlarged perspective view of the trailing edge surface 27 is shown. As shown, the dovetail 32 may also include a first corner 200 defined at the intersection between the leading edge surface 25 and the radially innermost surface 46 of the dovetail 32. Similarly, a second corner 202 may be defined at the intersection between the trailing surface 27 and the radially innermost surface 46. Figure 4 and Figure 5 As shown, the first corner 200 and the second corner 202 may be arcuate and / or generally smooth curved surfaces. In many embodiments, the first corner 200 and the second corner 202 may be at least partially used to provide a smooth surface for folding around the end of the gasket 52 without causing the gasket 52 to crack and / or break.

[0044] like Figure 4 As shown, in some embodiments, the first corner 200 and / or the second corner 202 may include an axial recess 204 relative to the leading edge surface 25. Specifically, the axial recess 204 may include an axially extending portion 206 and a radially extending portion 208 intersecting each other. Specifically, the axially extending portion 206 may be substantially perpendicular to the leading edge surface 25 and may extend between the leading edge surface 25 and the radially extending portion 208. The radially extending portion 208 may be substantially parallel to the leading edge surface 25 and may extend between the axially extending portion 206 and the first corner 200 and / or the radially innermost surface 46. The radially extending portion 208 of the axial recess 204 may be axially disposed inward from the leading edge surface 25. Although Figure 5 Not shown in the figure, but in many embodiments, the second corner 202 may also include an axial recess 204 relative to the trailing edge surface 27.

[0045] Figure 6 A rotor 34 (e.g., a steam turbine rotor) is shown that includes a plurality of dovetail slots 36 for coupling with dovetail tenons 32 of rotor blades 20. Each dovetail slot 36 of the plurality of dovetail slots 36 includes a plurality of recesses 44 that can be sized to receive a plurality of protrusions 40 extending from each dovetail tenon 32. Additionally, as shown, each dovetail slot 36 can include a radially innermost surface 210. The radially innermost surface 210 of the dovetail slot 36 can contact either or both of the radially innermost surface 46 of the dovetail tenon 32 and / or the shim 52 when the dovetail tenon 32 is installed in the dovetail slot 36. Figure 6

[0046] Figure 7 and Figure 8 The shim 52 is shown in greater detail. In various embodiments, the shim 52 can be sized to engage the tapered groove 33 in the rotor blade 20 and to hold the rotor blade 20 within the dovetail slot 36. In many embodiments, the shim 52 can include a body 68 having a first thickness (ti) measured between an upper or radially outer surface 70 and a lower or first radially inner surface 72 of the body 68. A thinned region 74 can extend from one end of the body 68 (e.g., the thicker end of the shim 52) and can include a second thickness (t2) measured between the radially outer surface 70 (which is continuous between the body 68 and the thinned region 74) and a thinned radially inner surface or second radially inner surface 76.

[0047] In some embodiments, the second thickness (t2) is between about 5% and about 70% of the first thickness (ti). In other embodiments, the second thickness (t2) is between about 15% and about 60% of the first thickness (ti). In many embodiments, the second thickness (t2) is between about 25% and about 50% of the first thickness (ti). In various embodiments, the second thickness (t2) is between about 35% and about 45% of the first thickness (ti). Connecting the body 68 and the thinned region 74 is a first tapered region 78 that tapers outwardly from the body 68 to the thinned region 74. In various embodiments, the length (I TR ) of the thinned region 74 can be equal to approximately one quarter of the length (I MB ) of the body 68, or one eighth of the length of the body 68, or three sixteenths of the length of the body 68, or between about 10% and about 25% of the length of the body 68.

[0048] ​In many embodiments, when the shim 52 is installed between the rotor 34 and the rotor blade 20, the radially outer surface 70 may contact the rotor blade 20, and the first radially inner surface 72 may contact the rotor 34 to advantageously retain the rotor blade 20 within the dovetail groove 36. It should be understood that the shim 52 may be inserted into the tapered groove 33 in a forward or rearward direction, depending on the clearance and desired installation technique.

[0049] As described herein, the gasket 52 is configured to fit within the tapered groove 33 and is located between the dovetail joint 32 of the rotor blade 20 and the dovetail groove 36 of the rotor 34, and helps to retain the rotor blade 20 within the rotor 34. Furthermore, in various embodiments, the thinning region 74 improves the ease of installing and removing the gasket 52 within the tight clearance of the steam turbine. That is, the thinning region 74 allows for flexure of the gasket 52 or folding of the end of the gasket 52 to lock the gasket to the rotor 34, for example, by folding the end of the gasket 52 above the first bend 200 and the second bend 202. Figure 4 and Figure 5 ).

[0050] The thinning region 74 is preferably located on the thicker end of the gasket 52, because the thicker end will be more difficult to fold than the relatively thinner end. Thinning of region 74 ensures a proper fold-to-thickness ratio so that cold working does not result in cracking or areas of high residual stress. The thickness reduction facilitates the folding of a portion of the gasket 52 to lock it to the rotor 34, and the opposite end near the thinner end can be folded in a similar manner to lock the gasket 52 to the rotor 34.

[0051] A key reason for the need for a fold at the thicker end is that, during operation, the radial clearance between the rotor dovetail bottom 210 and the blade dovetail bottom 46 can increase due to mechanical growth. This radial clearance will allow the wedge or shim to move toward the thinner end during operation, and then return to its normal height during shutdown. Since the wedge / shim may have moved forward and filled the large clearance, there will be no space for the blade to return to a stress-free state during shutdown. The filled radial clearance will cause excessive compression of the wedge / shim, making the stress potentially exceed the wedge's yield and / or disassembly, and making it virtually impossible to remove the wedge / shim due to the extremely high compressive load.

[0052] Figure 9 A cross-sectional view is shown of a rotor blade 20 engaged with a rotor 34 and a portion of an axially retaining member 64 within a space 66 for axially retaining the rotor blade 20 within the rotor 34. Figure 9As shown, the rotor blade 20 may also include an axially retaining feature 54 extending from a side surface 56 of the body 38. In many embodiments, the side surface 56 may be a leading edge surface 25, a trailing edge surface 27, or both. However, in Figure 9 In the illustrated embodiments, the axial retaining feature extends from the trailing edge surface 27. In many embodiments, the axial retaining feature 54 may include a hook 58 having a first member 60 extending generally perpendicularly from the trailing edge surface 27 and a second member 62 extending generally parallel to the trailing edge surface 27 from the first member 60. As further described herein, the axial retaining feature 54 may be used to provide space in which the axial retaining member 64 can be fitted to axially retain the dovetail tenon 32 within the dovetail groove 36. In various embodiments, the axial retaining feature 54 defines a space 66 between the second member 62 and the trailing edge surface 27, the dimensions of which are configured to engage the axial retaining member 64.

[0053] Figure 10 A radially outward perspective view (excluding blade 20) of an axial retaining member 64 positioned relative to rotor 34 is shown. In some cases, the axial retaining member 64 also includes an anti-rotation protrusion 65 for engaging hook 58. Figure 9 And to prevent the axial retaining member 64 from rotating within the space 66. Figure 9 Additionally, the anti-rotation pin 67 can be connected to the rotor 34 to prevent radial movement of the axial retaining member 64 within the space 66.

[0054] Figure 11 and Figure 12 A blown-out perspective view of rotor blade 20, rotor 34, and shim 52 is shown. Figure 11 As shown, the tapered groove 33 is provided along the radial innermost surface 46 of the dovetail tenon 32 of the rotor blade 20, and is positioned opposite to the radial innermost surface 210 within the dovetail groove 36 of the rotor 34. Similarly, the shim 52 can be sized to fit within the tapered groove 33 of the dovetail tenon 32 to space the radial innermost surface 210 of the dovetail groove 36 and the radial innermost surface 46 of the dovetail tenon 32, so that the rotor blade 20 is properly constrained within the rotor 34 during various operations of the steam turbine 100.

[0055] In many embodiments, the shim 52 serves to provide a rigid solution for locking the dovetail tenon 32 of the rotor blade 20 into the dovetail groove 36 of the rotor 34. Furthermore, in various embodiments, the shim 52 can be rigid, such that it retains the rotor blade 20 within the rotor 34 without folding, deflecting, buckling, or moving during operation of the steam turbine. In this way, the shim 52 may be superior to other flexible means of retaining the rotor blade 20 within the rotor 34 because it does not fold, deflect, or move during operation of the steam turbine 100.

[0056] As described herein, rotor blade 20 can be an L1-level rotor blade 20 and / or an L0-level rotor blade 20, meaning that rotor blade 20 can be much larger and heavier when compared to rotor blades in L2 and L3 levels. For example, the length of L0 and / or L1-level rotor blade 20 can be between about 20 inches and about 30 inches, and it can have a weight of more than 20 pounds. In some embodiments, L0 and / or L1-level rotor blade 20 can have a weight of more than 100 pounds. In other embodiments, L0 and / or L1-level rotor blade 20 can have a weight of more than 200 pounds. Therefore, the relatively larger L0 and / or L1-level rotor blade 20 will exert a much larger torque on the dovetail groove 36 of rotor 34 when compared to L2 and / or L3 levels. Therefore, elastic holding solutions (such as springs) that can successfully hold smaller L2 and / or L3-level rotor blades cannot accommodate the relatively larger and heavier L0 and / or L1-level rotor blade 20 due to their size and weight. Therefore, a robust and rigid retention solution (such as the gasket 52 shown and described herein) is required to accommodate the large L0 and / or L1 rotor blades 20.

[0057] Figure 13 A simplified cross-sectional view of a tapered groove 33 according to various embodiments is shown. As shown, the tapered groove 33 may include a flat portion 1101 near the leading edge surface 25 and / or the trailing edge surface 27, wherein the flat portion 1101 has a constant depth (i.e., it is not tapered). The tapered groove 33 at its deep end ( Figure 13 The depth 1102 at the left side is greater than that at the opposite end ( Figure 13 The depth of 1103 (and depth of 1104) is near the right side.

[0058] The flat section 1101 has a constant depth 1104 along its entire length. In some embodiments, the length of the flat section 1101 may be from about 3% to about 20% of the total length of the tapered groove 33. In other embodiments, the length of the flat section 1101 may be from about 5% to about 18% of the total length of the tapered groove 33. In various embodiments, the length of the flat section 1101 may be from about 7% to about 15% of the total length of the tapered groove 33. In many embodiments, the length of the flat section 1101 may be from about 9% to about 13% of the total length of the tapered groove 33.

[0059] The flat section 1101 facilitates the removal / removal of the gasket 52 after turbine operation and allows for on-site removal without the need for cutting tools. The flat section 1101 allows for greater clearance at the thin end of the wedge. This clearance allows the thin end to bend back almost straight, enabling the wedge to be tapped towards the thicker end. Without this additional clearance area, the end bend would create a "mushroom-shaped" fold area and would not allow for easy removal of the thin end. Furthermore, the flat section 1101 serves as a third-level reference for machining and inspecting the blades, as using a grooved taper would not be prudent or robust.

[0060] Figure 14 A simplified cross-sectional view of gasket 52 is shown. Gasket 52 includes a thick end 77 and an opposing thin end 75, with the overall thickness gradually transitioning between the opposing ends. A thinning region 74 is a region where the thickness decreases, allowing gasket 52 to be folded over corners 200, 202 to lock it in place. This is particularly effective when the two ends of the gasket are folded over corners 200, 202, as it prevents the gasket from moving in the axial direction (relative to the turbine). For example, the first end 75 of gasket 52 may have a first thickness 1202, and the opposing second end 77 of the gasket may have a second thickness 1201, wherein the second thickness 1201 is greater than the first thickness 1202. The intermediate height of gasket 52 gradually transitions from the first height 1202 to the second height 1201.

[0061] As shown and described herein, the gasket 52 may be tapered to perfectly match the dimensions of the tapered groove 33, such that the gasket is securely received and contained within the tapered groove 33. Therefore, the gasket 52 may be tapered to allow easy insertion into the tapered groove 33. Thus, a tapered gasket 52 may be superior to other types of gaskets (e.g., flat gaskets) because it is easier to insert into the tapered groove 33. For example, due to the tight tolerances and substantial weight of the LO and / or L1 rotor blades 20, it may be difficult or impossible to insert a flat gasket. Therefore, a tapered gasket, such as the tapered gasket 52 shown and described herein, may be advantageous.

[0062] In many embodiments, the gasket thinning region 74 may extend from the second (thicker) end 77 to the first tapered region 78. The first tapered region 78 allows the gasket 52 to transition from the thinning region 74 to the body 68. In various embodiments, as shown, the thickness of the gasket 52 may increase from the thinning region 74 to the body 68. In many embodiments, the thickness of the body 68 of the gasket may subsequently gradually decrease from the first tapered region 78 to the first (thinner) end 75.

[0063] Figure 15 A rotor assembly 300 according to an embodiment of the present disclosure is shown. (As shown) Figure 15As shown, the gasket 52 can be installed in the tapered groove 33 (not shown for clarity), and the ends of the gasket 52 can be folded over corners 200, 202. With both ends of the gasket 52 folded (as shown), axial movement of the gasket 52 relative to the wheel / rotor 34 is prevented (i.e., in...). Figure 15 (Move left or right). When the end is folded during installation, the curved and / or bow-shaped corners 200, 202 can advantageously reduce cold working stress on the gasket 52.

[0064] like Figure 15 As shown, the dovetail joint 32 may include a leading edge surface 25, a trailing edge surface 27, and a radially innermost surface 46 extending therebetween. In many embodiments, a gasket 52 may be positioned within a groove 33 (not shown) and between the radially innermost surface 46 of the dovetail joint 32 and the radially innermost surface 210 of the dovetail groove 36. Figure 15 As shown, the gasket 52 may extend radially at least partially along both the leading edge surface 25 and the trailing edge surface 27. In many embodiments, as shown, the gasket 52 may include a first radially extending portion 304 extending along the leading edge surface 25 and contacting the leading edge surface, and a second radially extending portion 306 extending along the trailing edge surface 27 and contacting the trailing edge surface. An axially extending portion 308 may be disposed within the groove 33 and positioned between the radially innermost surface 46 of the dovetail joint 32 and the radially innermost surface 210 of the dovetail groove 36 of the rotor 34.

[0065] In various embodiments, the first radial extension 304, the second radial extension 306, and the axial extension 308 may extend continuously from one another. For example, the first radial extension 304 of the gasket 52 may transition to the axial extension 308 of the gasket 52 at a first bend 305. Similarly, the second radial extension 306 of the gasket 52 may transition to the axial extension 308 of the gasket 52 at a second bend 307. Figure 15 As shown, the first curved portion 305 of the gasket 52 may be disposed between the first radially extending portion 304 and the axially extending portion 308. In many embodiments, the first curved portion 305 of the gasket 52 may extend along and contact the first corner 200, which is disposed between the leading edge surface 25 and the radially innermost surface 46 of the dovetail tenon 32.

[0066] Similarly, a second curved portion 307 of the gasket 52 may be disposed between the second radially extending portion 306 and the axially extending portion 308 of the gasket 52. Additionally, the second curved portion 307 may extend along and contact a second bend 202 disposed between the trailing edge surface 27 and the radially innermost surface 46 of the dovetail tenon 52. As shown and described herein, the first radially extending portion 304 and the second radially extending portion 306, as well as the first curved portion 305 and the second curved portion 307 of the gasket 52, can be used to advantageously provide axial retention of the dovetail tenon 32 within the rotor 34.

[0067] like Figure 15 As shown, the first corner 200 of the dovetail tenon 32 may be defined at the intersection between the leading edge surface 25 and the radially innermost surface 46 of the dovetail tenon 32. Similarly, the second corner 202 of the dovetail tenon 32 may be defined at the intersection between the trailing edge surface 27 and the radially innermost surface 46 of the dovetail tenon 32. As shown, the first corner 200 and the second corner 202 may be curved, arcuate, and / or substantially smooth surfaces located between the generally radially oriented leading edge surface 25 and trailing edge surface 27 of the dovetail tenon 32 and the generally axially oriented radially innermost surface 46.

[0068] The first and second corners 200 can be used to provide a smooth surface so that the end of the gasket 52 can be bent around it during installation without cracking. The radii of the corners 200, 202 are important because, for example, if the corner radii are too small (too small a bend and too sharp an angle), the end of the gasket 52 may crack and / or break during installation when folded over the corners 200, 202. Therefore, it is advantageous that the radii of the corners 200, 202 are at least 150% of the thickness of the gasket 52 at its ends. For example, in many embodiments, the radii of the corners 200, 202 may be between about 150% and about 300% of the thickness of the gasket 52 at its ends 75, 77. In other embodiments, the radii of the corners 200, 202 may be between about 175% and about 275% of the thickness of the gasket 52 at its ends 75, 77. In various embodiments, the radii of corners 200, 202 may be between about 200% and about 250% of the thickness of gasket 52 at its ends 75, 77. In a particular embodiment, the radius of corners 200, 202 may be about 225% of the thickness of gasket 52 at its ends 75, 77.

[0069] For several reasons, it may be advantageous to machine the first corner 200 and the second corner 202 onto the dovetail joint 32, rather than onto, for example, the rotor 34, as shown in the figure. Specifically, machining the first corner 200 and the second corner 202 onto the dovetail joint 32 instead of the rotor may involve fewer associated risks and be more cost-effective. For example, due to the complex shape of the rotor 34, machining the corners 200 and 202 onto the rotor 34 may be difficult, potentially leading to unwanted stress gradients within the rotor 34, and possibly resulting in the scrapping of the relatively expensive rotor 34 if not handled properly. However, compared to the rotor 34, it is much easier to machine the corners 200 and 202 onto the dovetail joint 32 of the rotor blade 20 due to the geometry and dimensions of the integral rotor blade 20. Furthermore, machining the corners 200 and 202 onto the dovetail joint 32 involves fewer associated risks compared to the rotor 34, because the rotor blade 20 is a lower-cost part to manufacture. Therefore, if an error occurs during the machining of corners 200 and 202, replacing a single rotor blade 20 will be more cost-effective than replacing the entire rotor 34.

[0070] like Figure 14 and Figure 15 As shown, the gasket 52 may further include a radially outer surface 70, a first radially inner surface 72, and a second radially inner surface 76. As shown, the radially outer surface 70 may extend continuously along the leading edge surface 25, the first corner 200, the groove 33, the second corner 202, and the trailing edge surface 27, and contact the leading edge surface, the first corner, the groove, the second corner, and the trailing edge surface without any contact gaps or spaces. Advantageously, the radially outer surface 70 of the gasket 52 has as much contact as possible with the radially innermost surface 46 of the dovetail joint 32 to maintain the gasket 52's retention during operation of the steam turbine 32. The first radially inner surface 72 may be spaced apart from the radially outer surface 70 and may extend along the radially innermost surface 210 of the dovetail groove 36. The second radially inner surface 76 may be spaced apart from the radially outer surface 70 and the radially innermost surface 210 of the rotor 34 dovetail groove 36. As shown, the second radially inner surface 76 may not contact any other surface, i.e., it may be exposed to ambient air.

[0071] Figure 16Another rotor assembly 300 according to an embodiment of the present disclosure is shown. As shown, the rotor assembly 300 may further include a first axial recess 204 relative to a leading edge surface 25 and a second axial recess 205 relative to a trailing edge surface 27. Specifically, each of the axial recesses 204, 205 may include intersecting axial extensions 206, 207 and radial extensions 208, 209. Specifically, the axial extension 206 on the leading edge side may be substantially perpendicular to the leading edge surface 25 and may extend between the leading edge surface 25 and the radial extension 208. The radial extension 208 may be substantially parallel to the leading edge surface 25 and may extend between the axial extension 206 and the first corner 200 and / or the radially innermost surface 46. Similarly, the axial extension 207 of the second axial recess 205 may be substantially perpendicular to the trailing edge surface 27 and may extend between the trailing edge surface 27 and the radial extension 209. The radial extension 209 of the second axial recess 205 may be substantially parallel to the trailing edge surface 27 and may extend between the axial extension 207 and the second corner 202 and / or the radial innermost surface 46.

[0072] The radially extending portions 208 and 209 of the axial recesses 204 and 205 may be axially spaced from the leading edge surface 25 or the trailing edge surface 27 to provide a protective pocket for the ends of the gasket 52 from corrosion caused by the steam path 302. In this way, portions of the gasket 52 extending along the corners 200 and 202 may be advantageously positioned outside or away from the steam path 302 to extend the life of the gasket 52 and prevent end corrosion. Undesirable corrosion of the ends of the gasket 52 may cause the gasket 52 to retract (i.e., be removed) from the groove 33 during operation of the steam turbine 100. Therefore, the axial recesses 204 and 205 advantageously provide a protective pocket for the radially extending portions 304 and 306 and the curved portions 305 and 307 spaced from the steam path 302 to prevent undesirable corrosion.

[0073] Figure 17 A flowchart is provided illustrating an example method 400 for mounting multiple rotor blades (such as rotor blade 20 and rotor 34 as described herein) within a rotor according to one or more exemplary embodiments of this disclosure. Figure 17 As shown, method 400 may include step 402 of machining a first concave angle 200 and a second concave angle 202 onto a dovetail tenon 32 of each of a plurality of rotor blades 20. The first concave angle 200 may be defined at the intersection between the leading edge surface 25 of the dovetail tenon 32 and the radially innermost surface 46 of the dovetail tenon 32. The second concave angle 202 may be defined at the intersection between the trailing edge surface 27 of the dovetail tenon 32 and the radially innermost surface 46 of the dovetail tenon 32.

[0074] In many embodiments, method 400 may further include step 404 of engaging the dovetail tenon 32 of each rotor blade 20 into a corresponding dovetail groove 36 defined within the rotor 34. A groove 33 may be defined between the radially innermost surface 46 of the dovetail tenon 32 and the radially innermost surface 210 of the dovetail groove 36. In various embodiments, method 400 may further include step 406 of inserting a shim 52 into the groove 33 until a first end 75 of the shim 52 extends axially beyond the trailing edge surface 27 and a second end 77 of the shim 52 extends axially beyond the leading edge surface 25. In many embodiments, method 400 may further include step 408 of folding the first end 75 of the shim around a second concave angle 202. In some embodiments, method 400 may include step 410 of folding the second end 77 of the shim 52 around a first concave angle 200. In some embodiments, step 406 occurs before either or both of steps 408 and 410 to ensure that the shim is fully inserted into the groove 33. The order of steps 408 and 410 can be reversed.

[0075] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims and may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A rotor assembly, the rotor assembly comprising: The rotor (34) has a dovetail groove (36) including a plurality of recesses (44) and a first radial innermost surface (210). Gasket (52), the gasket including a thick end (77), an opposing thin end (75), and a thinned region (74) extending from the thick end (77); and Rotor blade (20), the rotor blade having a platform (31), an airfoil (22) extending radially outward from the platform (31), and a dovetail tenon (32) extending radially inward from the platform (31), the dovetail tenon (32) comprising a plurality of protrusions (40) extending in opposite directions and received by the plurality of recesses (44) of the dovetail groove (36), the dovetail tenon (32) comprising: Leading edge surface (25); Trailing edge surface (27); The second radial innermost surface (46); and A groove (33) is defined along the second radial innermost surface (46) from the leading edge surface (25) to the trailing edge surface (27), wherein the groove is configured as a tapered groove, the tapered groove including a flat section near the leading edge surface and / or the trailing edge surface, wherein the flat section has a constant depth, and wherein the depth of the tapered groove at the deep end is greater than the depth near the opposite end, wherein the gasket (52) is positioned within the groove (33) and between the first radial innermost surface (210) and the second radial innermost surface (46), and wherein the gasket (52) extends at least partially radially along both the leading edge surface (25) and the trailing edge surface (27).

2. The rotor assembly according to claim 1, wherein the gasket (52) comprises: A first radial extension portion (304) extends along the leading edge surface (25) and contacts the leading edge surface; A second radial extension portion (306) extends along the trailing edge surface (27) and contacts the trailing edge surface; And an axially extending portion, which is disposed within the groove (33) and between the first radial innermost surface (210) and the second radial innermost surface (46).

3. The rotor assembly of claim 1, wherein a first corner (200) is defined at the junction between the leading edge surface (25) and the second radial innermost surface (46), and a second corner (202) is defined at the junction between the trailing edge surface and the second radial innermost surface (46), wherein the first corner (200) and the second corner (202) are arc-shaped.

4. The rotor assembly according to claim 3, wherein the first corner (200) is axially recessed relative to the leading edge surface (25), and the second corner (202) is axially recessed relative to the trailing edge surface (27).

5. The rotor assembly according to claim 4, wherein the gasket (52) is positioned to contact the first corner (200) and the second corner (202) such that the gasket (52) is outside the steam path.

6. The rotor assembly of claim 3, wherein the gasket (52) includes a radially outer surface (70) that extends along and contacts the leading edge surface (25), the first corner (200), the groove (33), the second corner (202), and the trailing edge surface (27).

7. The rotor assembly according to claim 2, wherein the gasket (52) includes a first radial inner surface (72) extending along the first radial innermost surface (210) of the dovetail groove (36) and a second radial inner surface (76) spaced apart from the first radial innermost surface (210) of the dovetail groove (36).

8. The rotor assembly of claim 1, wherein the groove (33) includes a depth radially defined within the dovetail tenon (32), and wherein the depth varies from the leading edge surface (25) to the trailing edge surface (27).

9. The rotor assembly of claim 1, wherein the groove (33) includes a first depth at the leading edge surface and a second depth at the trailing edge surface, and wherein the groove (33) tapers gradually from the first depth to the second depth along the second radial innermost surface (46).

10. A method for mounting a plurality of rotor blades in a rotor assembly, the method comprising: The first corner and the second corner are machined onto the dovetail joint (32) of each of the plurality of rotor blades (20), wherein the first corner is defined at the intersection between the leading edge surface (25) of the dovetail joint (32) and the second radial innermost surface of the dovetail joint (32), and the second corner is defined at the intersection between the trailing edge surface (27) of the dovetail joint (32) and the second radial innermost surface; The dovetail tenon (32) of each rotor blade (20) is engaged into a corresponding dovetail groove (36) defined within the rotor (34), wherein the groove (33) is defined between the second radial innermost surface of the dovetail tenon (32) and the first radial innermost surface of the dovetail groove (36), wherein the groove is constructed as a tapered groove, the tapered groove including a flat section near the leading edge surface and / or the trailing edge surface, wherein the flat section has a constant depth, and wherein the depth of the tapered groove at the deep end is greater than the depth near the opposite end; Insert the pad (52) into the groove (33) until the first end of the pad (52) extends axially beyond the trailing edge surface and the second end of the pad (52) extends axially beyond the leading edge surface, wherein the pad (52) includes a thick end (77), an opposite thin end (75) and a thinned region (74) extending from the thick end (77). Fold the first end of the gasket (52) around the second corner; and The second end of the gasket (52) is folded around the first corner.

11. The method of claim 10, wherein the step of folding the first end of the gasket (52) around the second corner causes the first end of the gasket (52) to no longer extend axially beyond the trailing edge surface (27).

12. The method of claim 10, wherein the step of folding the second end of the gasket (52) around the first corner causes the second end of the gasket (52) to no longer extend axially beyond the leading edge surface (25).

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