Power turbine shaft with hub assembly for a gas turbine engine - Patent Application 20070122997

Abstract

Traditionally, trim balancing of a power turbine (140) has been performed at an equipment coupling. The disclosed embodiment includes a hub (200) mounted on the shaft (102). The hub (200) allows for more effective trim balancing at the shaft (102) coupling, closer to the rotor. The disclosed hub (200) also allows for imbalance compensation to remain on the power turbine (140) even after decoupling. Additionally, the use of the hub (200) can improve efficiency and eliminate safety risks faced by field personnel when coupling the power turbine (140) to equipment.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The embodiments described herein are directed generally to gas turbine engines, and more particularly to a hub for a shaft of a turbine of a gas turbine engine. [Background technology]

[0002] Gas turbine engine turbine rotors can experience high vibrations in a test cell or in the field due to residual rotor imbalance and / or equipment coupling to the shaft. If the equipment hub is not mounted directly opposite or concentric with the shaft, the hub can cause further imbalance and / or misalignment as the shaft drives the equipment. This imbalance and misalignment can adversely affect the reliability and service life of gas turbine engine components such as blades, bearings, and seals.

[0003] Traditionally, it has not been possible to directly trim balance a turbine rotor. Therefore, trim balancing is performed by adding trim weights to the coupling flange of the equipment closest to the rotor. However, depending on the mode shape of the system, the coupling flange may not be the most efficient location for unbalance correction. Furthermore, if the coupling is replaced, the trim weights move with the coupling flange, not the turbine, so trim balancing must be repeated with the new coupling. Furthermore, if equipment needs to be coupled on-site, the equipment hub must be uniformly heated and then shrunk onto the shaft. Preparing the heat source and handling the heavy, heated hub poses significant safety risks to field workers.

[0004] The present disclosure is directed to overcoming one or more of the problems discovered by the inventors. Summary of the Invention

[0005] In one embodiment, a hub for a turbine shaft includes: a cylindrical body having an open forward end and an at least partially closed aft end along a longitudinal axis, the aft end having a plurality of first axial openings; an intermediate portion extending outward from the body, the intermediate portion including a plurality of trim weight holes circumferentially arranged about the longitudinal axis and configured to hold trim weights; and a flange extending outward from the intermediate portion, the flange including a plurality of second axial openings.

[0006] In one embodiment, a hub for a turbine shaft includes: a cylindrical body having an open front end and an at least partially closed rear end along a longitudinal axis, the rear end including a plurality of first axial openings, the body including a plurality of engagement members arranged along the circumference of an inner surface of the body, a plurality of first notches equally spaced around the circumference of an outer surface of the body, and a second notch on the outer surface of the body at an axial location along the longitudinal axis that differs from the axial locations of the first notches; an intermediate portion extending outward from a rear of the body, the intermediate portion including a plurality of trim weight holes circumferentially arranged about the longitudinal axis and configured to hold trim weights; and a flange extending outward from the intermediate portion, the flange including a plurality of second axial openings.

[0007] In one embodiment, the assembly includes: a turbine shaft including a plurality of first engagement members arranged along the periphery of an outer surface of the turbine shaft and a plurality of axial bores at an aft end of the turbine shaft; a hub including a cylindrical body surrounding a rear portion of the turbine shaft, the body having an at least partially closed aft end and including a plurality of first axial openings aligned with the plurality of axial bores at the aft end of the turbine shaft, the body including a plurality of second engagement members arranged along the periphery of an inner surface of the body that engage with the plurality of first engagement members; an intermediate portion extending outward from the body, the intermediate portion including a plurality of trim weight holes circumferentially arranged about a longitudinal axis of the turbine shaft, each of the plurality of trim weight holes configured to hold a trim weight; a flange extending outward from the intermediate portion, the flange including a plurality of second axial openings; and a plurality of fasteners, each of the plurality of fasteners passing through an aligned pair of one of the plurality of first axial openings and one of the plurality of axial holes, thereby securing the hub to the turbine shaft. [Brief explanation of the drawings]

[0008] The details of embodiments of the present disclosure, both as to their structure and operation, can be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts and in which:

[0009] [Figure 1] FIG. 1 illustrates a schematic diagram of a gas turbine engine, according to one embodiment. [Figure 2] FIG. 2 shows a front perspective view of a hub, according to one embodiment. [Figure 3] FIG. 3 shows a rear perspective view of the hub, according to one embodiment. [Figure 4] FIG. 4 shows a cross-sectional view of a hub attached to a shaft, according to one embodiment. [Figure 5] FIG. 5 shows a cross-sectional view of a coupling between an attached hub and an instrument, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The detailed description set forth below in connection with the accompanying drawings is intended as a description of various embodiments and is not intended to represent the only embodiments in which the present disclosure may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In some instances, well-known structures and components are shown in simplified form for ease of explanation.

[0011] For clarity and ease of illustration, some surfaces and details may be omitted in the description and figures. Furthermore, references herein to "upstream" and "downstream" or "forward" and "aft" are relative to the flow direction of the primary gases (e.g., air) used in the combustion process, unless otherwise specified. It should be understood that "upstream," "forward," and "leading" refer to a location closer to or toward the source of the primary gases, and that "downstream," "aft," and "trailing" refer to a location further from or away from the source of the primary gases. Thus, the trailing edge or end of a component (e.g., a turbine blade) is downstream from the leading edge or end of the same component. It should also be understood that, as used herein, the terms "side," "top," "bottom," "front," "aft," "upper," "lower," and the like are used for convenience of understanding to convey the relative positions of various components relative to one another and do not imply any particular orientation of those components in absolute terms (e.g., relative to the external environment or the ground). Additionally, as used herein, the terms "respectively" and "respectively" refer to the association of a member of a first group of components with a member of a second group of components. For example, the phrase "each component A is connected to a respective component B" means that A1 is connected to B1, A2 is connected to B2, ... and A1 is connected to BN.

[0012] It should also be understood that the various components illustrated herein are not necessarily drawn to scale. In other words, features disclosed in the various embodiments may be implemented using relative dimensions within and between components that differ from those illustrated in the figures.

[0013] FIG. 1 shows a schematic diagram of a gas turbine engine 100 according to one embodiment. The gas turbine engine 100 includes a shaft 102 having a central longitudinal axis L. Many other components of the gas turbine engine 100 are concentric with and may be annular with respect to the longitudinal axis L. A radial axis may refer to any axis or direction that extends radially outward from the longitudinal axis L at a substantially perpendicular angle to the longitudinal axis L, such as radial axis R in FIG. 1 . Thus, the terms “radially outward” or “radially outer” should be understood to mean farther or away from the longitudinal axis L, while the terms “radially inward” or “radially inward” should be understood to mean closer to or toward the longitudinal axis L. As used herein, the term “radial” refers to any axis or direction that is substantially perpendicular to the longitudinal axis L, and the term “axial” refers to any axis or direction that is substantially parallel to the longitudinal axis L.

[0014] In one embodiment, gas turbine engine 100 includes, from an upstream end to a downstream end, an inlet 110, a compressor 120, a combustor 130, a turbine 140, and an exhaust outlet 150. Additionally, the downstream end of gas turbine engine 100 may include an output coupling 104 to which equipment driven by gas turbine engine 100 (e.g., a generator set, a gas compressor, etc.) may be coupled. One or more of these components, including potentially all of gas turbine engine 100, may be fabricated from stainless steels and / or durable, high-temperature materials known as "superalloys." Superalloys are alloys that exhibit excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Examples of superalloys include, but are not limited to, Hastelloy, Inconel, Waspaloy, Rene alloys, Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX single crystal alloys.

[0015] The inlet 110 can channel a working fluid F (e.g., a primary gas such as air) into an annular flow path 112 about a longitudinal axis L. The working fluid F flows through the inlet 110 and into the compressor 120. While the working fluid F is illustrated flowing into the inlet 110 from a particular direction and at an angle substantially perpendicular to the longitudinal axis L, it should be understood that the inlet 110 can be configured to receive the working fluid F from any direction and at any angle suitable for a particular application of the gas turbine engine 100. While the working fluid F is primarily described herein as air, it should be understood that the working fluid F can include other fluids, including other gases.

[0016] The compressor 120 may include a series of compressor rotor assemblies 122 and stator assemblies 124. Each compressor rotor assembly 122 includes a rotor disk with a plurality of rotor blades arranged circumferentially. The rotor blades of a rotor disk are separated from the rotor blades of adjacent disks by the stator assemblies 124 along an axial axis parallel to the longitudinal axis L. The compressor 120 compresses a working fluid F through a series of stages corresponding to each compressor rotor assembly 122. The compressed working fluid F then flows from the compressor 120 into a combustor 130.

[0017] The combustor 130 may include a combustor case 132 that houses one or more, typically multiple, fuel injectors 134. In an embodiment with multiple fuel injectors 134, the fuel injectors 134 may be equally spaced circumferentially about the longitudinal axis L within the combustor case 132. The combustor case 132 disperses a working fluid F, and the fuel injectors 134 inject fuel into the working fluid F. The injected fuel is ignited, causing a combustion reaction in one or more combustion chambers 136. Products of the combustion reaction drive a turbine 140.

[0018] The turbine 140 may include one or more turbine rotor assemblies 142 and a stator assembly 144 (e.g., a nozzle), which may be collectively referred to herein as a "rotor." Each turbine rotor assembly 142 may correspond to one of a plurality of stages or a series of stages. The turbine 140 extracts energy from the combusting fuel and gas mixture as it passes through each stage. The energy extracted by the turbine 140 may be transmitted via the output coupling 104 (e.g., to an external system) and to the compressor 120 via the shaft 102.

[0019] Exhaust E from turbine 140 may enter exhaust outlet 150. Exhaust outlet 150 may include an exhaust diffuser 152 that diffuses the exhaust E and an exhaust collector 154 that collects, redirects, and discharges the exhaust E. It should be understood that the exhaust E discharged by exhaust collector 154 may be further treated, for example, to reduce harmful emissions, recover heat, and / or the like. Furthermore, although exhaust E is illustrated as exiting exhaust outlet 150 in a particular direction and at an angle substantially perpendicular to longitudinal axis L, it should be understood that exhaust outlet 150 may be configured to discharge exhaust E in any direction and at any angle appropriate for a particular application of gas turbine engine 100.

[0020] 2 shows a front perspective view of a hub 200, according to one embodiment. The hub comprises a body 210, a midsection 220 extending radially from the body 210, and a flange 230 extending from an aft end of the midsection 220. The midsection 220 may extend radially and / or axially outward from a portion (e.g., the aft portion) of the body 210 in a flared and / or stepped manner. The flange 230 may extend radially and / or axially outward from the aft end of the midsection 220. The body 210, the midsection 220, and the flange 230 may be manufactured as a single, integral piece of the same material, or as two or more distinct pieces of the same or different materials that are joined together (e.g., by welding).

[0021] The body 210 may be cylindrical about the longitudinal axis L and may be open at a forward end and closed at a rearward end along the longitudinal axis L. Alternatively, the body 210 may be partially closed at the rearward end, for example, by a circular opening, such that a portion of the shaft 102 is exposed therethrough. The open end of the body 210 is configured to receive and surround the rearward portion of the shaft 102. For example, the inner diameter of the body 210 may generally match the outer diameter of the rearward portion of the shaft 102. Thus, the hub 200 may be mounted onto the shaft 102 by sliding the forward end of the body 210 over the rearward portion of the shaft 102 such that the body 210 surrounds the shaft 102. In practice, the body 210 may have an inner diameter slightly smaller than the outer diameter of the rear portion of the shaft 102, so that during assembly, the hub 200 is heated to expand the inner diameter of the body 210, mounted onto the shaft 102, and then cooled, causing the body 210 to contract around the shaft 102.

[0022] The body 210 may include a plurality of axial openings 212 through the rear end of the body 210. The openings 212 may be equally spaced circumferentially about the longitudinal axis L. The openings 212 may align with axial holes in the rear end of the shaft 102. Thus, after the hub 200 is mounted onto the rear portion of the shaft 102, fasteners (e.g., bolts, screws, etc.) may be inserted upstream from the rear end of the body 210 through aligned pairs of one opening 212 and one hole. These fasteners prevent the hub 200 from sliding relative to the shaft 102 and also prevent the hub 200 from rotating relative to the shaft 102. Thus, when the shaft 102 rotates about the longitudinal axis L, the hub 200 rotates with the shaft 102 about the longitudinal axis L. In one embodiment where the body 210 is partially closed at the rear end, the opening should be shaped so as not to interfere with the proper installation of a fastener through the aligned pair of openings 212 and holes in the rear end of the shaft 102.

[0023] The inner surface of the body 210 may include a ring of engagement members 214. The engagement members 214 may be disposed along the periphery of the inner surface of the body 210. In one embodiment, the engagement members 214 include a plurality of parallel axial protrusions and / or parallel axial recesses forming alternating axially oriented (i.e., parallel to the longitudinal axis L) ridges and axially oriented grooves around the entire inner circumference of the inner surface of the body 210. The engagement members 214 are configured to engage with corresponding engagement members disposed along the periphery of the outer surface of the shaft 102. For example, the rear portion of the shaft 102 may include corresponding ridges and grooves such that each ridge of the engagement members 214 fits into a groove of an engagement member on the rear portion of the shaft 102, and each groove of an engagement member on the rear portion of the shaft 102 fits into a recess of the engagement member 214. The engagement member 214 engages with a corresponding engagement member on the rear portion of the shaft 102, thereby preventing rotation of the hub 200 relative to the shaft 102 when attached to the shaft 102. Thus, as the shaft 102 rotates about its longitudinal axis L, the hub 200 rotates with the shaft 102 about its longitudinal axis L. The use of corresponding engagement members on the hub 200 and the shaft 102 also facilitates alignment of the opening 212 with a corresponding hole in the rear end of the shaft 102.

[0024] The outer surface of the body 210 may include one or more sensor features that allow one or more sensors to measure one or more parameters of the shaft 102 through the hub 200. In the illustrated embodiment, these sensor features include a set of first notches 216 at the leading edge of the body 210 and a second notch 218 recessed from the leading edge of the body 210. In an alternative embodiment, the second notches 218 may be positioned at the leading edge of the body 210, the first notches 216 may be recessed from the leading edge of the body 210, or both the first notches 216 and the second notches 218 may be recessed from the leading edge of the body 210. The plurality of first notches 216 are equally spaced around the entire circumference of the outer surface of the body 210. The first notches 216 may be used by a speed pickup sensor to measure the rotational speed of the shaft 102, which is the rotational speed of the hub 200. The second notches 218 may be used by a key phase sensor to measure a key phase signal of the shaft 102. In other alternative embodiments, one or both of these sensor functions may be omitted and / or hub 200 may include one or more additional sensor functions.

[0025] The intermediate portion 220 includes a plurality of trim weight holes 222. The plurality of trim weight holes 222 may be equally spaced around the entire circumference of the intermediate portion 220. Each trim weight hole 222 is configured to hold a trim weight. The trim weight holes 222 may be oriented radially on the radially outward-facing surface of the intermediate portion 220 such that the trim weights may be inserted into and removed from the trim weight holes 222 along the radial axis. In an alternative embodiment, the trim weight holes 222 may be oriented axially or at an acute angle greater than zero relative to the radial axis. In the illustrated embodiment, there are 36 trim weight holes 222 (i.e., one trim weight hole 222 every 10 degrees). However, the intermediate portion 220 may include or consist of any number of trim weight holes 222 suitable for the applied design objectives.

[0026] The flange 230 may include a plurality of axial openings 232 therethrough. The plurality of openings 232 may be equally spaced about the longitudinal axis L. The openings 232 may align with corresponding axial openings in a standard coupling flange of the equipment coupled to the hub 200 and driven by the shaft 102. Thus, the equipment may be secured to the hub 200 by inserting fasteners (bolts, screws, etc.) through the aligned openings. In the illustrated embodiment, the number of openings 232 is equal to the number of trim weight holes 222 (e.g., 36). However, it should be understood that the flange 230 may include or consist of any number of openings 232, including a number of openings 232 that differs from the number of trim weight holes 222.

[0027] In a preferred embodiment, the openings 232 in the flange 230 are offset and / or sufficiently recessed from the trim weight holes 222 in the intermediate portion 220 so that a fastener passing through the openings 232 does not intersect the radial axis of any of the trim weight holes 222. In other words, about the longitudinal axis L, the positions of the trim weight holes 222 may be offset from the openings 232 so that none of the trim weight holes 222 has a radial axis that intersects with an axial axis passing through any of the openings 232 in the flange 230. This prevents fasteners in the openings 232 from blocking access to the trim weight holes 222. Thus, trim weights can be inserted into or removed from the trim weight holes 222 even when fasteners are inserted through the openings 232 (i.e., after the hub 200 is coupled to equipment).

[0028] By way of example, the equipment may include a generator set for generating electricity, a gas compressor for compressing gas, etc. The equipment itself may include a shaft secured to the coupling flange, and the shaft of the equipment may be driven by shaft 102 when the coupling flange is secured to hub 200.

[0029] 3 shows a rear perspective view of the hub 200, according to one embodiment. As shown, the openings 212 through the rear surface of the body 210 may be equally spaced about the longitudinal axis L and around the periphery of the rear end of the body 210. In the illustrated embodiment, there are twelve openings 212. However, it should be understood that the rear end of the body 210 may include or consist of any number of openings 212 suitable for the applied design objectives.

[0030] 4 shows a cross-sectional view of hub 200 attached to shaft 102 taken along a plane containing longitudinal axis L, according to one embodiment. As shown, hub 200 may be secured to the rear portion of shaft 102 via fasteners 414 inserted through an aligned pair of one of apertures 212 through the rear end of body 210 and one of axial bores 412 into the rear end of shaft 102. Additionally, one or more sensors, shown as a speed pickup sensor 416 and a key phase sensor 418, may be mounted within housing 400 around the rear portion of shaft 102 to take measurements of shaft 102 through hub 200.

[0031] For example, as shown, the speed pickup sensor 416 may be positioned radially outward from the axial position of the plurality of first notches 216. The speed pickup sensor 416 may include a magnetic pickup unit (MPU) at its radially innermost end. The magnetic pickup unit generates a magnetic field at its radially inner end. When a protrusion between the first notches 216 passes through the magnetic field of the magnetic pickup unit, a voltage is generated in the speed pickup sensor 416. The frequency of this voltage is converted into a signal or measurement indicative of the rotational speed of the shaft 102 by the speed pickup sensor 416 or an external system receiving the output signal from the speed pickup sensor 416.

[0032] The key phase sensor 418 may function similarly or identically to the speed pickup sensor 416, but uses the second notch 218. For example, as shown, the key phase sensor 418 may be positioned radially outward from the axial location of the second notch 418. The key phase sensor 418 may include a proximity probe, an optical pickup unit (OPU), or a magnetic pickup unit at its radially innermost end. The key phase sensor 418 may detect passage of the second notch 218 below its radially innermost end and output a key phase signal including a pulse for each detected passage. The body 210 may comprise a single second notch 218 such that only one passage of the second notch 218 occurs per rotation of the shaft 102. The pulse output by the key phase sensor 418 may be used as a zero-phase reference to detect imbalances (e.g., phase angles of unbalanced masses) on the rotor of the turbine 140. The key phase signal may be used to generate data including filtered vibration amplitude, phase delay, speed, and / or the like.

[0033] 5 illustrates a coupling between hub 200 and equipment 500, according to one embodiment. In the illustrated embodiment, flange 230 of hub 200 is coupled to coupling flange 530 of a generator configured as equipment 500. In particular, fasteners, illustrated as bolts 535, are secured through respective openings 232 on flange 230 and aligned openings 532 in coupling flange 530. It should be understood that the same or similar couplings may be utilized with other types of equipment 500.

[0034] During trim balancing, trim weights 224 may be radially inserted into one or more trim weight holes 222 in the intermediate section 220. The trim weights 224 may have the same weight or a different weight than one or more other trim weights 224. It should be understood that some trim weight holes 222 may be left empty. Trim weights 224 may be added to the appropriate trim weight holes 222 to correct rotational imbalances in the rotor of the turbine 140.

[0035] It is worth noting that trim weights can also be added to the coupling flange 530 or other components of the equipment 500. Thus, trim balancing can be performed in two balance planes. In particular, trim balancing can be performed in a first balance plane P1 by adding trim weights 224 to one or more trim weight holes 222, and trim balancing can be additionally performed in a second balance plane P2 by adding trim weights to the coupling flange 530 of the equipment 500. Thus, bending moments can be generated in both balance planes P1 and P2, changing both the amplitude and shape of the rotor motion. [Industrial Applicability]

[0036] Previously, trim weights had to be applied aft of the shaft (i.e., aft of the coupling flange 530). This not only reduced the effectiveness of trim balancing, but also required new trim balancing after the coupling was replaced. Furthermore, recoupling required heating and shrinking the coupling on the shaft 102, potentially posing a safety hazard to field personnel. The disclosed embodiments avoid these and other problems.

[0037] For example, the hub 200 may be installed once at the factory as part of the shaft 102. Once installed, the hub 200 may remain fixed to the shaft 102 for its lifetime. Factory installation is safer, more efficient, and can be performed more precisely to eliminate eccentricity issues.

[0038] Additionally, trim balancing can be performed at the factory, if desired, by installing trim weights 224 in one or more of the trim weight holes 222. These trim weights 224 remain on the hub 200 with the shaft 102. This contrasts with conventional systems in which the trim weights are attached to the equipment coupling flange 530 and are therefore removed with decoupling. In the disclosed embodiment, the imbalance correction remains on the shaft 102, which minimizes the effects of imbalance when replacing the coupling.

[0039] Furthermore, because the intermediate section 220 is closer to the radial bearing than the coupling flange 230, the trim weights 224 can be added closer to the radial bearing than with conventional trim balancing. In particular, the trim weights 224 can be added not only to the balance plane P2 but also to the balance plane P1. Placing the trim weights 224 closer to the radial bearing is effective in reducing the vibration level of the radial bearing. It also allows the use of heavier trim weights 224. As a result, the centrifugal force becomes significantly larger, which can be used to change the mode shape of the rotor.

[0040] Furthermore, hub 200 allows trim balancing adjustments at two balance planes, P1 and P2, which allows for greater flexibility in changing rotor mode shapes. In other words, weight can be added to one or both balance planes P1 and P2 to compensate for radial bearing vibration. Therefore, hub 200 improves the ability to control vibration response.

[0041] Additionally, the coupling flange 530 of the equipment 500 can be standardized across different types of equipment and can be easily and efficiently coupled and uncoupled from the flange 230 of the hub 200 without the need for special tools. This also reduces wear on other components, potentially extending the service life of the gas turbine engine 100. This is in contrast to conventional systems that required the coupling of the equipment 500 to be heated and shrunk onto the shaft 102. Using the hub 200, field workers no longer need to use a heat source or move heavy, heated components to couple the equipment 500 to the shaft 102. Thus, the hub 200 improves both efficiency and safety. A pilot fit at the flanges 230 and 530 can be used to ensure concentricity with the longitudinal axis L.

[0042] Hub 200 may also include sensor functionality, such as a first notch 216 for a speed pickup sensor 416 and a second notch 218 for a key phase sensor 418. Previously, such sensor functionality had to be incorporated into a separate, dedicated speed ring around shaft 102. Hub 200 eliminates the need for a separate speed ring.

[0043] It will be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments. It is intended that aspects described in connection with one embodiment can be used with other embodiments. Any description relating to one embodiment applies to similar features of other embodiments, and elements of multiple embodiments can be combined to form other embodiments. The embodiments are not limited to those that solve any or all of the described problems or have any or all of the described benefits and advantages.

[0044] The foregoing detailed description is merely exemplary in nature and is not intended to limit the invention or its application and uses. The described embodiments are not limited to use in connection with any particular type of machine. Thus, while the present embodiments are depicted and described as being implemented in a gas turbine engine and / or specific equipment for convenience of explanation, it will be understood that the present embodiments may be implemented in various other types of machines having rotors, various other types of equipment driven by rotors, and various other systems and environments. Furthermore, no attempt is made to be bound by any theory presented in the preceding paragraph. It should also be understood that the figures may include exaggerated dimensions and graphic representations to better illustrate the depicted and referenced items and are not to be considered limiting unless expressly so stated.

Claims

1. A hub (200) for a turbine shaft (102), said hub (200) comprising: a cylindrical body (210) that is open at a front end and at least partially closed at a rear end along a longitudinal axis (L), the rear end including a plurality of first axial openings (212); an intermediate portion (220) extending outward from the body (210), the intermediate portion (220) including a plurality of trim weight holes (222) arranged circumferentially about the longitudinal axis (L), each of the plurality of trim weight holes (222) configured to hold a trim weight (224); a flange (230) extending outwardly from said intermediate portion (220), said flange (230) including a plurality of second axial openings (232).

2. The hub (200) of claim 1, wherein the body (210) further comprises a plurality of engagement members (214) disposed about a periphery of an inner surface of the body (210).

3. The hub (200) of claim 2, wherein the plurality of engagement members (214) comprises alternating axially oriented ridges and axially oriented grooves.

4. The hub (200) of claim 1, wherein the body (210) further comprises a plurality of first notches (216) equally spaced about the circumference of the outer surface of the body (210).

5. The hub (200) of claim 4, wherein the plurality of first notches (216) are positioned on an edge of the forward end of the body (210).

6. 5. The hub (200) of claim 4, wherein the body (210) further comprises a second notch (218) on an outer surface of the body (210) at an axial position along the longitudinal axis (L) that is different from the axial positions of the plurality of first notches (216).

7. The hub (200) of claim 6, wherein the second notch (218) is closer to the aft end of the body (210) than the plurality of first notches (216).

8. The hub (200) of claim 1, wherein said body (210) further comprises at least one notch (216, 218) in an outer surface of said body (210).

9. The hub (200) of claim 8, wherein said at least one notch (218) is recessed from said forward edge of said body (210).

10. The hub (200) of claim 1, wherein each of said plurality of trim weight holes (222) is oriented along a radial axis that is perpendicular to said longitudinal axis (L).

11. 11. The hub (200) of claim 10, wherein the positions of the plurality of trim weight holes (222) are offset from the plurality of second axial openings (232) about the longitudinal axis (L), such that none of the plurality of trim weight holes (222) has a radial axis that intersects an axial axis passing through any of the plurality of second axial openings (232) in the flange (230).

12. 1. An assembly comprising: a turbine shaft (102) including a plurality of axial holes (412) at an aft end of the turbine shaft (102); 2. The hub (200) of claim 1, wherein the body (210) surrounds the aft portion of the turbine shaft (102) and is mounted on the aft portion of the turbine shaft (102) such that the plurality of first axial openings (212) at the aft end of the body (210) are aligned with the plurality of axial holes (412) at the aft end of the turbine shaft (102); a plurality of fasteners (414), each of the plurality of fasteners (414) passing through an aligned pair of one of the first axial openings (212) and one of the plurality of axial holes (412), thereby securing the hub (200) to the turbine shaft (102).

13. The body (210) of the hub (200) a plurality of first notches (216) equally spaced around the circumference of the outer surface of said body (210); a second notch (218) on the outer surface of the body (210) at an axial position along the longitudinal axis (L) that is different from the axial positions of the plurality of first notches (216); the assembly comprising: a velocity pickup sensor (416) positioned radially outward from the axial location of the plurality of first notches (216); The assembly of claim 12, further comprising: a key phase sensor (418) positioned radially outward from the axial location of the second notch (218).

14. 1. An assembly comprising: a turbine shaft (102) including a plurality of first engagement members disposed along a periphery of an outer surface of the turbine shaft (102) and a plurality of axial holes (412) at an aft end of the turbine shaft (102); 2. The hub (200) of claim 1, wherein the body (210) surrounds an aft portion of the turbine shaft (102), the plurality of first axial openings (212) align with the plurality of axial holes (412) in the aft end of the turbine shaft (102), and the body (210) includes a plurality of second engagement members (214) disposed along a periphery of an inner surface of the body (210) that engage with the plurality of first engagement members; a plurality of fasteners (414), each of the plurality of fasteners (414) passing through an aligned pair of one of the first axial openings (212) and one of the plurality of axial holes (412), thereby securing the hub (200) to the turbine shaft (102).

15. A gas turbine engine (100), comprising: a compressor (120); a combustor (130) downstream of the compressor (120); a turbine downstream of the combustor, the turbine including the assembly of claim 14.

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