Patent Description:
An aircraft propulsion system typically includes one or more acoustic panels for attenuating noise generated by a gas turbine engine. These acoustic panels are typically tuned to attenuate noise at a particular gas turbine engine operating state. Therefore, when the gas turbine engine is at another operating state, the acoustic panels may not efficiency and/or effectively attenuate the engine noise. There is a need in the art therefore for an acoustic panel that can attenuate noise across a wide and/or variable spectrum of different gas turbine engine operating states.

<CIT> discloses an acoustic liner comprising: a liner core comprising a multiplicity of acoustic chambers disposed adjacent to one another to form a honeycomb structure, each acoustic chamber comprising a rigid skeleton and an actuatable coating layer disposed on at least part of the internal surface of said rigid skeleton to thereby define a variable internal volume of the acoustic chamber.

<CIT> discloses tunable perforate acoustic liners using shape memory materials, which allow the acoustic liners to tune for multiple frequencies across a wide range.

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

The first constriction includes a shape memory material configured to deform between the first configuration and the second configuration when subject to an input.

The shape memory material may be configured as or otherwise include a shape memory polymer.

The shape memory material may also include a plurality of magnetic particles embedded within the shape memory polymer.

The shape memory material may be or otherwise include a magnetically actuated shape memory material.

The actuator is configured to remotely actuate deformation of the first constriction.

The actuator may be configured as or otherwise include an electromagnet.

The first constriction may be configured to deform from a first configuration to a second configuration in response to being subject to a first input.

The first constriction may be configured to deform from the second configuration to the first configuration in response to being subject to a second input.

The first constriction may form an aperture that fluidly couples the fluidly coupled sub-chambers together.

The first constriction may be configured to deform between a first configuration and a second configuration. A size of the aperture when the first constriction is in the first configuration may be different than the size of the aperture when the first constriction is in the second configuration.

The second end may be attached to the sidewall of the first chamber.

The second end may be laterally displaceable from the sidewall of the first chamber.

The first constriction may be arranged at a vertical end of the first chamber.

The first constriction is arranged intermediately vertically between the perforated first skin and the second skin.

The core may also include a honeycomb core structure that forms the chambers between the perforated first skin and the second skin. The first constriction may be attached to the honeycomb core structure.

The chambers may also include a second chamber. The core may also include a second constriction configured to divide the second chamber into a plurality of fluidly coupled sub-chambers. The second constriction may be configured from or otherwise include a shape memory material.

The acoustic panel system may also include a component of a nacelle for an aircraft propulsion system. The component of the nacelle may include the perforated first skin, the second skin and the core.

<FIG> is a partial perspective schematic illustration of a structural, acoustic panel <NUM> for attenuating sound; i.e., noise. This acoustic panel <NUM> may be configured to attenuate sound generated by an aircraft propulsion system such as, for example, a turbofan propulsion system or a turbojet propulsion system. With such a configuration, the acoustic panel <NUM> may be configured with a nacelle of the propulsion system. The acoustic panel <NUM>, for example, may be configured as or otherwise included as part of an inner or outer barrel, a translating sleeve, a blocker door, etc. Alternatively, the acoustic panel <NUM> may be configured with another component / structure of the aircraft such as its fuselage or a wing. Furthermore, the acoustic panel <NUM> may be configured to also or alternatively attenuate aircraft related sound other than sound generated by the propulsion system. The acoustic panel <NUM> of the present disclosure, of course, may alternatively be configured for non-aircraft applications.

The acoustic panel <NUM> extends laterally in a first lateral direction (e.g., an x-axis direction) along an x-axis. The acoustic panel <NUM> extends laterally in a second lateral direction (e.g., a y-axis direction) along a y-axis. The acoustic panel <NUM> extends vertically in a vertical direction (e.g., a z-axis direction) along a z-axis. Note, the term "lateral" may be used herein to generally describe the first lateral direction, the second lateral direction and/or any other direction within the x-y plane. Also note, the term "vertical" may be used herein to describe a depthwise panel direction and is not limited to a gravitational up/down direction. Furthermore, for ease of illustration, the x-y plane is shown as a generally flat plane. However, in other embodiments, the x-y plane and, thus, the acoustic panel <NUM> may be curved and/or follow an undulating and/or otherwise variable geometry. For example, the x-y plane and, thus, the acoustic panel <NUM> may be arcuate, cylindrical, conical, frustoconical, or tapered with or without radial undulations. In such embodiments, a solely vertical direction (e.g., z-axis direction) is defined relative to a position of interest on the x-y plane. For example, on a spherical x-y plane, the vertical direction (e.g., z-axis) direction is a radial direction.

The acoustic panel <NUM> includes a perforated first skin <NUM> (e.g., a face, front and/or exterior skin with one or more through-holes), a solid, non-perforated second skin <NUM> (e.g., a back and/or interior skin without any through-holes) and a structural cellular core <NUM>. Briefly, the cellular core <NUM> is arranged and extends vertically between the first skin <NUM> and the second skin <NUM>. The cellular core <NUM> is also connected to the first skin <NUM> and/or the second skin <NUM>. The cellular core <NUM>, for example, may be welded, brazed, fused, adhered or otherwise bonded to the first skin <NUM> and/or the second skin <NUM>. The cellular core <NUM> may also and/or alternatively be mechanically fastened to the first skin <NUM> and/or the second skin <NUM>. Alternatively, the cellular core <NUM> may be formed integral with the first skin <NUM> and/or the second skin <NUM> as a monolithic body using, for example, a molding process or an additive manufacturing process. The present disclosure, of course, is not limited to any particular manufacturing methods.

The first skin <NUM> may be configured as a relatively thin sheet or layer of material that extends laterally within the x-y plane. This first skin material may include, but is not limited to, metal, polymer (e.g., thermoplastic or thermoset material), a fiber reinforced composite (e.g., fiber reinforcement such as, but not limited to, fiberglass, carbon fiber and/or aramid fibers embedded within a polymer matrix), or a combination thereof. The first skin <NUM> has a vertical thickness <NUM>. This first skin vertical thickness <NUM> extends vertically between opposing side surfaces <NUM> and <NUM> of the first skin <NUM>. The first skin <NUM> includes a plurality of perforations <NUM>; e.g., apertures such as through-holes. Each of these first skin perforations <NUM> extends generally vertically through the first skin <NUM> between the first skin side surfaces <NUM> and <NUM>.

The second skin <NUM> may be configured as a relatively thin sheet or layer of (e.g., continuous and uninterrupted) material that extends laterally within the x-y plane. This second skin material may include, but is not limited to, metal, polymer (e.g., thermoplastic or thermoset material), a fiber reinforced composite (e.g., fiber reinforcement such as, but not limited to, fiberglass, carbon fiber and/or aramid fibers embedded within a polymer matrix), or a combination thereof. The second skin material may be the same as or different than the first skin material. The second skin <NUM> has a vertical thickness <NUM>. This second skin vertical thickness <NUM> extends vertically between opposing side surfaces <NUM> and <NUM> of the second skin <NUM>. The second skin vertical thickness <NUM> may be substantially equal to or different (e.g., greater or less) than the first skin vertical thickness <NUM>.

The cellular core <NUM> extends laterally within the x-y plane. The cellular core <NUM> has a vertical thickness <NUM>. This core vertical thickness <NUM> extends vertically between opposing sides <NUM> and <NUM> of the cellular core <NUM>, which core sides <NUM> and <NUM> are respectively abutted against the first skin interior side surface <NUM> and the second skin interior side surface <NUM>. The core vertical thickness <NUM> may be substantially greater than the first skin vertical thickness <NUM> and/or the second skin vertical thickness <NUM>. The core vertical thickness <NUM>, for example, may be at least ten to forty times (<NUM>-40x), or more, greater than the vertical thickness <NUM>, <NUM>; however, the acoustic panel <NUM> of the present disclosure is not limited to such an exemplary embodiment.

Referring to <FIG> and <FIG>, the cellular core <NUM> is configured to form one or more internal chambers <NUM> (e.g., acoustic resonance chambers, cavities, etc.) vertically between the first skin <NUM> and the second skin <NUM>. The cellular core <NUM> of <FIG> and <FIG>, for example, includes a cellular core structure <NUM>. This cellular core structure <NUM> may be configured as a honeycomb core structure. The cellular core structure <NUM> of <FIG>, for example, includes a plurality of corrugated sidewalls <NUM>. These sidewalls <NUM> are arranged in a side-by-side array and are connected to one another such that each adjacent (e.g., neighboring) pair of the sidewalls <NUM> forms an array of the chambers <NUM> laterally therebetween. Of course, in other embodiments, the sidewalls <NUM> may be formed integral with one another as a cellular grid structure as shown, for example, in <FIG>. The cellular core structure <NUM> and its sidewalls <NUM> are constructed from or otherwise include core material. This core material may include, but is not limited to, metal, polymer (e.g., thermoplastic or thermoset material), a fiber reinforced composite (e.g., fiber reinforcement such as, but not limited to, fiberglass, carbon fiber and/or aramid fibers embedded within a polymer matrix), or a combination thereof.

Referring to <FIG>, each of the chambers <NUM> extends vertically within / through the cellular core <NUM> to and between the first skin <NUM> and its interior side surface <NUM> and the second skin <NUM> and its interior side surface <NUM>. Referring to <FIG>, one or more or all of the chambers <NUM> may each have a polygonal (e.g., hexagonal) cross-sectional geometry when viewed, for example, in a (e.g., x-y) plane parallel to one or more of the elements <NUM>-<NUM> (see <FIG>); e.g., perpendicular to the z-axis. The present disclosure, however, is not limited to the foregoing exemplary cellular core configuration. For example, one or more or all of the chambers <NUM> may each have a circular, elliptical or other non-polygonal cross-sectional geometry. Furthermore, various other types of honeycomb cores and, more generally, various other types of cellular cores for an acoustic panel are known in the art, and the present disclosure is not limited to any particular ones thereof.

Referring to <FIG> and <FIG>, the cellular core <NUM> also includes one or more reconfigurable (e.g., deformable) chamber constrictions <NUM>; e.g., flow constrictions. Each of these constrictions <NUM> is arranged with a respective one of the chambers <NUM>. More particularly, each of the constrictions <NUM> are disposed within a respective one of the chambers <NUM>.

Referring to <FIG>, each of the constrictions <NUM> may fluidly divide / separate a respective one of the chambers <NUM> into a plurality of sub-chambers 46A and 46B. Each constriction <NUM> of <FIG>, for example, forms a septum that extends laterally (e.g., in both the x-axis and the y-axis directions) across the respective chamber <NUM>. With this arrangement, the first sub-chamber 46A is disposed vertically between the first skin <NUM> and the respective constriction <NUM> and fluidly coupled with one or more of the first skin perforations <NUM>. The first sub-chamber 46A, for example, extends vertically between and to the first skin interior side surface <NUM> and a first end <NUM> of the respective constriction <NUM>. This first sub-chamber 46A also extends laterally (e.g., in both the x-axis and the y-axis directions) between and to the opposing sidewalls <NUM> of the respective chamber <NUM>. The second sub-chamber 46B is disposed vertically between the second skin <NUM> and the respective constriction <NUM>. The second sub-chamber 46B, for example, extends vertically between and to the second skin interior side surface <NUM> and a second end <NUM> of the respective constriction <NUM>, which constriction second end <NUM> is vertically opposite the constriction first end <NUM>. This second sub-chamber 46B also extends laterally (e.g., in both the x-axis and the y-axis directions) between and to the opposing sidewalls <NUM> of the respective chamber <NUM>.

Each constriction <NUM> of <FIG> and <FIG> is configured with at least one variable constriction aperture <NUM>; e.g., a through hole. This aperture <NUM> of <FIG>extends vertically through the respective constriction <NUM> between and to the constriction first end <NUM> and the constriction second end <NUM>. The aperture <NUM> thereby fluidly couples the respective first sub-chamber 46A with the respective second sub-chamber 46B.

One or more or all of the constrictions <NUM> are configured with a variable geometry / have a variable configuration. Each constriction <NUM> in <FIG> and <FIG>, for example, is moveable, positionable, bendable, deformable or otherwise reconfigurable between a first configuration (e.g., see <FIG> and <FIG>) and a second configuration (e.g., see <FIG> and <FIG>). In the first configuration of <FIG> and <FIG>, a size <NUM> (e.g., a lateral width, diameter, etc.) of the aperture <NUM> in the respective constriction <NUM> has a first value. In the second configuration of <FIG> and <FIG>, the aperture size <NUM> has a second value that is different (e.g., less) than the first value. Each constriction <NUM> is thereby configured to alter (e.g., reduce) the size <NUM> of its aperture <NUM> (e.g., further constrict flow through the aperture <NUM>) as that constriction <NUM> deforms from the first configuration to the second configuration. Each constriction <NUM> may also change a size (e.g., area) and/or relative vertical position of its reflective surface area on its first end <NUM> and/or it second end <NUM>.

Referring to <FIG>, one or more or all of the constrictions <NUM> are constructed from or otherwise include a shape memory material (SMM) <NUM>. This shape memory material <NUM> is configured to selectively deform when subjected to an input such as, but not limited to, a magnetic field. The shape memory material <NUM> of <FIG>, for example, includes a (e.g., amorphous) shape memory polymer (SMP) <NUM> and one or more magnetic particles 66A and 66B (generally referred to as "<NUM>"). Examples of the shape memory polymer <NUM> include, but are not limited to, an acrylate-based amorphous polymer. The magnetic particles <NUM> may be particles of magnetic material such as, but not limited to, NdFeB and Fe<NUM>O<NUM>. For example, the first magnetic particles 66A may be particles of NdFeB, and the second magnetic particles 66B may be particles of Fe<NUM>O<NUM>. The present disclosure, however, is not limited to the foregoing exemplary shape memory material or components thereof.

Referring to <FIG>, the shape memory material <NUM> and, thus, the respective constriction <NUM> is actuated remotely (e.g., wirelessly) via an actuator <NUM> such as, but not limited to, an electromagnet of an acoustic panel system <NUM>. This actuator <NUM> may generate and transmit an input such as a magnetic field. Subjecting the shape memory material <NUM> to this input may cause the shape memory material <NUM> to deform in a predetermined manner. For example, a first magnetic field (e.g., a positive magnetic field) may be output by the actuator <NUM> of <FIG>. This first magnetic field may cause the shape memory material <NUM> and, thus, the respective constriction <NUM> to deform in a first direction; e.g., curve upwards in <FIG>. In another example, a second magnetic field (e.g., a negative magnetic field) opposite the first magnetic field may be output by the actuator <NUM> of <FIG>. This second magnetic field may cause the shape memory material <NUM> and, thus, the respective constriction <NUM> to deform in a second direction that is opposite the first direction; e.g., curve downward in <FIG>.

During deformation, the magnetic field may excite one or more of the magnetic particles <NUM> within the shape memory material <NUM> of <FIG>. This excitement may generate heat which softens the shape memory polymer <NUM>. The magnetic field may also exert a force on one or more of the magnetic particles <NUM>. This force may push or pull the one or more of the magnetic particles <NUM> in a certain predetermined direction (e.g., see <FIG>). Note, the magnetic particles <NUM> may be oriented (e.g., with common or different particle orientations) within the shape memory polymer <NUM> to move in different directions in order to deform the respective constriction <NUM> in a particular manner; e.g., see <FIG>. Once the magnetic field is turned off, the shape memory polymer <NUM> may rapidly cool and harden thereby holding the deformed shape of the respective constriction <NUM>.

Referring to <FIG>, during operation, the chambers <NUM> operate as resonance chambers for attenuating sound. Sound waves, for example, may enter each of the chambers <NUM> through the respective first skin perforation(s) <NUM>. Some of these sound waves (first sound waves) may travel through the respective first sub-chamber 46A to the respective constriction <NUM> and the surface at its first end <NUM>. This constriction <NUM> may reflect the first sound waves back through the respective first sub-chamber 46A to the respective first skin perforation(s) <NUM>. Others of the sound waves (second sound waves) may travel through the respective aperture <NUM> and into the respective second sub-chamber 46B to the second skin <NUM> and its interior surface <NUM>. The second skin <NUM> may reflect some of these second sound waves back through the respective second sub-chamber 46B, the respective aperture <NUM> and the respective first sub-chamber 46A to the respective first skin perforation(s) <NUM>. Some others of the second sound waves may bounce around (e.g., reflect multiple times) within the second sub-chamber 46B before exiting through the respective aperture <NUM>. With such an arrangement, each respective chamber may reverse phase of the sound waves of multiple different frequencies using known acoustic reflection principles and subsequently direct the reverse phase sound waves out of the acoustic panel <NUM> through the respective first skin perforation(s) <NUM> to destructively interfere with other incoming sound waves. The acoustic panel <NUM> may thereby attenuate noise. The constriction <NUM> may thereby function as a septum to facilitate attenuating multiple sound frequencies.

The sound attenuation may be tuned / varied during operation using the actuator <NUM>; e.g., the electromagnet. For example, when the actuator <NUM> outputs a first input (e.g., a first magnetic field), the constrictions <NUM> may deform to their first configuration of <FIG>. In this first configuration, the apertures <NUM> are relatively large. Then, the system may behave as a regular honeycomb liner, with resonances pre-determined by the core depth (or panel thickness). However, when the actuator <NUM> outputs a second input (e.g., a second magnetic field, which may be opposite and/or of a different magnitude than the first magnetic field), the constrictions <NUM> may deform to their second configuration of <FIG>. In this second configuration, the apertures <NUM> are relatively small. Thus, the constrictions <NUM> interfere with the simple one-dimensional (1D) sound propagation, generating mass-like phase shifts on the dynamics of the cell, leading to modified resonant frequencies. The constrictions <NUM> may create a shift towards lower frequencies. Depending on the vertical locations of the constrictions <NUM>, the shift may occur on some of the first, second, third or higher resonances (or anti-resonances), but typically not all of them for a given vertical location. In this manner, the constrictions <NUM> may be reconfigured (e.g., deformed) to attenuate different frequency bands during operation.

The constrictions <NUM> of the present disclosure may have various configurations and may be arranged at various locations within the chambers <NUM>. Examples of such configurations and locations are described below with reference to <FIG>, <FIG> and <FIG>. The present disclosure, however, is not limited to such exemplary constriction configurations or locations.

Referring to <FIG>, each constriction <NUM> may extend longitudinally (e.g., vertically) along a longitudinal centerline <NUM> of the respective chamber <NUM> between and to the first end <NUM> of the constriction <NUM> and the second end <NUM> of the constriction <NUM>. Each constriction <NUM> may also extend circumferentially about (e.g., completely around, or partially around) the longitudinal centerline <NUM> thereby providing the respective constriction <NUM> with, for example, an annular or tubular body. The constriction first end <NUM> (e.g., an annular edge) and the constriction second end <NUM> (e.g., an annular edge) of <FIG> are located next to and fixedly attached (e.g., bonded) to the chamber sidewall(s) <NUM>. An intermediate portion <NUM> of the constriction <NUM>, which is vertically between the constriction first end <NUM> and the constriction second end <NUM>, is displaceable from (e.g., not attached to) the chamber sidewall(s) <NUM>. With this arrangement, when excited by the actuator input (e.g., the magnetic field), the intermediate portion <NUM> of the respective constriction <NUM> may move laterally (e.g., radially inwards relative to the longitudinal centerline <NUM>) away from the chamber sidewall(s) <NUM> and thereby change (e.g., reduce) the size <NUM> (see <FIG>) of the respective aperture <NUM>. In the configuration of <FIG>, each constriction <NUM> may have a (e.g., approximately or exactly) tubular shape. In the configuration of <FIG>, each constriction <NUM> may have a partial (e.g., half) torus shape. More particularly, a sectional geometry of the respective constriction <NUM> is outwardly concave and (e.g., about) semicircular when viewed, for example, in a plane coincident with and/or parallel with the longitudinal centerline <NUM>. Here, an apex of the intermediate portion <NUM> of the respective constriction <NUM> forms a metering portion (e.g., a minimum lateral dimension) of the aperture <NUM>.

Both the constriction first and second ends <NUM> and <NUM> may be attached to the chamber sidewall(s) <NUM> as described above. Alternatively, referring to <FIG>, one of the constriction ends <NUM>, <NUM> may be displaceable from the chamber sidewall(s) <NUM>. The constriction second end <NUM> of <FIG>, is not attached to the chamber sidewall(s) <NUM>. With this arrangement, when excited by the actuator input (e.g., the magnetic field), the constriction second end <NUM> as well as the intermediate portion <NUM> of the respective constriction <NUM> may move laterally (e.g., radially inwards relative to the longitudinal centerline <NUM>) away from the chamber sidewall(s) <NUM> and thereby change (e.g., reduce) the size <NUM> (see <FIG>) of the respective aperture <NUM>. In the configuration of <FIG>, each constriction <NUM> may have a (e.g., approximately or exactly) tubular shape. In the configuration of <FIG>, each constriction <NUM> may have a partial (e.g., quarter) torus shape. More particularly, a sectional geometry of the respective constriction <NUM> is outwardly concave and (e.g., about) quarter-circular when viewed, for example, in a plane coincident with and/or parallel with the longitudinal centerline <NUM>. Here, the second end <NUM> of the respective constriction <NUM> forms a metering portion (e.g., a minimum lateral dimension) of the aperture <NUM>.

Referring to <FIG>, each constriction <NUM> is disposed within a respective chamber <NUM>. For example, referring to <FIG>, the constriction <NUM> may be arranged at (e.g., on, adjacent or proximate) one of the ends of the respective chamber <NUM>. The constriction <NUM> of <FIG>, for example, is disposed at a first end of the respective chamber <NUM> adjacent the first skin <NUM>. Of course, any one or more of the constrictions <NUM> may also or alternatively be disposed at an opposite second end of the respective chamber <NUM> adjacent the second skin <NUM> (see <FIG>); e.g., the reverse of what is shown in <FIG> along the chamber sidewall <NUM>. In another example, referring to <FIG>, the constriction <NUM> may be arranged longitudinally along an intermediate portion of the respective chamber <NUM> vertically between the chamber first end and the chamber second end.

In some embodiments, referring to <FIG>, the cellular core structure <NUM> may be connected directly to the first skin <NUM> and the second skin <NUM>. In other embodiments, referring to <FIG>, the cellular core structure <NUM> may be connected indirectly to one of the skins <NUM>, <NUM>. The chamber sidewalls <NUM> of <FIG>, for example, are connected indirectly to the first skin <NUM> through the shape memory material <NUM>. The shape memory material <NUM>, for example, may be draped over ends of the chamber sidewalls <NUM> during assembly of the acoustic panel <NUM>.

Claim 1:
An acoustic panel system (<NUM>), comprising:
a perforated first skin (<NUM>);
a second skin (<NUM>); and
a core (<NUM>) connected to the perforated first skin (<NUM>) and the second skin (<NUM>), the core (<NUM>) including a plurality of chambers (<NUM>) and a first constriction (<NUM>); and
an actuator (<NUM>) configured to remotely actuate deformation of the first constriction (<NUM>),
each of the plurality of chambers (<NUM>) extending vertically through the core (<NUM>) between the perforated first skin (<NUM>) and the second skin (<NUM>), and the plurality of chambers (<NUM>) comprising a first chamber;
the first constriction (<NUM>) configured to divide the first chamber into a plurality of fluidly coupled sub-chambers (46A, 46B), and the first constriction (<NUM>) comprising a shape memory material (<NUM>);
wherein the first constriction (<NUM>) includes and extends vertically between a first end (<NUM>) and a second end (<NUM>);
wherein the first end (<NUM>) is attached to a sidewall (<NUM>) of the first chamber, and
characterised in that an intermediate portion (<NUM>) of the first constriction (<NUM>), vertically between the first end (<NUM>) and the second end (<NUM>), is not attached to the sidewall (<NUM>) of the first chamber such that the intermediate portion (<NUM>) of the first constriction (<NUM>) is configured to move laterally away from the sidewall (<NUM>) of the first chamber when actuated by the actuator (<NUM>).