System and method for controlling vibrations in a rotor

Abstract

A rotor (102) operable to rotate about a rotational axis includes a first bearing (110) coupled to the rotor, and a second bearing (112) coupled to the rotor, the first bearing and the second bearing cooperating to support the rotor for rotation about the rotational axis at a rotational speed. A rotor body includes a first bearing surface coupled to the first bearing, a second bearing surface coupled to the second bearing and an operational surface that cooperates with the first bearing surface and the second bearing surface to completely define an exposed surface of the rotor body. A vibration modifier (210) is coupled to the rotor body and operates to counteract vibration of the rotor to reduce vibration of the rotor body measured at the first bearing and the second bearing.

Description

Docket No. 2024PF00270 SYSTEM AND METHOD FOR CONTROLLING VIBRATIONS IN A ROTOR BACKGROUND

[0001] Rotating equipment or turbo machinery such as turbine rotors, compressor rotors, generator rotors and the like are dynamically balanced before operation to reduce unwanted vibration. This is important for almost any rotor but is particularly important for high-speed rotors such as those that rotate above 4000 RPM. Many of these rotors pass through one or more critical frequencies before arriving at their rotating speed. Vibration at or around these critical speeds, even for short periods of time can cause damage or excessive wear for a rotor and its related components. SUMMARY

[0002] In one aspect, a rotor operable to rotate about a rotational axis includes a first bearing coupled to the rotor, and a second bearing coupled to the rotor, the first bearing and the second bearing cooperating to support the rotor for rotation about the rotational axis at a rotational speed. A rotor body includes a first bearing surface coupled to the first bearing, a second bearing surface coupled to the second bearing and an operational surface that cooperates with the first bearing surface and the second bearing surface to completely define an exposed surface of the rotor body. A vibration modifier is coupled to the rotor body and operates to counteract vibration of the rotor to reduce vibration of the rotor body measured at the first bearing and the second bearing.

[0003] In another aspect, a method of reducing vibration of a rotor that includes a rotor body includes supporting the rotor body for rotation about a rotational axis using a first bearing and a second bearing. The method also includes coupling a vibration modifier to the rotor body, the vibration modifier tuned to have a natural frequency within twenty percent of a first critical speed of the rotor body. The method further includes accelerating the rotor body toward an operating speed, passing through a first critical speed of the rotor body during the acceleratingDocket No. 2024PF00270 step, and inducing vibration in the vibration modifier at a bending mode of the rotor body to counteract and reduce vibration of the rotor body measured at the first bearing and the second bearing.

[0004] The foregoing has broadly outlined some of the technical features of the present disclosure so that those skilled in the art may better understand the detailed description that follows.

[0005] Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims. Those skilled in the art will appreciate that they may readily use the conception and the specific embodiments disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure in its broadest form.

[0006] Also, before undertaking the Detailed Description below, it should be understood that various definitions for certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases. While some terms may include a wide variety of embodiments, the appended claims may expressly limit these terms to specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0008] FIG. 1 is a schematic illustration of a rotor including a first bearing and a second bearing supporting the rotor for rotation about a rotational axis.

[0009] FIG. 2 is a schematic illustration of the rotor of FIG. 1 further including a vibration modifier in the form of a third bearing.Docket No. 2024PF00270

[0010] FIG. 3 is a schematic illustration of the rotor of FIG. 1 further including a vibration modifier in the form of a damping seal.

[0011] FIG. 4 is a schematic illustration of the rotor of FIG. 1 further including a vibration modifier in the form of a quill shaft and mass.

[0012] FIG. 5 is a schematic illustration of a portion of the rotor of FIG. 1 further including a vibration modifier in the form of a plurality of mass members.

[0013] FIG. 6 is an axial schematic illustration of the rotor of FIG. 5 further illustrating the vibration modifier.

[0014] FIG. 7 is a perspective schematic view of a mass member suitable for use in the vibration modifier of FIG. 5

[0015] FIG. 8 is a schematic illustration of a portion of the rotor of FIG. 1 further including a vibration modifier in the form of a plurality of mass members. DETAILED DESCRIPTION

[0016] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0017] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as beingDocket No. 2024PF00270 carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0018] It should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and / or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0019] Also, terms such as “first”, “second”, “third” and so forth may be used herein to refer to various elements, information, functions, or acts, but should not be considered as limiting in any way. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0020] In addition, the term “adjacent to” may mean that an element is relatively near to but not in contact with a further element or that the element is in contact with the further portion unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, aDocket No. 2024PF00270 variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0021] FIG. 1 schematically illustrates a rotor 100 supported by a first bearing 110 and a second bearing 112 for rotation about a rotational axis 114. The rotor 100 includes a first bearing surface 104 that engages the first bearing 110 and a second bearing surface 106 that engages the second bearing 112 to support the rotor 100. In the illustrated construction, the first bearing 110 and the second bearing 112 are journal bearings with other bearings including roller bearings, magnetic bearings, any other bearing suitable for supporting a rotor or shaft for rotation as well as thrust bearings being possible.

[0022] A damping arrangement 116 is shown connected to each of the first bearing 110 and the second bearing 112. One of ordinary skill will recognize this illustration as a representation of the dynamic damping characteristics of the bearing that are generally reduced to a spring 118 having a spring characteristic or constant and a damper 120. Of course, there is not necessarily a component or element that is defined as a spring 118 or a damper 120. The actual values or operating characteristics of the damping arrangement 116 are a function of the construction of the bearing, the supports for the bearing and other characteristics that are not critical to the system described herein.

[0023] The rotor body 102 includes an operational surface 108 that extends between the first bearing surface 104 and the second bearing surface 106 in the illustrated construction. The shape, contour, and content of the operational surface 108 is a function of the type of rotor 100. For example, a generator rotor may appear largely cylindrical. However, turbine rotors or compressor rotors may include rows of blades, vanes, fans, internal seals, shaft seals, or other components that are required for the particular rotor. It should be noted that while the illustrated operational surface 108 is between the first bearing 110 and the second bearing 112 other arrangements will include an operational surface 108 that extends beyond one or more of the bearings 110, 112. Thus, the operational surface 108 should be considered to include any surface of the rotor not disposed inside one of the bearings 110, 112.

[0024] During operation, all rotors 100 vibrate. While the rotor 100 is statically and dynamically balanced, vibrations still arise, particularly if the rotor operates near one of its critical speeds. The term “critical speed” refers to the theoretical angular velocity that excitesDocket No. 2024PF00270 the natural frequency of a rotating object, such as a shaft, propeller, leadscrew, or gear. As the speed of rotation approaches the object's natural frequency, the object begins to resonate, which dramatically increases system vibration. The resulting resonance occurs regardless of orientation. When the rotational speed is equal to the natural frequency, then that speed is referred to as a critical speed.

[0025] Many rotors 100 operate above their first critical speed meaning the rotor 100 must pass through that critical speed while accelerating to its operating speed. At the critical speed, increased vibration can occur. For high-speed rotors 100, such as rotors 100 that operate at greater than 4000 RPM it is possible that the rotor 100 must pass through two or more critical speeds before arriving at its desired operating speed.

[0026] In some systems, the first bearing 110 and / or the second bearing 112 is tuned to have a natural frequency that closely matches the frequency at the first critical speed or at another critical speed so that the tuned bearing vibrates at the or near the critical speed the rotor body 102, thereby counteracting and reducing the vibration of the rotor body 102. Terms such as “critical speed” and “bending mode” are used interchangeably herein.

[0027] As used herein, the term “closely matches” and similar terms mean that the natural frequency is within twenty percent of the target critical speed and more preferably within five percent of the target critical speed.

[0028] FIG. 2 illustrates an arrangement of a rotor similar to the rotor 100 of FIG. 1 and including a vibration modifier 210 that includes a third bearing 202 and a stub shaft 208 that extends from one end of the rotor body 102. The stub shaft 208 defines a third bearing surface 204 that engages the third bearing 202.

[0029] The third bearing 202 is not necessarily provided to support the rotor body 102 for rotation, but rather includes a tuned damping arrangement 206 that is tuned to reduce vibration of the rotor body 102 as measured at the first bearing 110 and / or the second bearing 112.

[0030] The tuned damping arrangement 206 includes elements that are tunable to adjust the stiffness (i.e., spring 118) and damping (i.e., damper 120) provided by the third bearing 202. Ideally, the third bearing 202 is tuned to resonate at a target natural frequency that is near a target critical speed of the rotor body 102. For example, the third bearing 202 is tuned toDocket No. 2024PF00270 resonate at a frequency that closely matches a vibration frequency of the rotor body 102 at a bending mode including either of the first bending mode, second bending mode, or any other mode as may arise when operating near the first critical speed, second critical speed or another critical speed. Thus, as the rotor body 102 passes through a mode to which the third bearing 202 is tuned, the third bearing 202 vibrates to counteract and reduce the vibration of the rotor body 102 as measured at the first bearing 110 and / or the second bearing 112.

[0031] In the construction of FIG. 3, the rotor body 102 includes an inner seal region 302 disposed in the rotor body 102 between the first bearing 110 and the second bearing 112. A vibration modifier in the form of a damper seal 304 is positioned within the inner seal region 302 and operates to form a seal that inhibits flow between the two portions of the rotor body 102 that are separated from one another by the placement of the inner seal region 302.

[0032] As an example, multi-stage compressors may include an inner seal region 302 and a damper seal 304 to separate a first compression region from a second compression region. Compressed gas my be forced to exit the compressor to flow to an intercooler or other device before returning to the second portion of the compressor on the opposite side of the inner seal region 302. One of ordinary skill in the art will recognize many other examples of rotor bodies 102 that may include one or more inner seal regions 302.

[0033] The damper seal 304 provides some level of vibration damping as represented by a tuned damping arrangement 306 coupled to the damper seal 304. The tuned damping arrangement 306 is tuned like the tuned damping arrangement 206 of FIG. 2. In reality, the type of seal, and the physical arrangement of that seal is selected to provide the level of damping desired.

[0034] For example, constructions could employ honeycomb seals that help reduce circumferential flow and swirl in the inner seal region 302, thereby reducing cross-coupled stiffness forces that can destabilize the rotor 100. In another example, pocket damper seals are employed. Pocket damper seals are modified labyrinth seals with pockets / steps on the stator side that introduce damping and reduce destabilizing cross-coupled stiffness forces. Pocket damper seals can completely eliminate sub-synchronous vibrations in some cases. Those of ordinary skill in the art will recognize that other arrangements of seals can operate as damper seals 304.Docket No. 2024PF00270

[0035] FIG. 4 illustrates another arrangement of a system for reducing vibrations in a rotor body 102 that includes two vibration modifiers. The first vibration modifier 410 includes a first quill shaft 402 that extends from a first end of the rotor body 102 and supports a first mass 406. Similarly, the second vibration modifier 412 includes a second quill shaft 404 that extends from the second end of the rotor body 102 and supports a second mass 408.

[0036] Each of the first quill shaft 402, the second quill shaft 404, the first mass 406, and the second mass 408 are selected to resonate at a frequency close to a target frequency. For example, each of the first vibration modifier 410 and the second vibration modifier 412 resonate at a frequency that closely matches the vibration frequency at a critical speed of the rotor body 102 that corresponds to a desired mode, or bending mode to be damped. Thus, as the rotor body 102 passes through this critical speed, the first vibration modifier 410 and the second vibration modifier 412 resonate to counteract and reduce the vibration of the rotor body 102 as measured at the first bearing 110 and the second bearing 112.

[0037] Factors that affect the resonant frequency of the first vibration modifier 410 and the second vibration modifier 412 include the materials selected for the quill shafts and masses, the diameter and length of the quill shafts, the size and shape of the shafts and the mass, and the like. One of ordinary skill will understand that there are many different arrangements that can achieve a desired resonance frequency.

[0038] FIG. 5 through FIG. 7 illustrate another arrangement of a vibration modifier 502 that includes a plurality of mass members 506 distributed around the circumference of the rotor body 102. FIG. 5 illustrates the arrangement for one mass member 506 of a plurality of mass members 506.

[0039] A rotor pocket 504 is formed in the rotor body 102 and includes a first side 510, a second side 512, and an innermost surface 514 with the rotor pocket 504 being open to the outermost surface of the rotor body 102. In the illustrated construction, the rotor pocket 504 is a rectangular cross-section cubic pocket having a long axis that extends in an axial direction between the first side 510 and the second side 512. Of course, other shapes and arrangements of the rotor pocket 504 are possible and could be used to achieve the desired results.

[0040] The mass member 506 has a rectangular cross-section that allows it to fit within the rotor pocket 504. The material used to construct the mass member 506 is selected to provideDocket No. 2024PF00270 the desired mass necessary to meet the desired objective. For example, if a large mass is required, tungsten might be selected while a lighter mass may use aluminum or other light materials.

[0041] The mass member 506 loosely fits within the rotor pocket 504 to allow some relative movement between the mass member 506 and the rotor body 102. To reduce any impacts or excessive movements, the construction of FIG. 5 includes a first resilient member 508 positioned axially between a first end of the mass member 506 and the rotor body 102 and a second resilient member 508 positioned axially between a second end of the mass member 506 and the rotor body 102. The resilience of the resilient member 508 can be selected to allow for the desired level of movement or restraint of the mass member 506 to tune the vibration modifier 502.

[0042] A groove 524 is formed in each of the first side 510 and the second side 512 and is sized to receive one of the resilient members 508. Of course, other constructions could form the grooves 524 in the mass member 506 rather than in the rotor body 102.

[0043] Additionally, in some constructions, the groove 524 completely surrounds the mass member 506 such that the resilient member 508 is positioned axially between the mass member 506 and the rotor body 102 as well as circumferentially between the mass member 506 and the rotor body 102.

[0044] A cover member 516 is coupled to the rotor body 102 and arranged to cover each of the mass members 506 and the rotor pockets 504 of the vibration modifier 502. The cover member 516 includes a first end 518, a second end 520, and an intermediate region 522 that extends between the first end 518 and the second end 520. The first end 518 and the second end 520 are sized to define a shrink-fit with the rotor body 102 to facilitate the connection of the cover member 516 to the rotor body 102. In the illustrated construction, the intermediate region 522 provides clearance between the cover member 516 and the mass member 506.

[0045] FIG. 6 is an axial view of the vibration modifier 502. As can be seen, each mass member 506 of the plurality of mass members is positioned within one rotor pocket 504 of a plurality of rotor pockets. In the illustrated construction, eight mass members 506 are positioned within eight rotor pockets 504 that are equally spaced around the circumference of the rotor body 102. Other constructions may include differently sized rotor pockets 504 andDocket No. 2024PF00270 mass members 506 or a different quantity of rotor pockets 504 and mass members 506. In addition, the spacing between adjacent rotor pockets 504 could be varied if desired.

[0046] FIG. 7 illustrates one arrangement of the mass member 506 and better illustrates the axial 702, radial 704, and circumferential 706 directions. As discussed, the mass member 506 is sized to fit within the rotor pocket 504 loosely such that some relative movement in the axial, circumferential, and radial directions are possible. The resilient members 508 are selected to at least partially restrain the mass member 506 within the rotor pocket 504.

[0047] In the illustrated construction, the outermost surface of the mass member 506 may be curved to closely match the curved surface of the cover member 516.

[0048] FIG. 8 illustrates a vibration modifier 802 that is similar to the vibration modifier 502. The vibration modifier 802 includes a plurality of rotor pockets arranged in a manner similar to that described with regard to the vibration modifier 502. Also, a mass member 806 is positioned within each of the rotor pockets 504 as previously described. Finally, the cover member 516 is arranged and positioned as described with regard to the vibration modifier 502.

[0049] The vibration modifier 802 of FIG. 8 differs from the vibration modifier 502 of FIG. 5 in that the mass members 506 of the vibration modifier 502 are restrained axially or axially and circumferentially by the resilient members 508 while the mass members 806 of the vibration modifier 802 are restrained radially or radially and circumferentially by a number of resilient members 804.

[0050] Specifically, the arrangement of FIG. 8 includes two grooves 524 formed in an innermost surface of the rotor pocket 504 that are each sized to receive a resilient member 804. Two additional grooves 524 are formed in the outermost surface of the mass member 806 with each groove 524 sized to receive a resilient member 804. Thus, the mass member 806 are each held in position using two resilient members 804 positioned radially between the rotor body 102 and the mass member 806 and two additional resilient members 804 positioned radially between the mass member 806 and the cover member 516.

[0051] Other constructions may include more or fewer grooves 524 and mass members 806 and may locate the grooves differently. For example, any of the grooves could be formed in the opposite component illustrated. Thus, the innermost grooves 524 could be formed in theDocket No. 2024PF00270 mass member 806 rather than in the rotor body 102. Similarly, the outermost grooves 524 could be formed in the cover member 516 rather than in the mass member 806.

[0052] Additionally, some constructions could include a single rotor pocket that extends around the rotor with a single mass member disposed therein. Typically, a split ring mass member would be employed to allow for assembly. One or more resilient members could be positioned between the rotor and the mass member as well as between the mass member and any cover as may be desired.

[0053] It should be noted that additional resilient members could be employed in the arrangement of FIG. 5 or FIG. 8 to restrain the mass member 506 or the mass member 806 in other directions. For example, the arrangement of FIG. 5 could include resilient members 804 positioned to restrain the mass member 506 radially as well as axially and / or circumferentially. Similarly, the arrangement of FIG. 8 could include additional resilient members 508 to restrain the mass member 806 in the axial and / or circumferential directions.

[0054] In operation, the rotor 100 is accelerated toward its desired operating speed or is decelerated from an operating speed to a lower speed or zero speed in case of a shutdown. During these accelerations, many rotors 100 must pass through a first critical speed and in some cases rotors 100 may pass through a second or even a third critical speed. During passage through these critical speeds, vibration increases of the rotor body 102 are often seen at the first bearing 110 and the second bearing 112. While the rotor body 102 is typically statically and dynamically balanced, these increases in vibration are often unavoidable and are managed by moving the rotor body 102 through the critical speeds as quickly as possible.

[0055] The arrangements illustrated in FIG. 2 through FIG. 8 further enhance the vibration characteristics of the rotor body 102 by counteracting or absorbing the vibrations in the rotor body 102. The construction of FIG. 2 includes a third bearing 202 that is tuned to resonate at or closely to a vibrational frequency of the rotor body 102 when rotating at one of the critical speeds of the rotor body 102 such that the third bearing 202 vibrates in place of the rotor body 102.

[0056] Similarly, the arrangement of FIG. 3 includes a damper seal 304 that is tuned to resonate at a frequency that is close to a vibrational frequency of the rotor body 102 whenDocket No. 2024PF00270 operating near a critical speed of the rotor body 102 such that the damper seal 304 vibrates in place of the rotor body 102.

[0057] The arrangement of FIG. 4 uses one or more (two in FIG. 4) quill shafts 402, 404 that each support a mass 406, 408 with the size, shape, length, mass, and arrangement of the quill shafts 402, 404 and the masses 406, 408 selected so that they resonate at a frequency that closely matches a vibrational frequency of the rotor body 102 when operating near a critical speed of the rotor body 102. Thus, the quill shafts 402, 404 and masses 406, 408 will vibrate at the critical frequency rather than the rotor body 102.

[0058] FIG. 5 through FIG. 8 illustrate another arrangement in which a plurality of mass members 506, 806 are positioned within the rotor body 102 and supported in a manner in which they can vibrate at least partially independent of the rotor body 102. The use of resilient members 508, 804 to hold each mass member 506, 806 allows for the tuning of the arrangement such that the mass members 506, 806 resonate at or closely to the frequency at a critical speed so that the mass members counteract or cancel the some of the vibrations of the rotor body 102.

[0059] The constructions described herein improve operation of rotating equipment by reducing the vibration that typically occurs as the rotor 100 passes through its critical speeds. The reduction in vibration can extend the life of the rotor 100 as well as other components that support or interact with the rotor 100.

[0060] Although at least one exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the scope of the disclosure in its broadest form.

[0061] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

Docket No. 2024PF00270 CLAIMS What is claimed is:

1. A rotor operable to rotate about a rotational axis, the rotor comprising: a first bearing coupled to the rotor; a second bearing coupled to the rotor, the first bearing and the second bearing cooperating to support the rotor for rotation about the rotational axis at a rotational speed; a rotor body including a first bearing surface coupled to the first bearing, a second bearing surface coupled to the second bearing and an operational surface that cooperates with the first bearing surface and the second bearing surface completely define an exposed surface of the rotor body; and a vibration modifier coupled to the rotor body and operable to counteract vibration of the rotor to reduce vibration of the rotor body measured at the first bearing and the second bearing.

2. The rotor of claim 1, wherein the vibration modifier includes a third bearing coupled to the rotor body and tuned to resonate within twenty percent of a bending mode of the rotor body.

3. The rotor of claim 2, wherein the third bearing is tuned to resonate within five percent of a second bending mode of the rotor body.

4. The rotor of claim 2, wherein the third bearing is a journal bearing.

5. The rotor of claim 2, wherein the rotor body includes a third bearing surface positioned on a first side of the second bearing, the first bearing positioned on a second side of the second bearing, the third bearing surface engaged with the third bearing.

6. The rotor of claim 1, wherein the vibration modifier includes a damper seal positioned between the first bearing and the second bearing and tuned to resonate within twenty percent of a bending mode of the rotor body.

7. The rotor of claim 6, wherein the third bearing is tuned to resonate within five percent of a second bending mode of the rotor body.Docket No. 2024PF00270 8. The rotor of claim 1, further comprising a first quill shaft coupled to the rotor body and a first mass coupled to the first quill shaft, the first quill shaft and the first mass selected to resonate at a frequency that is within twenty percent of a first critical speed of the rotor body.

9. The rotor of claim 8, further comprising a second quill shaft coupled to the rotor body and a second mass coupled to the second quill shaft, the second quill shaft and the second mass selected to resonate at a frequency that is within twenty percent of a first critical speed of the rotor body.

10. The rotor of claim 1, wherein the vibration modifier includes a rotor pocket that extends around the rotor, a mass member positioned within the rotor pocket and extending around the rotor, and a resilient member positioned between a surface of the rotor pocket and the mass member.

11. The rotor of claim 1, wherein the vibration modifier includes a plurality of mass members and a plurality of rotor pockets formed in the rotor body, each mass member positioned within one rotor pocket of the plurality of rotor pockets.

12. The rotor of claim 11, wherein each of the rotor pockets of the plurality of rotor pockets are equally spaced around the circumference of the rotor body.

13. The rotor of claim 11, further comprising a plurality of first resilient members with each first resilient member positioned axially between one of the mass members and a first side of one of the rotor pockets, and a plurality of second resilient members with each second resilient member positioned axially between one of the mass members and a second side of one of the rotor pockets such that each rotor pocket receives one of the first resilient members, the second resilient members, and one of the mass members positioned between the first resilient member and the second resilient member.

14. The rotor of claim 11, further comprising a cover member coupled to the rotor body and cooperating with the rotor body to completely cover the plurality of mass members.

15. The rotor of claim 14, wherein the cover member includes a first end, a second end, and an intermediate region disposed between the first end and the second end, the first end and the second end sized to cooperate with the rotor body to define a shrink-fit therebetween.Docket No. 2024PF00270 16. The rotor of claim 15, further comprising a plurality of first resilient members with each first resilient member positioned radially between one of the mass members and an outermost surface of one of the rotor pockets, and a plurality of second resilient members with each second resilient member positioned radially between one of the mass members and the cover member such that each rotor pocket receives one of the first resilient members, the second resilient members, and one of the mass members positioned between the first resilient member and the second resilient member.

17. The rotor of claim 16, further comprising a plurality of third resilient members with each third resilient member positioned radially between one of the mass members and the outermost surface of one of the rotor pockets, and a plurality of fourth resilient members with each fourth resilient member positioned radially between one of the mass members and the cover member such that each rotor pocket receives one of the first resilient members, second resilient members, third resilient members, and fourth resilient members, and one of the mass members is positioned between the first resilient member, the second resilient member, the third resilient member, and the fourth resilient member.

18. A method of reducing vibration of a rotor that includes a rotor body, the method comprising: supporting the rotor body for rotation about a rotational axis using a first bearing and a second bearing; coupling a vibration modifier to the rotor body the vibration modifier tuned to have a natural frequency within twenty percent of a first critical speed of the rotor body; accelerating the rotor body toward an operating speed; passing through a first critical speed of the rotor body during the accelerating step; and inducing vibration in the vibration modifier at a bending mode of the rotor body to counteract and reduce vibration of the rotor body measured at the first bearing and the second bearing.

19. The method of claim 18, wherein the vibration modifier includes a third bearing that is a tuned mass damper bearing that is tuned to have a natural frequency within five percent of a second bending mode of the rotor body.Docket No. 2024PF00270 20. The method of claim 18, wherein the vibration modifier includes a first quill shaft coupled to a first end of the rotor body and a first mass coupled to the first quill shaft, the first mass having a mass selected to tune the natural frequency of the first quill shaft and the first mass to within five percent of the second bending mode of the rotor body.

21. The method of claim 18, further comprising embedding a plurality of masses within the rotor body, each mass of the plurality of masses movable in one of the axial and radial directions, the mass of each of the masses selected to tune the natural frequency of the plurality of masses to within five percent of the second bending mode of the rotor body.

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