Exhaust assembly center body

In various embodiments, center body assemblies are described herein. The center body assembly may include an attachment ring, a center body, and a cavity structure. The center body may be configured to be coupled to the attachment ring. The cavity structure may be configured to be coupled to the attachment ring. The cavity structure may be configured to be separated from the center body by a gap. The center body and the cavity structure may be configured to expand independently of each other in response to an increase in temperature. In various embodiments, the cavity structure may comprise a baffle. In various embodiments, the center body may comprise a baffle.

FIELD

The present disclosure relates to turbine engine systems and, more specifically, to turbine engine exhaust assembly center bodies.

BACKGROUND

Turbine engine exhaust assemblies, e.g. for commercial airliners, form a nozzle for the high temperature exhaust air of the engine to generate thrust. Exhaust assemblies typically include a center body surrounded by an annular nozzle. The engine exhaust stream exits the engine's turbine stage through an annular passageway. The center body and the annular nozzle form an annular passageway between which conforms to the annular exhaust stream from the engine.

Exhaust center bodies are subject to the extreme heat of the exhaust stream. As the maximum temperatures of exhaust streams are trending higher, ceramic matrix composite (CMC) materials and other high temperature capability materials have been proposed as materials for forming exhaust assemblies. However, new designs for center bodies may be necessary or helpful in order to facilitate the use of materials such as CMCs, especially if the CMC is only used for a portion of the center body and differences in coefficients of thermal expansion exist between the dissimilar materials.

SUMMARY

In various embodiments, center body assemblies are described herein. A center body assembly is provided comprising an attachment ring, a center body, the center body configured to be coupled to the attachment ring, and a floating cavity structure (FCS), the FCS being configured to be coupled to the attachment ring and configured to be separated from the center body by a gap, wherein the center body has a first coefficient of thermal expansion and the FCS has a second coefficient of thermal expansion, the first coefficient of thermal expansion being different from the second coefficient of thermal expansion.

A center body assembly is provided comprising an attachment ring, a center body, the center body configured to be coupled to the attachment ring, and a floating cavity structure (FCS), the FCS being configured to be coupled to the attachment ring and being configured to be separated from the center body by a gap, wherein the center body comprises a baffle.

DETAILED DESCRIPTION

The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical, chemical and mechanical changes may be made without departing from the spirit and scope of the inventions. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented.

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. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.

A ceramic matrix composite (“CMC”) center body may be positioned around attachment ring made of a dissimilar material, such as an austenitic nickel-chromium-based superalloy. The CMC center body may have a reduced weight and improved thermal properties as compared to center bodies comprised of one or more metals. The attachment ring may have a greater coefficient of thermal expansion (CTE) than the center body. A plurality of bolts may be inserted through apertures in the center body and coupled to the attachment ring. The bolts may slide within the apertures, allowing the attachment ring to expand without applying a load on the center body.

An internal floating cavity structure or floating cavity structure (FCS) may be located radially inward of the center body. The FCS may be attached to the attachment ring. The attachment ring may have a CTE approximately equal to the FCS. The FCS may at least partially define acoustic chambers within the center body to provide acoustic attenuation during engine operation. The FCS may be separated from the center body by a gap. It may be desirable that the FCS not be fastened directly to the center body in order to avoid unwanted loads caused by different CTEs and/or different temperatures.

Hot gases ejected from a turbine engine may cause the FCS and center body to expand, and this expansion may occur at different rates due to the difference in CTE. For example, two components comprising different CTEs may expand and/or contract at different rates due to a difference in CTE between the two components. Furthermore, hot gases ejected from a turbine engine may comprise thermal gradients which may cause the FCS and center body to expand, and this expansion may occur at different rates due to a difference in temperatures. For example, two components comprising similar CTEs may expand and/or contract at different rates due to thermal gradients across the two components. Accordingly, various components of exhaust systems may experience differential thermal growth due to different CTEs and/or different temperatures. Accordingly, differential thermal growth may be used herein to describe the differential growth of two or more components due to thermal gradients and/or different CTEs. Thermal loads may be introduced between various components due to different CTEs and/or thermal gradients.

Referring toFIG. 1, a nacelle100for a gas turbine engine is illustrated according to various embodiments. Nacelle100may comprise an inlet110, a fan cowl120, and a thrust reverser130. Nacelle100may be coupled to a pylon140, which may mount the nacelle100to an aircraft wing or aircraft body. Nacelle100may further comprise a center body150. Hot gas from a gas turbine engine may exit the gas turbine engine around center body150. The center body150may be coupled to the gas turbine engine via an attachment ring.

Referring toFIG. 2A, an exploded view of an exemplary center body assembly is illustrated in accordance with various embodiments. Center body assembly200may couple to engine flange220via attachment ring230. FCS240may likewise be coupled to attachment ring230. Attachment ring230may have a CTE approximately equal to the CTE of FCS240. FCS240may be located radially inward of center body250. According to various embodiments, FCS240may comprise a forward circular plate242, a core246, an aft circular plate244, a plurality of baffles248, and a plurality of angle brackets245. Angle brackets245may be configured to couple aft circular plate244to FCS240. In various embodiments, the plurality of baffles248comprises four baffles, though in further embodiments, the plurality of baffles248may comprise at least two baffles. According to various embodiments, core246may be integral to plurality of baffles248, though in various embodiments core246may be fastened to plurality of baffles248via one or more suitable fasteners.

In various embodiments, FCS240and attachment ring230may be configured to be coupled together via apertures243and apertures233, respectively, using one or more suitable fasteners. In various embodiments, one or more fasteners may be inserted through apertures243of FCS240and through apertures233of attachment ring230.

According to various embodiments, center body250may be coupled to attachment ring230using one or more suitable fasteners. Attachment ring230may have a greater CTE than center body250. Attachment ring230and center body250may experience differential thermal growth. A plurality of bolts may be inserted through apertures256in center body250and coupled to attachment ring230via apertures236. The bolts may slide within apertures236, allowing the attachment ring230to expand without applying a load on center body250. FCS240may expand and contract without applying a load on center body250. Accordingly, center body250and FCS240may be independently coupled to attachment ring230. According to various embodiments, center body250may comprise an aft center body portion252and a forward center body portion254. Aft center body portion252may be located aft (in the positive z-direction) of forward center body portion254. Aft center body portion252and forward center body portion254may be complementary to the installation process of center body assembly200.

According to various embodiments, a plurality of seals247may be attached to FCS240. Seals247may be configured to allow center body250and FCS240to expand and contract without applying significant loads between center body250and FCS240. Seals247may be configured to be detachable from FCS240. For example, during the installation process of center body assembly200to an engine, one may first slide forward center body portion254over FCS240before attaching seals247. It may not be possible to slide forward center body portion254over FCS240with seals247attached to FCS240if the diameter of center body base258is less than the maximum diameter of FCS240including the seals247in the installed position. After FCS240and forward center body portion254have been attached to attachment ring230and the seals have been attached to FCS240, aft circular plate244may be coupled to plurality of baffles248via angle brackets245. Finally, aft center body portion252may be coupled to forward center body portion254.

According to various embodiments, seal247may comprise a curved piece of relatively elastic material, for example, a metal having relatively elastic properties. In other embodiments, seal247may be relatively stiff. In various embodiments, the seal247comprises an austenitic nickel-chromium-based alloy. Seal247may be configured to bridge the gap between baffles248which extend a certain radius from the center line of the FCS240, and the inside surface of forward center body portion254, which is located a further radius from the same center, in order to seal acoustically one acoustic chamber from the adjacent chambers.

With further reference toFIG. 2B, a cross sectional view of center body assembly200is illustrated in accordance with various embodiments. The cross-sectional view of center body assembly200in the installed position is taken at a location between forward of circular plate242and aft circular plate244. Center body250and baffles248of FCS240may be configured to be separated by gap “M”. FCS240may have a greater CTE than center body250. FCS240and center body250may experience differential thermal growth. Accordingly, FCS240may expand more than center body250in response to an increase in temperature. Gap “M” may be configured to allow center body250and FCS240to expand independently of each other. Having center body250and FCS240configured to be separated by gap “M” may eliminate load paths between center body250and FCS240. Accordingly, a load path may not exist between center body250and FCS240. In various embodiments, during thermal expansion of center body250and FCS240, gap “M” may be configured to decrease. In various embodiments, gap “M” may decrease in response to an increase in temperature. In various embodiments, gap “M” may increase in response to a decrease in temperature. In various embodiments, a plurality of seals247may occupy at least a portion of gap “M,” and ideally would occupy approximately the entire gap M when the components have undergone thermal growth and are at cruise condition temperatures.

In accordance with various embodiments, FCS240and center body250may at least partially define a plurality of acoustic chambers. In various embodiments, FCS240and center body250partially define acoustic chambers A, B, C, and D according to various embodiments. As illustrated, center body assembly200comprises four acoustic chambers. According to various embodiments, center body assembly200may comprise at least two acoustic chambers. According to various embodiments, the number of acoustic chambers may be defined by the number in the plurality of baffles248. For example, if there are four baffles, there may be four acoustic chambers at least partially defined by the four baffles.

According to various embodiments, center body250may include a plurality of apertures257. Apertures257may be configured to allow acoustic waves to enter into center body250. Apertures257may aide in acoustic mitigation of exhaust noise.

According to various embodiments, acoustic chambers A, B, C, and D may help attenuate exhaust noise, especially very low frequency acoustic noise. According to various embodiments, acoustic chambers A, B, C, and D may act similar to a Helmholtz resonator. Acoustic waves may enter center body250through apertures257into at least one of acoustic chamber A, B, C, and D. Acoustic waves may be reflected by at least a portion of acoustic chamber A, B, C, and D in a manner such that the reflected acoustic wave interferes with an entering acoustic wave, mitigating the acoustic signature of the exhaust noise. Center body assembly200may be configured to mitigate acoustic waves comprising relatively low frequencies such as frequencies of around 450 Hertz, for example. Acoustic chambers A, B, C, and D may be further subdivided by additional perforated baffles (not shown) in what may be referred to as a folding cavity design.

Referring toFIG. 3A, an exploded view of an exemplary center body assembly300is illustrated in accordance with various embodiments. Similar to center body assembly200ofFIG. 2, center body assembly300may include an engine flange220and an attachment ring230. Center body assembly300may further include FCS340and a center body350in accordance with various embodiments. Similar to center body assembly200ofFIG. 2, a plurality of fasteners may be inserted through apertures343of FCS340and through apertures233of attachment ring230to couple FCS340to attachment ring230. FCS340may comprise a forward circular plate342, a core346, and an aft circular plate344. Core346may extend from forward circular plate342to aft circular plate344. Accordingly, forward circular plate342and aft circular plate344may be separated by core346. Core346, forward circular plate342, and aft circular plate344may be integral to one another. In various embodiments, core346, forward circular plate342, and aft circular plate344may be coupled via one or more suitable fasteners. Aft circular plate344may comprise a plurality of slots349extending in the radial direction. The number of slots349may be equal to the number of baffles in plurality of baffles348.

According to various embodiments, center body350may comprise an aft center body portion352and a forward center body portion354. Center body350may be coupled to attachment ring230in the same manner as center body250of center body assembly200as illustrated byFIG. 2A. Accordingly, center body350may be coupled to attachment ring230via apertures356and apertures236in the same manner as previously mentioned. Aft center body portion352may be located aft (in the positive z-direction) of forward center body portion354. Center body350may further comprise a plurality of baffles358. Aft center body portion352and forward center body portion354may be complimentary to the manufacturing process of center body350and baffles358. The plurality of baffles358and center body350may be heat treated together as part of a CMC manufacturing process. Accordingly, the plurality of baffles358may be integral to center body350. Center body350, together with baffles358may be configured to slide over FCS340. The baffles may be configured to at least partially slide through slots349of aft circular plate344during installation.

Referring toFIG. 3B, a cross sectional view of center body assembly300is illustrated. The cross-sectional view of center body assembly300in the installed position is taken at the location of aft circular plate344. During installation, plurality of baffles358are slid into slots349of aft circular plate344. According to various embodiments, plurality of baffles358and aft circular plate344are configured to be separated by a gap “S”. According to various embodiments, center body350and aft circular plate344may be configured to be separated by gap “N”. FCS340may have a greater CTE than center body350. FCS340and center body350may experience differential thermal growth. Accordingly, FCS340may expand more than center body350in response to an increase in temperature. Gap “N” and gap “S” may be configured to allow center body350and FCS340to expand independently of each other. Having center body350and FCS340configured to be separated by gap “N” and gap “S” may eliminate load paths between center body350and FCS340. Accordingly, a load path may not exist between center body350and FCS340. In various embodiments, during thermal expansion of center body350and FCS340, gap “N” and gap “S” may be configured to decrease. In various embodiments, gap “N” and gap “S” may decrease in response to an increase in temperature. In various embodiments, gap “N” and gap “S” may increase in response to a decrease in temperature. According to various embodiments, the width of gap “N” and the width of gap “S” may be equal. According to various embodiments, the width of gap “N” may be greater than the width of gap “S”. According to various embodiments, the width of gap “N” may be less than the width of gap “S”.

With reference toFIG. 3C, a cross sectional view of center body assembly300is illustrated. The cross-sectional view of center body assembly300in the installed position is taken at a location between forward circular plate342and aft circular plate344. According to various embodiments, Center body350and FCS340may at least partially define a plurality of acoustic chambers E, F, G, and H. In various embodiments, center body assembly300comprises four acoustic chambers. According to various embodiments, center body assembly300may comprise at least two acoustic chambers. According to various embodiments, the number of acoustic chambers may be defined by the number of baffles in plurality of baffles358. For example, if there are four baffles there may be four acoustic chambers at least partially defined by the four baffles.

According to various embodiments, center body350may include a plurality of apertures357. Apertures357may be configured to allow acoustic waves to enter into center body350. Apertures357may aide in acoustic mitigation of exhaust noise.

According to various embodiments, acoustic chambers E, F, G, and H may help attenuate exhaust noise. According to various embodiments, acoustic chambers E, F, G, and H may act as a Helmholtz resonator. Acoustic waves may enter center body350through apertures357into at least one of acoustic chamber E, F, G, and H. Acoustic waves may be reflected by at least a portion of acoustic chamber E, F, G, or H in a manner such that the reflected acoustic wave interferes with an entering acoustic wave, mitigating the acoustic signature of the exhaust. Center body assembly300may be configured to mitigate acoustic waves comprising relatively low frequencies such as frequencies of around 450 Hertz, for example.

With reference toFIG. 2AandFIG. 3A, core246,346may be any geometric shape including, for example, round, triangular, square, and pentagonal, in accordance with various embodiments. According to various embodiments, the size of core246may at least partially define the size of acoustic chambers A, B, C, and/or D. According to various embodiments, the size of core346may at least partially define the size of acoustic chambers E, F, G, and/or H. For example, if the diameter of core246increased, the depth of acoustic chambers A, B, C, and/or D may decrease. In various embodiments, the size of core246and acoustic chambers A, B, C, and D may affect the mitigation of exhaust acoustics. In various embodiments, the size of core346and acoustic chambers E, F, G, and H may affect the mitigation of exhaust acoustics.

In various embodiments, the attachment ring230may comprise a CTE greater than the CTE of the center body250,350. In various embodiments, the center body attachment ring230and/or baffles258,358may comprise an austenitic nickel-chromium-based alloy such as Inconel®, which is available from Special Metals Corporation of New Hartford, N.Y., USA. However, the center body attachment ring230and/or plurality of baffles258,358may comprise a variety of nickel and chromium based alloys, such as Inconel® MA754, an oxide dispersion strengthened nickel-chromium super alloy; René 41, a nickel-cobalt high temperature alloy; Haynes® 244, a nickel-cobalt alloy manufactured by Haynes International, Inc.; or Haynes® 282, a wrought gamma-prime strengthened superalloy manufactured by Haynes International, Inc. The center body assembly200,300may be subject to operating environments that experience a wide range of temperatures, such as from 0° F. to 1,400° F. (−20° C. to 760° C.). The center body attachment ring230may expand more than the center body250,350in response to the same increase in temperature.

In various embodiments, center body assemblies may comprise multiple materials, or any material configuration suitable to enhance or reinforce the resiliency and/or support of the system when subjected to wear in an aircraft operating environment or to satisfy other desired electromagnetic, chemical, physical, or biological properties, for example radar signature, load capacity, and/or heat tolerance.

In various embodiments, various components may comprise a CMC. For example, various aspects of the center body250,350and/or plurality of baffles258,358may comprise a CMC. However, in various embodiments, the center body250,350and/or baffles258,358may comprise at least one of a carbon-carbon composite, a ceramic material, graphite, or any other suitable material. Thus, as discussed herein, the center body250,350may exhibit a different CTE than the engine flange220and the center body attachment ring230. In various embodiments, a CMC may generally comprise one or more ceramic materials disposed on or within another material, such as, for example, a ceramic material disposed within a structure comprised of a fibrous material. Fibrous materials, such as carbon fiber, aramid fibers, fiberglass fibers, and the like may be formed into fibrous structures suitable for this purpose. Deposition of a ceramic material into or onto a fibrous material may be accomplished using chemical vapor infiltration (CVI), melt infiltration (MI), and slurry casting (SC) may be used, alone or in various combinations, to partially or fully impregnate a fibrous structure with the ceramic material.

While the center body assemblies described herein have been described as including an FCS240,340comprising a metallic material and a center body250,350comprising a CMC, FCS240,340and center body250,350may both comprise a metallic material. Furthermore, FCS240,340and center body250,350may both comprise a CMC. In such embodiments, differential thermal growth may be dominated by the effect of thermal gradients. Furthermore, the materials used for FCS240,340, as described herein, and the materials used for center body250,350, as described herein, may be interchanged. For example, FCS240,340may comprise a CMC and center body250,350may comprise a metallic material. In such embodiments, differential thermal growth may be dominated by the effect of different material properties such as CTE.

Moreover, the center body250,350may comprise any material suitably lightweight and heat tolerant. In various embodiments, various aspects of the center body250,350and/or baffles258,358may comprise refractory metal, for example, an alloy of titanium, for example titanium-zirconium-molybdenum (TZM).

While the center body assemblies described herein have been described in the context of aircraft applications, one will appreciate in light of the present disclosure that the system described herein may be used in connection with various other vehicles, for example, a launch vehicle, a spacecraft, an unmanned aerial vehicle, a missile, cars, trucks, busses, trains, boats, and submersible vehicles, or any other vehicle or device, or in connection with industrial processes, or propulsion systems, or any other system or process having different materials exposed to fluctuating temperatures.

Additionally, although described primarily with reference to ceramic matrix composite center bodies, the present disclosure may be used with various materials having relatively low CTEs, such as carbon-carbon composites, ceramic materials, and graphite.