Patent Description:
The combustor section includes a chamber where the fuel/air mixture is ignited to generate the high energy exhaust gas flow. Thus, the combustor is generally subject to high thermal loads for prolonged periods of time. Combustor liners have been proposed made of ceramic matrix composite materials, which have higher temperature capabilities. However, mounting ceramic combustor liners within the combustor may present challenges.

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

<CIT> discloses a prior art gas turbine combustion chamber with mixing air orifices.

<CIT> discloses a prior art ceramic combustion liner.

<CIT> discloses a prior art CMC BOAS axial retaining cup.

According to the invention, there is provided a combustor liner assembly for a gas turbine engine as recited in claim <NUM>.

There is also provided a combustor assembly as recited in claim <NUM>.

There is also provided 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>. "Low corrected fan tip speed" is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R)/(<NUM> °R)]<NUM> (where °R = K x <NUM>/<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> schematically illustrates a portion of an example combustor assembly <NUM>. The combustor assembly <NUM> may be utilized in combustor section <NUM> of the engine <NUM> of <FIG>, with products of combustion delivered downstream to the turbine section <NUM>, for example. The combustion chamber <NUM> may be an annulus swept about the engine central longitudinal axis A, for example. In other examples, the combustor section <NUM> may include a plurality of combustor assemblies <NUM> disposed in an array about the engine axis A, each associated with a respective combustion chamber <NUM> that can have a substantially cylindrical profile, for example. Although the combustor assembly <NUM> is primarily discussed with respect to a turbofan gas turbine engine such as engine <NUM>, other systems may also benefit from the teachings herein, including land-based and marine-based gas turbine engines.

The combustor assembly <NUM> includes an outer panel assembly <NUM> and an inner panel assembly <NUM>. The inner and outer panel assemblies <NUM>, <NUM> support a plurality of liner panels <NUM>, <NUM>, <NUM>, <NUM> within a housing <NUM>. The outer panel assembly <NUM> includes a forward panel <NUM> and an aft panel <NUM>. The inner panel assembly <NUM> includes a forward panel <NUM> and an aft panel <NUM>. The forward panels <NUM>, <NUM> extend in an aft direction from a generally radially extending bulkhead <NUM>. The forward panels <NUM>, <NUM> and the aft panels <NUM>, <NUM> are secured by inner and outer support bands <NUM>, <NUM>. That is, the outer forward panel <NUM> and the outer aft panel <NUM> are both engaged with the outer support band <NUM> and the inner forward panel <NUM> and the inner aft panel <NUM> are both engaged with the inner attachment (or support) band <NUM>. The support bands <NUM>, <NUM> may be an integral part of the combustor housing <NUM>, and may be bolted or welded in place, for example.

The combustor liner panels <NUM>, <NUM>, <NUM>, <NUM> may be formed of a ceramic matrix composite ("CMC") material. For example, the liner panels <NUM>, <NUM>, <NUM>, <NUM> may be formed of a plurality of CMC laminate sheets. The laminate sheets may be silicon carbide fibers, formed into a braided or woven fabric in each layer. In other examples, the liner panels <NUM>, <NUM>, <NUM>, <NUM> may be made of a monolithic ceramic. CMC components such as the combustor liner panels <NUM>, <NUM>, <NUM>, <NUM> are formed by laying fiber material, such as laminate sheets or braids, in tooling, injecting a gaseous infiltrant or melt into the tooling, and reacting to form a solid composite component. The component may be further processed by adding additional material to coat the laminate sheets. The liner panels <NUM>, <NUM>, <NUM>, <NUM> may be formed as a unitary ceramic component, for example. In some examples, the bulkhead <NUM> is also formed from a CMC material. CMC components may have higher operating temperatures than components formed from other materials.

The support bands <NUM>, <NUM> provide support for the CMC liner panels <NUM>, <NUM>, <NUM>, <NUM> while also having a plurality of holes <NUM>, <NUM> that provide dilution holes. The support bands <NUM>, <NUM> may be metallic, such as a nickel-based superalloy, for example. Each of the support bands <NUM>, <NUM> has an outer platform <NUM>, <NUM>, respectively, that is radially outward of the combustion chamber <NUM>. The outer platform <NUM>, <NUM> is secured to the housing <NUM>. In one example, the outer platforms <NUM>, <NUM> are flush with the housing <NUM>. In some examples, the dilution holes <NUM>, <NUM> may be the same size, while in other examples, the dilution holes <NUM>, <NUM> may be different sizes. Further, in some examples, the dilution holes <NUM> in the outer band <NUM> or the dilution holes <NUM> in the inner band <NUM> may be differing sizes within the band. For example, the dilution holes <NUM> may alternate between different sizes about the support band <NUM>, <NUM>, depending on the particular combustor arrangement.

Several additional structures may also secure the panels <NUM>, <NUM>, <NUM>, <NUM> within the assembly <NUM>. The forward liner panels <NUM>, <NUM> are secured at a forward end of the combustion chamber <NUM> via retainer structures <NUM>, <NUM>, respectively. The structures <NUM>, <NUM> may also secure the bulkhead <NUM>. The aft liner panels <NUM>, <NUM> are secured at an aft end of the combustion chamber <NUM> via support rings <NUM>, <NUM>. The liner panels <NUM>, <NUM>, <NUM>, <NUM> may also be held in place by one or more spring supports <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The retainer structures <NUM>, <NUM>, spring supports <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and support rings <NUM>, <NUM> may be metallic, such as a nickel-based superalloy, for example. The spring supports <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> bias the liner panels <NUM>, <NUM>, <NUM>, <NUM> radially, while accommodating differences in thermal expansion within the assembly.

The outer and inner support bands <NUM>, <NUM> also provide support to the liner panels <NUM>, <NUM>, <NUM>, <NUM>. A protrusion <NUM> extends inward from the outer platform <NUM> of the outer support band <NUM> towards the combustion chamber <NUM>. The protrusion <NUM> has first and second angled surfaces <NUM>, <NUM> for engagement with the aft and forward liner panels <NUM>, <NUM>, respectively. A protrusion <NUM> extends outward from the inner platform <NUM> of the support band <NUM> towards the combustion chamber <NUM>. The protrusion <NUM> has first and second angled surfaces <NUM>, <NUM> for engagement with the aft and forward liner panels <NUM>, <NUM>, respectively. The angled surfaces <NUM>, <NUM>, <NUM>, <NUM> support the liner panels <NUM>, <NUM>, <NUM>, <NUM> in the radial direction while also accommodating differences in thermal expansion between the band <NUM>, <NUM> and the panels <NUM>, <NUM>, <NUM>, <NUM>.

<FIG> schematically illustrates a portion of the example inner combustor liner assembly <NUM>. The forward liner panel <NUM> abuts the retainer structure <NUM> at a forward end, and the aft panel <NUM> abuts an aft support ring <NUM> at an aft end. The retainer structure <NUM> secures the forward end of the panel <NUM> to the housing <NUM> and may also secure the bulkhead <NUM>, for example. The inner support band <NUM> is arranged between the forward and aft liner panels <NUM>, <NUM>. The outer platform <NUM> of the support band <NUM> abuts outer surfaces <NUM>, <NUM> of the liner panels <NUM>, <NUM>, while the angled surfaces <NUM>, <NUM> abut the forward end <NUM> of the aft panel <NUM> and the aft end <NUM> of the forward panel <NUM> (shown in <FIG>).

<FIG> schematically illustrates a portion of the example outer combustor liner assembly <NUM>. The outer liner panels <NUM>, <NUM> and outer support band <NUM> are arranged in a similar manner as the inner combustor liner assembly <NUM>. A forward end <NUM> of the forward liner panel <NUM> is configured to engage the retainer structure <NUM>, while an aft end <NUM> of the aft liner panel <NUM> is configured to engage the support ring <NUM> (shown in <FIG>). The forward liner panel <NUM> and aft liner panel <NUM> may each be formed from a plurality of panel segments 118A, 118B, 120A, 120B, respectively. In this example, the forward liner panel <NUM> and aft liner panel <NUM> have segments that are the same width in a circumferential direction, and thus the forward liner panel <NUM> and aft liner panel <NUM> have the same number of segments. However, in other examples, the forward and aft liner panels <NUM>, <NUM> may have panel segments of different sizes and/or a different number of segments.

<FIG> schematically illustrates a portion of the example combustor liner assembly <NUM>. The forward liner panel <NUM> extends between a forward end <NUM> and an aft end <NUM>, and the aft liner panel <NUM> extends between a forward end <NUM> and an aft end <NUM>. The liner panels <NUM>, <NUM> each have an inner surface <NUM>, <NUM>, respectively, and an outer surface <NUM>, <NUM>, respectively, relative to the combustion chamber <NUM>. The inner surfaces <NUM>, <NUM> are substantially parallel to the outer surfaces <NUM>, <NUM>. The inner surfaces <NUM>, <NUM> are exposed to the hot gases in the combustion chamber <NUM>, while the outer surfaces <NUM>, <NUM> are arranged near the housing and may engage with the spring supports <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. In some examples, cooling air may flow between the housing <NUM> and the outer surfaces <NUM>, <NUM> to cool the panels <NUM>, <NUM>.

The forward and aft ends <NUM>, <NUM>, <NUM>, <NUM> are angled with respect to the inner and outer surfaces <NUM>, <NUM>, <NUM>, <NUM>. The ends may have an angle <NUM> with respect to the outer surfaces <NUM> of between <NUM>° and <NUM>°, for example. In a further embodiment, the angle <NUM> may be about <NUM>°. The forward and aft ends <NUM>, <NUM>, <NUM>, <NUM> may all have the same angle or may have different angles. The angled forward end <NUM> of the forward liner panel <NUM> and the angled aft end <NUM> of the aft liner panel <NUM> are engaged with retainer structure <NUM> and support ring <NUM>, respectively (shown in <FIG>).

The aft end <NUM> of the forward liner panel <NUM> and the forward end <NUM> of the aft liner panel <NUM> may have a plurality of grooves <NUM>. In this example, the grooves <NUM> are spaced circumferentially along the ends <NUM>, <NUM> to form a scallop pattern. The grooves <NUM> on the forward liner panel <NUM> and the aft liner panel <NUM> are aligned with one another. The grooves <NUM> are also aligned with the holes <NUM> of the support band <NUM>. In other words, each hole <NUM> is aligned with a groove <NUM> in the circumferential direction, such that the holes <NUM> on the support band <NUM> fit within the grooves <NUM>. The angled ends <NUM>, <NUM> form a partially conical shape for engagement with the angled surfaces <NUM>, <NUM> of the support band <NUM>. The angled surfaces <NUM>, <NUM> also provide a wavy shape that provides partially conical portions for engagement with the angled ends <NUM>, <NUM>. This arrangement permits a large amount of the combustion chamber <NUM> to be lined with a ceramic material. The angled surface arrangement also provides sealing between the components.

<FIG> schematically illustrates a portion of the example combustor liner assembly. The support band <NUM> extends circumferentially about the combustion chamber <NUM>. A plurality of segments of liner panels <NUM>, <NUM> are configured to be arranged circumferentially about the support band <NUM> to form the inner combustor liner assembly <NUM>. Although the inner combustor liner assembly <NUM> is shown, the outer combustor liner assembly <NUM> may be configured similarly, with a unitary support band <NUM> extending circumferentially about the combustion chamber <NUM>. Although a plurality of liner panel segments are shown, in some examples, one or more of the liner panels <NUM>, <NUM>, <NUM>, <NUM> may be a full hoop extending circumferentially about the support band <NUM>, <NUM>.

Metallic combustor liners have limited maximum temperature capabilities and may require large amounts of cooling. CMC combustor liners provide a significant increase in thermal capabilities. However, mounting and sealing a CMC combustor liner to adjacent metallic structure presents challenges due to differences in thermal expansion and poor local load capability in the CMC. The disclosed support bands with integral dilution holes support CMC combustor liner panels without the need for additional stud fasteners. The support band may be an integral part of the combustor outer housing <NUM>, and may be bolted or welded in place, for example. The disclosed support band arrangement also permits existing combustor architecture to be used with minimal impact to the required envelope. The reduced need for support studs on the backside surface of the CMC liner panel allows cooling flow to be supplied more uniformly along the surface. Individual panels are replaceable for maintainability and reduced manufacturing cost. Although a straight wall combustor with a single dilution hole support band is shown, the teachings of this disclosure may apply to a kinked wall combustor, which has a wall with at least one angled portion, in other examples.

In this disclosure, "generally axially" means a direction having a vector component in the axial direction that is greater than a vector component in the circumferential direction, "generally radially" means a direction having a vector component in the radial direction that is greater than a vector component in the axial direction and "generally circumferentially" means a direction having a vector component in the circumferential direction that is greater than a vector component in the axial direction.

Claim 1:
A combustor liner assembly (<NUM>; <NUM>) for a gas turbine engine (<NUM>), comprising
a first liner panel (<NUM>; <NUM>) having a first forward end (<NUM>; <NUM>) and a first aft end (<NUM>);
a second liner panel (<NUM>; <NUM>) having a second forward end (<NUM>) and a second aft end (<NUM>; <NUM>); and
a support band (<NUM>; <NUM>) having a plurality of circumferentially spaced holes (<NUM>; <NUM>), the support band (<NUM>; <NUM>) arranged between the first liner panel (<NUM>; <NUM>) and the second liner panel (<NUM>; <NUM>), the support band (<NUM>; <NUM>) has a protrusion (<NUM>; <NUM>) with a first angled surface (<NUM>; <NUM>) and a second angled surface (<NUM>; <NUM>), the second angled surface (<NUM>; <NUM>) in engagement with the first aft end (<NUM>) and the first angled surface (<NUM>; <NUM>) in engagement with the second forward end (<NUM>),
wherein the first aft end (<NUM>) is angled with respect to an inner surface (<NUM>) of the first liner panel (<NUM>; <NUM>) and the second forward end (<NUM>) is angled with respect to a second inner surface (<NUM>) of the second liner panel (<NUM>; <NUM>),
wherein the first aft end (<NUM>) and the second forward end (<NUM>) each have an angle (<NUM>) between <NUM>° and <NUM>°,
characterised in that
the first aft end (<NUM>) and the second forward end (<NUM>) each have a plurality of grooves (<NUM>), wherein the grooves (<NUM>) are spaced circumferentially along the first aft end (<NUM>) and second forward end (<NUM>) respectively to form a scallop pattern, wherein the grooves (<NUM>) on the first aft end (<NUM>) are aligned with the grooves on the second forward end (<NUM>), and wherein the grooves (<NUM>) are aligned with the circumferentially spaced holes (<NUM>; <NUM>), wherein the first forward end (<NUM>; <NUM>) and the second aft end (<NUM>; <NUM>) are angled and form a partially conical shape for engagement with the first angled surface (<NUM>; <NUM>) and the second angled surface (<NUM>; <NUM>), wherein the first angled surface (<NUM>; <NUM>) and the second angled surface (<NUM>; <NUM>) provide a wavy shape that provides partially conical portions for engagement with the angled ends (<NUM>; <NUM>).