Patent Publication Number: US-2022213793-A1

Title: Rotor damping devices for a turbomachine

Description:
FIELD 
     The present subject matter relates generally to a turbomachine or a gas turbine engine, or more particularly to a rotor damping device for a turbomachine. 
     BACKGROUND 
     Fluid film journal bearings have long been used to dampen the vibration created by turbomachines. Rotors in aircraft gas turbine engines and industrial centrifugal compressors often use squeeze film damper bearings supported by spring bars to reduce the amount of vibration transmitted from the rotor to the supporting structure. In a fluid film bearing, a thin fluid film forms a buffer between the rotating journal surface and the stationary bearing surface, and dampens vibration from the rotor. In a squeeze film damper bearing, a thin film of fluid is squeezed by two non-rotating cylindrical surfaces. One surface is stationary while the other is positioned by a spring bar support structure and oscillates with the motion of the rotor. The squeezing of the fluid film dampens rotor vibration through the bearing support. 
     Damping the vibration in a turbomachine provides quiet and comfortable operation of the machine, reduced fatigue stress on the machine and its supports, and a safeguard to the damage that can be caused by unstable vibration. Vibration in a turbomachine is usually caused by a rotating mass imbalance, e.g., rotor, or by aerodynamic forces within the turbine and/or compressor. These vibrations are not static, but vary with the operating speed and operating characteristics of the turbomachine. Turbomachine vibration has a dynamic range that varies in magnitude and frequency with the operating speed of the turbomachine. 
     Conventional systems only having a single fluid damper can be made ineffective when a fluid, such as oil, runs out; when vibrations are so high that the fluid damper bottoms out; and/or when oil viscosity is very high during cold temperatures causing the damper to become more rigid. 
     BRIEF DESCRIPTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one exemplary embodiment of the present disclosure, a rotor damping device for a turbomachine is provided. The rotor damping device includes a first fluid damper; and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition, and wherein, during the interruption condition, the wire mesh of the second damper dampens vibration of the turbomachine. 
     In certain exemplary embodiments the second damper is in parallel configuration with the first fluid damper. 
     In certain exemplary embodiments the second damper is in series configuration with the first fluid damper. 
     In certain exemplary embodiments the rotor damping device includes a sidewall portion between a static structure, wherein the wire mesh is contained within the sidewall portion to constrain axial deflection and apply a preload. 
     In certain exemplary embodiments the rotor damping device includes a ball bearing mounted on a first portion of a squirrel cage and a roller bearing mounted on a second portion of the squirrel cage. 
     In certain exemplary embodiments the first fluid damper includes a film of fluid squeezed between a first non-rotating surface and a second non-rotating surface. 
     In certain exemplary embodiments the film of fluid is oil. 
     In certain exemplary embodiments the first fluid damper includes a damper housing having an outer rim, an inner rim, and a first cavity defined between the outer rim and the inner rim. 
     In certain exemplary embodiments a damper oil is contained within the first cavity and the wire mesh is contained within the first cavity immersed in the damper oil. 
     In certain exemplary embodiments the wire mesh is metal. 
     In certain exemplary embodiments the first fluid damper further includes a second cavity spaced apart from the first cavity. 
     In certain exemplary embodiments a damper oil is contained within the first cavity and the wire mesh is contained within the second cavity. 
     In certain exemplary embodiments the wire mesh is a shape memory material. 
     In certain exemplary embodiments the first fluid damper transitions to the interruption condition when a fluid runs out or when bottomed out. 
     In another exemplary embodiment of the present disclosure, a rotor damping device for a turbomachine is provided. The rotor damping device includes a first fluid damper comprising a damper housing having an outer rim, an inner rim, and a first cavity defined between the outer rim and the inner rim; and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition, and wherein, during the interruption condition, the wire mesh of the second damper dampens vibration of the turbomachine. 
     In certain exemplary embodiments a damper oil is contained within the first cavity and the wire mesh is contained within the first cavity immersed in the damper oil. 
     In certain exemplary embodiments the wire mesh is metal. 
     In certain exemplary embodiments the first fluid damper further includes a second cavity spaced apart from the first cavity. 
     In certain exemplary embodiments a damper oil is contained within the first cavity and the wire mesh is contained within the second cavity. 
     In an exemplary aspect of the present disclosure, a method is provided for damping vibration of a turbomachine. The method includes providing a rotor damping device comprising a first fluid damper and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition; and damping vibration of the turbomachine with the second damper during the interruption condition. 
     These and other features, aspects and advantages 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 invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, 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  is a schematic, cross-sectional view of an exemplary gas turbine engine in accordance with exemplary embodiments of the present disclosure. 
         FIG. 2A  is a schematic, cross-sectional view of a first fluid damper of a rotor damping device in accordance with exemplary embodiments of the present disclosure. 
         FIG. 2B  is a schematic, cross-sectional view of a first fluid damper of a rotor damping device in accordance with exemplary embodiments of the present disclosure. 
         FIG. 3  is a perspective view of a wire mesh of a second fluid damper of a rotor damping device in accordance with exemplary embodiments of the present disclosure. 
         FIG. 4  is a perspective view of a squirrel cage of a rotor damping device in accordance with exemplary embodiments of the present disclosure. 
         FIG. 5A  is a schematic, cross-sectional view of a first exemplary rotor damping device in a parallel configuration in normal operation in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 5B  is a schematic, cross-sectional view of a first exemplary rotor damping device in a parallel configuration in oil starved operation in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 5C  is a schematic, cross-sectional view of a first exemplary rotor damping device in a parallel configuration in a bottomed out operation in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 5D  is a schematic, cross-sectional view of a wire mesh of a first exemplary rotor damping device in a first configuration in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 5E  is a schematic, cross-sectional view of a wire mesh of a first exemplary rotor damping device in a second configuration in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 6A  is a schematic, cross-sectional view of a second exemplary rotor damping device in a series configuration in normal operation in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 6B  is a schematic, cross-sectional view of a second exemplary rotor damping device in a series configuration in oil starved operation in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 6C  is a schematic, cross-sectional view of a second exemplary rotor damping device in a series configuration in a bottomed out operation in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 7A  is a perspective view of a squirrel cage of a rotor damping device in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 7B  is a schematic, cross-sectional view of a third exemplary rotor damping device in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 7C  is a schematic, cross-sectional view of a third exemplary rotor damping device in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 7D  is a schematic, cross-sectional view of a third exemplary rotor damping device in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 7E  is a schematic, cross-sectional view of a third exemplary rotor damping device in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 8  is a schematic, cross-sectional view of a fourth exemplary rotor damping device in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 9  is a schematic, cross-sectional view of a variety of different wire mesh geometrical shapes in accordance with exemplary embodiments of the present disclosure. 
         FIG. 10A  is a schematic, cross-sectional view of a fifth exemplary rotor damping device in a configuration in normal operation in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 10B  is a schematic, cross-sectional view of a fifth exemplary rotor damping device in a configuration in oil starved operation in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 10C  is a schematic, cross-sectional view of a fifth exemplary rotor damping device in a configuration in a bottomed out operation in accordance with another exemplary embodiment of the present disclosure. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the disclosure, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. 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. 
     The following description is provided to enable those skilled in the art to make and use the described embodiments contemplated for carrying out the invention. Various modifications, equivalents, variations, and alternatives, however, will remain readily apparent to those skilled in the art. Any and all such modifications, variations, equivalents, and alternatives are intended to fall within the spirit and scope of the present invention. 
     For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “forward” and “aft” refer to relative positions within a gas turbine engine, with forward referring to a position closer to an engine inlet and aft referring to a position closer to an engine nozzle or exhaust. 
     The terms “upstream” and “downstream” refer to the relative direction 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 singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. 
     Additionally, the terms “low,” “high,” or their respective comparative degrees (e.g., lower, higher, where applicable) each refer to relative speeds within an engine, unless otherwise specified. For example, a “low-pressure turbine” operates at a pressure generally lower than a “high-pressure turbine.” Alternatively, unless otherwise specified, the aforementioned terms may be understood in their superlative degree. For example, a “low-pressure turbine” may refer to the lowest maximum pressure turbine within a turbine section, and a “high-pressure turbine” may refer to the highest maximum pressure turbine within the turbine section. 
     Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a ten percent margin. Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. 
     Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. 
     A rotor damping device of the present disclosure includes a first fluid damper and a second damper in communication with the first fluid damper. Systems only having a single fluid damper can be made ineffective when a fluid, such as oil, runs out and/or when vibrations are so high that the fluid damper bottoms out. In other words, a first fluid damper is transitionable between a working condition, i.e., a condition in which the first fluid damper dampens vibration of the turbomachine, and an interruption condition, i.e., when the first fluid damper ineffectively dampens vibration of the turbomachine. 
     Accordingly, a rotor damping device of the present disclosure further includes a second damper in communication with the first fluid damper. In this manner, during any interruption condition of the first fluid damper, the second damper dampens vibration of the turbomachine. 
     Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,  FIG. 1  is a schematic cross-sectional view of a gas turbine engine in accordance with an exemplary embodiment of the present disclosure. More particularly, for the embodiment of  FIG. 1 , the gas turbine engine is a high-bypass turbofan jet engine  10 , referred to herein as “turbofan engine  10 .” As shown in  FIG. 1 , the turbofan engine  10  defines an axial direction A (extending parallel to a longitudinal centerline or axis  12  provided for reference) and a radial direction R. In general, the turbofan  10  includes a fan section  14  and a turbomachine  16  disposed downstream from the fan section  14 . Exemplary rotor damping devices  100  of the present disclosure are compatible with rotor components of an exemplary turbomachine  16  of engine  10  of  FIG. 1 . 
     The exemplary turbomachine  16  depicted generally includes a substantially tubular outer casing  18  that defines an annular inlet  20 . The outer casing  18  encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor  22  and a high pressure (HP) compressor  24 ; a combustion section  26 ; a turbine section including a high pressure (HP) turbine  28  and a low pressure (LP) turbine  30 ; and a jet exhaust nozzle section  32 . A high pressure (HP) shaft or spool  34  drivingly connects the HP turbine  28  to the HP compressor  24 . A low pressure (LP) shaft or spool  36  drivingly connects the LP turbine  30  to the LP compressor  22 . Additionally, the compressor section, combustion section  26 , and turbine section together define at least in part a core air flowpath  37  extending therethrough. Each compressor  22 ,  24  may, in turn, include one or more rows of stator vanes interdigitated with one or more rows of compressor rotor blades. Moreover, each turbine  28 ,  30  may, in turn, include one or more rows of stator vanes interdigitated with one or more rows of turbine rotor blades. 
     For the embodiment depicted, the fan section  14  includes a variable pitch fan  38  having a plurality of fan blades  40  coupled to a disk  42  in a spaced apart manner. As depicted, the fan blades  40  extend outwardly from disk  42  generally along the radial direction R. Each fan blade  40  is rotatable relative to the disk  42  about a pitch axis P by virtue of the fan blades  40  being operatively coupled to a suitable actuation member  44  configured to collectively vary the pitch of the fan blades  40  in unison. The fan blades  40 , disk  42 , and actuation member  44  are together rotatable about the longitudinal axis  12  by LP shaft  36  across a power gear box  46 . The power gear box  46  includes a plurality of gears for stepping down the rotational speed of the LP shaft  36  to a more efficient rotational fan speed. In an exemplary embodiment of the present disclosure, the fan  14  may include a number of rotor stages, each of which includes a row of fan blades or rotor airfoils mounted to a rotor having a rotatable disk. The fan  14  may also include at least one stator stage including a row of stationary or stator airfoils that serve to turn the airflow passing therethrough. As used herein, the term “fan” refers to any apparatus in a turbine engine having a rotor with airfoils operable to produce a fluid flow. It is contemplated that the principles of the present invention are equally applicable to multi-stage fans, single-stage fans, and other fan configurations; as well as with low-bypass turbofan engines, high-bypass turbofan engines, and other engine configurations. 
     Referring still to the exemplary embodiment of  FIG. 1 , the disk  42  is covered by rotatable front nacelle  48  aerodynamically contoured to promote an airflow through the plurality of fan blades  40 . Additionally, the exemplary fan section  14  includes an annular fan casing or outer nacelle  50  that circumferentially surrounds the fan  38  and/or at least a portion of the turbomachine  16 . The nacelle  50  is, for the embodiment depicted, supported relative to the turbomachine  16  by a plurality of circumferentially-spaced outlet guide vanes  52 . Additionally, a downstream section  54  of the nacelle  50  extends over an outer portion of the turbomachine  16  so as to define a bypass airflow passage  56  therebetween. 
     During operation of the turbofan engine  10 , a volume of air  58  enters the turbofan  10  through an associated inlet  60  of the nacelle  50  and/or fan section  14 . As the volume of air  58  passes across the fan blades  40 , a first portion of the air  58  as indicated by arrows  62  is directed or routed into the bypass airflow passage  56  and a second portion of the air  58  as indicated by arrow  64  is directed or routed into the LP compressor  22 . The ratio between the first portion of air  62  and the second portion of air  64  is commonly known as a bypass ratio. The pressure of the second portion of air  64  is then increased as it is routed through the high pressure (HP) compressor  24  and into the combustion section  26 , where it is mixed with fuel and burned to provide combustion gases  66 . 
     The combustion gases  66  are routed through the HP turbine  28  where a portion of thermal and/or kinetic energy from the combustion gases  66  is extracted via sequential stages of HP turbine stator vanes  68  that are coupled to the outer casing  18  and HP turbine rotor blades  70  that are coupled to the HP shaft or spool  34 , thus causing the HP shaft or spool  34  to rotate, thereby supporting operation of the HP compressor  24 . The combustion gases  66  are then routed through the LP turbine  30  where a second portion of thermal and kinetic energy is extracted from the combustion gases  66  via sequential stages of LP turbine stator vanes  72  that are coupled to the outer casing  18  and LP turbine rotor blades  74  that are coupled to the LP shaft or spool  36 , thus causing the LP shaft or spool  36  to rotate, thereby supporting operation of the LP compressor  22  and/or rotation of the fan  38 . 
     The combustion gases  66  are subsequently routed through the jet exhaust nozzle section  32  of the turbomachine  16  to provide propulsive thrust. Simultaneously, the pressure of the first portion of air  62  is substantially increased as the first portion of air  62  is routed through the bypass airflow passage  56  before it is exhausted from a fan nozzle exhaust section  76  of the turbofan  10 , also providing propulsive thrust. The HP turbine  28 , the LP turbine  30 , and the jet exhaust nozzle section  32  at least partially define a hot gas path  78  for routing the combustion gases  66  through the turbomachine  16 . 
     It should be appreciated, however, that the exemplary turbofan engine  10  depicted in  FIG. 1  is by way of example only, and that in other exemplary embodiments, the turbofan engine  10  may have any other suitable configuration. For example, in other exemplary embodiments, the turbofan engine  10  may be a direct drive turbofan engine (i.e., not including the power gearbox  46 ), may include a fixed pitch fan  38 , etc. Additionally, or alternatively, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine, such as a turboshaft engine, turboprop engine, turbojet engine, open rotor or unducted turbofan engine, a land-based gas turbine engine for power generation, an aeroderivative gas turbine engine, etc. 
     Referring to  FIGS. 2A-10C , exemplary rotor damping devices  100  of the present disclosure include a first fluid damper  102  and a second damper  104  in communication with the first fluid damper  102 . 
     However, systems only having a single fluid damper can be made ineffective when a fluid, such as oil, runs out; when vibrations are so high that the fluid damper bottoms out; and/or when oil viscosity is very high during cold temperatures causing the damper to become more rigid. In other words, the first fluid damper  102  is transitionable between a working condition, i.e., a condition in which the first fluid damper  102  dampens vibration of the turbomachine  16 , and an interruption condition, i.e., when the first fluid damper  102  ineffectively dampens vibration of the turbomachine  16 . 
     Accordingly, a rotor damping device  100  of the present disclosure further includes a second damper  104  in communication with the first fluid damper  102 . In this manner, during any interruption condition of the first fluid damper  102 , the second damper  104  dampens vibration of the turbomachine  16 . 
     Referring now to  FIGS. 2A and 2B , an exemplary embodiment of a first fluid damper  102  will now be described. The first fluid damper  102  provides a first damping portion of the rotor damping device  100  of the present disclosure and is used to dampen the vibration created by turbomachine  16 . 
     In some exemplary embodiments, the first fluid damper  102  includes a film of fluid  110  squeezed between a first non-rotating surface  112  and a second non-rotating surface  114 . In an exemplary embodiment, the film of fluid  110  is oil. The first fluid damper  102  of the present disclosure may comprise a squeeze film damper supported by spring bars to reduce the amount of vibration transmitted from the rotor to the supporting structure. 
     Referring to  FIG. 2B , the thin fluid film  110  forms a buffer between the first non-rotating surface  112  and the second non-rotating surface  114 , and dampens vibration from the rotor. For example, the thin film of fluid  110  may be squeezed by two non-rotating cylindrical surfaces. One surface is stationary while the other is positioned by a spring bar support structure and oscillates with the motion of the rotor. The squeezing of the fluid film dampens rotor vibration through the bearing support. 
     Referring to  FIG. 2B , in an exemplary embodiment, a first fluid damper  102  includes a fluid film  110  formed between a first surface  112 , e.g., an inside surface of a squeeze film cylinder and a second surface  114 , e.g., an inside surface of a spring support. The first fluid damper includes fluid ports  80  of the assembly that pass fluid directly to the fluid film  110  through the annular stationary ring assembly  82 . Just inside of the squeeze film cylinder are two annular fluid plenums  84  that receive fluid from fluid ports  80 . 
     The fluid film  110  acts as a squeeze film vibration damper. The energy adsorbed in forcing oil in and out of the squeeze film dampens vibration. In some exemplary embodiments, when a bearing spring support flexes with respect to the squeeze film, oil is pushed out or drawn into the squeeze films. The movement of oil in and out of the squeeze film adsorbs energy and, thus, dampens vibration. 
     However, systems only having a single fluid damper can be made ineffective when a fluid, such as oil, runs out; when vibrations are so high that the fluid damper bottoms out; and/or when oil viscosity is very high during cold temperatures causing the damper to become more rigid. 
     In other words, the first fluid damper  102  is transitionable between a working condition, i.e., a condition in which the first fluid damper  102  dampens vibration of the turbomachine  16 , and an interruption condition, i.e., when the first fluid damper  102  ineffectively dampens vibration of the turbomachine  16 . 
     Accordingly, referring to  FIGS. 2A-10C , rotor damping devices  100  of the present disclosure further include a second damper  104  in communication with the first fluid damper  102 . In this manner, during any interruption condition of the first fluid damper  102 , the second damper  104  dampens vibration of the turbomachine  16 . 
     Referring to  FIG. 3 , the second damper  104  of the present disclosure includes a wire mesh  106 . In some exemplary embodiments, the wire mesh  106  of the present disclosure may be formed of a conventional material. In other exemplary embodiments, the wire mesh  106  of the present disclosure may be formed of a metal material. In further exemplary embodiments, the wire mesh  106  of the present disclosure may be formed of a special material like shape memory materials. 
     The wire mesh  106  of the present disclosure may be an oil-free integral wire mesh damper. The wire mesh  106  may be a knitted wire mesh including a metal wire or plastic strand knitted into a mesh structure. The knitting process produces mesh of interlocking loops. These loops can move relative to each other in the same plane without distorting the mesh, giving the knitted mesh a two-way stretch. Because each loop acts as a small spring when subjected to tensile or compressive stress, knitted metal has an inherent resiliency. Knitted metal also provides high mechanical oil-free damping characteristics and non-linear spring rates. Vibration and mechanical shock can be effectively controlled to eliminate the violent resonant conditions and provide ample protection from dynamic overloads. The wire mesh  106  of the present disclosure may provide at least thirty times the damping as compared to a conventional air foil bearing. It is contemplated that the wire mesh  106  of the present disclosure may also be formed from a variety of materials, such as steel, Inconel, aluminum, copper, tantalum, platinum, polypropylene, nylon, polyethylene, and the like. The density and dimensions of the wire mesh  106  can be adjusted to meet a particular design application. 
     Referring to  FIG. 4 , the rotor damping device  100  may be incorporated with a squirrel cage  109 . The squirrel cage  109  takes up axial load and may be the primary element that makes up the bearing support stiffness. 
     Referring to  FIGS. 5A-5E , in an exemplary embodiment, a rotor damping device  100 A includes a second damper  104  that is in parallel configuration with a first fluid damper  102 . Referring to  FIG. 5A-5E , the rotor damping device  100 A includes a first fluid damper  102  and a second fluid damper  104  mounted on a squirrel cage  109  and a static structure  139  in parallel configuration. Furthermore, the rotor damping device  100 A includes a stator portion  140 , a ball bearing  142  mounted on a first portion  146  of the squirrel cage  109 , a roller bearing  144  mounted on a second portion  148  of the squirrel cage  109 , and a sidewall portion  150  extending between the static structure  139 . 
     Referring to  FIG. 5A , in a first configuration of the rotor damping device  100 A, the first fluid damper  102  is in a working condition and is dampening vibration of the turbomachine  16 . In this configuration, the second damper  104  provides a supplemental damping which can be helpful, for example, during hot day starts of the engine  10  ( FIG. 1 ). 
     Referring to  FIG. 5B , in a second configuration of the rotor damping device  100 A, the first fluid damper  102  is in an interruption condition, e.g., the first fluid damper is oil starved and ineffectively dampens vibration of the turbomachine  16 . In this configuration, the second damper  104  provides a backup damping system that is able to effectively dampen vibrations of the turbomachine  16 . In such a configuration, referring to  FIGS. 5D and 5E , the backup damping of the second damper  104  is provided according to the deflection of the wire mesh  106  within the sidewall portion  150 . For example, the wire mesh  106  is contained within the sidewall portion  150  to constrain axial deflection and apply a preload for optimum damping. 
     Referring to  FIG. 5C , in a third configuration of the rotor damping device  100 A, the first fluid damper  102  is in an interruption condition, e.g., the first fluid damper is bottomed out and ineffectively dampens vibration of the turbomachine  16 . In this configuration, the second damper  104  provides a backup damping system that is able to effectively dampen vibrations of the turbomachine  16 . In such a configuration, the backup damping of the second damper  104  is provided even when the first fluid damper  102  is fused. 
     Referring to  FIGS. 6A-6C , in another exemplary embodiment, a rotor damping device  100 B includes a second damper  104  that is in series configuration with a first fluid damper  102 . Referring to  FIG. 6A-6C , the rotor damping device  100 B includes a first fluid damper  102  and a second fluid damper  104  mounted on a squirrel cage  109  in series configuration. Furthermore, the rotor damping device  100 B includes a stator portion  140 , a ball bearing  142  mounted on a first portion  146  of the squirrel cage  109 , a roller bearing  144  mounted on a second portion  148  of the squirrel cage  109 , and a sidewall portion  150  extending between the squirrel cage  109 . 
     Referring to  FIG. 6A , in a first configuration of the rotor damping device  100 B, the first fluid damper  102  is in a working condition and is dampening vibration of the turbomachine  16 . In this configuration, the second damper  104  provides a supplemental damping and allows for a larger first fluid damper  102  gap. 
     Referring to  FIG. 6B , in a second configuration of the rotor damping device  100 B, the first fluid damper  102  is in an interruption condition, e.g., the first fluid damper is oil starved and ineffectively dampens vibration of the turbomachine  16 . In this configuration, the second damper  104  provides a backup damping system that is able to effectively dampen vibrations of the turbomachine  16 . In such a configuration, referring to  FIG. 6B , the backup damping of the second damper  104  is able to dampen the turbomachine  16  as much as the larger gap will allow. 
     Referring to  FIG. 6C , in a third configuration of the rotor damping device  100 B, the first fluid damper  102  is in an interruption condition, e.g., the first fluid damper is bottomed out and ineffectively dampens vibration of the turbomachine  16 . 
     Referring to  FIGS. 10A-10C , in another exemplary embodiment, a rotor damping device  100 E includes a squirrel cage  109  and a second damper  104  in a parallel configuration and a first fluid damper  102  in a series configuration. In such a configuration, the first fluid damper  102  is uncentered and mounted directly on bearing  144 . Referring to  FIG. 10C , in this configuration, the second damper  104  provides a backup damping system that is able to provide additional dampening of vibrations of the turbomachine  16  during a bottomed out or cold temperature condition. 
     Referring to  FIGS. 7A-7E , in another exemplary embodiment, a rotor damping device  100 C includes a second damper  104  that is in configuration with a first fluid damper  102 . Referring to  FIG. 7B , the rotor damping device  100 C of the present disclosure includes a wire mesh  106  that is contained within the same cavity as a damper oil and the wire mesh  106  is within the cavity immersed in the damper oil as described in detail below. 
     Referring to  FIG. 7A-7C , the rotor damping device  100 C includes a first fluid damper  102  and a second fluid damper  104  mounted on a squirrel cage  210 . In this embodiment, the squirrel cage  210  takes up axial load and is the primary element that makes up the bearing support stiffness. 
     Referring to  FIGS. 7A-7E , the rotor damping device  100 C includes a squirrel cage  210 , a damper housing  212  having an outer rim  214 , an inner rim  216 , a first cavity  218  defined between the outer rim  214  and the inner rim  216 , damper oil  219  contained within the first cavity  218 , integral springs  220 , wire mesh portions  106 , an inner stop portion  222 , damper end seals  224 , end seals  226 , angular contact ball bearings  228 , an outer stop portion  230 , oil feed ports  232 , and an oil exit portion  234 . Referring to  FIG. 7B , the damper oil  219  is contained within the first cavity  218  and the wire mesh  106  is contained within the first cavity  218  immersed in the damper oil  219 . 
     The damper housing  212  includes the integral springs  220  and wire mesh segments  106 . The outer rim  214  may float within a bore of the housing  212  and allows for thermal axial growth and has a tight clearance radially. The outer rim  214  is held stationary and requires anti-rotation when not connected a portion of the squirrel cage  210 . The inner rim  216  vibrates and whirls due to rotodynamic shaft unbalance. This interfaces with the roller bearing  144 . The integral springs  220  segments the damper land preventing or blocking circumferential flow and also contributes to the radial stiffness of the device. The springs  220  are in parallel with the squirrel cage  210 . 
     Referring to  FIGS. 7A-7E , the rotor damping device  100 C combines a first fluid damper  102 , e.g., a segmented squeeze film damper or integral squeeze film damper, and a second fluid damper  104  including a wire mesh  106 . In such an embodiment, the wire mesh  106  may be formed of metal mesh damper segments. Advantageously, the wire mesh  106  is located in the same axial locations and in the same radial envelop as the first fluid damper  102 , e.g., the wire mesh  106  is located in the same first cavity  218  as the damper oil  219  and is submersed in the damper oil  219 . By using metal mesh damper segments to form the wire mesh  106 , the wire mesh  106  is porous and therefore oil will flow through the wire mesh  106  and out the end seals  226  which control the damping through the damper end seal clearance  224 . In exemplary embodiments, the second fluid damper  104  is in a parallel configuration with the first fluid damper  102 . 
     Referring to  FIG. 8 , the rotor damping device  100 D includes a first fluid damper  102  and a second fluid damper  104  mounted on a squirrel cage  210 . The difference with rotor damping device  100 D shown in  FIG. 8  is that the wire mesh portions  106  are not contained in the same cavity as the first fluid damper  102 . 
     Referring to  FIG. 8 , the rotor damping device  100 D includes a damper housing  212  having an outer rim  214 , an inner rim  216 , and a first cavity  218  defined between the outer rim  214  and the inner rim  216 . However, in the embodiment of  FIG. 8 , the rotor damping device  100 D further includes a second cavity  250  spaced apart from the first cavity  218 . In such an embodiment, the damper oil  219  is contained within the first cavity  218  and the wire mesh  106  is contained within the second cavity  250  and is separate and apart from the damper oil  219 . 
     In the embodiments discussed above with respect to  FIGS. 7A-7E , the wire mesh  106  is contained within the first cavity  218  immersed in the damper oil  219 . Thus, the exemplary embodiment shown in  FIG. 8  is similar to the embodiments of  FIGS. 7A-7E  except that the wire mesh  106  is not in the same cavity of the first fluid damper  102 . The wire mesh  106  occupies its own cavity  250  or circumferential slow thereby decreasing the angular span of the first fluid damper  102 . 
     Referring to the exemplary embodiments shown in  FIGS. 5A-8 , the wire mesh portions  106  are shown having a rectangular cross-sectional shape. However, it is contemplated that the wire mesh portions  106  of the present disclosure can have any other geometric cross-sectional shapes for a variety of different applications and advantages. For example, referring to  FIG. 9 , the wire mesh portions  106  may have any geometrical cross-sectional shape for a variety of different applications including the following design parameters: (A) inner diameter width and height; (B) outer diameter width and height; (C) height of a support wall; (D) mesh density (stiffness to damping ratio); (E) axial preload; (F) general shape and/or profile; and (G) any other desired design parameters. 
     In an exemplary aspect of the present disclosure, a method is provided for damping vibration of a turbomachine. The method includes providing a rotor damping device comprising a first fluid damper and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition; and damping vibration of the turbomachine with the second damper during the interruption condition. 
     Further aspects of the invention are provided by the subject matter of the following clauses: 
     1. A rotor damping device for a turbomachine, comprising: a first fluid damper; and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition, and wherein, during the interruption condition, the wire mesh of the second damper dampens vibration of the turbomachine. 
     2. The rotor damping device of any preceding clause, wherein the second damper is in parallel configuration with the first fluid damper. 
     3. The rotor damping device of any preceding clause, wherein the second damper is in series configuration with the first fluid damper. 
     4. The rotor damping device of any preceding clause, further comprising: a sidewall portion between a static structure, wherein the wire mesh is contained within the sidewall portion to constrain axial deflection and apply a preload. 
     5. The rotor damping device of any preceding clause, further comprising: a ball bearing mounted on a first portion of a squirrel cage; and a roller bearing mounted on a second portion of the squirrel cage. 
     6. The rotor damping device of any preceding clause, wherein the first fluid damper includes a film of fluid squeezed between a first non-rotating surface and a second non-rotating surface. 
     7. The rotor damping device of any preceding clause, wherein the film of fluid is oil. 
     8. The rotor damping device of any preceding clause, wherein the first fluid damper includes a damper housing having an outer rim, an inner rim, and a first cavity defined between the outer rim and the inner rim. 
     9. The rotor damping device of any preceding clause, wherein a damper oil is contained within the first cavity and the wire mesh is contained within the first cavity immersed in the damper oil. 
     10. The rotor damping device of any preceding clause, wherein the wire mesh is metal. 
     11. The rotor damping device of any preceding clause, wherein the first fluid damper further includes a second cavity spaced apart from the first cavity. 
     12. The rotor damping device of any preceding clause, wherein a damper oil is contained within the first cavity and the wire mesh is contained within the second cavity. 
     13. The rotor damping device of any preceding clause, wherein the wire mesh is a shape memory material. 
     14. The rotor damping device of any preceding clause, wherein the first fluid damper transitions to the interruption condition when a fluid runs out or when bottomed out. 
     15. A rotor damping device for a turbomachine, comprising: a first fluid damper comprising a damper housing having an outer rim, an inner rim, and a first cavity defined between the outer rim and the inner rim; and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition, and wherein, during the interruption condition, the wire mesh of the second damper dampens vibration of the turbomachine. 
     16. The rotor damping device of any preceding clause, wherein a damper oil is contained within the first cavity and the wire mesh is contained within the first cavity immersed in the damper oil. 
     17. The rotor damping device of any preceding clause, wherein the wire mesh is metal. 
     18. The rotor damping device of any preceding clause, wherein the first fluid damper further includes a second cavity spaced apart from the first cavity. 
     19. The rotor damping device of any preceding clause, wherein a damper oil is contained within the first cavity and the wire mesh is contained within the second cavity. 
     20. A method for damping vibration of a turbomachine, the method comprising: providing a rotor damping device comprising a first fluid damper and a second damper in communication with the first fluid damper, the second damper comprising a wire mesh, wherein the first fluid damper is transitionable between a working condition and an interruption condition; and damping vibration of the turbomachine with the second damper during the interruption condition. 
     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. 
     While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.