A variable geometry inlet system of an aircraft engine includes an inlet duct. The inlet duct includes at least first and second sections moveable between extended and retracted positions such that the inlet duct defines a variable axial length of an inlet passage for selective flight conditions. The inclusion of acoustic treatment may assist in controlling noise.

An assembly including two juxtaposed acoustic panels. Resistive faces of the acoustic panels are in the continuation of one another. A first resistive face extends as far as the first end wall of a first panel. The first end wall is in contact with a second end wall of a second panel in the region of the first resistive face and of the second resistive face. A connecting piece is interposed between the first end wall and the second end wall over a part of the length thereof so that the connecting piece does not extend as far as the first and second resistive faces. That makes it possible to form an acoustic cladding that is continuous, exhibiting no non-acoustic zone or reduced-acoustic zone at the junction between the acoustic panels of which it is formed. A nacelle of an aircraft propulsion unit is one application.

An acoustic panel for an aircraft nacelle includes, from a central axis of the nacelle to the exterior thereof, a resistive skin perforated with sound-absorbing micro-perforations, a first attenuation stage, a septum perforated with holes, a second attenuation stage, and a back skin configured to provide the mechanical strength of the acoustic panel. The septum is a planar wall having a thickness greater than that of the resistive skin, preferably greater than 4 mm. Such a panel is configured to attenuate several frequency ranges one of which being a low-frequency range, while optimizing the weight, the cost and the air intake functions. The thickness of the septum, the dimensions of the holes in the septum, the OAR of the septum and the height of the second attenuation stage are adjusted to match the mean attenuated low frequency to the vibration frequency of the aircraft engine.

An acoustic liner includes a core including a plurality of cells extending between a first side of the core and a second side of the core opposite the first side of the core. The acoustic liner further includes a back skin including a light-reflecting layer. The light-reflecting layer includes a first side attached to the first side of the core. The acoustic liner further includes a face skin. The face skin includes a first side attached to the second side of the core.

A nacelle inlet structure for an aircraft propulsion system. This nacelle inlet structure includes an inlet lip, a bulkhead and a reinforcement structure. The inlet lip extends circumferentially about an axial centerline. The bulkhead extends circumferentially about the axial centerline. The bulkhead is configured with the inlet lip to form a cavity axially between the inlet lip and the bulkhead. The reinforcement structure extends circumferentially about the axial centerline. The reinforcement structure is connected to and extends axially between the inlet lip and the bulkhead thereby radially dividing the cavity into an inner sub-cavity and an outer sub-cavity.

Acoustic cores and methods for forming and for assembling acoustic cores are provided. For example, an acoustic core of a gas turbine engine comprises a first attenuation section having a first plurality of attenuation members and a first mating wall having a planar first mating surface. The first mating wall is integrally formed with at least a portion of the first plurality of attenuation members and defines a portion of a perimeter of the first attenuation section. A method for forming an acoustic core comprises additively manufacturing a first attenuation section of the acoustic core, which comprises a first plurality of attenuation members and a first mating wall that are integrally formed as a single unit. A method for assembling an acoustic core comprises applying an adhesive to mating surfaces of first and second attenuation sections and pressing together the mating surfaces to join the first and second attenuation sections.

An air intake includes a substantially cylindrical inner wall, a substantially cylindrical outer wall, a front lip connecting the inner wall and the outer wall, a front mounting flange, and a support structure. The front mounting flange is configured to cooperate with a rear flange of a wall of an aircraft engine. The support structure is configured to be secured to the wall of the aircraft engine at a location longitudinally downstream of the mounting flange. The outer wall includes a downstream end configured to be positioned in a junction area flush with a front end of a fan external cowl. A portion of the outer wall being configured to bear at least against the support structure. The support structure is configured to be secured to the wall of the aircraft engine so that a load path passes directly from the outer wall towards the fan casing.

Systems and methods are provided for septa for acoustic cells. One embodiment is a method that includes fabricating a septum of a cell of an acoustic panel, by heating a material into a molten material, depositing the molten material to form a lower chamber of the septum that extends vertically upwards and includes an entry, iteratively depositing layers of the molten material, each layer comprising a filament at the entry that includes overhangs with respect to vertically adjacent layers, and forming openings at locations of the overhangs.

A co-curable thermoset acoustic liner and method of forming the same includes a sound attenuating core having a plurality of core cells. An inner face sheet having a plurality of face sheet apertures is coupled to the core by an inner thermoset adhesive sheet, which has a plurality of adhesive sheet apertures. Each of the plurality of adhesive sheet apertures is aligned within a corresponding one of the plurality of face sheet apertures so that the plurality of core cells are placed in fluid communication with airflow over the inner face sheet to create a Single Degree of Freedom (SDOF) acoustic liner.

There is provided a jet engine air inlet arrangement having a front annular casing arrangement and a heating pipe arrangement. The heating pipe arrangement is supported onto an annular internal bulkhead, wherein the annular internal bulkhead provides a back wall to the cavity. The annular internal bulkhead is fabricated from deformed metal sheet, and includes a plurality of radially disposed stiffening projections and recesses in the back wall, and wherein the annular internal bulkhead includes inner and outer circumferential flanges that engage onto inside surfaces of the front annular casing arrangement behind the back wall. The plurality of radially disposed stiffening projections and recesses result in the flanges being disposed at a distance of more than 60 mm behind the plurality of radially disposed stiffening projections and recesses.