Abstract: An acoustic panel with a cellular core includes cells that are provided with one or more obstacles, each of the obstacles extending transversely in relation to the main axis of the associated cell so as to increase the length of the path (F) that sound waves travel through the cell. Methods enabling the production of such a panel implements steps of cutting, folding and bonding that are suitable for creating cells provided with such obstacles.

Abstract: The invention relates to an air intake of an aircraft turbojet engine nacelle extending along an axis X, in which an air flow circulates from upstream to downstream, the air intake comprising an inner wall and an outer wall which are connected by a leading edge and an inner partition so as to delimit an annular cavity, the air intake comprising means for injecting at least one hot air flow into the inner cavity and at least one ventilation orifice formed in the outer wall in order to allow the hot air flow to escape after heating the inner cavity, the air intake comprising at least one acoustic member positioned in the inner cavity facing the ventilation orifice so as to modify the acoustic resonance frequencies and/or to attenuate the acoustic waves formed in the inner cavity via the ventilation orifice.

Abstract: An acoustic attenuation panel for a propulsion assembly includes an acoustic front skin having perforations, and a central structure formed from partitions arranged perpendicularly in order to make up cells, wherein the front skin and the central structure form the panel which is made as a single piece and is provided for directly covering a surface of an element of the propulsion assembly forming a rear skin which closes the cells of the central structure at the rear.

Abstract: The invention relates to an air intake of an aircraft turbojet engine nacelle, extending along an axis X, in which an air flow circulates from upstream to downstream, the air intake comprising an inner wall facing the axis X and an outer 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. The air intake comprises means for injecting at least one hot air flow into the inner cavity and at least one ventilation orifice formed in the outer wall to allow the hot air flow to escape after heating the inner cavity, the ventilation orifice comprising an upstream edge, the circumferential profile of which is discontinuous in order to generate turbulences, and a downstream edge, the radial profile of which is aerodynamic in order to limit the formation of pressure fluctuations.

Abstract: The invention relates to an air intake of an aircraft turbojet engine nacelle, extending along an axis X, in which an air flow circulates from upstream to downstream, the air intake extending circumferentially around the axis X and comprising an inner wall, which faces the axis X 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. The air intake comprises means for injecting at least one hot air flow into the inner cavity and at least one ventilation orifice formed in the outer wall in order to allow the hot air flow to escape after heating the internal cavity, the air intake comprising at least one disruption member of the external air flow, positioned upstream of the ventilation orifice, which extends outwardly from the outer wall.

Abstract: A method for manufacturing an alveolar core structure includes at least one cell including a secondary duct having a first end defining a sound wave inlet, and an opposite second end, the secondary duct comprising a sound wave outlet. The method also includes a fastening step in which adhesive tapes transverse to the longitudinal direction of said first plate are applied on a first longitudinal plate. The secondary duct in the form of a flattened element is fastened, on the first plate, by gluing at its sound wave inlet. A second plate is applied. A step of deploying the first and second plates so as to form the peripheral wall of the cells and so that the flattened element is deployed.

Abstract: An air inflow lip of a nacelle for a turbojet of an aircraft, including a cavity defined by a leading edge of the nacelle and by an annular wall, includes an inner wall, an acoustic treatment device, and a pneumatic de-icing device including a de-icing fluid supply device. The inner wall of the air inflow lip includes acoustic boreholes and the pneumatic de-icing device includes a honeycombed de-icing plate mounted inside the cavity on the inner wall of the air inflow lip. Also included are conduits for the circulation of a de-icing fluid and acoustic wells communicating with the acoustic boreholes.

Abstract: An acoustic attenuation panel includes a cellular structure including a plurality of acoustic cells separated from one another by peripheral partitions, a perforated acoustic structure, the perforated acoustic structure and the cellular structure being formed in one piece in a first material, and a porous acoustic layer formed of a second material and fastened to a surface of the perforated acoustic structure by entangling the first material and the second material.

Abstract: An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.

Abstract: An acoustic attenuation panel includes a perforated acoustic wall, a first honeycomb structure coupled to the perforated acoustic wall and including a plurality of acoustic cells defined by peripheral partitions, a second honeycomb structure including a plurality of acoustic cells defined by peripheral partitions, and a septum which includes a plurality of macro-perforations and is positioned between the first honeycomb structure and the second honeycomb structure. Each acoustic cell of the first honeycomb structure and each acoustic cell of the at least second honeycomb structure are arranged opposite a single perforation of the septum.

Abstract: The invention relates to an air intake of an aircraft turbojet engine nacelle extending along an axis X, in which an air flow circulates from upstream to downstream, the air intake comprising an inner wall and an outer wall which are connected by a leading edge and an inner partition so as to delimit an annular cavity, the air intake comprising means for injecting at least one hot air flow into the inner cavity and at least one ventilation orifice formed in the outer wall in order to allow the hot air flow to escape after heating the inner cavity, the air intake comprising at least one acoustic member positioned in the inner cavity facing the ventilation orifice so as to modify the acoustic resonance frequencies and/or to attenuate the acoustic waves formed in the inner cavity via the ventilation orifice.

Abstract: The invention relates to an air intake of an aircraft turbojet engine nacelle, extending along an axis X, in which an air flow circulates from upstream to downstream, the air intake comprising an inner wall facing the axis X and an outer 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. The air intake comprises means for injecting at least one hot air flow into the inner cavity and at least one ventilation orifice formed in the outer wall to allow the hot air flow to escape after heating the inner cavity, the ventilation orifice comprising an upstream edge, the circumferential profile of which is discontinuous in order to generate turbulences, and a downstream edge, the radial profile of which is aerodynamic in order to limit the formation of pressure fluctuations.

Abstract: The invention relates to an air intake of an aircraft turbojet engine nacelle, extending along an axis X, in which an air flow circulates from upstream to downstream, the air intake extending circumferentially around the axis X and comprising an inner wall, which faces the axis X 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. The air intake comprises means for injecting at least one hot air flow into the inner cavity and at least one ventilation orifice formed in the outer wall in order to allow the hot air flow to escape after heating the internal cavity, the air intake comprising at least one disruption member of the external air flow, positioned upstream of the ventilation orifice, which extends outwardly from the outer wall.

Abstract: An air intake of a turbojet engine nacelle includes an annular structure including an outer fairing defining an aerodynamic outer surface and an inner fairing defining an aerodynamic inner surface. The outer and inner fairings are connected upstream by an air intake lip forming a leading edge. The inner fairing includes an outer skin fixed to the air intake lip by an upstream fixation flange, and the outer skin is configured to be fixed to an outer fan casing by a downstream fixation flange. The air intake includes at least one independent acoustic panel attached to the outer skin and which includes a perforated acoustic skin and a cellular core.

Abstract: An air intake for a nacelle for an aircraft engine includes a front lip connecting a substantially cylindrical internal wall and a substantially cylindrical external wall, and at least one acoustic structure including acoustic cells. The acoustic structure is situated in the space delimited by the internal wall, the external wall and the front lip. The acoustic structure is an added part secured to the air intake. The acoustic cells of the acoustic structure are arranged facing a region of the internal wall or of the lip at a predetermined distance so that the acoustic cells of the acoustic structure are not in contact with the internal wall or the lip while providing an acoustic attenuation function.

Abstract: An acoustic attenuation panel for a propulsion unit including a nacelle and a turbojet engine includes a cellular core disposed between an inner skin and an outer skin, called acoustic skin, the acoustic skin including a plurality of acoustic apertures, the acoustic apertures being inclined, at a non-zero inclination angle (?) relative to the direction normal to the acoustic skin, upstream with respect to the flow direction of the air or gas flow to which the panel is intended to be subjected under normal operating conditions, that is to say upstream of the propulsion unit when the panel is mounted in such a unit.

Abstract: A method for manufacturing a sound attenuating panel uses an alveolar-core structure including a first edge and a second edge separated by alveolar cells, the alveolar cells including walls extending from the first and second edges and defining a primary conduit for the circulation of a sound wave that is to be attenuated. The method includes covering the first edge or the second edge of the alveolar-core structure with a compartmentation wall; deforming the compartmentation wall to define at least one secondary conduit for the circulation of a sound wave that is to be attenuated, the secondary conduit extending at least partially within said primary conduit; and creating an opening in the compartmentation wall to permit communication between the primary and secondary conduits.

Abstract: A method for producing an acoustic attenuation panel from a composite material with a ceramic oxide matrix is provided that includes draping a plurality of plies having fibrous reinforcements including fibers of ceramic material in a mold to define a first skin, depositing blocks made of fugitive material on the first skin such that a space between two blocks is defined, and draping a second plurality of plies on a surface formed by the blocks such that a second skin is defined. Rounded corners of the blocks define radii for connecting the first and second skins with walls of a honeycomb core of the acoustic panel. The method further includes using a liquid medium to infiltrate the skins and spaces with a precursor of a ceramic phase, removing the liquid medium by evaporation or polymerization, and sintering to consolidate the ceramic oxide material and removal the fugitive material.

Abstract: The present disclosure particularly relates to an acoustic attenuation structure for a propulsion assembly of an aircraft. The acoustic attenuation structure includes an acoustically reflective wall and a sandwich panel. The sandwich panel includes a honeycomb structure surrounded by two acoustically porous skins, a rear skin and a skin. The acoustically reflective wall and the sandwich panel are arranged in such a way as to be separated by a layer of air.

Abstract: An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.