Damper element with flexible legs for vibration damping system of turbine blades

Abstract

The present disclosure provides a damper element and a vibration damping system (120, 320) comprising a plurality of stacked damper elements (170, 370). These damper elements (170, 370) may be used in a body opening (160) in a rotating blade (114) in a turbine (108). The damper elements (170, 370) include a head member (172, 202, 224, 342) having an at least partially inclined surface (174, 204, 226, 344) and a plurality of flexible legs (180) extending from the head member. Each flexible leg (180) includes a radially extending body portion (182) having an end portion (184), and the end portion has an outer end face (186) and an inner end face (188). Centrifugal force caused by rotation of the rotating blade (114) causes the head member (172, 202, 224, 342) of adjacent damper elements (170, 370) to force the outer end faces (186) of the plurality of flexible legs (180) into frictional engagement with an inner surface (162) of the body opening (160) to attenuate vibration. In some embodiments, the elongate body (392) may extend through an opening (390) in the head member of the damper elements.

Description

Technical Field

[0001] The present disclosure generally relates to attenuating vibrations in rotating blades. More particularly, the present disclosure relates to a vibration reduction system including a plurality of damper elements, each damper element having a plurality of flexible legs. Background Art

[0002] One problem in turbine operation is the tendency of rotating turbine blades to be subjected to vibration stresses during operation. In many facilities, turbines are operated under conditions of frequent acceleration and deceleration. During acceleration or deceleration of the turbine, the airfoils of the blades are temporarily subjected to vibration stresses of at least certain frequencies, and in many cases, to vibration stresses of the second or third frequency. The nozzle airfoils are also subjected to similar vibration stresses. For example, changes in gas temperature, pressure and / or density may excite vibrations throughout the rotor assembly, especially within the blade airfoils. Gases leaving the turbine and / or compressor section upstream in a periodic or "pulsating" manner may also excite undesirable vibrations. When the airfoils are subjected to vibration stresses, their vibration amplitudes can easily accumulate to a degree that may have a negative impact on gas turbine operation and / or component life. Stacked solid damper elements in turbine blades have been used for vibration reduction, but centrifugal forces can cause the damper elements to lock together, thereby reducing or eliminating their vibration reduction capabilities. Summary of the invention

[0003] All aspects, examples and features mentioned below can be combined in any technically possible way.

[0004] One aspect of the present disclosure provides a damper element for a vibration reduction system in a body opening in a rotating blade in a turbine, the damper element comprising: a head member having an at least partially inclined surface; and a plurality of flexible legs extending from the head member, wherein each flexible leg comprises a radially extending body portion having an end portion having an outer end surface and an inner end surface.

[0005] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the at least partially inclined surface has an angle in the range between 25° and 55° relative to the inner surface of the main body opening, and the inner end surfaces of the multiple flexible legs have an angle in the range between 25° and 55° relative to the inner surface of the main body opening.

[0006] Another aspect of the present disclosure includes any of the aforementioned aspects, and the head member and the radially extending main body portion of the plurality of flexible legs each have a first outer diameter, and the outer end surfaces of the plurality of flexible legs jointly define a second outer diameter greater than the first outer diameter.

[0007] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the main body opening has an inner surface having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby in a relaxed state, the plurality of flexible legs pass freely within the main body opening.

[0008] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the inner end surfaces of the multiple flexible legs are configured to receive the at least partially inclined surface of the head component of the adjacent damper element, wherein under the influence of the centrifugal force caused by the rotation of the rotating blade at a speed higher than a predetermined speed, the head component of the adjacent damper element forces the outer end surfaces of the multiple flexible legs to frictionally engage with the inner surface of the main body opening to reduce vibration.

[0009] Another aspect of the present disclosure includes any of the foregoing aspects, and the outer end surface of each flexible leg is frictionally engaged with the inner surface of the main body opening at a line.

[0010] Another aspect of the present disclosure includes any one of the aforementioned aspects, and in a relaxed state of the plurality of flexible legs, the outer end surface of each flexible leg is parallel to the inner surface of the main body opening.

[0011] Another aspect of the present disclosure includes any of the preceding aspects, and adjacent radially extending body portions of the flexible legs define a slot therebetween having a rounded radially outer extent.

[0012] Another aspect of the present disclosure includes any of the preceding aspects, and the head member having the at least partially inclined surface has a frustoconical shape.

[0013] One aspect of the present disclosure includes a vibration reduction system for a rotating blade, the vibration reduction system comprising: a plurality of stacked damper elements, the plurality of stacked damper elements being used to be positioned in a body opening defined in the rotating blade, each damper element comprising: a head member having a surface that is at least partially inclined; and a plurality of flexible legs extending from the head member, wherein each flexible leg comprises a radially extending body portion having an end portion, the end portion having an outer end surface and an inner end surface.

[0014] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the at least partially inclined surface of each damper element has an angle in the range between 25° and 55° relative to the inner surface of the main body opening, and the inner end surfaces of the multiple flexible legs have an angle in the range between 25° and 55° relative to the inner surface of the main body opening.

[0015] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the head member of each damper element and the radially extending main body portion of the multiple flexible legs each have a first outer diameter, and the outer end surfaces of the multiple flexible legs of each damper element jointly define a second outer diameter that is larger than the first outer diameter.

[0016] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the main body opening has an inner surface having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby in a relaxed state, the multiple flexible legs of each damper element pass freely within the main body opening.

[0017] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the inner end surface of the multiple flexible legs of each damper element is configured to receive the at least partially inclined surface of the head component of an adjacent damper element among the multiple stacked damper elements, wherein under the influence of the centrifugal force caused by the rotation of the rotating blade at a speed higher than a predetermined speed, the head component of the adjacent damper element forces the outer end surfaces of the multiple flexible legs to frictionally engage with the inner surface of the main body opening to reduce vibration.

[0018] Another aspect of the present disclosure includes any of the foregoing aspects, and the outer end surface of each flexible leg is frictionally engaged with the inner surface of the main body opening at a line.

[0019] Another aspect of the present disclosure includes any of the preceding aspects, and adjacent radially extending body portions of the plurality of flexible legs of each damper element define a slot therebetween having a rounded radially outer extent.

[0020] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the plurality of flexible legs extend radially inward from a corresponding head member of each damper element in the plurality of damper elements, and also includes a radially inner end member having a head member, the head member having an at least partially inclined surface, the at least partially inclined surface being configured to engage an inner end surface of the plurality of flexible legs of a radially innermost damper element in the plurality of stacked damper elements.

[0021] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the plurality of flexible legs extend radially outward from the corresponding head member of each damper element in the plurality of damper elements, and also includes a radially outer end element, which is configured to engage the plurality of flexible legs of the radially outermost damper element in the plurality of stacked damper elements.

[0022] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the multiple damper elements have at least one of the following characteristics that is different between at least two damper elements: total mass, total radial length, radial length of the multiple flexible legs, force required to bend the multiple flexible legs outward, shape of the inner end surface, shape of the outer end surface, and angle of the at least partially inclined surface.

[0023] Another aspect of the present disclosure includes any of the preceding aspects, and the head member of each damper element has an at least partially inclined surface in the shape of a frustoconical cone.

[0024] One aspect of the present disclosure includes a damper element for a vibration reduction system in a main body opening in a rotating blade in a turbine, the damper element comprising: a head member having an at least partially inclined surface and an opening defined through the center of the head member; a plurality of flexible legs extending from the head member, wherein each flexible leg includes a radially extending main body portion having an end portion having an outer end face and an inner end face; and a slender body extending through the opening in the head member.

[0025] Another aspect of the present disclosure includes any of the preceding aspects, and the elongated body is configured to resonate at the same frequency as the rotating blade, whereby the elongated body generates a force on the damper element.

[0026] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the at least partially inclined surface has an angle in the range between 25° and 55° relative to the inner surface of the main body opening, and the inner end surfaces of the multiple flexible legs have an angle in the range between 25° and 55° relative to the inner surface of the main body opening.

[0027] Another aspect of the present disclosure includes any of the aforementioned aspects, and the head member and the radially extending main body portion of the plurality of flexible legs each have a first outer diameter, and the outer end surfaces of the plurality of flexible legs jointly define a second outer diameter greater than the first outer diameter.

[0028] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the main body opening has an inner surface having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby in a relaxed state, the plurality of flexible legs pass freely within the main body opening.

[0029] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the inner end surfaces of the multiple flexible legs are configured to receive the at least partially inclined surface of the head component of the adjacent damper element, wherein under the influence of the centrifugal force caused by the rotation of the rotating blade at a speed higher than a predetermined speed, the head component of the adjacent damper element forces the outer end surfaces of the multiple flexible legs to frictionally engage with the inner surface of the main body opening to reduce vibration.

[0030] Another aspect of the present disclosure includes any of the foregoing aspects, and the outer end surface of each flexible leg is frictionally engaged with the inner surface of the main body opening at a line.

[0031] Another aspect of the present disclosure includes any of the preceding aspects, and adjacent radially extending body portions of the plurality of flexible legs define a slot therebetween having a rounded radially outer extent.

[0032] Another aspect of the present disclosure includes any of the foregoing aspects, and the head member of each damper element has an at least partially inclined surface in the shape of a frustoconical cone, the opening extending through the at least partially inclined surface.

[0033] One aspect of the present disclosure includes a vibration reduction system for a rotating blade, the vibration reduction system comprising: a plurality of stacked damper elements, the plurality of stacked damper elements being used to be positioned in a main body opening defined in the rotating blade, each damper element comprising: a head member having an at least partially inclined surface and an opening defined through the center of the head member; a plurality of flexible legs extending from the head member, wherein each flexible leg comprises a radially extending main body portion having an end portion, the end portion having an outer end face and an inner end face; and a slender body extending through the opening in the head member of each damper element in the plurality of damper elements.

[0034] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the at least partially inclined surface of each damper element has an angle in the range between 25° and 55° relative to the inner surface of the main body opening, and the inner end surfaces of the multiple flexible legs have an angle in the range between 25° and 55° relative to the inner surface of the main body opening.

[0035] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the head member of each damper element and the radially extending main body portion of the multiple flexible legs each have a first outer diameter, and the outer end surfaces of the multiple flexible legs of each damper element jointly define a second outer diameter that is larger than the first outer diameter.

[0036] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the main body opening has an inner surface having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby in a relaxed state, the multiple flexible legs of each damper element pass freely within the main body opening.

[0037] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the inner end surface of the multiple flexible legs of each damper element is configured to receive the at least partially inclined surface of the head component of an adjacent damper element among the multiple stacked damper elements, wherein under the influence of the centrifugal force caused by the rotation of the rotating blade at a speed higher than a predetermined speed, the head component of the adjacent damper element forces the outer end surfaces of the multiple flexible legs to frictionally engage with the inner surface of the main body opening to reduce vibration.

[0038] Another aspect of the present disclosure includes any of the foregoing aspects, and the outer end surface of each flexible leg is frictionally engaged with the inner surface of the main body opening at a line.

[0039] Another aspect of the present disclosure includes any of the preceding aspects, and adjacent radially extending body portions of the plurality of flexible legs of each damper element define a slot therebetween having a rounded radially outer extent.

[0040] Another aspect of the present disclosure includes any of the preceding aspects and further includes a radially outer retainer element secured to the elongated body to retain the plurality of stacked damper elements thereon.

[0041] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the plurality of flexible legs extend radially inward from a corresponding head member of each damper element in the plurality of damper elements, and also includes a radially inner end member, the radially inner end member having: a head member having an at least partially inclined surface, the at least partially inclined surface being configured to engage the inner end surface of the plurality of flexible legs of the radially innermost damper element in the plurality of stacked damper elements; an opening through the radially inner end member, the slender body extending through the opening, wherein the radially inner end member can slide on the slender body.

[0042] Another aspect of the present disclosure includes any of the aforementioned aspects, and the plurality of flexible legs extend radially outward from a corresponding head member of each of the plurality of damper elements, and also includes a radially inner end element, which is configured to engage the head member of the radially innermost damper element of the plurality of stacked damper elements, the radially inner end element including an opening, the slender body extending through the opening, wherein the radially inner end element can slide on the slender body.

[0043] Another aspect of the present disclosure includes any one of the aforementioned aspects, and the multiple damper elements have at least one of the following characteristics that is different between at least two damper elements: total mass, total radial length, radial length of the multiple flexible legs, force required to bend the multiple flexible legs outward, shape of the inner end surface, shape of the outer end surface, and angle of the at least partially inclined surface.

[0044] Another aspect of the present disclosure includes any of the foregoing aspects, and the head member of each damper element has an at least partially inclined surface in the shape of a frustoconical cone, the opening extending through the at least partially inclined surface.

[0045] Two or more aspects described in this disclosure (including those described in this summary) can be combined to form a specific implementation not specifically described herein. That is, all embodiments described herein can be combined with each other.

[0046] The details of one or more implementations are set forth in the drawings and description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] These and other features of the present disclosure will be more readily understood from the following detailed description of various aspects of the present disclosure taken in conjunction with the accompanying drawings which depict various embodiments of the present disclosure, wherein:

[0048] Figure 1 shows a cross-sectional view of an illustrative turbomachine in the form of a gas turbine system including a turbine;

[0049] Figure 2 shows a cross-sectional view of a portion of an exemplary turbine according to an embodiment of the present disclosure;

[0050] Figure 3 shows a perspective view of an exemplary turbine blade including a vibration reduction system according to an embodiment of the present disclosure;

[0051] Figure 4 shows a schematic cross-sectional view of a turbine blade having a vibration reduction system including a plurality of damper elements according to an embodiment of the present disclosure;

[0052] Figure 5 shows a schematic cross-sectional view of a turbine blade having a vibration reduction system including a plurality of damper elements according to an embodiment of the present disclosure;

[0053] Figure 6 shows a side view of a damper element according to an embodiment of the present disclosure;

[0054] Fig. 7A illustrates a side partial cross-sectional view of a vibration reduction system including a plurality of stacked damper elements in a first position according to an embodiment of the present disclosure;

[0055] Figure 7B illustrates a side partial cross-sectional view of a vibration reduction system including a plurality of stacked damper elements in a second position according to an embodiment of the present disclosure;

[0056] Fig. 8A Shown along Fig. 7A A top view of the sight line 8A-8A in FIG.

[0057] Figure 8B Shown along Figure 7B A top view of the sight line 8B-8B in FIG.

[0058] Fig. 9 shows a side partial cross-sectional view of a radially inner end member for a vibration reduction system according to an optional embodiment of the present disclosure;

[0059] Fig.10 shows a side partial cross-sectional view of a radially outer end member for a vibration reduction system according to an optional embodiment of the present disclosure;

[0060] Fig.11 shows a perspective view of a damper element according to other embodiments of the present disclosure;

[0061] Fig.12 shows a schematic cross-sectional view of a turbine blade having a vibration reduction system including a plurality of damper elements according to other embodiments of the present disclosure;

[0062] Fig.13 shows a schematic cross-sectional view of a turbine blade having a vibration reduction system including a plurality of damper elements according to other embodiments of the present disclosure;

[0063] Fig.14 shows a side view of a damper element according to other embodiments of the present disclosure, with the top surface of the damper element superimposed above the damper element;

[0064] Fig.15A illustrates a side partial cross-sectional view of a vibration reduction system including a plurality of stacked damper elements in a first position according to other embodiments of the present disclosure;

[0065] Fig. 15B illustrates a side partial cross-sectional view of a vibration reduction system including a plurality of stacked damper elements in a second position according to other embodiments of the present disclosure;

[0066] Fig.16A Shown along Fig.15A A top view of the sight line 16A-16A in FIG. 16A-16A; and

[0067] Fig. 16B Shown along Fig. 16B A top view of the sight line 16B-16B.

[0068] It should be noted that the drawings of the present disclosure are not necessarily drawn to scale. The drawings are intended to depict only typical aspects of the present disclosure and therefore should not be considered to limit the scope of the present disclosure. In the drawings, like numbers represent like elements between drawings. DETAILED DESCRIPTION

[0069] First, in order to clearly describe the subject matter of the present disclosure, it will be necessary to select certain terms when referring to and describing the relevant machine components within the turbine. To the extent possible, common industry terms will be used and adopted in a manner consistent with the accepted meaning of the terms. Unless otherwise stated, such terms should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. A person of ordinary skill in the art will understand that several different or overlapping terms may be used to refer to a particular component. An object that may be described as a single part in this article may include multiple parts and be referenced as consisting of multiple parts in another context. Alternatively, an object that may be described as including multiple parts in this article may be referred to as a single part elsewhere.

[0070] In addition, several descriptive terms may be used regularly throughout this document, and it should prove helpful to define these terms at the beginning of this section. It is often necessary to describe parts that are arranged at different radial positions relative to a central axis. The term "radial" refers to movement or position perpendicular to the axis. For example, if a first component is closer to the axis than a second component, this document will describe the first component as being "radially inward" along the second component or on the "inside" of the second component. On the other hand, if the first component resides farther away from the axis than the second component, this document may describe the first component as being "radially outward" or "outside" of the second component. The term "axial" refers to movement or position parallel to the axis. Finally, the term "circumferential" refers to movement or position around the axis. It should be understood that such terms can be applied relative to the central axis of the damper element or the central axis of the turbine.

[0071] In addition, several descriptive terms may be used regularly herein, as described below. The terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of individual components.

[0072] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "one", "a kind of" and "the" are intended to also include plural forms, unless the context clearly indicates otherwise. It will be further understood that when used in the specification, the terms "include" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups. "Optional" or "optionally" means that the event or situation described subsequently may or may not occur, or the parts or elements described subsequently may or may not exist, and the description includes the situation where the event occurs or the parts exist and the situation where the event does not occur or the parts do not exist.

[0073] Where an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to," it may be directly on, engaged to, connected to, or coupled to, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to," there are no intervening elements or layers. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0074] Embodiments of the present disclosure provide a damper element and a vibration reduction system for turbine blades. The vibration reduction system includes a plurality of stacked damper elements. The damper element for the vibration reduction system can be used in a main body opening in a rotating blade in a turbine. The damper element includes a head member having a surface that is at least partially inclined and a plurality of flexible legs extending from the head member. Each flexible leg includes a radially extending main body portion having an end portion, and the end portion has an outer end face and an inner end face. Under the influence of the centrifugal force caused by the rotation of the rotating blade at a speed higher than a predetermined speed, the head member of the adjacent damper element forces the outer end faces of the plurality of flexible legs of the damper element to frictionally engage with the inner surface of the main body opening to reduce vibration. In certain embodiments, the elongated body may extend through the opening in the head member of the damper element.

[0075] Compared to other stacked damping pins, the damper element according to the embodiments of the present disclosure is more likely to capture relative motion because it is forced to expand and contact the inner surface of the body opening in the rotating blade. This arrangement is advantageous because it allows the damper element to move with the inner surface of the body opening in the rotating blade in close proximity, i.e., in situations where centrifugal forces may not be able to expand the flexible legs, and the sliding movement from the unloaded flexible legs to the loaded bent legs produces a stick-slip motion, which is effective for vibration reduction. The vibration reduction system reduces blade vibrations through a simple arrangement and does not add much additional mass to the blade. Therefore, the vibration reduction system and damper element do not increase the overall centrifugal force at the tip end of the blade, and do not require changes to the blade configuration.

[0076] With reference to the accompanying drawings, Figure 1 is a cross-sectional view of an exemplary machine including a turbine to which the teachings of the present disclosure may be applied. Figure 1 , a turbomachine 90 in the form of a combustion turbine or gas turbine (GT) system 100 (hereinafter referred to as "GT system 100") is shown. GT system 100 includes a compressor 102 and a combustor 104. Combustor 104 includes a combustion region 105 and a fuel nozzle section 106. GT system 100 also includes a turbine 108 and a common compressor / turbine shaft 110 (hereinafter referred to as "rotor 110").

[0077] GT system 100 may be, for example, a 7HA.03 engine commercially available from General Electric Company, Greenville, SC. ​​The present disclosure is not limited to any one particular GT system and may be implemented with other engines, including, for example, General Electric Company's HA, F, B, LM, GT, TM, and E-class engine models, as well as engine models from other companies. More importantly, the teachings of the present disclosure are not necessarily applicable only to turbines in GT systems, and may be applied to virtually any type of industrial machine or other turbine, such as steam turbines, jet engines, compressors (e.g., Figure 1 ), a turbofan, a turbocharger, etc. Therefore, reference to the turbine 108 of the GT system 100 is for descriptive purposes only and is not limiting.

[0078] Figure 2 A cross-sectional view of an exemplary portion of turbine 108 is shown. In the example shown, turbine 108 includes Figure 11 and 2. The GT system 100 of FIG. 1 is used with four stages L0-L3. The four stages are referred to as L0, L1, L2, and L3. Stage L0 is the first stage and is the smallest stage (in the radial direction) of the four stages. Stage L1 is the second stage and is disposed adjacent to the first stage L0 in the axial direction. Stage L2 is the third stage and is disposed adjacent to the second stage L1 in the axial direction. Stage L3 is the fourth stage (the last stage) and is the largest (in the radial direction). It should be understood that four stages are shown as an example only, and each turbine may have more or less than four stages.

[0079] A plurality of stationary turbine blades or nozzles 112 (hereinafter referred to as “nozzles 112” or “nozzles 112”) may cooperate with a plurality of rotating turbine blades 114 (hereinafter referred to as “blades 114” or “blades 114”) to form each stage L0-L3 of the turbine 108 and define a portion of the working fluid path through the turbine 108. The blades 114 of each stage are formed by, for example, coupling them circumferentially to the rotor 110 ( Figure 1 ) is coupled to the rotor 110 ( Figure 1 That is, blades 114 are mechanically coupled to rotor 110 in a circumferentially spaced manner, for example, via rotor wheel 116. Stationary nozzle segment 115 includes a housing 118 mounted thereto and surrounding rotor 110 ( Figure 1 ) a plurality of nozzles 112 spaced circumferentially. It should be appreciated that the blades 114 are spaced circumferentially from the rotor 110 ( Figure 1 ) rotates together and is therefore subjected to centrifugal forces, while nozzle 112 is stationary.

[0080] refer to Figure 1 and Figure 2 In operation, air flows through the compressor 102, and the pressurized air is supplied to the combustor 104. Specifically, the pressurized air is supplied to the fuel nozzle section 106, which is integral with the combustor 104. The fuel nozzle section 106 is in fluid communication with the combustion zone 105. The fuel nozzle section 106 is also connected to a fuel source ( Figure 1The compressor 102 may also be rotatably coupled to the rotor 110. At least one end of the rotor 110 may extend axially away from the compressor 102 or the turbine 108 and may be attached to a load or machine (not shown), such as, but not limited to, a generator, a load compressor, and / or another turbine.

[0081] Figure 3 A perspective view of a (rotating) blade 114 of the type in which embodiments of the vibration reduction system 120, 320 of the present disclosure may be employed is shown. As will be described herein, Figure 4 and Figure 5 A schematic cross-sectional view of a blade 114 including a vibration reduction system 120 , 320 is shown according to various embodiments of the present disclosure.

[0082] refer to Figure 3 Each blade 114 includes a body 128 having a base end 130, a tip end 132, and an airfoil 134 extending between the base end 130 and the tip end 132. Figure 3 As shown, the blade 114 includes a dovetail 140 at the base end 130 by which the blade 114 is attached to the rotor 110 ( Figure 1 ) of the rotor wheel 116 ( Figure 2 ). The base end 130 of the blade 114 may also include a shank 142 extending between the dovetail 140 and a platform 146. The platform 146 is disposed at the junction of the airfoil 134 and the shank 142 and defines a working fluid path through the turbine 108 ( Figure 2 ) is a portion of the inner boundary of a .

[0083] It should be understood that the airfoil 134 in the blade 114 is the active component of the blade 114 that intercepts the flow of the working fluid and causes the rotor 110 ( Figure 1) rotation. It can be seen that the airfoil 134 of the blade 114 includes a concave pressure side (PS) outer sidewall 150 and a circumferentially or laterally opposed convex suction side (SS) outer sidewall 152, which extend axially between opposite leading edges 154 and trailing edges 156, respectively. The sidewalls 150 and 152 also extend in a radial direction from the base end 130 (i.e., the platform 146 of the blade 114) to the tip end 132 (i.e., the tip end 158 of the blade 114). Note that in the example shown, the blade 114 does not include a tip shroud; however, the teachings of the present disclosure are equally applicable to blades that include a tip shroud located at the tip end 158. Figure 3 The illustrated blade 114 is merely illustrative, and the teachings of the present disclosure may be applicable to a variety of blades.

[0084] During operation of the turbine, the blades 114 can be excited into vibration by a number of different forcing functions. For example, changes in the working fluid temperature, pressure, and / or density can excite vibrations throughout the rotor assembly, particularly within the airfoils and / or tips of the blades 114. Gases exiting the turbine and / or compressor section upstream in a periodic or "pulsating" manner can also excite undesirable vibrations. Embodiments of the present disclosure reduce vibrations of the rotating blades 114 without significantly changing the blade design.

[0085] Figure 4 and Figure 5 Schematic cross-sectional views of a blade 114 including a vibration reduction system 120 according to an embodiment of the present disclosure are each shown. The vibration reduction system 120 for the blade 114 may include a body opening 160 that extends through the body 128 at least partially between the tip end 132 and the base end 130 and through the airfoil 134. The body opening 160 may extend a portion of the distance between the base end 130 and the tip end 132, or it may extend through one or more of the base end 130 or the tip end 132. The body opening 160 may be defined in any portion of any structure of the body 128. For example, where the body 128 includes an internal dividing wall (not shown), for example, for defining a cooling circuit therein, the body opening 160 may be defined as an inner cavity in the dividing wall in the body 128. The body opening 160 generally extends radially in the body 128. However, the body opening 160 may be angled relative to the radial extent of the body 128 and may be curved. The body opening 160 has an inner surface 162. The body opening may have an inner diameter ID.

[0086] like Figure 4 The body opening 160 may begin at the base end 130 of the blade 114, as shown, or may begin at the base end 130 of the blade 114, as shown. Figure 5 As shown, it may start at the tip end 132 of the blade 114. More specifically, as Figure 4 As shown, the body opening 160 may open in the base end 130 and terminate in the tip end 132, or as shown in FIG. Figure 5 As shown, it may open in the tip end 132 and terminate in the base end 130. Regardless of where the body opening 160 is located, it may facilitate assembly of the vibration reduction system 120 in the blade 114 and may allow the system to be retrofitted into existing blades. Figure 4 As shown, in the case where the main body opening 160 extends through the base end 130, a closing member 164 for closing the main body opening 160 may be provided. Figure 5 As shown, with the body opening 160 extending through the tip end 132, a closure member 166 may be provided for the body opening 160. In addition to closing the body opening 160, the closure members 164, 166 also prevent the vibration reduction system 120 from being removed from the body opening 160, such as during use. The body opening 160 may have a radially inner end 206 and a radially outer end 210, each of which may be provided at least in part by the closure members 164, 166 according to an embodiment.

[0087] Figure 6 A perspective view of a damper element 170 is shown in accordance with an embodiment of the present disclosure. Fig. 7A shows a partial cross-sectional view of a vibration reduction system 120 in a first position according to an embodiment of the present disclosure, and Figure 7B A partial cross-sectional view of a vibration reduction system 120 in a second position is shown according to an embodiment of the present disclosure. Fig. 8A Shown along Fig. 7A A top view of the sight line 8A-8A in FIG. 8A-8A; and Figure 8B Shown along Figure 7B A top view of the sight line 8B-8B.

[0088] like FIG. 7A to FIG. 7B As shown, a damper element 170 for the vibration reduction system 120 is shown at the turbine 108 ( Figure 1 ) in the main body opening 160 in the rotating blade 114. Figure 6 and FIG. 7A to FIG. 7B As shown, the damper element 170 includes a head member 172 having an at least partially inclined surface 174. The damper element 170 also includes a plurality of flexible legs 180 (hereinafter referred to as "flexible legs 180") extending from the head member 172. Each flexible leg 180 includes a radially extending body portion 182 (relative to the blade 114) having a tip portion 184. The tip portion 184 has an outer end surface 186 and an inner end surface 188. As will be further described herein, and as shown in Figure 7B and Figure 8BAs shown, the head member 172 engages with the flexible legs 180 of another adjacent damper element 170 so that its flexible legs 180 bend outwardly and frictionally engage with the inner surface 162 of the main body opening 160 under the influence of the centrifugal force CF caused by the rotation of the rotating blades 114 at a speed higher than a predetermined speed to reduce vibration.

[0089] Each flexible leg 180 may have any structure capable of allowing it to flex outwardly so that the outer end surface 186 can frictionally engage the inner surface 162 of the body opening 160 in the blade 114. In the exemplary embodiment shown, adjacent radially extending body portions 182 (hereinafter referred to as "body portions 182") of the flexible legs 180 define a slot 190 therebetween. The slot 190 may terminate at the head member 172. The slot 190 may have a rounded radial outer extent 192, such as a U-shape; however, other shapes are possible, such as a V-shape, a spire shape, etc. Any number of flexible legs 180 may be provided on each damper element 170. In certain embodiments, between three (3) and six (6) flexible legs 180 are used on each damper element 170, but other numbers are possible. In other embodiments, the body portion 182 may have alternative structures for assisting and / or controlling its flexure, such as, but not limited to: wider or thinner portions, curvatures, gaps, etc.

[0090] As previously mentioned, the head member 172 has an at least partially inclined surface 174. The at least partially inclined surface 174 (hereinafter referred to as "inclined surface 174") may extend completely around it, for example as a solid circular surface, or partially around the head member 172, i.e., with interruptions or open areas between similar inclined surfaces. The inclined surface 174 may have an angle α in the range between 25° and 55° relative to the inner surface 162 of the body opening 160. As previously mentioned, the body opening 160 may extend generally radially in the body 128 of the blade 114. The inner end surfaces 188 of the plurality of flexible legs 180 are configured to receive the inclined surface 174 of the head member 172 of the adjacent damper element 170, i.e., to engage and move under the influence of the inclined surface 174. The inner end surfaces 188 of the flexible legs 180 may have an angle β in the range between 25° and 55° relative to the inner surface 162 of the body opening 160. The angle α and the angle β may be the same, but this is not necessary in all cases, as long as the head member 172 is able to push the legs 180 of the adjacent damper element 170 outward toward the inner surface 162 of the body opening 160. That is, when a certain centrifugal force CF is applied based on a predetermined rotational speed of the blade 114, the head member 172 of the adjacent damper element 170 may force the outer end surface 186 of the flexible leg 180 to frictionally engage with the inner surface 162 of the body opening 160 to dampen vibration.

[0091] In certain embodiments, the head member 172 and the main body portion 182 of the flexible leg 180 each have a first outer diameter OD1. The outer end surface 186 of the flexible leg 180 collectively defines a second outer diameter OD2 that is greater than the first outer diameter OD1. Therefore, the head member 172 and the main body portion 182 have an outer diameter OD1 that is smaller than the outer end surface 186 (i.e., OD2) of the flexible leg. Although shown and described as having the same outer diameter OD1, the main body portion 182 and the head member 172 may have different outer diameters as long as they are both smaller than the outer diameter OD2 of the outer end surface 186. Fig. 7A and Fig. 8A As shown, the second outer diameter OD2 of the outer end surface 186 is smaller than the inner diameter ID of the body opening 160, whereby, in a relaxed state, the flexible legs 180 can freely pass through the body opening 160. In addition, in some embodiments, in a relaxed state of the plurality of flexible legs 180, the outer end surface 186 of each flexible leg 180 can be parallel to the inner surface 162 of the body opening 160. In other embodiments, in a relaxed state of the plurality of flexible legs 180, the outer end surface 186 of each flexible leg 180 can be non-parallel to the inner surface 162 of the body opening 160, but not more than + / - 5°. In any case, the damper element 170 can be easily inserted into the body opening 160 individually or in a pre-stacked manner, and the outer end surface 186 of the end portion 184 thereof does not interfere with the insertion.

[0092] like Figure 7B and Figure 8B As shown, under the influence of the centrifugal force CF caused by the rotation of the rotating blades 114 at a speed higher than the predetermined speed, the head members 172 of the adjacent damper elements 170 force the outer end surfaces 186 of the flexible legs 180 to frictionally engage with the inner surface 162 of the main body opening 160 to reduce vibration. In certain embodiments, as shown, the outer end surface 186 of each flexible leg 180 may include an edge 194 that frictionally engages with the inner surface 162 of the main body opening 160 at a line. In the relaxed state of the plurality of flexible legs 180, the outer end surface 186 of each flexible leg 180 is parallel to the inner surface 162 of the main body opening 160, but is inclined to meet the inner surface 162 at its edge 194 as the flexible legs 180 bend outward.

[0093] like 7A to 8BAs shown, the vibration reduction system 120 for the rotating blade 114 includes a plurality of stacked damper elements 170 for positioning in a body opening 160 defined in the rotating blade 114. Any number of damper elements 170 may be used. As previously described, each damper element 170 includes a head member 172 having an at least partially inclined surface 174, and a plurality of flexible legs 180 extending from the head member 172. Each flexible leg 180 includes a radially extending body portion 182 having an end portion 184 having an outer end surface 186 and an inner end surface 188. The inner end surface 188 of the plurality of flexible legs 180 of each damper element 170 is configured to receive the inclined surface 174 of the head member 172 of an adjacent damper element 170 in the plurality of stacked damper elements 170. As shown in FIG. Figure 7B and Figure 8B As shown, under the influence of the centrifugal force CF caused by the rotation of the rotating blades 114 at a speed higher than a predetermined speed, the head member 172 of the adjacent damper element 170 forces the outer end surfaces 186 of the plurality of flexible legs 180 to frictionally engage with the inner surface 162 of the main body opening 160 to dampen vibration.

[0094] In the case where the damper elements 170 within the stack are identical, they can all function in the same manner, such as causing the flexible legs 180 to pop outwards simultaneously or sequentially within the stack. However, in other embodiments, two or more damper elements 170 may be customized to function in different ways. In this case, the plurality of damper elements 170 have at least one of the following characteristics that differ between at least two damper elements: total mass, total radial length, radial length of the plurality of flexible legs, force required to bend the plurality of flexible legs outwards, shape of the inner end face, shape of the outer end face, and / or angle of the at least partially inclined surface. Different damper elements 170 may be activated to friction damping in different situations. For example, one or more damper elements 170 may be activated at a first predetermined rotational speed ω1 of the rotating blade 114 under a first centrifugal force CF1, and one or more different damper elements 170 may be activated at a second predetermined rotational speed ω2 (different from the first predetermined rotational speed ω1) of the rotating blade 114 under a second centrifugal force CF2 (different from the first centrifugal force CF1). As those skilled in the art will appreciate, a number of different characteristics and different damper elements 170 may be used to provide customized vibration reduction, for example, at different centrifugal forces, different radii along the blade 114, and other operating parameters.

[0095] In certain embodiments, such as Figure 4 and Figure 5 As shown, the vibration reduction system 120 includes only a plurality of stacked damper elements 170, that is, the damper elements are connected to the radially outer ends 210 (ie, as shown in FIG. Figure 4 2, the end of the body opening 160) interacts with, or with, a closure member 166 (such as a closure member 166) that provides at least a portion of the radially outer end 210. Figure 5 shown) interactions.

[0096] Fig. 9 A cross-sectional view of an optional embodiment is shown, wherein Figure 4 As shown, a plurality of flexible legs 180 extend radially inwardly from respective head members 172 of the damper element 170. Fig. 9 , the vibration reduction system 120 also includes a radially inner end element 200 having a head member 202 having an at least partially inclined surface 204 that is configured to engage the inner end surface 188 of the plurality of flexible legs 180 of the radially innermost damper element 170I of the plurality of stacked damper elements 170. The inclined surface 204 of the radially inner end element 200 may have a configuration similar to the inclined surface 174 of the head member 172 of the damper element 170. More specifically, the radially inner end element 200 may have a radially inner end portion 208 that is configured to engage the radially inner end 206 of the body opening 160 (i.e., the body opening 160 with or without the closure member 164 (in a relaxed, non-operating state) of the rotating blade 114. Fig. 9 In the working state of the blade 114, the centrifugal force CF forces the radially inner end element 200 to abut against the radially innermost damper element 170I to force the outer end surface 186 (i.e., edge 194) of its flexible leg 180 to frictionally engage with the inner surface 162 of the body opening 160 to reduce vibration. The radially inner end element 200 can be weighted to increase the radially outward centrifugal force CF applied to the stacked damper elements 170.

[0097] Fig.10 A cross-sectional view of an optional embodiment is shown, wherein Figure 5 As shown, a plurality of flexible legs 180 extend radially outwardly from a corresponding head member 172 of each damper element in the plurality of stacked damper elements 170. Fig.10 In the embodiment, the vibration reduction system 120 may further include a radially outer end element 220 configured to engage the flexible leg 180 of the radially outermost damper element 170X of the plurality of stacked damper elements 170. More specifically, the radially outer end element 220 may have: a radially outer end portion 222 configured to engage the radially outer end 210 of the main body opening 160 (i.e., the main body opening 160 with or without the closure member 166 (in Fig. 9160 ); and a head member 224 having an at least partially inclined surface 226 configured to engage the inner end surface 188 of the plurality of flexible legs 180 of the radially outermost damper element 170X of the plurality of stacked damper elements 170. The inclined surface 226 of the radially outer end member 220 may have a similar configuration to the inclined surface 174 of the head member 172 of the damper element 170. The centrifugal force CF forces the radially outermost damper element 170X against the radially outer end member 220 to force its outer end surface 186 (i.e., edge 194) into frictional engagement with the inner surface 162 of the body opening 160 to attenuate vibration.

[0098] Further references Figure 4 and Figure 5 , Figure 4 A cross-sectional view of an embodiment is shown in which a plurality of flexible legs 180 extend radially inwardly from a corresponding head member 172 of each of a plurality of damper elements 170 and a closure member 164 is located at the base end 130 of the blade 114. In addition, Figure 5 A cross-sectional view of an embodiment is shown in which a plurality of flexible legs 180 extend radially outward from a corresponding head member 172 of each damper element in a plurality of stacked damper elements 170 and a closure member 166 is located in the tip end 132 of the blade 114. It is emphasized that Figure 4 and Figure 5 The arrangement of the stacked damper elements 170 in is switchable. That is, Figure 5 The arrangement of the damper element 170 shown may be used, for example, Figure 4 The blade 114 is shown with the closure member 164 located in the base end 130 of the blade 114, and Figure 4 The arrangement of the damper element 170 shown may be used, for example, Figure 5 The blade 114 is shown with the closure member 166 located in the tip end 132 of the blade 114. Optional embodiments of the end elements 200, 220 may also be used in those alternative arrangements as desired.

[0099] exist Figures 4 to 10 , the head member 172 of the damper element 170 has an inclined surface 174 in the shape of a frustoconical cone. Fig.11 A perspective view of a damper element 170 according to another embodiment is shown, wherein the head member 172 has an inclined surface 174 but has a domed tip 230, ie, it has a rounded end instead of a flat end.

[0100] In operation, the stacked damper elements 170 each provide flexible legs 180 that will expand to frictionally engage the inner surface 162 of the body opening 160. As described above, the damper elements 170 can be customized in a variety of ways to expand and frictionally engage under different operating parameters. The stacked damper elements 170 are more likely to capture relative motion because they are forced to expand and contact the inner surface 162 of the body opening 160 of the blade 114. This arrangement is advantageous because it not only allows the damper elements 170 to move with the body opening 160 in the blade 114, but the sliding between adjacent damper elements 170 also produces a stick-slip motion, which is also effective for vibration reduction.

[0101] Figures 12 to 16B A vibration reduction system 320 is shown having a plurality of stacked damper elements 370 according to other embodiments of the present disclosure. Figures 12 to 16B Similar in layout to Figures 4 to 8B More specifically, Fig.12 shows a schematic cross-sectional view of a turbine blade having a vibration reduction system 320 including a damper element 370 according to other embodiments of the present disclosure; and Fig.13 A schematic cross-sectional view of a turbine blade having a vibration reduction system 320 including a plurality of damper elements 370 is shown according to further embodiments of the present disclosure. Fig.14 A side view of the damper element 370 is shown with the top surface 388 of the damper element superimposed above the damper element. Fig.15A shows a side partial cross-sectional view of a vibration reduction system 320 including a plurality of stacked damper elements 370 in a first position; and Fig. 15B A side partial cross-sectional view of a vibration reduction system 320 including a plurality of stacked damper elements 370 in a second position is shown according to other embodiments of the present disclosure. Fig.16A Shown along Fig.15A A top view of the sight line 16A-16A in FIG. 16A-16A; and Fig. 16B Shown along Fig. 16B A top view of the sight line 16B-16B.

[0102] like Fig.12 and Fig.13As shown, a vibration reduction system 320 for a blade 114 may include a body opening 160 that extends through the body 128 at least partially between the tip end 132 and the base end 130 of the body and through the airfoil 134. The body opening 160 may extend a portion of the distance between the base end 130 and the tip end 132, or it may extend through one or more of the base end 130 or the tip end 132. The body opening 160 may be defined in any portion of any structure of the body 128. For example, where the body 128 includes an internal dividing wall (not shown), for example, for defining a cooling circuit therein, the body opening 160 may be defined as an inner cavity in the dividing wall in the body 128. The body opening 160 generally extends radially in the body 128. However, the body opening 160 may be angled relative to the radial extent of the body 128 and may be curved. The body opening 160 has an inner surface 162. The body opening may have an inner diameter ID.

[0103] like Fig.12 The body opening 160 may begin at the base end 130 of the blade 114, as shown, or may begin at the base end 130 of the blade 114, as shown. Fig.13 As shown, it may start at the tip end 132 of the blade 114. More specifically, as Fig.12 As shown, the body opening 160 may open in the base end 130 and terminate in the tip end 132, or as shown in FIG. Fig.13 As shown, it may be open in the tip end 132 and terminate in the base end 130. The open end may facilitate assembly of the vibration reduction system 120 in the blade 114 and may allow the system to be retrofitted into existing blades. Fig.12 As shown, in the case where the main body opening 160 extends through the base end 130, a closing member 164 for closing the main body opening 160 may be provided. Fig.13 As shown, with the body opening 160 extending through the tip end 132, a closure member 166 may be provided for the body opening 160. In addition to closing the body opening 160, the closure members 164, 166 also prevent the vibration reduction system 120 from being removed from the body opening 160, such as during use. The body opening 160 may have a radially inner end 206 and a radially outer end 210, each of which may be provided at least in part by the closure members 164, 166 according to an embodiment.

[0104] The vibration reduction system 320 (and its damper element 370) is substantially similar in structure and function to the vibration reduction systems (and its damper elements) described with respect to other embodiments herein. For example, the damper element 370 is substantially similar with respect to Figures 4 to 8BThe damper element 170 is described. It is noted that the damper element 370 includes a head member 172 having an at least partially inclined surface 174, and a plurality of flexible legs 180 extending from the head member 172. Figures 4 to 8B ), the damper element 370 includes an opening 390 defined through the center of the head member 172 and an elongated body 392 extending through the opening 390 in the head member 172. Fig.14 As shown, the head member 172 of each damper element 370 has an inclined surface 174 in the shape of a frustoconical cone through which the opening 390 extends. Other shapes of the head member 172 are possible.

[0105] The opening 390 and the elongated body 392 may have any matching cross-sectional shapes, such as circular (e.g., Fig.14 ), rectangular or oval, polygonal, etc. A single elongated body 392 may extend through each damper element 370 in the stack of damper elements 370 in the vibration reduction system 320. The elongated body 392 is configured to resonate at the same frequency as the rotating blade 114, whereby the elongated body 392 generates a force on the damper element 370. The elongated body 392 may be configured to resonate at the same frequency as the rotating blade 114 by controlling factors such as its mass, curvature, stiffness, diameter, and length. The elongated body 392 slides freely in the opening 390, but has a close clearance therewith, so that the movement of the elongated body 392 caused by the vibration of the blade 114 will physically impact the interior of the opening 390, thereby causing the corresponding damper element 370 to move. In this way, the elongated body 392 can reduce the possibility of the damper elements 370 getting stuck on the inner surface 162 of the body opening 160 or getting stuck to each other.

[0106] The vibration reduction system 320 may include only stacked damper elements 370, similar to Figure 4 and Figure 5 The arrangement of the damper element 170 is shown in FIG. Fig.12 and Fig.13 As shown, the vibration reduction system 320 may also include a radially outer retainer element 330 that is fixed to the elongated body 392 to retain the plurality of stacked damper elements 370 on the elongated body 392. The radially outer retainer element 330 may take a variety of forms. In one example, as shown in FIG. Fig.12 As shown, the radially outer retainer element 330 may include an end portion 332 that is configured to abut the radially outer end 210 of the body opening 160 during use, that is, the body opening 160 with or without the closure member 166 ( Fig.13) end. The radially outer retainer element 330 may also include a radially inner end 334 having a shape corresponding to the head member 172 of the radially outermost damper element 370X. More specifically, as Fig.12 As shown, with a plurality of flexible legs 180 extending radially outward from a corresponding head member 172 of each of a plurality of damper elements 370, a radially inner end 334 of a radially outer retainer element 330 has a shape that engages or receives a head member 172 of a radially outermost damper element 370X. For example, the radially inner end 334 of the radially outer retainer element 330 may have a flat surface to engage the head member 172, or it may have a trapezoidal concave cross-section (as shown) to (complementarily) receive a matching head member 172. In the case where the head member 172 has a different shape, the radially inner end 334 of the radially outer retainer element 330 may be of a complementary shape. Fig.13 , where the plurality of flexible legs 180 extend radially outward from the corresponding head member 172 of each of the plurality of damper elements 370, the radially inner end 334 of the radially outer retainer element 330 has a shape similar to the head member 172 of the radially outermost damper element 370X, i.e., has a frustoconical shape, to force the flexible legs 180 of the radially outermost damper element 370X into frictional engagement with the inner surface 162 of the body opening 160. Where the head member 172 has a different shape, the radially inner end 334 of the radially outer retainer element 330 may be of a complementary shape.

[0107] In addition, if Fig.12 and Fig.13 As shown, the vibration reduction system 320 may also include a radially inner end element 340 that is slidably connected to the elongated body 392 to apply additional centrifugal force to the plurality of stacked damper elements 370 on the elongated body 392. Fig.12 As shown, with the flexible legs 180 extending radially inwardly from the corresponding head member 172 of each damper element in the plurality of damper elements 370, the radially inner end element 340 may include: a radially outer end (head member) 342 having an at least partially inclined surface 344 configured to engage the plurality of flexible legs 180 ( FIG. 15A to FIG. 15B ) of the inner end surface 188 ( FIG. 15A to FIG. 15B); and an opening 346 through the radially inner end element 340 through which the elongated body 392 extends. The radially inner end element 340 can slide on the elongated body 392, i.e., apply additional centrifugal force to the stacked damper elements 370. The radially inner end 348 of the radially inner end element 340 can have any shape to abut the radially inner end 206 of the body opening 160 in the non-operating state of the blade 114 (i.e., with or without the closure member 164 ( Fig.12 )).

[0108] like Fig.13 As shown, the radially inner end member 340 may be configured to extend from the corresponding head member 172 ( FIG. 15A to FIG. 15B ) radially outwardly extending, the head member 172 ( Fig.14 ). For example, the radially outer end 342 of the radially inner end element 340 may have a flat surface to engage the head component 172, or it may have a trapezoidal concave cross-section (as shown) to (complementarily) receive the mating head component 172. The radially inner end element 340 also includes an opening 346 through which the elongated body 392 extends. The radially inner end element 340 can slide on the elongated body 392, i.e., apply additional centrifugal force to the stacked damper elements 370. Fig.13 , the radially inner end 348 of the radially inner end element 340 may have any shape to abut the radially inner end 206 of the body opening 160 in the non-operating state of the blade 114 (ie, with or without the closure member 164 ( Fig.12 )).

[0109] The vibration reduction system 320 for the rotating blade 114 includes a plurality of stacked damper elements 370 for positioning in a body opening 160 defined in the rotating blade 114. As noted, each damper element 370 includes a head member 172 having an at least partially inclined surface 174 and an opening 390 defined through the center of the head member 172. A plurality of flexible legs 180 extend from the head member 172, and an elongated body 392 extends through the opening 390 in the head member 172 of each of the damper elements 370. Other aspects of the vibration reduction system 320 may be described with respect to the vibration reduction system 120 ( Figure 4 , Figure 5 , 7A to 8B ) is arranged as described.

[0110] In certain embodiments, when the damper elements 370 in the stack are identical, they can all function in the same manner, such as causing the flexible legs 180 to pop outwards simultaneously or sequentially within the stack. However, in other embodiments, two or more damper elements 370 may be customized to function in different manners. In this case, the plurality of damper elements 370 have at least one of the following characteristics that differ between at least two damper elements: total mass, total radial length, radial length of the plurality of flexible legs, force required to bend the plurality of flexible legs outwards, shape of the inner end face, shape of the outer end face, angle of the at least partially inclined surface. In this way, different damper elements 370 can be activated into friction damping in different circumstances. For example, one or more damper elements 370 can be activated at a first predetermined rotational speed ω1 of the rotating blade 114 under a first centrifugal force CF1 (not shown in the drawings), and one or more different damper elements 370 can be activated at a second predetermined rotational speed ω2 (different from the first predetermined rotational speed ω1) of the rotating blade 114 under a second centrifugal force CF2 (different from the first centrifugal force CF1). As those skilled in the art will appreciate, a number of different characteristics and different damper elements 370 may be used to provide customized vibration reduction, for example, at different centrifugal forces, different radii along the blade 114, and other operating parameters.

[0111] In operation, the stacked damper elements 370 each provide flexible legs 180 that will expand to frictionally engage the inner surface 162 of the body opening 160. As described above, the damper elements 370 can be customized in a variety of ways to expand and frictionally engage under different operating parameters. The stacked damper elements 370 are more likely to capture relative motion because they are forced to expand and contact the inner surface 162 of the body opening 160 of the blade 114. This arrangement is advantageous because it not only allows the damper elements 370 to move with the body opening 160 in the blade 114, but the sliding between adjacent damper elements 370 also produces a stick-slip motion, which is also effective for vibration reduction. The elongated body 392 reduces the possibility of the damper elements 370 getting stuck on the inner surface 162 of the body opening 160 or getting stuck to each other.

[0112] The damper elements 170, 370 may be formed using any now known or later developed manufacturing process (e.g., casting). In certain preferred embodiments, the damper elements 170, 370 may be additively manufactured from any material (including, but not limited to, cobalt-chromium) that can withstand the environment in which they are used. The damper elements 170, 370, the elongated body 392, and the various end elements 200, 220, 330, 340 may be made of any material that has sufficient strength, flexibility, and durability for their described function and environment within the blade 114.

[0113] Embodiments of the present disclosure provide various technical and commercial advantages, examples of which are discussed herein. Damper elements and vibration reduction systems having damper elements are more likely to capture relative motion because they are forced to expand and contact the inner surface of the main body opening in the rotating blade. The various arrangements described herein are advantageous because they not only allow the damper element to move with the inner surface of the main body opening in the rotating blade in close proximity, i.e., in the event that centrifugal force fails to expand the flexible legs, but also the sliding from the unloaded flexible legs to the loaded bent legs produces a stick-slip motion, which is effective for vibration reduction. The vibration reduction system also reduces blade vibrations through a simple arrangement and does not add much additional mass to the blade. Therefore, the vibration reduction system and damper element do not significantly increase the overall centrifugal force at the tip end of the blade, and do not require changes to the blade configuration.

[0114] As used throughout the specification and claims, approximate language can be used to modify any quantitative representation that can be permitted to vary without resulting in a change in the basic function to which it is associated. Therefore, values ​​modified by one or more terms (such as "about", "approximately" and "substantially") are not limited to the precise values ​​specified. In at least some cases, approximate language can correspond to the precision of the instrument used to measure the value. Here and throughout the specification and claims, range limitations can be combined and / or interchanged; unless the context or language indicates otherwise, these ranges are identified and include all subranges contained therein. "About" or "approximately" applied to a particular value of a range applies to both end values ​​and may indicate + / -10% of the value unless otherwise dependent on the precision of the instrument for measuring the value.

[0115] The corresponding structures, materials, actions and equivalents of all means or steps plus function elements in the following claims are intended to include any structure, material or action for performing functions in conjunction with other claimed elements specifically claimed. A description of the present disclosure has been given for the purpose of illustration and description, but it is not intended to be exhaustive or to limit the present disclosure to the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and essence of the present disclosure. Embodiments have been selected and described in order to best explain the principles and practical applications of the present disclosure, and to enable other persons of ordinary skill in the art to understand the various embodiments of the present disclosure and various modifications thereof suitable for the intended specific use.

Claims

1. A damper element (170, 370) for a vibration reduction system (120, 320) in a body opening (260) in a rotating blade (114) in a turbine (108), the damper element (170, 370) comprising: a head member (172, 202, 224, 342) having an at least partially inclined surface (174, 204, 226, 344) and an opening (390) defined through a center of the head member (172, 202, 224, 342); a plurality of flexible legs (180) extending from the head member (172, 202, 224, 342), wherein each flexible leg (180) includes a radially extending body portion (182) having a distal end portion (184), the distal end portion (184) having an outer end surface (186) and an inner end surface (188); and An elongated body (392) extends through the opening (390) in the head member (172, 202, 224, 342).

2. The damper element (170, 370) of claim 1, wherein the elongated body (392) is configured to resonate at the same frequency as the rotating blade (114), whereby the elongated body (392) generates a force on the damper element (170, 370).

3. The damper element (170, 370) according to claim 1, wherein the at least partially inclined surface (174, 204, 226, 344) has an angle in the range between 25° and 55° relative to the inner surface (162) of the body opening (160), and the inner end surfaces (188) of the plurality of flexible legs (180) have an angle in the range between 25° and 55° relative to the inner surface (162) of the body opening (160).

4. The damper element (170, 370) of claim 1, wherein the head member (172, 202, 224, 342) and the radially extending body portion (182) of the plurality of flexible legs (180) each have a first outer diameter, and the outer end surfaces (186) of the plurality of flexible legs (180) collectively define a second outer diameter that is greater than the first outer diameter.

5. The damper element (170, 370) of claim 4, wherein the body opening (160) has an inner surface (162) having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby in a relaxed state, the plurality of flexible legs (180) pass freely within the body opening (160).

6. The damper element (170, 370) of claim 4, wherein the inner end surface (188) of the plurality of flexible legs (180) is configured to receive the at least partially inclined surface (174, 204, 226, 344) of the head member (172, 202, 224, 342) of an adjacent damper element (170, 370), Wherein, under the influence of centrifugal force caused by the rotation of the rotating blade (114) at a speed higher than a predetermined speed, the head member (172, 202, 224, 342) of the adjacent damper element (170, 370) forces the outer end surfaces (186) of the plurality of flexible legs (180) to frictionally engage with the inner surface (162) of the main body opening (160) to reduce vibration.

7. The damper element (170, 370) of claim 6, wherein the outer end surface (186) of each flexible leg (180) frictionally engages the inner surface (162) of the body opening at a line.

8. The damper element (170, 370) of claim 1, wherein adjacent radially extending body portions (182) of the plurality of flexible legs (180) define a slot (190) therebetween having a rounded radial outer extent (192).

9. The vibration reduction system (120, 320) of claim 1, wherein the head member (172, 202, 224, 342) of each damper element (170, 370) has an at least partially inclined surface (174, 204, 226, 344), the at least partially inclined surface having a frustoconical shape, the opening (390) extending through the at least partially inclined surface.

10. A vibration reduction system (120, 320) for a rotating blade (114), the vibration reduction system (120, 320) comprising: A plurality of stacked damper elements (170, 370) for positioning in a body opening (160) defined in the rotating blade (114), each damper element (170, 370) comprising: a head member (172, 202, 224, 342) having an at least partially inclined surface (174, 204, 226, 344) and an opening (390) defined through a center of the head member (172, 202, 224, 342); A plurality of flexible legs (180) extending from the head member (172, 202, 224, 342), wherein each flexible leg (180) includes a radially extending body portion (182) having a distal end portion (184) having an outer end surface (186) and an inner end surface (188); and An elongated body (392) extends through the opening (390) in the head member (172, 202, 224, 342) of each damper element of the plurality of damper elements (170, 370).

11. The vibration reduction system (120, 320) of claim 10, wherein the at least partially inclined surface (174, 204, 226, 344) of each damper element (170, 370) has an angle in the range between 25° and 55° relative to the inner surface (162) of the body opening (160), and the inner end surfaces (188) of the plurality of flexible legs (180) have an angle in the range between 25° and 55° relative to the inner surface (162) of the body opening (160).

12. The vibration reduction system (120, 320) of claim 10, wherein the head member (172, 202, 224, 342) of each damper element (170, 370) and the radially extending body portion (182) of the plurality of flexible legs (180) each have a first outer diameter, and the outer end surfaces (186) of the plurality of flexible legs (180) of each damper element (170, 370) collectively define a second outer diameter that is greater than the first outer diameter.

13. The vibration reduction system (120, 320) of claim 12, wherein the body opening (160) has an inner surface (162) having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby in a relaxed state, the plurality of flexible legs (180) of each damper element (170, 370) freely pass within the body opening (160).

14. The vibration reduction system (120, 320) of claim 12, wherein the inner end surface (188) of the plurality of flexible legs (180) of each damper element (170, 370) is configured to receive the at least partially inclined surface (174, 204, 226, 344) of the head member (172, 202, 224, 342) of an adjacent damper element (170, 370) in the plurality of stacked damper elements (170, 370), Wherein, under the influence of centrifugal force caused by the rotation of the rotating blade (114) at a speed higher than a predetermined speed, the head member (172, 202, 224, 342) of the adjacent damper element (170, 370) forces the outer end surfaces (186) of the plurality of flexible legs (180) to frictionally engage with the inner surface (162) of the main body opening (160) to reduce vibration.

15. The vibration reduction system (120, 320) of claim 14, wherein the outer end surface (186) of each flexible leg (180) frictionally engages the inner surface (162) of the body opening (160) at a line.

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