Patent Description:
Turbojet engines for aircraft may frequently include variable area exhaust nozzles to accommodate subsonic, transonic, and supersonic speeds. Due to the different properties of exhaust gases as they flow through the nozzle at different speeds, there may be a need to vary the area of the nozzle at one or more locations within the nozzle in order to ensure proper and efficient turbojet operation over a range of aircraft flight conditions. What is needed are variable area nozzle assemblies which improve upon variable area nozzle assemblies conventionally known in the art. <CIT> and <CIT> disclose arrangements of the prior art.

According to an aspect of the present invention, a gas turbine engine is provided according to claim <NUM>.

In any of the aspects or embodiments described above and herein, the radially outer surface of the nozzle may define a door recess in which the fixed ring is positioned with the nozzle in the first position.

In any of the aspects or embodiments described above and herein, with the nozzle in the first position and the first thrust reverser door and the second thrust reverser door in the respective stowed positions, the radially outer surface, the radially outer ring side, the first thrust reverser door, and the second thrust reverser door may define a substantially flush exterior surface.

In any of the aspects or embodiments described above and herein, the nozzle may include an axially forward end and an axially aft end and the fixed ring may be positioned entirely axially between the axially forward end and the axially aft end.

In any of the aspects or embodiments described above and herein, the variable area nozzle assembly may further include a plurality of actuators. Each actuator of the plurality of actuators may include a first actuator end pivotably mounted to the fixed ring and a second actuator end pivotably mounted to the nozzle.

In any of the aspects or embodiments described above and herein, the fixed ring may be axially spaced from the fixed structure and the fixed ring may be founded to the fixed structure by at least one side beam.

In any of the aspects or embodiments described above and herein, the gas turbine engine may further include at least one actuation system mounted to the fixed ring circumferentially between the first recess and the second recess with respect to the nozzle centerline.

In any of the aspects or embodiments described above and herein, the at least one actuation system may include a linear actuator and a carrier mounted to the linear actuator. The linear actuator may be configured to translate the carrier in a substantially axial direction. The carrier may be connected to each of the first thrust reverser door and the second thrust reverser door by at least one linkage.

According to another aspect of the present invention, a method for operating a variable area nozzle assembly of a gas turbine engine is provided according to claim <NUM>.

In any of the aspects or embodiments described above and herein, the step of moving the nozzle relative to the nozzle centerline of the nozzle from the first position toward the second position may include moving the nozzle with a plurality of actuators. Each actuator of the plurality of actuators may include a first actuator end pivotably mounted to the fixed ring and a second actuator end pivotably mounted to the nozzle.

The present disclosure, and all its aspects, embodiments and advantages associated therewith will become more readily apparent in view of the detailed description provided below, including the accompanying drawings.

Referring to <FIG>, an exemplary gas turbine engine <NUM> capable of using aspects of the present disclosure is schematically illustrated. Although depicted as a turbojet gas turbine engine in the disclosed non-limiting embodiments, it should be understood that the concepts described herein are not limited to use with turbojets and may be applicable to other configurations of aircraft gas turbine engines as well including, but not limited to turboprop and turbofan gas turbine engines.

The gas turbine engine <NUM> generally includes a fan <NUM> through which ambient air is propelled along a core flow path <NUM>, a compressor <NUM> for pressurizing the air received from the fan <NUM> and a combustor <NUM> wherein the compressed air is mixed with fuel and ignited for generating combustion gases. The gas turbine engine <NUM> further includes a turbine section <NUM> for extracting energy from the combustion gases. The resultant combustion gases from the combustor <NUM> are expanded over the turbine section <NUM> and then exhausted via an exhaust section <NUM>, thereby providing thrust. The fan <NUM>, compressor <NUM>, combustor <NUM>, and turbine <NUM> are typically all concentric about a common axial centerline <NUM> of the gas turbine engine <NUM>.

The gas turbine engine <NUM> may further comprise a low-pressure compressor located upstream of a high-pressure compressor and a high-pressure turbine located upstream of a low-pressure turbine. For example, the compressor <NUM> may be a multi-stage compressor <NUM> that has a low-pressure compressor and a high-pressure compressor and the turbine <NUM> may be a multistage turbine <NUM> that has a high-pressure turbine and a low-pressure turbine. In one embodiment, the low-pressure compressor may be connected to the low-pressure turbine by a low-pressure shaft and the high-pressure compressor may be connected to the high-pressure turbine by a high-pressure shaft. In some embodiments, a gear arrangement (not shown) may connect the fan <NUM> and the compressor <NUM> such that the fan <NUM> and compressor <NUM> are enabled to have different rotational speeds. In other embodiments, the gas turbine engine <NUM> may be a direct drive engine.

Referring to <FIG>, aspects of the present disclosure include a variable area nozzle assembly <NUM> for the exhaust section <NUM>. The variable area nozzle assembly <NUM> includes a fixed structure <NUM> of the gas turbine engine <NUM> which may be defined, for example, by a core cowling, an engine nacelle, or other suitable fixed structure of the gas turbine engine <NUM>. The fixed structure <NUM> radially surrounds an exhaust duct <NUM> generally disposed about a nozzle centerline <NUM> which may or may not be colinear with the axial centerline <NUM> of the gas turbine engine <NUM>. The variable area nozzle assembly <NUM> is configured to direct core gases along the core flow path <NUM> from the turbine section <NUM> and/or bypass gases to a variable area nozzle <NUM> located at a downstream end of the exhaust section <NUM>. As shown, for example, in <FIG>, the nozzle <NUM> may be configured as a convergent-divergent nozzle. However, the present disclosure is not limited to this particular nozzle configuration and aspects of the present disclosure may be applicable to other configurations of variable area nozzles as well.

The nozzle <NUM> includes a plurality of outer petals <NUM> (e.g., "flaps") pivotally mounted to the fixed structure <NUM>. Each of the plurality of outer petals <NUM> includes a forward end <NUM> pivotally mounted to the fixed structure <NUM> and an aft end <NUM> opposite the forward end <NUM>. The plurality of outer petals <NUM> are circumferentially disposed about the nozzle centerline <NUM> to define a radially outer surface <NUM> of the nozzle <NUM>. The nozzle <NUM> further includes a plurality of inner petals <NUM> radially inward of the outer petals <NUM> with respect to the nozzle centerline <NUM>. The plurality of inner petals <NUM> are circumferentially disposed about the nozzle centerline <NUM> to define a radially inner surface <NUM> of the nozzle <NUM>. The plurality of inner petals <NUM> includes a first portion of inner petals <NUM> pivotally mounted to the exhaust duct <NUM> or the fixed structure <NUM>. The first portion of inner petals <NUM> define an upstream "A8" axial portion of the nozzle <NUM> which may be a converging portion of the nozzle <NUM>. The plurality of inner petals <NUM> further includes a second portion of inner petals <NUM> pivotally mounted to respective petals of the first portion of inner petals <NUM> at respective pivot joints <NUM>. The first portion of inner petals <NUM> and the second portion of inner petals <NUM> define a variable "throat" cross-sectional area <NUM> of the nozzle <NUM> at the axial location of the pivot joints <NUM>. The second portion of inner petals <NUM> define a downstream "A9" axial portion of the nozzle <NUM> which may be a diverging portion of the nozzle <NUM>. The second portion of inner petals <NUM> defines a variable "outlet" cross-sectional area <NUM> of the nozzle <NUM> at the downstream axial end <NUM> of the second portion of inner petals <NUM>. The outer petals <NUM> may be pivotally mounted to the second portion of inner petals <NUM> at or proximate the downstream axial end <NUM>.

In some embodiments, the second portion of inner petals <NUM> may be further divided into a forward portion of inner petals 72A and an aft portion of inner petals 72B. The forward portion inner petals 72A and the aft portion of inner petals 72B may engage one another at a slip joint <NUM> where the forward portion of inner petals 72A and the aft portion of inner petals 72B overlap one another. The configuration of the slip joint <NUM> allows a length of the second portion of inner petals <NUM> to change as the A9 position of the nozzle <NUM> is varied between the maximum A9 position (see <FIG>) and the minimum A9 position (see <FIG>).

The nozzle <NUM> is moveable relative to the nozzle centerline <NUM>. The petals <NUM>, <NUM> of the nozzle <NUM> may be actuated to selectively vary the areas of the throat cross-sectional area <NUM> and/or the outlet cross-sectional area <NUM>. As shown in <FIG>, for example, the nozzle <NUM> is in a radially outermost position such that the radially inner surface <NUM> defines a maximum area of the outlet cross-sectional area <NUM> (e.g., a "maximum A9 position"). As shown in <FIG>, for example, the nozzle <NUM> is in a radially innermost position such that the radially inner surface <NUM> defines a minimum area of the outlet cross-sectional area <NUM> (e.g., a "minimum A9 position"). As will be appreciated by those of ordinary skill in the art, variable area nozzle assemblies, such as the variable area nozzle assembly <NUM>, may include actuation systems configured for moving petals of a variable area nozzle which are well known in the art. Accordingly, for the sake of clarity, said actuation systems have been omitted from the figures and description herein. The present disclosure is not limited to any particular actuation system for actuation of the petals <NUM>, <NUM> to selectively vary the areas of the throat cross-sectional area <NUM> and/or the outlet cross-sectional area <NUM>.

The variable area nozzle assembly <NUM> includes a fixed ring <NUM> radially surrounding the nozzle <NUM>. The fixed ring <NUM> includes a radially outer ring side <NUM> and a radially inner ring side <NUM> opposite the radially outer ring side <NUM>. Each of the radially outer ring side <NUM> and the radially inner ring side <NUM> extend between a forward ring end <NUM> and an aft ring end <NUM>. The fixed ring <NUM> is axially spaced from the fixed structure <NUM> and may be mounted to the fixed structure <NUM> by one or more side beams <NUM>. In some embodiments, the fixed ring <NUM> may be axially positioned within the axial span of the plurality of outer petals <NUM>. For example, the forward ring end <NUM> may be axially spaced aft of the forward end <NUM> of the plurality of outer petals <NUM> and the aft ring end <NUM> may be axially spaced forward of the aft end <NUM> of the plurality of outer petals <NUM>.

As shown in <FIG>, the fixed ring <NUM> is positioned relative to the nozzle <NUM> such that, with the nozzle <NUM> in the maximum A9 position, the radially outer surface <NUM> of the nozzle <NUM> may contact the radially inner ring side <NUM> of the fixed ring <NUM>. Accordingly, the fixed ring <NUM> is configured to provide structural support for the nozzle <NUM> with the nozzle in the maximum A9 position. The maximum A9 position may typically be a position of the nozzle <NUM> during cruising operations and/or when operating at supersonic speeds. Moreover, loads on the nozzle <NUM> may typically be greatest during cruising and/or supersonic operations due to the large pressure differential developed between the inside of the nozzle <NUM> and the ambient air outside the nozzle <NUM>. Thus, contact between the fixed ring <NUM> and the nozzle <NUM> may improve the structural stability of the variable area nozzle assembly <NUM> at the maximum A9 position by allowing hoop loading of the petals <NUM>, <NUM> onto the fixed ring <NUM>, thereby providing an efficient load path for the petals <NUM>, <NUM>. In some embodiments, the variable area nozzle assembly <NUM> may include one or more resilient bumpers (not shown) mounted between the fixed ring <NUM> and the nozzle <NUM> and configured to contact both of the fixed ring <NUM> and the nozzle <NUM> with the nozzle in the maximum A9 position.

As will be discussed in further detail, the fixed ring <NUM> may additionally provide structural support for additional components of one or more embodiments of the variable area nozzle assembly <NUM> according to the present disclosure. In some embodiments, the side beams <NUM> may be used to structurally support one or more additional components of the variable area nozzle assembly <NUM>. The side beams <NUM> may extend in a generally axial direction along the radially outer ring side <NUM> of the fixed ring <NUM> and may include portions of the fixed ring <NUM>. In some embodiments, the side beams <NUM> may extend axially aft of the aft ring end <NUM> of the fixed ring <NUM> as shown, for example, in <FIG> and <FIG>, to define an axial extension portion <NUM> of the side beams <NUM>. In some embodiments, the side beams <NUM> may include a detachable fairing <NUM> used to cover one or more variable area nozzle assembly <NUM> components mounted to the fixed ring <NUM>. The radially outer ring side <NUM> of the fixed ring <NUM> and the detachable fairing <NUM> may define a radial gap therebetween.

Further, as shown in <FIG>, the fixed ring <NUM> may be positioned relative to the nozzle <NUM> such that, with the nozzle positioned radially inward of the maximum A9 position, the radially outer surface <NUM> of the nozzle <NUM> may be spaced (e.g., radially spaced) from the radially inner ring side <NUM> of the fixed ring <NUM> to define a gap <NUM>. As shown in <FIG>, air external to the nozzle <NUM> (illustrated in <FIG> as air flow <NUM>) may flow along the radially outer ring side <NUM> of the fixed ring <NUM> as well as through the gap <NUM> defined between the fixed ring <NUM> and the nozzle <NUM>. As the nozzle approaches the maximum A9 position and contacts the fixed ring <NUM>, the air flow <NUM> through the gap <NUM> may be entirely or substantially eliminated.

Still referring to <FIG>, in some embodiments, the radially outer surface <NUM> of the nozzle <NUM> may define a door recess <NUM> in which the fixed ring <NUM> is positioned with the nozzle <NUM> in the maximum A9 position (see, e.g., <FIG>). In some embodiments, with the nozzle <NUM> in the maximum A9 position, the radially outer surface <NUM> of the nozzle <NUM> and the radially outer ring side <NUM> of the fixed ring <NUM> may define a flush or substantially flush (e.g., within component design and operational tolerances) exterior surface <NUM> of the variable area nozzle assembly <NUM>, thereby minimizing or eliminating any aerodynamic drag which might otherwise be caused by the fixed ring <NUM>.

Referring to <FIG>, in some embodiments, the variable area nozzle assembly <NUM> may include a plurality of actuators <NUM> connecting the fixed ring <NUM> to the nozzle <NUM> and configured to selectively position the nozzle <NUM> between the maximum A9 position (see <FIG>) and the minimum A9 position (see <FIG>). The plurality of actuators <NUM> are circumferentially spaced from one another about the nozzle centerline <NUM>. In some embodiments, each of the petals <NUM> of the plurality of outer petals <NUM> may be operably connected to the fixed ring <NUM> by a respective actuator <NUM> of the plurality of actuators <NUM>. However, in some embodiments, fewer than each of the petals <NUM> of the plurality of outer petals <NUM> may be operably connected to the fixed ring <NUM> by a respective actuator <NUM> of the plurality of actuators <NUM> (e.g., every other outer petal, every third outer petal, etc.). The plurality of outer petals <NUM> may define a plurality of recesses <NUM> in the radially outer surface <NUM> of the nozzle <NUM> within which respective actuators <NUM> of the plurality of actuators <NUM> may be at least partially retained, as shown in <FIG>. Each actuator <NUM> of the plurality of actuators <NUM> may include a first end <NUM> pivotably mounted to the radially inner ring side <NUM> of the fixed ring <NUM>. Each actuator <NUM> of the plurality of actuators <NUM> may further include a second end <NUM> pivotably mounted to a respective outer petal <NUM> of the plurality of outer petals <NUM>, for example, within a respective recess <NUM> of the plurality of recesses <NUM>. Accordingly, the plurality of actuators <NUM> may actuate (e.g., linearly expand or contract) to control a position of the nozzle <NUM> (e.g., the A9 position) relative to the nozzle centerline <NUM>. The plurality of actuators <NUM> may include pneumatic actuators, hydraulic actuators, electrical-mechanical actuators, or the like, and the present disclosure is not limited to any particular configuration of actuator.

Referring to <FIG>, in some embodiments, the variable area nozzle assembly <NUM> may include a thrust reverser system <NUM> including a first thrust reverser door <NUM> and a second thrust reverser door <NUM>. Each of the first thrust reverser door <NUM> and the second thrust reverser door <NUM> are movable between a stowed position (see, e.g., <FIG>) and a deployed position (see, e.g., <FIG>). In the stowed position, the first thrust reverser door <NUM> and the second thrust reverser door <NUM> are mounted against the radially outer ring side <NUM> of the fixed ring <NUM>. In the deployed position, the first thrust reverser door <NUM> and the second thrust reverser door <NUM> are positioned axially aft of the nozzle <NUM> to block and/or deflect exhaust gases exiting the nozzle <NUM>. In some common flight conditions, the thrust reverser doors <NUM>, <NUM> may be actuated to move from the stowed position to the deployed position with the nozzle <NUM> positioned at or near the minimum A9 position.

As shown in <FIG>, in the stowed position, the thrust reverser doors <NUM>, <NUM> may be positioned so that the thrust reverser doors <NUM>, <NUM> are entirely disposed within the axial span of the fixed ring <NUM>. In some conventional thrust reverser systems, thrust reverser doors may be stowed in a position axially forward of the exhaust nozzle (e.g., adjacent the fixed structure axially forward of the nozzle) and may be repositioned axially aft of the exhaust nozzle when deployment of the thrust reverser system is necessary. This thrust reverser door configuration may be impractical, for example, in aircraft designs where it is desirable to position the exhaust nozzle of a gas turbine engine proximate an aircraft body structure (e.g., an aircraft body structure <NUM> such as a wing or fuselage of an aircraft), as the aircraft body structure might obstruct movement of the thrust reverser doors between the stowed and deployed positions. The thrust reverser system <NUM> of embodiments of the present disclosure is configured with a comparatively reduced axial span due to stowed position of the thrust reverser doors <NUM>, <NUM> adjacent the fixed ring <NUM> surrounding the nozzle <NUM>. Accordingly, greater flexibility in gas turbine engine orientation, and particularly variable area nozzle orientation, relative to aircraft body structures may be achieved.

In some embodiments, the radially outer ring side <NUM> of the fixed ring <NUM> may define a first recess <NUM> and a second recess <NUM> in which the first thrust reverser door <NUM> and the second thrust reverser door <NUM>, respectively, are positioned in the stowed position. In some embodiments, with the nozzle <NUM> in the maximum A9 position and the thrust reverser doors <NUM>, <NUM> in the respective stowed positions, the radially outer surface <NUM> of the nozzle <NUM>, the radially outer ring side <NUM> of the fixed ring <NUM>, the first thrust reverser door <NUM>, and the second thrust reverser door <NUM>, may define the flush or substantially flush (e.g., within component design and operational tolerances) exterior surface <NUM> of the variable area nozzle assembly <NUM>, thereby minimizing or eliminating any aerodynamic drag which might otherwise be caused by the fixed ring <NUM> and the thrust reverser doors <NUM>, <NUM>.

The thrust reverser system <NUM> includes at least one actuation system <NUM> configured for moving the thrust reverser doors <NUM>, <NUM> between the stowed and deployed positions. In <FIG> and <FIG>, illustration of the detachable fairing <NUM> has been omitted to clearly show the configuration of the at least one actuation system <NUM>. The embodiments of the at least one actuation system <NUM> shown and described herein are configured as a four-bar actuation system, however, it should be understood that the present disclosure is not limited to any particular actuation system configuration for effecting movement of the thrust reverser doors <NUM>, <NUM> and that other actuation system configurations may be contemplated within the scope of the present disclosure.

The at least one actuation system <NUM> may include a first actuation system and a second similar actuation system each positioned on opposing sides of the variable area nozzle assembly <NUM>. However, for purposes of clarity, the at least one actuation system <NUM> will be described with respect to an actuation system disposed on one side of the variable area nozzle assembly <NUM>. The at least one actuation system <NUM> includes an actuator <NUM> mounted to the fixed structure <NUM> and extending from the fixed structure <NUM> in a direction generally adjacent and/or through the fixed ring <NUM>. The actuator <NUM> may be a pneumatic actuator, a hydraulic actuator, an electrical-mechanical actuator, or the like. A distal end <NUM> of the actuator <NUM> is mounted to a carrier <NUM> such that the actuator <NUM> is configured to effect linear translation of the carrier <NUM> adjacent the fixed ring <NUM>.

Through linear translation of the carrier <NUM>, the at least one actuation system <NUM> may be configured to effect movement of the thrust reverser doors <NUM>, <NUM> between the respective stowed and deployed positions using a series of linkages. Each thrust reverser door <NUM>, <NUM> may be pivotally mounted to the fixed ring <NUM> by a forward linkage <NUM>. The forward linkage <NUM> may include a first end <NUM> rotatably mounted to the fixed ring <NUM> and a second end <NUM> rotatably mounted to a respective one of the thrust reverser doors <NUM>, <NUM>. Each thrust reverser door <NUM>, <NUM> may be pivotally mounted to the axial extension portion <NUM> of the side beam <NUM> by an aft linkage <NUM>. The aft linkage <NUM> may include a first end <NUM> rotatably mounted to the axial extension portion <NUM> and a second end <NUM> rotatably mounted to a respective one of the thrust reverser doors <NUM>, <NUM>. The carrier <NUM> may be pivotally mounted to each forward linkage <NUM> by a drive linkage <NUM>. The drive linkage <NUM> may include a first end <NUM> rotatably mounted to the carrier <NUM> and a second end <NUM> rotatably mounted to a respective forward linkage <NUM> at a position between the first end <NUM> and the second end <NUM> of the respective forward linkage <NUM>. Accordingly, linear translation of the carrier <NUM> by the actuator <NUM> in a first direction (e.g., a generally aftward direction) may cause the thrust reverser doors <NUM>, <NUM> to move from the stowed position to the deployed position and linear translation of the carrier <NUM> by the actuator <NUM> in a second direction (e.g., a generally forward direction) may cause the thrust reverser doors <NUM>, <NUM> to move from the deployed position to the stowed position.

In some embodiments, radially outer ring side <NUM> of the fixed ring <NUM> may further define at least one actuator recess <NUM>. The at least one actuator recess <NUM> may be circumferentially aligned with a respective one of the side beams <NUM> such that the detachable fairing <NUM> (see, e.g., <FIG> and <FIG>) may be installed over the at least one actuator recess <NUM>. The actuator <NUM> and carrier <NUM> for each actuation system of the at least one actuation system <NUM> may be disposed within and configured for linear translation within a respective actuator recess of the at least one actuator recess <NUM>. In some embodiments, the carrier <NUM> may be retained within a slot (not shown) defined by the fixed ring <NUM> such that the fixed ring <NUM> allows axial translation of the carrier <NUM> but restricts radial and/or circumferential movement of the carrier <NUM>.

Claim 1:
A gas turbine engine (<NUM>) comprising:
a fixed structure (<NUM>) comprising a fixed ring (<NUM>); and
a variable area nozzle assembly (<NUM>) comprising:
a nozzle (<NUM>) hingedly mounted to the fixed structure (<NUM>), the nozzle (<NUM>) disposed about a nozzle centerline (<NUM>), the nozzle (<NUM>) comprising a radially outer surface (<NUM>) and a radially inner surface (<NUM>), the radially inner surface (<NUM>) defining an outlet cross-sectional area (<NUM>) of the nozzle (<NUM>), the nozzle (<NUM>) movable relative to the nozzle centerline (<NUM>) between a first position of the radially inner surface (<NUM>) defining a maximum area of the outlet cross-sectional area (<NUM>) and a second position of the radially inner surface (<NUM>) defining a minimum area of the outlet cross-sectional area (<NUM>), and
a first thrust reverser door (<NUM>) and a second thrust reverser door (<NUM>), each of the first thrust reverser door (<NUM>) and the second thrust reverser door (<NUM>) moveable between a stowed position in which the first thrust reverser door (<NUM>) and the second thrust reverser door (<NUM>) are mounted against the fixed ring (<NUM>) and a deployed position in which the first thrust reverser door (<NUM>) and the second thrust reverser door (<NUM>) are positioned axially aft of the nozzle (<NUM>),
the gas turbine engine characterised by:
the fixed ring (<NUM>) radially surrounding the nozzle (<NUM>) such that with the nozzle (<NUM>) in the first position the radially outer surface (<NUM>) contacts the fixed ring (<NUM>) and with the nozzle (<NUM>) in the second position the radially outer surface (<NUM>) is spaced from the fixed ring (<NUM>),
wherein the fixed ring (<NUM>) comprises a radially outer ring side (<NUM>) and a radially inner ring side (<NUM>) and wherein the radially outer ring side (<NUM>) defines a first recess (<NUM>) and a second recess (<NUM>) in which the first thrust reverser door (<NUM>) and the second thrust reverser door (<NUM>), respectively, are positioned in the stowed position.