Patent Description:
An aircraft propulsion system may include an inlet structure and a gas turbine engine. The inlet structure directs air into the gas turbine engine. Some known inlet structures include a variable airflow inlet area, also known as an auxiliary inlet, for tailoring a mass flow of the air entering the gas turbine engine. While these known inlet structures have various advantages, there is still room in the art for improvement. There is a need in the art therefore for an improved inlet assembly with a variable airflow inlet area.

<CIT> discloses an engine nacelle for a turbofan engine, having a nacelle wall and an engine inlet, wherein the nacelle wall has a stationary downstream section and an upstream section that is displaceable in the axial direction, and the displaceable upstream section is displaceable between a first upstream position and a second downstream position.

<CIT> discloses an aircraft turbomachine comprising a fan with two rotors supporting coaxial and counter-rotating blades, respectively upstream and downstream, and an annular nacelle.

<CIT> discloses an air intake of an aircraft turbojet engine nacelle, extending along an axis, in which an air flow circulates from upstream to downstream, the air intake extending circumferentially around the axis and comprising an inner wall, which faces the axis in order to guide an inner air flow, and an outer wall, which is opposite the inner wall, for guiding an external air flow, the walls being connected by a leading edge and an inner partition so as to delimit an annular cavity.

According to an aspect of the present disclosure, an assembly is provided as recited in claim <NUM>.

Further, optional features are recited in each of claims <NUM> to <NUM>.

<FIG> illustrates an aircraft propulsion system <NUM> for an aircraft such as, but not limited to, a commercial airliner or cargo plane. The aircraft propulsion system <NUM> includes a gas turbine engine <NUM> and a nacelle <NUM>.

The gas turbine engine <NUM> may be configured as a high-bypass turbofan engine. The gas turbine engine <NUM> of <FIG>, for example, includes a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. The compressor section <NUM> may include a low pressure compressor (LPC) section 27A and a high pressure compressor (HPC) section 27B. The turbine section <NUM> may include a high pressure turbine (HPT) section 29A and a low pressure turbine (LPT) section 29B.

The engine sections <NUM>-29B are arranged sequentially along an axial centerline <NUM> (e.g., a rotational axis) of the gas turbine engine <NUM> within an aircraft propulsion system housing <NUM>. This aircraft propulsion system housing <NUM> includes an outer housing structure <NUM> and an inner housing structure <NUM>.

The outer housing structure <NUM> includes an outer case <NUM> (e.g., a fan case) and an outer structure <NUM> of the nacelle <NUM>; e.g., an outer nacelle structure. The outer case <NUM> houses at least the fan section <NUM>. The outer nacelle structure <NUM> houses and provides an aerodynamic cover for the outer case <NUM>. The outer nacelle structure <NUM> also covers a portion of an inner structure <NUM> of the nacelle <NUM>; e.g., an inner nacelle structure, which may also be referred to as an inner fixed structure (IFS). More particularly, the outer nacelle structure <NUM> axially overlaps and extends circumferentially about (e.g., completely around) the inner nacelle structure <NUM>. The outer nacelle structure <NUM> and the inner nacelle structure <NUM> thereby at least partially or completely form an annular bypass flowpath <NUM> within the aircraft propulsion system <NUM>.

The inner housing structure <NUM> includes an inner case <NUM> (e.g., a core case) and the inner nacelle structure <NUM>. The inner case <NUM> houses one or more of the engine sections 27A-29B, which engine sections 27A-29B may be collectively referred to as an engine core. The inner nacelle structure <NUM> houses and provides an aerodynamic cover for the inner case <NUM>.

Each of the engine sections <NUM>, 27A, 27B, 29A and 29B includes a bladed rotor <NUM>-<NUM>. The fan rotor <NUM> and the LPC rotor <NUM> are connected to and driven by the LPT rotor <NUM> through a low speed shaft <NUM>. The HPC rotor <NUM> is connected to and driven by the HPT rotor <NUM> through a high speed shaft <NUM>. The shafts <NUM> and <NUM> are rotatably supported by a plurality of bearings (not shown). Each of these bearings is connected to the aircraft propulsion system housing <NUM> (e.g., the inner case <NUM>) by at least one stationary structure such as, for example, an annular support strut.

During operation, air enters the aircraft propulsion system <NUM> through an aircraft propulsion system inlet structure <NUM>. This air is directed through an inlet duct <NUM> and into an annular core flowpath <NUM> and the bypass flowpath <NUM>. The core flowpath <NUM> extends axially along the axial centerline <NUM> within the aircraft propulsion system <NUM>, through the engine sections 27A-29B, to a core nozzle outlet, where the core flowpath <NUM> is radially within the inner case <NUM>. The bypass flowpath <NUM> extends axially along the axial centerline <NUM> within the aircraft propulsion system <NUM> to a bypass nozzle outlet, where the bypass flowpath <NUM> is radially between the outer nacelle structure <NUM> and the inner nacelle structure <NUM>. The air within the core flowpath <NUM> may be referred to as "core air". The air within the bypass flowpath <NUM> may be referred to as "bypass air".

The core air is compressed by the compressor rotors <NUM> and <NUM> and directed into a combustion chamber of a combustor in the combustor section <NUM>. Fuel is injected into the combustion chamber and mixed with the compressed core air to provide a fuel-air mixture. This fuel-air mixture is ignited and combustion products thereof flow through and sequentially cause the turbine rotors <NUM> and <NUM> to rotate. The rotation of the turbine rotors <NUM> and <NUM> respectively drive rotation of the compressor rotors <NUM> and <NUM> and, thus, compression of the air received from a core airflow inlet <NUM>. The rotation of the LPT rotor <NUM> also drives rotation of the fan rotor <NUM>, which propels bypass air through and out of the bypass flowpath <NUM>. The propulsion of the bypass air may account for a majority of thrust generated by the gas turbine engine <NUM>. The aircraft propulsion system <NUM> of the present disclosure, however, is not limited to the exemplary gas turbine engine configuration described above.

Optimal mass flow requirements of the air entering the aircraft propulsion system <NUM> through the aircraft propulsion system inlet structure <NUM> may change depending upon one or more parameters. These parameters may include, but are not limited to, modes of operation, aircraft maneuvers and operating conditions. For example, where the aircraft flies at supersonic speeds, a first mass flow of the air may be directed through the aircraft propulsion system inlet structure <NUM> into the aircraft propulsion system <NUM>. When the aircraft flies at subsonic speeds, a second mass flow of the air may be directed through the aircraft propulsion system inlet structure <NUM> into the aircraft propulsion system <NUM>, where the second mass flow may be different (e.g., greater) than the first mass flow.

To accommodate the changing mass flow requirements for the aircraft propulsion system <NUM>, the aircraft propulsion system inlet structure <NUM> is configured as a variable area inlet <NUM>. Referring to <FIG> and <FIG>, this variable area inlet <NUM> includes a center body <NUM>, an aft fixed structure <NUM> and a forward moveable (e.g., a translating) structure <NUM>. These inlet components <NUM>, <NUM> and <NUM> are configured to provide the variable area inlet <NUM> with an annular inner airflow inlet passage <NUM> and one or more outer airflow inlet passages <NUM>, also known as auxiliary inlets (see <FIG>). Briefly, the inner airflow inlet passage <NUM> of <FIG> and <FIG> is configured as a primary airflow inlet passage, which inlet passage may be a variable area inlet passage or a fixed area airflow inlet passage. The outer airflow inlet passages <NUM> of <FIG> are configured as secondary airflow inlet passages, which inlet passages are variable area airflow inlet passages.

Referring to <FIG>, the center body <NUM> is configured to form an inlet cone and/or an inlet spike for the aircraft propulsion system <NUM>. The center body <NUM> extends axially along an axial centerline <NUM> (e.g., an axis) of the variable area inlet <NUM> (see <FIG> and <FIG>) from a downstream, aft end <NUM> of the center body <NUM> to an upstream, forward end <NUM> (e.g., a tip, a point) of the center body <NUM>, which centerline <NUM> may be coaxial with the axial centerline <NUM>. The center body <NUM> extends radially outward to an outer side <NUM> of the center body <NUM>. This center body outer side <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>, <NUM>. At least a forward portion of the center body outer side <NUM> radially tapers inward as the center body <NUM> extends axially to its forward end <NUM>; e.g., a tip / a leading end point of the center body <NUM>.

Referring to <FIG>, the fixed structure <NUM> is configured to form at least a forward portion of the inlet duct <NUM> (see also <FIG> and <FIG>). Briefly, referring to <FIG> and <FIG>, an aft portion of the inlet duct <NUM> may be formed by the outer case <NUM>. However, in other embodiments, the fixed structure <NUM> may form an entirety of the inlet duct <NUM> where, for example, the gas turbine engine <NUM> is configured as a turbojet engine without the bypass flowpath <NUM>. Referring again to <FIG>, the fixed structure <NUM> includes a tubular inner barrel <NUM> and a tubular outer barrel <NUM>.

The inner barrel <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>, <NUM>. The inner barrel <NUM> extends axially along the axial centerline <NUM>, <NUM> between and to (or about) an upstream, forward end <NUM> of the fixed structure <NUM> and a downstream, aft end <NUM> of the fixed structure <NUM>. At the fixed structure aft end <NUM> of <FIG>, the inner barrel <NUM> is connected to an upstream, forward end <NUM> of the outer case <NUM>. The inner barrel <NUM> may be configured to attenuate noise generated during aircraft propulsion system operation and, more particularly for example, noise generated by rotation of the fan rotor <NUM>. The inner barrel <NUM> of <FIG>, for example, may include at least one tubular noise attenuating acoustic panel <NUM> or a circumferential array of arcuate noise attenuating acoustic panels <NUM> (see dashed lines) arranged around the axial centerline <NUM>, <NUM>. The present disclosure, however, is not limited to such an acoustic inner barrel configuration.

The outer barrel <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>, <NUM>. The outer barrel <NUM> extends axially along the axial centerline <NUM>, <NUM> between and to (or about) the fixed structure forward end <NUM> and the fixed structure aft end <NUM>. At the fixed structure aft end <NUM> of <FIG>, the outer barrel <NUM> is disposed next to respective (e.g., upstream, forward) ends <NUM> of a pair of fan cowls of the outer nacelle structure <NUM>.

The fixed structure <NUM> of <FIG> is configured with receptacle <NUM> (e.g., an annular cavity) for the moveable structure <NUM>; see <FIG>. The receptacle <NUM> is disposed at (e.g., on, adjacent or proximate) the fixed structure forward end <NUM>. The receptacle <NUM> of <FIG>, for example, projects axially along the axial centerline <NUM>, <NUM> into the fixed structure <NUM> from the fixed structure forward end <NUM> to an interior receptacle end <NUM>. The receptacle <NUM> extends radially within the fixed structure <NUM> between and to a receptacle inner side <NUM> and a receptacle outer side <NUM>. The receptacle <NUM> extends circumferentially within the fixed structure <NUM> circumferentially about (e.g., completely around) the axial centerline <NUM>, <NUM>.

Referring to <FIG>, the moveable structure <NUM> extends axially along the axial centerline <NUM>, <NUM> between and to an upstream, forward end <NUM> of the moveable structure <NUM> and a downstream, aft end <NUM> of the moveable structure <NUM>. The moveable structure <NUM> of <FIG> includes a tubular inlet lip structure <NUM> and a support structure <NUM>; e.g., a sleeve, a frame, etc..

The inlet lip structure <NUM> is disposed at the moveable structure forward end <NUM>. The inlet lip structure <NUM> is configured to form a leading edge <NUM> of the nacelle <NUM> (see <FIG>) as well as an outer peripheral boundary of the inner airflow inlet passage <NUM>. The inlet lip structure <NUM> of <FIG> has a cupped (e.g., a generally V-shafted or U-shaped) side sectional geometry when viewed, for example, in a plane parallel with and/or coincident with the axial centerline <NUM>, <NUM>. The inlet lip structure <NUM> and its cupped side sectional geometry extend circumferentially about (e.g., completely around) the axial centerline <NUM>, <NUM>. The inlet lip structure <NUM> of <FIG>, for example, includes axially overlapping inner and outer lip portions <NUM> and <NUM>. The inner lip portion <NUM> is connected to and may be integral with the outer lip portion <NUM> at and along the nacelle leading edge <NUM>. An aft, downstream end of the inner lip portion <NUM> is located at a downstream, aft end <NUM> of the inlet lip structure <NUM>. A downstream, aft end of the outer lip portion <NUM> is also located at the inlet lip structure aft end <NUM>.

The support structure <NUM> is disposed at the moveable structure aft end <NUM>. The support structure <NUM> is connected to the inlet lip structure <NUM>. The support structure <NUM> projects axially along the axial centerline <NUM>, <NUM> out from the aft end <NUM> of the inlet lip structure <NUM> to the moveable structure aft end <NUM>. The support structure <NUM> extends radially between and to an inner side <NUM> of the support structure <NUM> and an outer side <NUM> of the support structure <NUM>. The support structure inner side <NUM> of <FIG> is radially recessed outward from the inner lip portion <NUM> at the inlet lip structure aft end <NUM>, which provides a (e.g., annular) shoulder <NUM> between the inner lip portion <NUM> and the support structure inner side <NUM>. The support structure outer side <NUM> may be contiguous with the outer lip portion <NUM>. The support structure <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>, <NUM>.

The moveable structure <NUM> of <FIG> is configured with one or more apertures <NUM>; e.g., ports, windows, etc. These apertures <NUM> are arranged circumferentially about the axial centerline <NUM>, <NUM> in an annular array. Each of the apertures <NUM> is configured to at least partially or completely form a respective one of the outer airflow inlet passages <NUM>. For ease of description, the apertures <NUM> are described below with reference to the outer airflow inlet passages <NUM>.

Each of the outer airflow inlet passages <NUM> of <FIG> extends longitudinally along a longitudinal centerline <NUM> of the respective outer airflow inlet passage <NUM> (e.g., radially) through the moveable structure <NUM> and its support structure <NUM> from an inlet <NUM> of the respective outer airflow inlet passage <NUM> to an outlet <NUM> of the respective outer airflow inlet passage <NUM>. The passage inlet <NUM> forms an inlet orifice to the respective outer airflow inlet passage <NUM>, and is disposed at the support structure outer side <NUM>. The passage outlet <NUM> may form an outlet orifice from the respective outer airflow inlet passage <NUM>, and is disposed at the support structure inner side <NUM>. Referring to <FIG>, each of the outer airflow inlet passages <NUM> extends laterally (e.g., circumferentially or tangentially) between and to opposing lateral sides <NUM> and <NUM> of the respective outer airflow inlet passage <NUM>. Each of the outer airflow inlet passages <NUM> extends transversely (e.g., axially along the axial centerline <NUM>, <NUM>) between and to an upstream, forward end <NUM> of the respective outer airflow inlet passage <NUM> and a downstream, aft end <NUM> of the respective outer airflow inlet passage <NUM>.

The passage first side <NUM>, the passage second side <NUM> and the passage aft end <NUM> of <FIG> are formed (e.g., completely) by the support structure <NUM>. The passage forward end <NUM> of <FIG> is at least partially (or completely) formed by the inlet lip structure <NUM> at its aft end <NUM>. The present disclosure, however, is not limited to such an exemplary outer airflow inlet passage arrangement. For example, referring to <FIG>, the passage forward end <NUM> may alternatively be formed by the support structure <NUM>. One or more or all of the outer airflow inlet passages <NUM>, for example, may be axially displaced from the inlet lip structure aft end <NUM> by an axial distance.

The support structure <NUM> of <FIG> includes a (e.g., annular or tubular) support structure base <NUM> and one or more pylons <NUM>; e.g., struts, beams, etc. The support structure base <NUM> is arranged at the moveable structure aft end <NUM>. The pylons <NUM> are arranged circumferentially about the axial centerline <NUM>, <NUM> in an array. Each of the pylons <NUM> is located circumferentially between and separates a circumferentially neighboring (e.g., adjacent) pair of the outer airflow inlet passages <NUM>. Each of the pylons <NUM> of <FIG> extends axially along the axial centerline <NUM>, <NUM> between and is connected to the inlet lip structure <NUM> and the support structure base <NUM>.

Referring to <FIG>, the moveable structure <NUM> is mated with the fixed structure <NUM>. The support structure <NUM> of <FIG>, for example, is arranged within the receptacle <NUM>. The moveable structure <NUM> is further moveably coupled with the fixed structure <NUM>. The support structure base <NUM>, for example, may be slidably connected to the fixed structure <NUM> by one or more slider and/or track assemblies and/or other devices. With this configuration, the moveable structure <NUM> is configured to move (e.g., translate) axially along the axial centerline <NUM>, <NUM> between an aft (e.g., retracted, fully closed) position (see <FIG>) and a forward (e.g., extended, fully open) position (see <FIG>).

At the aft position of <FIG>, the inlet lip structure aft end <NUM> is abutted axially against the fixed structure forward end <NUM>. The inlet lip structure <NUM> may axially (e.g., sealingly) engage the fixed structure <NUM> through, for example, a seal element such as a gasket. With this arrangement, the support structure <NUM> and its elements <NUM> and <NUM> are (e.g., completely) stowed (e.g., received) within the receptacle <NUM>. Each of the outer airflow inlet passages <NUM> and its passage inlet <NUM> are covered and thereby closed by a respective portion of the fixed structure <NUM> and its outer barrel <NUM>.

At the forward position of <FIG>, the inlet lip structure aft end <NUM> is axially displaced from the fixed structure forward end <NUM> by an axial distance along the axial centerline <NUM>, <NUM>. With this arrangement, the pylons <NUM> and at least a forward end portion of the support structure base <NUM> project axially out from the receptacle <NUM> and the fixed structure forward end <NUM>. Each of the outer airflow inlet passages <NUM> and its passage inlet <NUM> are uncovered and thereby opened.

Referring to <FIG> and <FIG>, the center body <NUM> is fixedly connected to the fixed structure <NUM>. The center body <NUM> of <FIG>, for example, is structurally tied to the fixed structure <NUM> by one or more struts <NUM>.

With the foregoing configuration of <FIG> and <FIG>, the variable area inlet elements <NUM>, <NUM> and <NUM> are configured as a valve <NUM>. This valve <NUM> is configured to regulate the flow of air through at least the outer airflow inlet passages <NUM> to the inlet duct <NUM>. For example, in the aft position of <FIG>, the valve <NUM> is configured to (e.g., fully, completely) close the outer airflow inlet passages <NUM> (see <FIG>). The valve <NUM> may thereby fluidly decouple the outer airflow inlet passages <NUM> from the inlet duct <NUM>. However, in the forward position of <FIG>, the valve <NUM> is configured to (e.g., fully, completely) open the outer airflow inlet passages <NUM>. The valve <NUM> may thereby fluidly couple the outer airflow inlet passages <NUM> with the inlet duct <NUM>. While the moveable structure <NUM> is described above as moving (e.g., axially translating) between its aft position (see <FIG>) and its forward position (see <FIG>), it is contemplated the moveable structure <NUM> may also move to one or more intermediate positions axially therebetween in order to variably modulate / regulate the flow of air through the outer airflow inlet passages <NUM> to the inlet duct <NUM>.

Referring to <FIG>, under certain conditions, air may flow across a respective passage inlet <NUM> and interact with the passage aft end <NUM>. Some of the air, for example, may impinge against the passage aft end <NUM> at the passage inlet <NUM>. The passage aft end <NUM> may redirect this air downward into the respective outer airflow inlet passage <NUM> towards the inlet duct <NUM>. Some of the air may also flow past / skip by an edge between the passage aft end <NUM> and the support structure outer side <NUM>. These and/or other fluid dynamic interactions between the air and the variable area inlet elements (e.g., <NUM>, <NUM>, <NUM> and/or <NUM>) may generate noise; e.g., whistling. Referring to <FIG>, such noise generation may be related to an axial distance <NUM> measured between the passage forward end <NUM> and the passage aft end <NUM> at the passage inlet <NUM>. Therefore, to mitigate / reduce generation of noise (e.g., whistling) when the moveable structure <NUM> is deployed and the outer airflow passages are opened, the axial distance <NUM> for one or more or all of the outer airflow inlet passages <NUM> is varied laterally across the passage inlet <NUM> between the opposing sides <NUM> and <NUM>. The outer airflow inlet passages <NUM>, for example, are configured with (e.g., tuned to have) different resonant frequencies laterally cross the passage inlet <NUM>.

Each outer airflow inlet passage <NUM> and its passage inlet <NUM> of <FIG> has a cross-sectional geometry when viewed, for example, in a reference plane. This reference plane may be parallel and radially displaced from the axial centerline <NUM>, <NUM>. The reference plane may also or alternatively be perpendicular to and coincident with the longitudinal centerline <NUM> of the respective outer airflow inlet passage <NUM> and its passage inlet <NUM>. The cross-sectional geometry may have a polygonal shape or other shape; e.g., see <FIG> and <FIG>.

The cross-sectional geometry of <FIG> includes a forward end <NUM>, opposing sides <NUM> and <NUM> and an aft end <NUM>. The forward end <NUM> is formed by the passage forward end <NUM> at the passage inlet <NUM>. The first side <NUM> is formed by the passage first side <NUM> at the passage inlet <NUM>. The second side <NUM> is formed by the passage second side <NUM> at the passage inlet <NUM>. The aft end <NUM> is formed by the passage aft end <NUM> at the passage inlet <NUM>.

The forward end <NUM> of <FIG> has a straight geometry as the forward end <NUM> extends laterally between and to the opposing sides <NUM> and <NUM>. This forward end <NUM> may be arranged perpendicular to the axial centerline <NUM>, <NUM>. Each of the opposing sides <NUM>, <NUM> of <FIG> has a straight geometry as the respective side <NUM>, <NUM> extends transversely (e.g., axially) between and to the forward end <NUM> and the aft end <NUM>. Each of these sides <NUM> and <NUM> may be arranged parallel with the axial centerline <NUM>, <NUM>. The aft end <NUM> of <FIG> has a non-straight geometry; e.g., a V-shaped geometry. The axial distance <NUM>, for example, may continuously (or incrementally) increase as the respective passage inlet <NUM> extends laterally from the first side <NUM> to an intermediate (e.g., center) position <NUM>. The axial distance <NUM> may then continuously (or incrementally) decrease as the respective passage inlet <NUM> extends laterally from the intermediate position <NUM> to the second side <NUM>. Thus, a value of the axial distance <NUM> at the first side <NUM> may be equal to a value of the axial distance <NUM> at the second side <NUM>. However, the value of the axial distance <NUM> at the first side <NUM> and/or the second side <NUM> may be different (e.g., less) than a value of the axial distance <NUM> at the intermediate position <NUM>. A first portion (e.g., half) of the passage inlet <NUM> of <FIG>, for example, axially tapers as the passage inlet <NUM> extends laterally from the intermediate position <NUM> (in a first lateral direction) to the first side <NUM>. A second portion (e.g., half) of the passage inlet <NUM> of <FIG> axially tapers as the passage inlet <NUM> extends laterally from the intermediate position <NUM> (in a second lateral direction) to the second side <NUM>.

The aft end <NUM> may have various geometries other than the exemplary non-straight geometry described above. For example, referring to <FIG>, the aft end <NUM> may have a curved geometry. The passage aft end <NUM> and, thus, the aft end <NUM>, for example, may be configured with an arcuate (e.g., partially circular, partially oval, etc.) profile. Referring to <FIG>, the aft end <NUM> may alternatively have a tortuous (e.g., axially undulating) geometry. The aft ends <NUM> of <FIG>, for example, have wavy geometries with one or more peaks <NUM> and one or more valleys <NUM>. The peaks <NUM> and/or the valleys <NUM> may have sharp transitions (e.g., tips, creases) as shown, for example, in <FIG>. The peaks <NUM> and/or the valleys <NUM> may alternatively have eased (e.g., rounded) transitions as shown, for example, in <FIG>. With each of the foregoing configurations, at least a portion / segment of the aft end <NUM> is angularly offset from and laterally overlaps a corresponding portion / segment of the forward end <NUM>.

Referring to <FIG>, the aft end <NUM> may alternatively have a straight geometry between the opposing sides <NUM> and <NUM>, where the aft end <NUM> is non-parallel with / angularly offset from the forward end <NUM>. The axial distance <NUM> of <FIG> may thereby continuously decrease as the respective passage inlet <NUM> extends from one of the opposing sides <NUM>, <NUM> (e.g., the first side <NUM>) to the other of the opposing sides <NUM>, <NUM> (e.g., the second side <NUM>). The value of the axial distance <NUM> at the first side <NUM> may thereby be different (e.g., greater) than the value of the axial distance <NUM> at the second side <NUM>.

The axial distance <NUM> between the forward end <NUM> and the aft end <NUM> is (e.g., continuously or incrementally) varied in <FIG> and <FIG> by varying a geometry and/or skewing an orientation of the aft end <NUM>. It is contemplated, however, the axial distance <NUM> may also or alternatively be varied by varying a geometry and/or skewing an orientation of the forward end <NUM>. The forward end <NUM>, for example, may be configured with any of the geometries / orientations described above with respect to the aft end <NUM>.

The aircraft propulsion system <NUM> and its variable area inlet <NUM> may be configured with various gas turbine engines other than the one described above. The gas turbine engine, for example, may be configured as a geared or a direct drive turbine engine. The gas turbine engine may be configured with a single spool, with two spools (e.g., see <FIG>), or with more than two spools. The gas turbine engine may be configured as a turbofan engine, a turbojet engine or any other type of turbine engine. The present invention therefore is not limited to any particular types or configurations of gas turbine engines. The present disclosure is also not limited to applications where the aircraft is capable of traveling supersonic speeds.

Claim 1:
An assembly for an aircraft propulsion system (<NUM>), comprising:
a variable area inlet (<NUM>) comprising a moveable structure (<NUM>) configured to move axially along an axial centerline (<NUM>, <NUM>) between a first position and a second position;
the variable area inlet (<NUM>) configured to open an airflow inlet passage (<NUM>) into the aircraft propulsion system (<NUM>) when the moveable structure (<NUM>) is in the first position, and the variable area inlet (<NUM>) configured to close the airflow inlet passage (<NUM>) when the moveable structure (<NUM>) is in the second position; and
the airflow inlet passage (<NUM>) comprising an inlet, the inlet extending axially along the axial centerline (<NUM>, <NUM>) from a first end to a second end, and a distance from the first end to the second end changing as the inlet extends laterally between a first side (<NUM>) and a second side (<NUM>);
wherein the moveable structure (<NUM>) includes an inlet lip structure (<NUM>) and a support structure (<NUM>);
wherein the first end of the inlet is formed by the inlet lip structure (<NUM>);
wherein the second end of the inlet is formed by the support structure (<NUM>); and characterised in that:
the first side (<NUM>) of the inlet and the second side (<NUM>) of the inlet are formed by the support structure (<NUM>), and
the variable area inlet (<NUM>) further comprises a fixed structure (<NUM>); and the support structure (<NUM>) is received within a receptacle (<NUM>) of the fixed structure (<NUM>) when the moveable structure (<NUM>) is in the second position.