Patent Description:
Gas turbine engines typically include a compressor section and a turbine section. The air is compressed in the compressor section. From the compressor section the air is introduced into a combustor section where it is mixed with fuel and ignited in a combustor. Products of this combustion pass downstream over a turbine section to extract energy for driving the compressor section. The components may be exposed to hot gases in the gas path. Various cooling schemes may be utilized to cool portions of the components. A seal may be utilized to limit flow of hot gases from the gas path and/or cooling flow into the gas path.

<CIT> discloses a prior art gas turbine engine as set forth in the preamble of claim <NUM>.

<CIT> discloses a prior art multi-plane brush seal.

From one aspect, there is provided a gas turbine engine as recited in claim <NUM>.

There is also provided a method of assembly for a gas turbine engine as recited in claim <NUM>.

The engine parameters described above and those in this paragraph are measured at this condition unless otherwise specified. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about <NUM>, or more narrowly greater than or equal to <NUM>. The "Low corrected fan tip speed" as disclosed herein according to one non-limiting embodiment is less than about <NUM> ft / second (<NUM> meters/second), and can be greater than or equal to <NUM> ft / second (<NUM> meters/second).

<FIG> illustrates an exemplary section <NUM> for a gas turbine engine. The section <NUM> may be incorporated into the gas turbine engine <NUM> of <FIG>, such as the compressor section <NUM> or the turbine section <NUM>. The section <NUM> includes a rotor <NUM> carrying one or more blades or airfoils <NUM> that are rotatable about a longitudinal axis LA. The longitudinal axis LA may be collinear or otherwise parallel to the engine axis A of <FIG>.

Each airfoil <NUM> includes a platform 62P and an airfoil section 62A extending in a radial direction R from the platform 62P to a tip 62T. The airfoil section 62A generally extends in a chordwise or axial direction X between a leading edge 62LE and a trailing edge 62TE. A root section 62R of the airfoil <NUM> is mounted to, or integrally formed with, the rotor <NUM>. A blade outer air seal (BOAS) <NUM> is spaced radially outward from the tip 62T of the adjacent airfoil <NUM>. The BOAS <NUM> can include a plurality of seal arc segments that are circumferentially arranged in an annulus around the longitudinal axis LA. The tip 62T of the airfoil section 62A and adjacent BOAS <NUM> are arranged in close radial proximity to reduce the amount of gas flow that is redirected toward and over the rotating blade airfoil tip 62T through a corresponding clearance gap.

The BOAS <NUM> can include one or more seal arc segments <NUM> mounted or otherwise secured to one or more carriers 63C. Each carrier 63C can be secured to an engine static structure such as the engine case <NUM> or another portion of the engine static structure <NUM> of <FIG>.

A vane <NUM> can be positioned along the longitudinal axis LA and adjacent to the airfoil <NUM>. The vane <NUM> includes an airfoil section 64A extending between an inner platform 64PI and an outer platform 64PO to define a portion of the gas path GP. The inner platform 64PI and outer platform 64PO are dimensioned to bound radially inner and outer portions of the gas path GP.

Each vane <NUM> can include a spar member <NUM> secured to a fairing <NUM>. The spar member <NUM> may include a portion 65P at least partially received in a cavity 66C of the fairing <NUM>. The portion 65P may be a hollow strut or conduit that extends radially inwardly towards the longitudinal axis LA. The spar member <NUM> may be secured to the engine static structure. The spar member <NUM> may be a load bearing structure that is dimensioned to at least partially support a respective fairing <NUM>.

The spar member <NUM> may be coupled to a coolant source CS (shown in dashed lines for illustrative purposes). The coolant source CS can be configured to supply or convey pressurized cooling flow to cool portions of the section <NUM> including each vane <NUM>. The coolant source CS can include bleed air from an upstream stage of the compressor section <NUM> (<FIG>), bypass air, or a secondary cooling system aboard the aircraft, for example. Various materials may be utilized to form the spar member <NUM> and fairing <NUM>. The spar member <NUM> may be formed of a metallic material, such as a high temperature metal or alloy. The fairing <NUM> can be a monolithic component formed of a ceramic material, such as a ceramic matrix composite (CMC) material that establishes the airfoil section 64A and/or platform sections 64PI, 64PO. The CMC materials disclosed herein may include continuous or discontinuous fibers in a matrix arranged in one or more layers to establish a CMC layup.

The section <NUM> can include an array of airfoils <NUM>, an array of vanes <NUM>, and an array of BOAS <NUM> arranged circumferentially about the longitudinal axis LA. The array of the BOAS <NUM> can be distributed in a circumferential or thickness direction T about an array of the airfoils <NUM> to bound a gas path GP, such as the core flow path C of <FIG>.

The section <NUM> can include one or more seal assemblies <NUM>. Each seal assembly <NUM> can be arranged to establish sealing relationships with one or more adjacent gas turbine engine components of the section <NUM>, such as a first gas turbine engine component <NUM> and second gas turbine engine component <NUM> adjacent the gas path GP. The first component <NUM> can be an adjacent vane(s) <NUM>, and the second component <NUM> can be an adjacent BOAS <NUM> as illustrated in <FIG>, or vice versa. The section <NUM> can include two or more seal assemblies <NUM> distributed along the longitudinal axis LA to establish sealing relationships that limit flow to and/or from the gas path GP.

<FIG> illustrate an exemplary seal assembly <NUM> for a section <NUM> of a gas turbine engine. The section <NUM> and seal assembly <NUM> may be incorporated into a section of the gas turbine engine <NUM> of <FIG> and/or <NUM>, such as the turbine section <NUM>. Other portions of the gas turbine engine <NUM> and other systems may benefit from the teachings disclosed herein, including gas turbine engines lacking a fan for propulsion. In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding original elements. The seal assembly <NUM> can be arranged to establish sealing relationships with non-rotating or static components and/or rotating components such as shafts and bearing arrangements (e.g., inner shaft <NUM> or outer shaft <NUM> of <FIG>).

The seal assembly <NUM> can include a first side plate <NUM>, second side plate <NUM>, backing plate <NUM>, first brush seal <NUM> and second brush seal <NUM>. The first side plate <NUM>, second side plate <NUM>, backing plate <NUM> and brush seals <NUM>, <NUM> can be dimensioned to extend circumferentially about an assembly axis AA, as illustrated in <FIG>. The assembly axis AA may be colinear with or otherwise parallel to a longitudinal axis LA of the section <NUM>. The seal assembly <NUM> can be dimensioned to extend along an array of vanes <NUM> and/or array of BOAS <NUM> in the circumferential direction T as illustrated in <FIG> and/or span between the array of vanes <NUM> and array of BOAS <NUM> in the axial direction X as illustrated by <FIG>. Each of the first side plate <NUM>, second side plate <NUM>, backing plate <NUM> and/or brush seals <NUM>, <NUM> can be a full hoop or can include one or more arc segments dimensioned to extend at least partially or completely about the assembly axis AA.

The first and second brush seals <NUM>, <NUM> may cooperate to establish a double brush seal arrangement. The first brush seal <NUM> can include a first bristle pack <NUM>. The second brush seal <NUM> can include a second bristle pack <NUM>. Each bristle pack <NUM>, <NUM> can include a set of bristles that are joined together as a unit. The bristles may be formed of non-metallic materials or metallic materials such as high temperature metal or nickel-based alloy. The seal assembly <NUM> can have a unitary construction. The bristle packs <NUM>, <NUM> may be arranged in a compressed state between the side plates <NUM>, <NUM> and backing plate <NUM>. The first bristle pack <NUM> can be welded or otherwise mechanically attached to the first side plate <NUM> and backing plate <NUM> and the second bristle pack <NUM> can be welded or otherwise mechanically attached to the second side plate <NUM> and backing plate <NUM> to establish the unitary construction.

The first brush seal <NUM> and second brush seal <NUM> can be arranged in various configurations. The first and second brush seals <NUM>, <NUM> can be positioned on opposite sides of the backing plate <NUM>. The first brush seal <NUM> can be sandwiched or otherwise situated between the first side plate <NUM> and backing plate <NUM>. The second brush seal <NUM> can be sandwiched or otherwise situated between the second side plate <NUM> and backing plate <NUM>. In some implementations, the first and/or second side plates <NUM>, <NUM> are omitted.

The first and second brush seals <NUM>, <NUM> can be arranged at various positions and/or orientations relative to each other and one or more gas turbine engine components to establish respective sealing relationships. The brush seals <NUM>, <NUM> can be dimensioned to extend radially inward and/or radially outward in the same or different directions relative to the assembly axis AA, or can be dimensioned to extend axially in the same or different directions relative to the assembly axis AA. The first brush seal <NUM> can be dimensioned to establish a first sealing relationship with a first gas turbine engine component <NUM>. The second brush seal <NUM> can be dimensioned to establish a second seal relationship with a second gas turbine engine component <NUM>. The gas turbine engine components <NUM>, <NUM> can include any of the components disclosed herein. The components <NUM>, <NUM> can be different portions of the same gas turbine engine component or can be separate and distinct components. For example, the first component <NUM> can be a turbine vane or associated mounting structure, such as the vane <NUM>, and the second component <NUM> can be a BOAS or associated mounting structure, such as the BOAS <NUM> or the carrier 63C (<FIG>). In the illustrated example of <FIG>, the first brush seal <NUM> is dimensioned to establish a first sealing relationship with the array of vanes <NUM>, and the second brush seal <NUM> is dimensioned to establish the second sealing relationship with the array of blade outer air seals <NUM>.

Various materials may be utilized to form the first and second components <NUM>, <NUM>, including any of the materials disclosed herein. For example, portions of the first and/or second components <NUM>, <NUM> that establish the respective first and/or second sealing relationships may comprise a ceramic material such as a monolithic ceramic or CMC material. Monolithic ceramics may be, but are not limited to, silicon carbide (SiC) or silicon nitride (Si<NUM>N<NUM>).

The array of vanes <NUM> and array of BOAS <NUM> can establish an axial gap G relative to the longitudinal axis LA, as illustrated in <FIG>. The axial gap G extends outwardly from a gas path GP such as the core flow path C of <FIG>. The seal assembly <NUM> can be dimensioned to span the axial gap G between adjacent vanes <NUM> and BOAS <NUM>.

Each of the vanes <NUM> can include a fairing <NUM> that establishes a platform section 164P of the vane <NUM>. The platform section 164P can be one of the platform sections 64PI, 64PO of the vane <NUM> of <FIG>, such as the outer platform section 64PO. The platform section 164P can be arranged to establish the first and/or sealing relationships with the respective brush seal <NUM>, <NUM>, such as the first brush seal <NUM> as illustrated in <FIG>, and can comprise any of the materials disclosed herein.

The first and second brush seals <NUM>, <NUM> are dimensioned to extend radially inward in the radial direction R from an inner periphery <NUM> of the backing plate <NUM> relative to the assembly axis AA to establish the first and second sealing relationships. The first and second brush seals <NUM>, <NUM> can be dimensioned such that the first and second sealing relationships are established at the same radial position or at different radial positions relative to the longitudinal axis LA as illustrated in <FIG>.

Various techniques may be utilized to secure the seal assembly <NUM>. The seal assembly <NUM> may be dimensioned to be trapped between one or more (or each) of the spar members <NUM> and one or more (or each) of the BOAS <NUM> opposing the spar members <NUM> in an installed position, as illustrated in <FIG>. In the installed position, the spar members <NUM> and BOAS <NUM> cooperate to limit axial movement of the seal assembly <NUM> relative to the longitudinal axis LA.

The second side plate <NUM> can include a plate body <NUM> and an annular flange <NUM> extending outwardly from the plate body <NUM>. The annular flange <NUM> can be dimensioned to extend circumferentially in the circumferential direction T about the assembly axis AA. The annular flange <NUM> can be dimensioned to engage an outer periphery of the second component <NUM> (or first component <NUM>), such as an outer periphery 163PO of two or more BOAS <NUM> as illustrated in <FIG> to secure the seal assembly <NUM> to an engine static structure, such as the engine static structure <NUM> of <FIG>. Engagement between the annular flange <NUM> and second component <NUM> can limit radial movement of the seal assembly <NUM> in the radial direction R relative to the longitudinal axis LA.

The brush seals <NUM>, <NUM> can be arranged at various orientations relative to each other to establish the respective sealing relationships. The backing plate <NUM> can have a generally quadrilateral or trapezoidal cross sectional geometry. The backing plate <NUM> can include a main body <NUM> extending radially between the inner periphery <NUM> and an outer periphery <NUM> and circumferentially between first and second sidewalls <NUM>, <NUM> on opposite sides of the main body <NUM>. The inner and outer peripheries <NUM>, <NUM> can be substantially parallel to each other or can be transverse as illustrated in <FIG>. The sidewalls <NUM>, <NUM> can be substantially parallel to each other or can be transverse as illustrated in <FIG>.

The sidewalls <NUM>, <NUM> can be dimensioned such that the brush seals <NUM>, <NUM> slope outwardly from the outer periphery <NUM> of the backing plate <NUM> towards the inner periphery <NUM> of the backing plate <NUM>. The first sidewall <NUM> can be dimensioned such that the first brush seal <NUM> slopes outwardly from the outer periphery <NUM> in a first direction D1 relative to the assembly axis AA. The second sidewall <NUM> can be dimensioned such that the second brush seal <NUM> slopes outwardly from the outer periphery <NUM> in a second direction D2 relative to the assembly axis AA, as illustrated in <FIG>. The second direction D2 can be opposed to the first direction D1. The sidewalls <NUM>, <NUM> can be dimensioned to have a major component in the radial direction R and a minor a component in the axial direction X to establish the sloping arrangement. For example, the first and/or second brush seals <NUM>, <NUM> can be angled approximately <NUM> degrees to approximately <NUM> degrees relative to a radial axis RA extending in the radial direction R (RA shown in dashed lines in <FIG> for illustrative purposes). For the purposes of this disclosure, the terms "substantially" and "approximately" mean ±<NUM> percent of the stated value or relationship unless otherwise indicated.

The backing plate <NUM> can include various weight reduction features. In the illustrative example of <FIG>, backing plate <NUM> includes one or more scallops <NUM> formed in a main body <NUM> of the backing plate <NUM>. The backing plate <NUM> can include a plurality of scallops <NUM> circumferentially distributed about a periphery of the backing plate <NUM>, such as an outer periphery <NUM>. The scallops <NUM> can be formed in the backing plate <NUM> to reduce an overall weight of the seal assembly.

<FIG> illustrate a section <NUM> including a seal assembly <NUM> according to another example. The seal assembly <NUM> can include one or more anti-rotation features that clock the seal assembly <NUM> and limit relative movement between the seal assembly <NUM> and adjacent components <NUM>, <NUM>. In implementations, the anti-rotation features can include one or more protrusions or keys <NUM> that may mate or interfit with respective recesses or keyways <NUM> associated with the components <NUM>, <NUM> to limit relative rotation. The keys <NUM> may extend outwardly from one of the side plates <NUM>, <NUM>, such as the first side plate <NUM>. The keyways <NUM> may be established in the one of the gas turbine engine components <NUM>, <NUM> or associated support structure, such as one or more of the spars <NUM> (shown in dashed lines in <FIG> for illustrative purposes). Each keyway <NUM> is dimensioned to interfit with a respective one of the keys <NUM> to limit circumferential movement in the circumferential direction T between the seal assembly <NUM> and adjacent components <NUM>, <NUM>. The section <NUM> can include an array of the keys <NUM> and keyways <NUM> distributed about the longitudinal axis LA. In implementations, the anti-rotation features are incorporated in the second side plate <NUM> and the second component <NUM> or associated structure.

<FIG> illustrates a seal assembly <NUM> according to another example which does not fall under the scope of the appended claims. The seal assembly <NUM> can be secured to an engine static structure, including any of the static structures disclosed herein. The seal assembly <NUM> includes a first brush seal <NUM> and a second brush seal <NUM>. The first brush seal <NUM> is dimensioned to establish a first sealing relationship with a first gas turbine engine component <NUM>. The second brush seal <NUM> is dimensioned to establish a second sealing relationship with a second gas turbine engine component <NUM>.

The first brush seal <NUM> can be dimensioned to extend in a first axial direction D1 from a backing plate <NUM> relative to an assembly axis AA such that the first sealing relationships established along an axial face <NUM> of the first component <NUM>. The axial face <NUM> may be established by one or more of the spar members <NUM> of <FIG>, for example. The second brush seal <NUM> can be dimensioned to extend in a second axial direction D2 from the backing plate <NUM> relative to the assembly axis AA such that a second sealing relationship is established along an axial face <NUM> of the second component <NUM>. The second axial direction D2 can be opposed to the first axial direction D1. The axial face <NUM> may be established by one or more BOAS <NUM> of <FIG> or one or more carriers 63C associated with the BOAS <NUM> of <FIG>, for example. In other implementations, the brush seals <NUM>, <NUM> extend generally in the same direction.

<FIG> illustrates an exemplary method of assembly for a gas turbine engine in a flowchart <NUM>. The method may be utilized to assemble any of the sections and seal assemblies disclosed herein. Reference is made to the seal assembly <NUM> of <FIG> for illustrative purposes.

At step 596A, the first brush seal <NUM> and second brush seal <NUM> are positioned relative the backing plate <NUM>. Step 596A can include positioning the first brush seal <NUM> and second brush seal <NUM> on opposite sides of the backing plate <NUM>.

At step 596B, the first brush seal <NUM> and second brush seal <NUM> are positioned relative to the first side plate <NUM> and second side plate <NUM>. Step 596B can include positioning the first and second brush seals <NUM>, <NUM> between the side plates <NUM>, <NUM> such that the first brush seal <NUM> is sandwiched between the first side plate <NUM> and backing plate <NUM> and such that the second brush seal <NUM> is sandwiched between the second side plate <NUM> and backing plate <NUM>.

At step 596C, two or more of the components can be secured together to establish the seal assembly <NUM>, including the first and second brush seals <NUM>, <NUM>, first and second plates <NUM>, <NUM> and/or backing plate <NUM>. Various techniques can be utilized to secure the components, including any of the techniques disclosed herein. Step 596C can include mechanically attaching the brush seals <NUM>, <NUM> to the backing plate <NUM> and respective ones of the side plates <NUM>, <NUM> to establish the seal assembly <NUM>. Step 596C can include welding the brush seals <NUM>, <NUM> to the backing plate <NUM> and to respective ones of the side plates <NUM>, <NUM> to establish a unitary construction, which can occur prior to positioning the seal assembly <NUM> relative to one or more gas turbine engine components <NUM>, <NUM>. In other implementations, the brush seals <NUM>, <NUM> are crimped to secure the brush seals <NUM>, <NUM> to the side plates <NUM>, <NUM> and backing plate <NUM>.

At step 596D, the seal assembly <NUM> is positioned such that the first brush seal <NUM> establishes a first sealing relationship with a first gas turbine engine component <NUM> and such that the second brush seal <NUM> establishes a second sealing relationship with a second gas turbine engine component <NUM>. The second component <NUM> can be adjacent to the first gas turbine engine component <NUM>. A portion of the first component <NUM> that establishes the first sealing relationship and/or a portion of the second component <NUM> that establishes the second sealing relationship can comprise any of the materials disclosed herein, including a ceramic material such as a monolithic ceramic or CMC material.

Step 596D can include positioning the seal assembly <NUM> as a single unit established at step 596C relative to the components <NUM>, <NUM>. In other implementations, step 596A, 596B and/or 596C can occur during and/or subsequent to step 596D. Step 596D can include positioning the seal assembly <NUM> at any of the positions and/or orientations disclosed herein. Step 596D can include positioning the seal assembly <NUM> to span across a gap between the adjacent components <NUM>, <NUM>, such as the axial gap G of <FIG>.

The bristles of the brush seals <NUM>, <NUM> may be angled in the circumferential direction prior to positioning the seal assembly <NUM> in the section <NUM>. For example, the bristles may be oriented at an approximately <NUM> degree angle in a clockwise or counterclockwise direction. Step 596D can include rotating the seal assembly <NUM> about the longitudinal axis LA in an opposed clockwise or counterclockwise direction subsequent to positioning the seal assembly <NUM> in abutment with the first and/or second components <NUM>, <NUM> to establish an interference fit between the brush seals <NUM>, <NUM> and respective components <NUM>, <NUM>.

The disclosed seal assemblies can be utilized to establish a double seal arrangement. The brush seals may be packaged in a single unit, which may reduce assembly time and complexity. The disclosed seal assemblies may improve sealing effectiveness and reduce parts counts by utilizing a common backing plate for the brush seals. The disclosed seal assemblies may be relatively more compact, which may facilitate incorporation of the seal assemblies in reduced space designs. The disclosed seal assemblies may reduce the need to incorporate one or more face seals that may otherwise extend between the backing plate and mating hardware, which can reduce complexity and weight. The seal assemblies may be utilized to establish sealing relationships with components incorporating CMC materials, which may be associated with relatively greater leaking paths and variability due to interaction between the CMC components and metallic support.

It should be understood that relative positional terms such as "forward," "aft," "upper," "lower," "above," "below," and the like are with reference to the normal operational altitude of the vehicle and should not be considered otherwise limiting.

Claim 1:
A gas turbine engine (<NUM>) comprising:
a section (<NUM>; <NUM>) including an array of blades (<NUM>) rotatable about a longitudinal axis (LA), an array of vanes (<NUM>; <NUM>) adjacent to the array of blades (<NUM>), and an array of blade outer air seals (<NUM>; <NUM>) arranged circumferentially about the array of blades (<NUM>) relative to the longitudinal axis (LA); and
a seal assembly (<NUM>; <NUM>; <NUM>; <NUM>) dimensioned to span between the array of vanes (<NUM>; <NUM>) and the array of blade outer air seals (<NUM>; <NUM>), the seal assembly (<NUM>; <NUM>; <NUM>; <NUM>) comprising:
a first side plate (<NUM>; <NUM>; <NUM>), a second side plate (<NUM>; <NUM>; <NUM>) and a backing plate (<NUM>; <NUM>; <NUM>; <NUM>) that extend circumferentially about the longitudinal axis (LA);
a first brush seal (<NUM>; <NUM>; <NUM>) between the first side plate (<NUM>; <NUM>; <NUM>) and the backing plate (<NUM>; <NUM>; <NUM>; <NUM>);
a second brush seal (<NUM>; <NUM>; <NUM>) between the second side plate (<NUM>; <NUM>; <NUM>) and the backing plate (<NUM>; <NUM>; <NUM>; <NUM>); and
wherein the first brush seal (<NUM>; <NUM>; <NUM>) is dimensioned to establish a first sealing relationship with the array of vanes (<NUM>; <NUM>), and the second brush seal (<NUM>; <NUM>; <NUM>) is dimensioned to establish a second sealing relationship with the array of blade outer air seals (<NUM>; <NUM>),
characterised in that
the first and second brush seals (<NUM>, <NUM>; <NUM>, <NUM>; <NUM>, <NUM>) extend radially inward from a radially inner periphery (<NUM>; <NUM>) of the backing plate (<NUM>; <NUM>; <NUM>; <NUM>) to establish the first and second sealing relationships.