Tuned mass damper for tubes

A tuned mass damper for reducing vibration on a component includes a shaft connector member configured to be coupled to the component and a cable termination member. The tuned mass damper also includes at least one cable coupled to the shaft connector member and to the cable termination member such that vibration of the component is transferred to the at least one cable via the shaft connector member and increased or decreased by the at least one cable.

FIELD

The present disclosure is directed to a tuned mass damper coupled to a shaft and tuned to reduce vibrations at a resonant frequency of the shaft.

BACKGROUND

Exhaust from turbine sections of gas turbine engines may include uncombusted oxygen gas (O2). Similarly, if the gas turbine engine is a bypass engine, the bypass air also contains oxygen gas. Some gas turbine engines may include an augmentor section capable of providing afterburning capabilities. In these gas turbine engines, a turbine exhaust case may output additional fuel that mixes with the exhaust from the turbine section and/or the bypass air. The mixture of fuel and exhaust/bypass air may be combusted in the augmentor section. This secondary combustion further increases the thrust of the gas turbine engine by increasing velocity of the fluid exiting the gas turbine engine.

SUMMARY

Disclosed herein is a tuned mass damper for increasing or decreasing vibration on a component. The tuned mass damper includes a shaft connector member configured to be coupled to the component and a cable termination member. The tuned mass damper also includes at least one cable coupled to the shaft connector member and to the cable termination member such that vibration of the component is transferred to the at least one cable via the shaft connector member and increased or decreased by the at least one cable.

In any of the foregoing tuned mass dampers, the component is a shaft and the cable termination member is configured to be annularly positioned about the shaft, wherein the cable termination member and the shaft define a gap.

In any of the foregoing tuned mass dampers, the tuned mass damper is tuned to have a damper frequency that reduces vibrations at a resonant frequency of the component.

In any of the foregoing tuned mass dampers, the tuned mass damper is tuned by adjusting at least one of a length of the at least one cable, a mass of the cable termination member, a total number of cables, a total number of strands of the at least one cable, a diameter of the at least one cable, or a material of the at least one cable.

In any of the foregoing tuned mass dampers, the component is a shaft of an augmentor spray bar of a gas turbine engine.

In any of the foregoing tuned mass dampers, each of the shaft connector member, the at least one cable, and the cable termination member include at least one of a nickel-chromium-based alloy or a stainless steel.

In any of the foregoing tuned mass dampers, the shaft connector member includes a first portion and a second portion configured to be positioned about the component and coupled together to annularly surround a portion of the component.

In any of the foregoing tuned mass dampers, the first portion and the second portion of the shaft connector member are configured to be coupled together via at least one of welding, brazing, or a physical connector.

Also described is in augmentor spray bar for use in a gas turbine engine. The augmentor spray bar includes a tubular shaft that defines a fuel passageway through which fuel may flow. The augmentor spray bar also includes a fuel jet coupled to the shaft and designed to receive the fuel from the fuel passageway and to output the fuel. The augmentor spray bar also includes a tuned mass damper that has a shaft connector member coupled to the shaft, a cable termination member, and at least one cable coupled to the shaft connector member and to the cable termination member such that vibration of the shaft is transferred to the at least one cable via the shaft connector member and dampened by the at least one cable.

In any of the foregoing augmentor spray bars, the cable termination member is positioned annularly about the shaft and the cable termination member and the shaft define a gap.

In any of the foregoing augmentor spray bars, the tuned mass damper is tuned to have a damper frequency that reduces vibrations at a resonant frequency of the shaft.

In any of the foregoing augmentor spray bars, the tuned mass damper is tuned by adjusting at least one of a length of the at least one cable, a mass of the cable termination member, a total number of cables, a total number of strands of the at least one cable, a diameter of the at least one cable, or a material of the at least one cable.

In any of the foregoing augmentor spray bars, each of the shaft connector member, the at least one cable, and the cable termination member include at least one of a nickel-chromium-based alloy or a stainless steel.

In any of the foregoing augmentor spray bars, the shaft connector member includes a first portion and a second portion configured to be positioned about the shaft and coupled together.

Also described is a strut box for use in a turbine exhaust case of a gas turbine engine having afterburning capabilities. The strut box includes a casing defining a cavity the strut box also includes an augmentor spray bar at least partially positioned within the cavity and having a shaft. The strut box also includes a tuned mass damper that has a shaft connector member positioned annularly about the shaft and coupled to the shaft. The tuned mass damper also has a cable termination member positioned annularly about the shaft. The tuned mass damper also has at least one cable coupled to the shaft connector member and to the cable termination member such that vibration of the shaft is transferred to the at least one cable via the shaft connector member and dampened by the at least one cable.

In any of the foregoing strut boxes, the cable termination member and the shaft define a gap.

In any of the foregoing strut boxes, the tuned mass damper is tuned to have a damper frequency that reduces vibrations at a resonant frequency of the shaft.

In any of the foregoing strut boxes, the tuned mass damper is tuned by adjusting at least one of a length of the at least one cable, a mass of the cable termination member, a total number of cables, a total number of strands of the at least one cable, a diameter of the at least one cable, or a material of the at least one cable.

In any of the foregoing strut boxes, each of the shaft connector member, the at least one cable, and the cable termination member include at least one of a nickel-chromium-based alloy or a stainless steel.

In any of the foregoing strut boxes, the shaft connector member includes a first portion and a second portion configured to be positioned about the shaft and coupled together.

DETAILED DESCRIPTION

Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

As used herein, “aft” refers to the direction associated with the exhaust (e.g., the back end) of a gas turbine engine. As used herein, “forward” refers to the direction associated with the intake (e.g., the front end) of a gas turbine engine.

A first component that is “axially outward” of a second component means that a first component is positioned at a greater distance in the aft or forward direction away from the longitudinal center of the gas turbine along the longitudinal axis of the gas turbine, than the second component. A first component that is “axially inward” of a second component means that the first component is positioned closer to the longitudinal center of the gas turbine along the longitudinal axis of the gas turbine, than the second component.

A first component that is “radially outward” of a second component means that the first component is positioned at a greater distance away from the engine central longitudinal axis than the second component. A first component that is “radially inward” of a second component means that the first component is positioned closer to the engine central longitudinal axis than the second component. In the case of components that rotate circumferentially about the engine central longitudinal axis, a first component that is radially inward of a second component rotates through a circumferentially shorter path than the second component. The terminology “radially outward” and “radially inward” may also be used relative to references other than the engine central longitudinal axis. For example, a first component of a combustor that is radially inward or radially outward of a second component of a combustor is positioned relative to the central longitudinal axis of the combustor.

Referring now toFIG. 1, a gas turbine engine100having afterburning capabilities may include a nose cone102, a fan section104, a compressor section106, a combustor section108, a turbine section110, an augmentor section112, and a turbine exhaust case (TEC)114. Gas turbine engine100may also include a tail cone116, an augmentor liner118, a nozzle convergent section120, a nozzle divergent section122, and bypass ducts124.

Nose cone102may improve the aerodynamics of gas turbine engine100. Nose cone102may also provide vibration control functions.

Fan section104may include a plurality of fan blades that rotate about an axis X-X′ of gas turbine engine100and propel fluid (such as air) aftward towards compressor section106and bypass ducts124. In that regard, a portion of the air propelled aftward by fan section104may be received by compressor section106and a portion of the air propelled aftward by fan section104may be received by bypass ducts124.

The air received by compressor section106may be compressed using a plurality of stages of rotors that rotate about axis X-X′. Compressor section106may include stators for turning the airflow in a desired direction to increase efficiency of compressor section106.

Combustor section108may receive the compressed air and fuel and may provide a chamber in which the air and fuel mix. Combustor section108may also include an ignition source. The mixture of air and fuel may be ignited, creating a flow of exhaust in the aft direction. The exhaust may include compounds created during the combustion and residual oxygen gas that did not react during the combustion.

Turbine section110may include multiple stages of blades and vanes. The exhaust created by combustor section108is received by turbine section110. In response to receiving the exhaust, the turbine blades rotate, creating torque. The torque created in turbine section110may then be mechanically transferred to the plurality of fan blades in fan section104and/or to rotors in compressor section106.

Augmentor liner118may include a material defining a plurality of holes such that fluid may pass from one side of augmentor liner118to the other side of augmentor liner. In that regard, augmentor section112may receive the air flowing through bypass ducts124via augmentor liner118.

Exhaust from turbine section110may flow through TEC114where fuel may be added to the exhaust. The combination of exhaust and fuel from TEC114and bypass air from bypass ducts124may be ignited.

The exhaust from turbine section110and the bypass air from bypass ducts124has an aftward velocity. After combustion in augmentor section112, a second exhaust is generated having a higher aftward velocity than the turbine exhaust and bypass air. Thus, more thrust is generated when combustion occurs in augmentor section112than when combustion does not occur in augmentor section112.

Tail cone116may direct the flow from TEC114towards augmentor section112. Tail cone116may also provide vibration control functions.

In various embodiments, an angle θ of nozzle convergent section120relative to nozzle divergent section122can be controlled. In that regard, nozzle convergent section120and/or nozzle divergent section122can be controlled to provide tunable acceleration of exhaust based on whether or not combustion occurs in augmentor section112.

Turning toFIG. 2A, TEC114includes an outer annular casing204, an inner structure206, and a plurality of strut boxes200, including a strut box202, extending between the outer annular casing204and the inner structure206. Strut box202may be coupled to outer annular casing204only, may be coupled to inner structure206only, or may be coupled to outer annular casing204and inner structure206.

Turning now toFIGS. 2A and 2B, each of the plurality of strut boxes200may include an augmentor spray bar. For example, strut box202may include a casing256that defines a cavity257and an augmentor spray bar250at least partially positioned within cavity257. Augmentor spray bar250may include a cantilever portion252which may be coupled to casing256.

Referring now toFIG. 2B, augmentor spray bar250may also include a shaft254and a plurality of fuel jets253coupled to shaft254. Shaft254may define a fuel passageway255which may receive fuel. Fuel within fuel passageway255may be received by each of the plurality of fuel jets253. Each of the plurality of fuel jets253may be controllable to output fuel to be received by augmentor section112ofFIG. 1for afterburning purposes.

In response to operation of gas turbine engine100ofFIG. 1, strut box202and, in particular augmentor spray bar250, may experience vibration. Occasionally, this vibration may have a frequency similar to a resonant frequency of augmentor spray bar250. In response to the frequency of vibration experienced by strut box202being similar to the resonant frequency of augmentor spray bar250, vibration of augmentor spray bar250may undesirably increase in magnitude. In that regard, augmentor spray bar250may include a tuned mass damper258and/or tuned mass damper258may be assembled onto augmentor spray bar250.

Tuned mass damper258may be tuned to have a damping effect on vibrations having a frequency similar to the resonant frequency of augmentor spray bar250. In that regard, in response to strut box202experiencing vibrations at a frequency similar to the resonant frequency of augmentor spray bar250, tuned mass damper258may reduce or eliminate any change in magnitude of the vibration that would otherwise be experienced by augmentor spray bar250.

Tuned mass damper258may have a maximum diameter262. Maximum diameter262may be less than a distance260of casing256such that tuned mass damper258and augmentor spray bar250may fit within cavity257.

Turning now toFIG. 3, tuned mass damper258may include a shaft connector member300, a cable termination member302, and at least one cable304including a cable306. Cable306may be coupled to shaft connector member300and cable termination member302by, for example, welding, brazing, swedging, crimping, or the like.

Shaft connector member300may be coupled to shaft254via, for example, a friction fit, welding, brazing, mechanical attachment, or the like. In various embodiments, shaft connector member300may be integrally formed with shaft254.

In various embodiments, shaft connector member300may include a first portion308and a second portion310. First portion308and second portion310may each have a semi-annular shape. In that regard, first portion308and second portion310may be positioned about shaft254such that together first portion308and a second portion310surround a portion of a circumference of shaft254.

First portion308and second portion310may be coupled together via, for example, brazing, welding, mechanical attachment as described below, or the like. In various embodiments, first portion308and second portion310may be integrally formed such that shaft connector member300includes a single piece of material. In response to first portion308being coupled to second portion310about shaft254, shaft connector member300may be coupled to shaft254via a friction fit.

For example, shaft connector member300may define an aperture314designed to receive shaft254. Aperture314may have a diameter316. Similarly, shaft254may have a diameter312. Diameter312and diameter316may be similar, such as within 2 percent (2%), 1%, or 0.5% of each other. In order to prevent damage to shaft connector member300and/or shaft254, and to prevent movement of shaft connector member300relative to shaft254, a material of shaft connector member300may have a similar coefficient of thermal expansion as a material of shaft254. For example, a coefficient of thermal expansion of shaft connector member300may be within 5%, 2%, or 1% of a coefficient of thermal expansion of shaft254.

In various embodiments, each of shaft254, shaft connector member300, and cable termination member302may include one or more of an austenitic nickel-chromium-based alloy such as that sold under the trademark Inconel® which is available from Special Metals Corporation of New Hartford, N.Y., USA, a stainless steel, or other material capable of withstanding the pressures and temperatures experienced by TEC114. For example, shaft254and shaft connector member300may include Inconel® and cable termination member302may include a stainless steel. In various embodiments, cable306may include a stainless steel or other material capable of withstanding the pressures and temperatures experienced by TEC114.

Referring now toFIGS. 2A, 2B, and 3, shaft connector member300may be positioned radially inward relative to cable termination member302(i.e., shaft connector member300may be closer to inner structure206than a cable termination member302) or shaft connector member300may be positioned radially outward relative to cable termination member302. Furthermore, tuned mass damper258may be positioned at any location along augmentor spray bar250such as between two of the plurality of fuel jets253as shown, between one of the plurality of fuel jets253and casing256, or outside of casing256relative to the plurality of fuel jets253.

As augmentor spray bar250experiences vibration having a frequency similar to the resonant frequency of augmentor spray bar250, the vibration travels through shaft connector member300and is received by cable306and cable termination member302where the vibration is dampened.

Turning now toFIG. 4, a cross-sectional view of tuned mass damper258illustrates various features of tuned mass damper258that can be tuned to adjust the frequency at which vibrations received by tuned mass damper will be reduced (i.e., tuned to adjust the frequency response of tuned mass damper258).

Cable304has a length408extending between shaft connector member300and cable termination member302. The length408of cable304may be increased or decreased to adjust the frequency response of tuned mass damper258. For example, the length408of cable304may be between 2.54 centimeters (2.54 cm, 1 inch) and 30.5 cm (12 inches), between 2.54 cm (1 inch) and 15.2 cm (6 inches), or between 2.54 cm (1 inch) and 7.62 cm (3 inches).

At least one cable304may include a plurality of cables305. A total number of cables of plurality of cables305may be increased or decreased to adjust the frequency response of tuned mass damper258. For example, plurality of cables305may include between 1 and 12 cables, between 3 and 8 cables, or between 3 and 5 cables.

Each of plurality of cables305may include a plurality of strands401. For example, cable306includes a first strand402, a second strand404, and a third strand406. Each strand of plurality of strands401may rub against each other during vibration, converting motion into heat (i.e., causing friction). This friction dissipates the vibration energy, thus damping the vibration experienced by tuned mass damper258.

The total number of strands of plurality of strands401may be increased or decreased to adjust the frequency response of tuned mass damper258. For example, plurality of strands401may include between 1 strand and 50 strands, between 3 strands and 25 strands, or between 5 strands and 10 strands.

Cable termination member302may have a length414and a thickness412. A mass of cable termination member302may be based on length414, thickness412, and a density of the material of cable termination member302. The mass of cable termination member302may be increased or decreased to change the frequency response of tuned mass damper258.

In that regard, at least one of the material of cable termination member302, the length414of cable termination member302, or the thickness412of cable termination member302may be changed in order to adjust the frequency response of tuned mass damper258. For example, length414of cable termination member302may be between 0.254 cm (0.1 inch) and 7.62 cm (3 inches), between 0.762 cm (0.3 inches) and 5.08 cm (2 inches), or between 1.27 cm (0.5 inches) and 2.54 cm (1 inch). For example, thickness412of cable termination member302may be between 0.254 cm (0.1 inch) and 7.62 cm (3 inches), between 0.762 cm (0.3 inches) and 5.08 cm (2 inches), or between 1.27 cm (0.5 inches) and 2.54 cm (1 inch).

Cable306may have a diameter416. Diameter416of cable306may be increased or decreased in order to adjust the frequency response of tuned mass damper258. For example, diameter416of cable306may be between 0.0254 cm (0.01 inch) and 2.54 cm (1 inch), between 0.254 cm (0.1 inch) and 1.27 cm (0.5 inches), or between 0.508 cm (0.2 inches) and 1.02 cm (0.4 inches).

As described above, cable306may be made of a material such as stainless steel. Different materials provide different properties and, thus, the material of cable306may be changed in order to adjust the frequency response of tuned mass damper258.

As shown, cable termination member302may be separated from shaft254by a gap410. Gap410may be sufficiently large that cable termination member302may not contact shaft254when tuned mass damper258is dampening vibration of shaft254. For example, gap410may be between 0.254 cm (0.1 inch) and 7.62 cm (3 inches), between 0.762 cm (0.3 inches) and 5.08 cm (2 inches), or between 1.27 cm (0.5 inches) and 2.54 cm (1 inch).

Referring briefly toFIGS. 2A and 4, each of the plurality of strut boxes200may include a tuned mass damper such as tuned mass damper258. In that regard, cable306may be sufficiently stiff that cable termination member302remains separated from shaft254by gap410regardless of the orientation of tuned mass damper258relative to a ground surface and, thus, the effects of gravity.

Turning now toFIG. 5, another tuned mass damper500may include a shaft connector member502coupled to a shaft520, a cable termination member508, and a plurality of cables514. Shaft connector member502may include a first portion504and a second portion506. First portion504and second portion506of shaft connector member502may be coupled together via a connector501.

For example, at least one of first portion504or second portion506may define a connector aperture503. In various embodiments, connector aperture503may include threading. In that regard, connector501may include a set screw designed to be received by connector aperture503to couple first portion504to second portion506. In various embodiments, a mechanical connection between the first portion504and second portion506may be made via rivets501or other types of connectors.

Cable termination member508may also include a first portion510and a second portion512. First portion510and second portion512may be coupled together via, for example, welding, brazing, a mechanical connection such as a set screw, or the like. In various embodiments, first portion510and second portion512may be held in place relative to each other by one or more snap ring516positioned about an outer circumference of cable termination member508. Snap ring516may reduce the likelihood of first portion510separating from second portion512. In various embodiments, a second snap ring518may be positioned about the circumference of cable termination member508to further reduce the likelihood of first portion510separating from second portion512.

Turning now toFIGS. 3 and 6, a graph600illustrates the effects of tuned mass damper258on shaft254. The X axis of graph600illustrates a frequency of vibration experienced by shaft254and the y-axis illustrates a magnitude of the vibration. A first line602illustrates vibration on shaft254without use of tuned mass damper258. As shown in the graph600, the resonant frequency of shaft254may be one hertz. Thus, as the frequency of vibration approaches one hertz, the magnitude of the vibration may increase exponentially.

A second line604illustrates vibration on shaft254with use of tuned mass damper258. As the frequency gets within 0.25 hertz of the one hertz resonant frequency of shaft254, the magnitude of the vibration begins to increase. However, as the frequency gets closer to one hertz, tuned mass damper258begins to dampen the vibrations and, thus, the magnitude of the vibration decreases. This reduction in magnitude is achieved because tuned mass damper258has been tuned to have a frequency response of about one hertz (i.e., within 5% or within 10% or within 20% of one hertz), which is similar to the resonant frequency of shaft254.

While the disclosure is described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the disclosure. In addition, different modifications may be made to adapt the teachings of the disclosure to particular situations or materials, without departing from the essential scope thereof. The disclosure is thus not limited to the particular examples disclosed herein, but includes all embodiments falling within the scope of the appended claims.