Gas turbine duct liner coupling assembly

A duct liner assembly for a gas turbine engine includes a first ring and a second ring. Also included is a first duct liner having a first end and a second end, the first duct liner mounted proximate the first end of the first duct liner to the first ring. Further included is a second duct liner having a first end and a second end, the second duct liner mounted proximate the second end of the second duct liner to the second ring. Yet further included is a coupling assembly including a threaded insert, a retaining bracket, and a threaded fastener extending through the retaining bracket and in threaded engagement with the threaded insert to couple the retaining bracket to the second duct liner.

BACKGROUND

Exemplary embodiments pertain to the art of gas turbine engines and, more particularly, to a duct liner coupling assembly for gas turbine engines.

Gas turbine engines include airstreams that are at least partially defined by duct liners. In some cases, the duct lining is split for various reasons. Securing the split duct liners to each other may be challenging, particularly if thermal growth of the coupled components must be accounted for. For example, coupled duct liners may need to accommodate axial growth, but radially constrain one component relative to the other component. The assembly sequence may dictate the order in which the components must be loaded onto each other. However, if there isn't enough axial space to slide one component onto another component within a component utilized for radial constraint, assembly may be further complicated, particularly if assembling stiff, conical, cylindrical or partially conical duct liners, as typically done in gas turbine engine applications.

BRIEF DESCRIPTION

Disclosed is a duct liner assembly for a gas turbine engine that includes a first ring and a second ring. Also included is a first duct liner having a first end and a second end, the first duct liner mounted proximate the first end of the first duct liner to the first ring. Further included is a second duct liner having a first end and a second end, the second duct liner mounted proximate the second end of the second duct liner to the second ring. Yet further included is a coupling assembly including a threaded insert operatively coupled to a wall defining an aperture through one of the first duct liner and the second duct liner. The coupling assembly also includes a retaining bracket having a mating segment and a retaining segment, wherein a hole extends through the mating segment, the second end of the first duct liner disposed between the retaining segment and the second duct liner. The coupling assembly further includes a threaded fastener extending through the hole of the retaining bracket and in threaded engagement with the threaded insert to couple the retaining bracket to the second duct liner.

In addition to one or more of the features described above, or as an alternative, further embodiments may include a bushing operatively coupled to the threaded insert and disposed within the aperture and coupled to the wall.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that at least a portion of the bushing is disposed between the threaded insert and the wall.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the threaded insert is heat staked to the bushing.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the bushing is metal.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the bushing is riveted to the wall.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the retaining bracket is a single, integrally formed component.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the retaining bracket comprises a plurality of components operatively coupled to each other.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the coupling assembly allows relative axial deflection between the first and second duct liners and constrains relative radial deflection between the first and second duct liners.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the threaded insert is stainless steel.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the second duct liner includes an organic matrix composite (OMC).

Also disclosed is a gas turbine engine including a compressor section, a combustor section and a turbine section. Also included is a duct liner assembly surrounding at least one of the compressor section and the turbine section. The duct liner assembly includes a first duct liner. The duct liner assembly also includes a second duct liner. The duct liner assembly further includes a coupling assembly operatively coupling the first duct liner to the second duct liner to allow relative axial deflection between the first and second duct liners and constrain relative radial deflection between the first and second duct liners, the coupling assembly comprising a retaining bracket having a mating segment and a retaining segment, the first duct liner disposed between the retaining segment and the second duct liner, the mating segment operatively coupled to the second duct liner.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the coupling assembly further comprises a threaded insert operatively coupled to a wall defining an aperture through one of the first duct liner and the second duct liner. The coupling assembly also includes a threaded fastener extending through a hole defined by the mating segment of the retaining bracket and in threaded engagement with the threaded insert to couple the retaining bracket to the second duct liner.

In addition to one or more of the features described above, or as an alternative, further embodiments may include a bushing operatively coupled to the threaded insert and disposed within the aperture and coupled to the wall.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the threaded insert is heat staked to the bushing.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the bushing is metal.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the threaded insert is stainless steel.

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the second duct liner includes an organic matrix composite (OMC).

In addition to one or more of the features described above, or as an alternative, further embodiments may include that the gas turbine engine includes a first airstream path and a second airstream path, each of the airstream paths being annular and radially spaced from each other.

Further disclosed is a method of assembling a duct liner assembly for a gas turbine engine. The method includes operatively coupling a first duct liner to a first ring. The method also includes placing an end of a second duct liner on a radially outer surface of the first duct liner. The method further includes coupling a retaining bracket to the first duct liner after the second duct liner has been placed on the first duct liner, a portion of the retaining bracket axially overlapping with the end of the second duct liner and being radially outward of the second duct liner to constrain radial movement of the second duct liner and allow axial movement of the second duct liner.

DETAILED DESCRIPTION

FIG. 1schematically illustrates a gas turbine engine20. The gas turbine engine20is disclosed herein as a two-spool turbofan that generally incorporates a fan section22, a compressor section24, a combustor section26, a turbine section28, an augmenter section30and a nozzle section32. The sections are defined along a central longitudinal engine axis A. Although depicted as an augmented low bypass gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are applicable to other gas turbine engines including geared or non-geared high bypass architecture engines, direct drive turbofans, turboshaft engines and others.

The compressor section24, the combustor section26and the turbine section28are generally referred to as the engine core. The fan section22and a low pressure turbine34of the turbine section28are coupled by a first shaft36to define a low spool. The compressor section24and a high pressure turbine38of the turbine section28are coupled by a second shaft40to define a high spool.

An outer engine case structure42and an inner engine structure44define a generally annular secondary flow path46around a core flow path48of the engine core. It should be understood that various structure within the engine may define the outer engine case structure42and the inner engine structure44which essentially define an exoskeleton to support the core engine therein.

Air which enters the fan section22is divided between a core flow through the core flow path48and a secondary flow through the secondary flow path46. The core flow passes through the combustor section26, the turbine section28, then the augmentor section30where fuel may be selectively injected and burned to generate additional thrust through the nozzle section32. The secondary flow may be utilized for a multiple of purposes to include, for example, cooling and pressurization. The secondary flow as defined herein is any flow different from the primary combustion gas exhaust core flow. The secondary flow passes through an annulus defined by the outer engine case structure42and the inner engine structure44then may be at least partially injected into the core flow adjacent the nozzle section32.

The outer engine case structure42and the inner engine structure44as well as other engine structures are often manufactured of Ceramic Matrix Composite, Organic Matrix Composite materials and combinations thereof which are moisture sensitive. The Ceramic Matrix Composite and the Organic Matrix Composite materials will hereinafter be referred to herein as composite materials but it should be understood that any such moisture sensitive materials and structured are also contemplated.

Referring now toFIGS. 2 and 3, a portion of the gas turbine engine20is illustrated in greater detail. In some embodiments, the portion of the gas turbine engine20is the augmentor section30. In particular, multiple airstream paths, and the structural components defining the paths, are illustrated. In some embodiments, three airstream paths are provided, such as a first airstream path59and a second airstream path60. Regardless of the number of airstream paths, the paths are typically annular paths radially spaced from each other that route fluid along an axial direction of the engine20. Various structural components, which are also referred to herein as liners, ducts, duct liners or the like, define the airstream paths. As such, it is to be understood that these terms may be used interchangeably for purposes herein. The outer liner components include a first duct liner70and a second duct liner72. In some embodiments, the first duct liner70may be referred to as a rear outer augmentor duct (ROAD) and the second duct liner72may be referred to as a nozzle duct. The duct liners70,72may be formed of various contemplated materials. In some embodiments, the first duct liner70is formed of a metal, such as titanium. In some embodiments, the second duct liner72is formed of a composite material, such as an organic matrix composite (OMC).

The first duct liner70and the second duct liner72are coupled at an interface region74, as described in detail herein. The interface region74must allow axial growth (i.e., relative axial motion), but constrain relative radial deflections. This is complicated by the assembly sequence that is typically required, specifically installation of the first duct liner70after installation of the second duct liner72. The coupling techniques described herein accommodate the necessary assembly sequence, while meeting the desired relative motion demands.

As shown inFIG. 2, the first duct liner70includes a first axial end76and a second axial end78. The first duct liner70is operatively coupled to a first ring79proximate the first axial end76. The first ring79may be referred to as a mount ring. The second duct liner72also includes a first axial end80and a second axial end82. The second duct liner72is operatively coupled to a second ring84proximate the second axial end82. In some embodiments, the second ring84is referred to as a ring-strut-ring. The interface region74is located proximate an overlapping region proximate the second axial end78of the first duct liner70and the first axial end80of the second duct liner72.

Referring now toFIG. 4, the interface region74is illustrated in greater detail. As noted above, the first duct liner70must be installed subsequent to installation of the second duct liner72, but the axial space available proves such installation of the conical, cylindrical or partially conical, component challenging. A coupling assembly100is provided to assist with the installation process. In particular, after the second duct liner72is installed (e.g., operatively coupled to the second ring84), the first duct liner70may simply be placed in an overlapping manner with an outer surface102of the second duct liner72. The coupling assembly100then provides the above-described required axial growth allowance and the radial deflection constraint.

Although a single coupling assembly100is described herein, it is to be understood that some embodiments include a plurality of circumferentially spaced coupling assemblies, as shown inFIG. 3.

The coupling assembly100includes a retaining bracket104having a retaining segment106and a mating segment108. The retaining bracket104may be formed as a single, integrally formed component or assembled with multiple portions. During assembly, the second axial end78of the first duct liner70is placed on the outer surface102of the first axial end80and the retaining segment106of the retaining bracket104is then placed over (i.e., radially outward of) the second axial end78of the first duct liner70. This disposes a portion of the first duct liner70between the second duct liner72and the retaining segment106. The geometry of the retaining bracket104sandwiches the first duct liner70between the retaining segment106and the outer surface102of the second duct liner72, effectively constraining radial deflection of the first duct liner70relative to the second duct liner72.

The mating segment108of the retaining bracket104is coupled to the second duct liner72. In the illustrated embodiment, the mating segment108defines a hole110that is aligned with an aperture112defined by a wall114of the second duct liner72. Upon alignment, a threaded fastener116is inserted through the hole110and the aperture112for threaded engagement with a threaded insert118that is operatively coupled to the wall114of the second duct liner72. In some embodiments, the threaded insert118is formed with stainless steel. In embodiments where the second duct liner72is formed of OMC, it may not be desirable or practical to directly couple the threaded insert118to the wall114. In such embodiments, a bushing120is disposed therebetween to facilitate coupling. The bushing120is metal in some embodiments. For example, the bushing120may be formed of titanium. The threaded insert118may be heat staked to the bushing120and the bushing120may be riveted to the wall114. Although specific joining processes are described herein by way of example, it is to be appreciated that other techniques may be employed.

As shown inFIG. 4sealing may be achieved with a finger seal71in some embodiments, but it is to be appreciated that other sealing structures are contemplated. Furthermore, sealing may not be required in some embodiments.

The embodiments described herein provide a lightweight solution to the assembly sequence issues described above, while constraining radial deflection and allowing axial growth.