阅读说明：本技术 改进的转子叶片阻尼结构 (Improved rotor blade damping structure ) 是由 马丁·詹姆斯·贾斯珀 C·W·韦尔斯 于 2021-03-12 设计创作，主要内容包括：本发明题为“改进的转子叶片阻尼结构”。本发明提供了转子叶片(30)和涡轮机。转子叶片(30)包括具有柄部(38)、平台(42)和从柄部(38)径向向外延伸的翼型件(36)的主体(35)。主体(35)还包括压力侧冲击面(56)和吸力侧冲击面(58)。压力侧冲击面(56)和吸力侧冲击面(58)中的每一者均包括阻尼器刃带(90)、(120)并限定狭槽(70)。阻尼器刃带(90)、(120)从狭槽(70)径向向内设置。(The invention provides an improved rotor blade damping structure. The invention provides a rotor blade (30) and a turbine. The rotor blade (30) includes a body (35) having a shank (38), a platform (42), and an airfoil (36) extending radially outward from the shank (38). The body (35) also includes a pressure side impact surface (56) and a suction side impact surface (58). Each of the pressure side slash face (56) and the suction side slash face (58) includes a damper land (90), (120) and defines a slot (70). The damper lands (90), (120) are disposed radially inward from the slot (70).)

1. A rotor blade (30) for a turbomachine, the rotor blade (30) comprising:

a body (35) having a shank (38), a platform (42), and an airfoil (36) extending radially outward from the shank (38), the body (35) including a pressure side impingement surface (56) and a suction side impingement surface (58);

wherein each of the pressure side impact face (56) and the suction side impact face (58) includes a damper land (90), (120) and defines a slot (70); and is

Wherein the damper land (90) of the pressure side slash face (56) is disposed radially inward from the slot (70) of the pressure side slash face (56) and the damper land (120) of the suction side slash face (58) is disposed radially inward from the slot (70) of the suction side slash face (58).

2. The rotor blade (30) of claim 1, wherein the damper land (90) of the pressure side impact face (56) and the damper land (120) of the suction side impact face (58) each include a first end (92), (122) and a second end (94), (124), the first end (92), (122) being spaced apart from the second end (94), (124) in an axial direction.

3. The rotor blade (30) of claim 2, wherein the suction side slash face (58) further comprises one or more undercuts (100), (102) positioned radially inward of the first end (122) and the second end (124) of the damper blade (120) of the suction side slash face (58), wherein each of the one or more undercuts (100), (102) has a maximum undercut depth (106) defined in the circumferential direction.

4. The rotor blade (30) as recited in any one of claims 2-3, wherein the pressure side impact face (56) further comprises one or more undercuts (100), (102) positioned radially inward of the first and second ends (92), (94) of the damper land (90) of the pressure side impact face (56), wherein each of the one or more undercuts (100), (102) has a maximum undercut depth (106) defined in the circumferential direction.

5. The rotor blade (30) of claim 4, wherein each of the one or more undercuts (100), (102) is arcuate.

6. The rotor blade (30) of any of claims 4-5, wherein the maximum undercut depth (106) of each of the one or more undercuts (100), (102) is up to about 1.5 inches.

7. Rotor blade (30) according to any of claims 4 to 6, wherein the one or more undercuts (100), (102) at least partially define the slot (70) of the pressure side impact surface (56).

8. Rotor blade (30) according to any of claims 1 to 7, wherein the slot (70) of the pressure side impact surface (56) and the slot (70) of the suction side impact surface (58) each comprise a leading edge section (72), a platform section (74) and a trailing edge section (76); and wherein the leading edge segment (72) is defined along a leading edge face (52), the platform segment (74) is defined along the platform (42), and the trailing edge segment (76) is defined along a trailing edge face (54).

9. The rotor blade (30) of claim 8, wherein the damper land (90) of the pressure side impingement face (56) is positioned radially inward of the platform segment (74) of the slot (70) defined in the pressure side impingement face (56); and wherein the damper land (120) of the suction side slash face (58) is positioned radially inward of the platform segment (74) of the slot (70) defined in the suction side slash face (58).

10. A turbomachine, comprising:

a compressor section (14);

a combustor section (16);

a turbine section (18);

a plurality of rotor blades (30) disposed in at least one of the compressor section (14) or the turbine section (18), each of the plurality of rotor blades (30) comprising:

a body (35) having a shank (38), a platform (42), and an airfoil (36) extending radially outward from the shank (38), the body (35) including a pressure side impingement surface and a suction side impingement surface (58);

wherein each of the pressure side impact face (56) and the suction side impact face (58) each include a damper land (90), (120) and define a slot (70); and is

Wherein the damper land (90) of the pressure side slash face (56) is disposed radially inward from the slot (70) of the pressure side slash face (56) and the damper land (120) of the suction side slash face (58) is disposed radially inward from the slot (70) of the suction side slash face (58).

11. The turbomachine of claim 10, wherein the damper land (90) of the pressure side slash face (56) and the damper land (120) of the suction side slash face (58) each include a first end (92), (122) and a second end (94), (124), the first end (92), (122) being spaced apart from the second end (94), (124) in an axial direction.

12. The turbomachine of claim 11, wherein the suction side slash face (58) further comprises one or more undercuts (100), (102) positioned radially inward of the first end (122) and the second end (124) of the damper land (120) of the suction side slash face (58), wherein each of the one or more undercuts (100), (102) has a maximum undercut depth (106) defined in the circumferential direction.

13. The turbomachine of any one of claims 11 to 12, wherein the pressure side impingement face (56) further comprises one or more undercuts (100), (102) positioned radially inward of the first and second ends (92), (94) of the damper land (90) of the pressure side impingement face (56), wherein each of the one or more undercuts (100), (102) has a maximum undercut depth (106) defined in the circumferential direction.

14. The turbomachine of claim 13, wherein each of the one or more undercuts (100), (102) is arcuate.

15. The turbomachine of any one of claims 13 to 14, wherein the maximum undercut depth (106) of each of the one or more undercuts (100), (102) is up to about 1.5 inches.

Technical Field

The present disclosure relates generally to rotor blades for turbomachinery and, more particularly, to an improved rotor blade damping structure.

Background

Turbomachines are used in various industries and applications for energy transfer purposes. For example, gas turbine engines typically include a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section gradually increases the pressure of the working fluid entering the gas turbine engine and supplies the compressed working fluid to the combustion section. The compressed working fluid and a fuel (e.g., natural gas) are mixed within the combustion section and combusted in the combustion chamber to generate high pressure and temperature combustion gases. The combustion gases flow from the combustion section into a turbine section where the combustion gases expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected to, for example, an electrical generator to produce electrical power. The combustion gases then exit the gas turbine via an exhaust section.

The compressor section and the turbine section generally include a plurality of rotor blades, typically arranged in a plurality of stages. During operation of the engine, vibrations may be introduced into the rotor blades. For example, flow fluctuations of the compressed working fluid or hot combustion gases or steam may cause the rotor blades to vibrate. One of the basic design considerations of turbine designers is to avoid or minimize resonance with the natural frequency of the rotor blades and dynamic stresses resulting from forced response and/or aeroelastic instability, thereby controlling high cycle fatigue of the rotor blades.

For example, to improve the high cycle fatigue life of the rotor blades, vibration dampers are typically provided below and/or between the platforms to frictionally dissipate vibration energy and reduce the corresponding amplitude of vibration during operation.

There are problems with using vibration dampers in known rotor blade platforms. The design of the rotor blade platform directly affects the effect of the vibration damper during operation. For example, one known problem is that the stiffness of known blade platforms required to maintain structural integrity results in a lower vibration damping effect. Another problem with many known blade platforms is the limited space on the platform itself to mount the vibration damper. For example, the use of vibration dampers on blade platforms may limit or inhibit the use of leak-proof seals due to lack of space.

Accordingly, there is a need in the art for improved rotor blade platform designs. In particular, platforms providing reduced stiffness while still providing the required structural integrity to the blade are desired. Furthermore, rotor blade platform designs that allow for the use of both vibration dampers and platform seals are desired.

Disclosure of Invention

Aspects and advantages of rotor blades and turbines according to the present disclosure will be set forth in part in the description which follows, or may be obvious from the description, or may be learned by practice of the present techniques.

According to one embodiment, a rotor blade for a turbomachine is provided. The rotor blade includes a body having a shank, a platform, and an airfoil extending radially outward from the shank. The body also includes a pressure side impact surface and a suction side impact surface. Each of the pressure side and suction side slash faces includes a dampener land and defines a slot. The damper land is disposed radially inward from the slot in both the pressure side impingement face and the suction side impingement face.

According to another embodiment, a turbine is provided. The turbomachine includes a compressor section, a combustor section, and a turbine section. The turbomachine also includes a plurality of rotor blades disposed in at least one of the compressor section or the turbine section. Each rotor blade of the plurality of rotor blades includes a body having a shank, a platform, and an airfoil extending radially outward from the shank. The body includes a pressure side impact surface and a suction side impact surface. Each of the pressure side and suction side slash faces includes a dampener land and defines a slot. The damper land is disposed radially inward from the slot in both the pressure side impingement face and the suction side impingement face.

These and other features, aspects, and advantages of the rotor blades and turbines of the present invention 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 together with the description, serve to explain the principles of the technology.

Drawings

A full and enabling disclosure of the damper stack, rotor blade, and turbine of the present invention, including the best mode of making and using the system and method of the present invention, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 shows a schematic view of a turbomachine in accordance with an embodiment of the present disclosure;

FIG. 2 illustrates a pressure side perspective view of a rotor blade according to an embodiment of the present disclosure;

FIG. 3 illustrates a suction side perspective view of a rotor blade and a damper pin according to an embodiment of the present disclosure;

FIG. 4 is a side view illustrating adjacent rotor blades according to an embodiment of the present disclosure;

FIG. 5 illustrates an enlarged pressure side perspective view of a rotor blade according to an embodiment of the present disclosure;

FIG. 6 illustrates an enlarged pressure side perspective view of a rotor blade according to other embodiments of the present disclosure;

FIG. 7 illustrates an enlarged pressure side perspective view of a rotor blade according to yet another embodiment of the present disclosure; and is

FIG. 8 is an enlarged cross-sectional view illustrating damper margins of two adjacent rotor blades according to an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to embodiments of the rotor blades and turbines of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the present technology, not limitation of the present technology. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Detailed description 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 invention. As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one element from another and are not intended to denote the position or importance of the various elements.

As used herein, the terms "upstream" (or "upward") and "downstream" (or "downward") refer to relative directions with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows. The term "radially" refers to an opposite direction substantially perpendicular to the axial centerline of a particular component; the term "axially" refers to an opposite direction that is substantially parallel and/or coaxially aligned with an axial centerline of a particular component; and the term "circumferentially" refers to the relative directions extending about the axial centerline of a particular component.

Approximate terms, such as "generally" or "about," include values within ten percent of the specified value or less. When used in the context of an angle or direction, such terms are included within ten degrees of greater or less than the angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction (e.g., clockwise or counterclockwise).

Referring now to the drawings, FIG. 1 shows a schematic view of a turbomachine, which in the illustrated embodiment is a gas turbine 10. Although an industrial or land-based gas turbine is shown and described herein, the present disclosure is not limited to land-based and/or industrial gas turbines unless otherwise specified in the claims. For example, the invention as described herein may be used with any type of turbomachine, including but not limited to a steam turbine, an aircraft gas turbine, or a marine gas turbine.

As shown, the gas turbine 10 generally includes an inlet section 12, a compressor section 14 disposed downstream of the inlet section 12, a plurality of combustors (not shown) disposed within a combustor section 16 downstream of the compressor section 14, a turbine section 18 disposed downstream of the combustor section 16, and an exhaust section 20 disposed downstream of the turbine section 18. Additionally, the gas turbine 10 may include one or more shafts 22 coupled between the compressor section 14 and the turbine section 18.

Compressor section 14 may generally include a plurality of rotor disks 24 (one of which is shown) and a plurality of rotor blades 26 extending radially outward from and coupled to each rotor disk 24. Each rotor disk 24, in turn, may be coupled to or may form a portion of shaft 22 that extends through compressor section 14.

The turbine section 18 may generally include a plurality of rotor disks 28 (one of which is shown) and a plurality of rotor blades 30 extending radially outward from and interconnected to each rotor disk 28. Each rotor disk 28, in turn, may be coupled to or may form a portion of shaft 22 that extends through turbine section 18. Turbine section 18 also includes an outer casing 31 that circumferentially surrounds portions of shaft 22 and rotor blades 30, thereby at least partially defining a hot gas path 32 through turbine section 18.

During operation, a working fluid, such as air, flows through inlet section 12 and into compressor section 14, where the air is progressively compressed, thereby providing pressurized air to one or more combustors of combustion section 16. The pressurized air is mixed with fuel and combusted within each combustor to produce combustion gases 34. Combustion gases 34 flow from the combustor section 16 through the hot gas path 32 and into the turbine section 18 where energy (kinetic and/or thermal) is transferred from the combustion gases 34 to the rotor blades 30, causing the shaft 22 to rotate. The mechanical rotational energy may then be used to power compressor section 14 and/or generate electricity. The combustion gases 34 exiting the turbine section 18 may then be exhausted from the gas turbine 10 via the exhaust section 20.

Fig. 2-8 illustrate embodiments of a rotor blade according to embodiments of the present disclosure. In the illustrated embodiment, the rotor blade is a turbine blade or bucket 30, but in an alternative embodiment, the rotor blade may be a compressor blade or bucket 26.

The rotor blade 30 may include a body 35 including an airfoil 36 and a shank 38. The airfoil 36 may extend and be positioned radially outward from the shank 38. The shank 38 may include a root or dovetail 40 that may be attached to the rotor disk 28 to facilitate rotation of the rotor blade 30.

The airfoil 36 may have a generally aerodynamic profile. For example, the airfoil 36 may have an outer surface defining a pressure side and a suction side each extending between a leading edge and a trailing edge. The outer surfaces of the shank 38 may include a pressure side surface, a suction side surface, a leading edge surface, and a trailing edge surface.

The body 35 may also include a platform 42. The exemplary platform may be located at an intersection or transition between the airfoil 36 and the shank 38, and may extend outwardly relative to the shank in generally axial and tangential directions, as shown. In the turbine section 18, the platform 42 generally serves as a radially inward flow boundary for the combustion gases 34 flowing through the hot gas path 32. The platform 42 may include a leading edge face 52 axially spaced from a trailing edge face 54. A leading edge face 52 is positioned in the combustion gas flow 34, and a trailing edge face 54 is positioned downstream of the leading edge face 52. Further, the body 35 may include a pressure side slash face 56 circumferentially spaced from a suction side slash face 58.

In some embodiments, as shown in fig. 2 and 3, the pressure side impingement surface 56 and/or the suction side impingement surface 58 may be generally planar surfaces (which may be generally planar or inclined). In other embodiments, such as the embodiments shown in fig. 5-7, the pressure side slash face 56 and/or the suction side slash face 58, or at least a portion thereof, may be curved planar. For example, the impingement surfaces 56 and/or 58 may be curved with respect to an axial direction, a radial direction, and/or a tangential direction.

FIG. 4 shows a pair of circumferentially adjacent rotor blades 30', 30 ". As shown, when rotor blade 30 is so positioned, pressure side impact surface 56 of rotor blade 30 faces suction side impact surface 58 of an adjacent rotor blade 30. As discussed above, a plurality of rotor blades 30 may be disposed on each of the one or more rotor disks 28 and may extend radially outward from each rotor disk. Rotor blades 30 disposed on rotor disk 28 may be assembled in a circumferential array such that, when rotor blades 30 are so assembled, a pressure side slash face 56 of each rotor blade 30 faces a suction side slash face 58 of each adjacent rotor blade 30. In some embodiments, the pressure side impact surface 56 of each rotor blade 30 and the suction side impact surface 58 of each adjacent rotor blade 30 may define a gap 60 in the circumferential direction.

Referring again to FIG. 3, in accordance with the present disclosure, one or more damper pins 95 may be disposed in the rotor blade 30. Each damper pin 95 may include a first end 200 axially separated from a second end 202. The first end 200 and the second end 202 may include shoulders 204, 206, respectively. Each damper pin 95 may be disposed at and in contact with an impingement surface 56, 58 (e.g., pressure side impingement surface 56 or suction side impingement surface 58) of the rotor blade 30, and may extend generally in the axial direction and thus generally along the length of the impingement surface 56, 58, as shown.

Further, as shown in FIG. 4, a damper pin 95 according to the present disclosure may be disposed between and in contact with adjacent, pressure side 56-facing or suction side 58 impingement surfaces of circumferentially adjacent rotor blades 30.

The damper pin 95 according to the present disclosure advantageously functions as a vibration damper. In operation, the damper pin 95 frictionally dissipates the vibrational energy and reduces the corresponding amplitude of the vibration.

Fig. 2 and 3 show the pressure side impact surface 56 and the suction side impact surface 58 of the main body 35. As shown, the body 35 may include one or more slots 70 defined within the pressure side slash face 56 and/or the suction side slash face 58 of the body 35. In some embodiments, the slot 70 may be one continuous groove defined along each of the pressure side impingement surface 56 and/or the suction side impingement surface 58. The slot 70 may include a leading edge segment 72, a platform segment 74, and a trailing edge segment 76. The leading edge segment 72 may be defined along the leading edge face 52, the platform segment 92 may be defined along the platform 42, and the trailing edge segment 76 may be defined along the trailing edge face 56. As used herein, terms such as "along.. define" and its cognates may mean "substantially parallel to" or "substantially in line with.

In other embodiments, the leading edge segments 72 and trailing edge segments 76 of the slots 70 may be generally radially oriented relative to an axial centerline of the gas turbine 10. Likewise, the platform segments 74 of the slots 70 may be generally axially oriented with respect to an axial centerline of the gas turbine 10. In some embodiments, the leading edge segment 72 may be directly connected to and continuous with the platform segment 74, and the platform segment 74 may be directly connected to and continuous with the trailing edge segment 76. In some embodiments, the platform segment 74 may be defined within the platform 42 and oriented axially relative to an axial centerline of the gas turbine 10.

In an alternative embodiment (not shown), the slot 70 may be discontinuous. In such embodiments, the leading edge segment 72, the platform segment 74, and the trailing edge segment 76 may be completely separate slots or grooves defined circumferentially within the pressure side impingement surface 56 and/or the suction side impingement surface 58.

As shown in FIG. 3, the body 35 may also include a suction side damper land 120. Suction side damper blade 120 may include a first end 122 axially separated from a second end 124. In many embodiments, the cut 121 may be defined in the suction side damper land 120. The cutout 121 includes a shoulder slot portion 126 defined at a first end 122 and a second end 124 of the suction side damper land 120. The shoulder slot portion 126 defines a support surface 128, which in an exemplary embodiment may be a flat planar surface. In these embodiments, the shoulders 204 and 206 of the damper pin 95 may be disposed in the shoulder slot portion 126 such that the support surface 128 may contact the shoulders 204 and 206. Accordingly, the damper pin 95 may be supported in the suction side damper land 120 and may reduce or prevent undesired over-rotation during use and operation.

Further, as shown in FIG. 3, the slot 70 may be sized to securely receive a portion of the seal 84 therein, i.e., the slot 70 may be sized to prevent the seal 84 from sliding out of the slot 70 during operation of the gas turbine 10. The seal 84 may include a first end 86 and a second end 88, and may extend therebetween. The seal 84 may be sized to at least partially sealingly fit into the slot 70.

When two or more blades 30 are arranged adjacent to one another on the rotor disk 24, such as shown in fig. 4 and 8 and in the configurations discussed above, the slots 70 of the pressure side impact surface 56 of each rotor blade 30 are aligned with the slots 70 of the suction side impact surface 58 of an adjacent rotor blade 30 to define a channel. The rotor blades 30 disposed adjacent to one another may include rotor blades 30 that are directly adjacent to one another on the rotor disk 24 and/or rotor blades 30 that are in direct contact with one another. A seal 84 (shown in fig. 3) may be received within the channel defined by each slot 70. The seal 84 may extend between and into two slots 70 of adjacent rotor blades 30', 30 ". In some embodiments, seals 84 prevent unwanted hot gases from turbine section 18 from leaking into body 35 of blade 30. Alternatively or additionally, in many embodiments, the seal 84 may prevent compressed cooling air from the compressor section 14 from leaking out of the shank 38 and into the turbine section 18.

As shown in FIGS. 5-7, the pressure side slash face 56 may also include a pressure side damper land 90 having a first end 92 and a second end 94. In some embodiments, the first end 92 of the pressure side damper land 90 may be axially separated from the second end 94. In various embodiments, the first end 92 of the pressure side damper land may partially define the leading edge segment 72 of the slot 70 and may extend to a second end 94 that partially defines the trailing edge segment 76 of the slot 70. In many embodiments, the pressure side damper land 90 may be located radially inward from the slot 70. Specifically, the pressure side damper land 90 may be located radially inward from the platform section 74 of the slot 70. In some embodiments, the pressure side damper land 90 may be oriented parallel to the platform section 74 of the slot 70. In other embodiments, pressure side damper land 90 may be oriented axially with respect to an axial centerline of gas turbine 10.

The pressure side damper land 90 may be used to provide a surface for the damper pin 95 to be positioned thereon and to provide vibration damping for the rotor blade 30. In many embodiments, the surface of the pressure side damper land 90 may be contoured slightly to the shape of the damper pin 95 to provide increased surface contact and vibration damping. For example, pressure side damper land 90 also includes a curved portion 96 and a flat portion 98. The curved portion 96 may curve circumferentially inward from the platform 42 to a flat portion 98. The flat portion 98 of the pressure side damper land 90 may extend radially inward from the curved portion 96 to the shank cutout 39 defined in the body 35. The flat portion 98 may be generally parallel to the platform 42 relative to both the axial and radial directions of the gas turbine 10.

In some implementations, the pressure side damper land 90 may be substantially cantilevered due to the slot 70 and its flat portion 98. For example, the flat portion 98 of the pressure side damper land 90 may extend radially inward from the curved portion 96 to a free end 99. The free end 99 may be substantially cantilevered within the shank cutout 39 to advantageously provide increased compliance throughout the platform 42 of the rotor blade 30, thereby effectively increasing vibration damping. In various embodiments, the flat portion 98 of the pressure side damper land may taper axially inward from the curved portion 96 to the free end 99. In various embodiments, the flat portion 98 of the pressure side damper land 90 may taper away from the first and second undercuts 100, 102 at their respective ends.

In addition to providing a housing for seal 84, slot 70 may also provide reduced material stiffness and increased compliance in pressure side damper land 90, which allows for increased vibration damping of the entire blade 30. Additionally, the slot 70 may include a slot depth 71. Varying the slot depth (i.e., increasing or decreasing) 71 may advantageously increase or decrease the overall stiffness of the pressure side land 90, resulting in an increase in the overall damping effect.

In some embodiments, such as shown in fig. 5-7, the pressure side impingement surface 56 may also include a first undercut 100 and a second undercut 102. The first and second undercuts 100, 102 serve to advantageously alter, i.e., increase or decrease, the stiffness of the shank 38 to improve the overall vibration damping effect. In the embodiment shown in FIG. 5, the first and second undercuts 100, 102 may be semi-circular cutouts defined circumferentially inward on the body 35 of the rotor blade 30. In some embodiments, the first undercut 100 and the second undercut 102 may be substantially curved or arcuate. In other embodiments, such as the embodiment shown in fig. 6 and 7, the first and second undercuts 100, 102 may comprise a plurality of semicircular cutouts or trapezoidal cutouts.

In many embodiments, the first undercut 100 may be disposed directly radially inward from the first end 92 of the pressure side damper land 90, and the second undercut 102 may be axially separated from the first undercut 100 and may be disposed directly radially inward from the second end 94 of the pressure side damper land 90. In some embodiments, first and second undercuts 100, 102 may extend generally radially inward from first and second ends 92, 94, respectively, of pressure side damper land 90. In many embodiments, both the first undercut 100 and the second undercut 102 may extend radially inward past the free end 99 of the pressure side damper land 90.

The first and second undercuts 100, 102 may each partially define the slot 70. More specifically, the first undercut 100 may partially define the leading edge segment 72 of the slot 70. Likewise, the second slot 102 may partially define the trailing edge section 76 of the slot 70. In various embodiments, the first undercut 100 may be disposed axially between the leading edge segment 72 of the slot 70 and the flat portion 98 of the pressure side damper land 90. A second undercut 102 may be axially disposed between the flat portion 98 of the pressure side damper land 90 and the trailing edge section 76 of the slot 70.

The first undercut 100 and the second undercut 102 may each include a maximum undercut depth 106 defined in the circumferential direction. The maximum undercut depth 106 of the first undercut 100 may be the same as or different from the maximum undercut depth 106 of the second undercut 102. Varying the maximum undercut depth 106 of the first and/or second undercuts 102 will advantageously vary (i.e., increase or decrease) the stiffness of the pressure side damper land 90, resulting in an increased damping effect. In some embodiments, the maximum undercut depth 106 of the respective undercuts 100, 102 may be up to about 1.5 inches. In other embodiments, the maximum undercut depth 106 may be up to about 1 inch. In some embodiments, the maximum undercut depth 106 may be up to about 0.75 inches. In various embodiments, the maximum undercut depth 106 may be up to about 0.5 inches. In other embodiments, the maximum undercut depth 106 may be up to about 0.25 inches.

FIG. 8 illustrates a cross-sectional view of a pair of circumferentially adjacent rotor blades. As shown, when rotor blades 30 ', 30 "are so positioned, pressure side damper land 90 of a first rotor blade 30' is aligned with suction side damper land 120 of an adjacent second rotor blade 30". As shown in FIG. 8, damper pin 95 may be disposed along suction side damper land 120. In operation, the damper pin 95 moves in the direction along arrow 130 and contacts both the pressure side damper land 90 and the suction side damper land 120 to provide vibration damping to the adjacent rotor blades 30', 30 ".

Further, the slot depth 71' of the pressure side slash face 56 may be different than the slot depth 71 "of the suction side slash face 58. For example, the slot depth 71' of the pressure side slash-face 56 may be greater than the slot depth 71 "of the suction side slash-face 58, and vice versa. Generally, the sum of the slot depth 71' of the pressure side impingement surface 56, the width of the gap 60 in the circumferential direction (shown in FIG. 4), and the slot depth 71 "of the suction side impingement surface 58 may be generally equal to or slightly greater than the width of the seal 84. In various embodiments, the seal 84 may be smaller than the slot 70 and may have space for thermal expansion within the slot 70. Additionally, the seal 84 may be sized to allow for manufacturing variations thereof.

For example, in many embodiments, the width of the seal 84 may be between about 5% and about 30% of the width of the channel to allow for both manufacturing variations and thermal expansion within the slot 70. The embodiment shown in fig. 2-8 allows for the use of both the vibration damper pin 95 and the seal 84. In various embodiments, the blade 30 may include only the vibration damper pin 95, only the seal 84, or both the vibration damper pin 95 and the seal 84.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.