Abstract:
An anterior part of an aircraft propulsion assembly nacelle, having an air intake lip disposed at a front end and an outer panel, of which an outer face extends an outer part of the air intake lip. A front edge of the outer panel and a rear edge of the air intake lip are shaped so as to overlap radially and to nest so as to ensure a continuous surface between the outer surface of the outer part of the air intake lip and the outer face of the outer panel. Moreover, the front edge of the outer panel is connected to the rear edge of the air intake lip with no added rigid element. This permits a rigid connection while avoiding creating local irregularities on the outer surface of the nacelle, which irregularities might disrupt the flow of air around the nacelle, giving rise to additional drag.
Abstract:
A method for producing an alveolar soundproofing structure in which a portion of a membrane of a diaphragm including an acoustic outlet is inserted into a hole of a perforated membrane which covers a cell of the alveolar structure, and the diaphragm is pressed into the cell with the perforated membrane becoming deformed and is fixed at that location. It also relates to the alveolar structure. Such a method enables different types of diaphragms to be inserted into different configurations of cells and enables the diaphragm to be fixed therein, in accordance with the sound frequencies to be processed.
Abstract:
A resistive skin shell for an acoustic panel or inner wall of an aircraft air intake, comprising an alternation, in a transverse direction, of perforated metal bands and of composite solid bands extending in a longitudinal direction. The perforated metal bands and the composite solid bands form a smooth outer face configured to be in contact with an aerodynamic stream, and a crenelated inner face. The composite solid bands have a thickness greater than the perforated metal bands. Since the perforations are provided in metal bands, which are intrinsically resistant to wear and erosion, the future proofing of the acoustic performance of the resistive skin is guaranteed. Since the composite solid bands, which are thicker, can ensure the mechanical strength of the skin, the thickness of the perforated metal bands can be reduced, allowing perforations with dimensions that are also reduced, having a lower impact on drag.
Abstract:
An acoustic panel comprising a cellular structure, such as a honeycomb structure, having cells that open at least onto a first frontal face of the structure. The panel comprises a capsular skin which is fastened to the first frontal face of the cellular structure next to a plurality of cells. The capsular skin including a continuous layer of material, in one piece, forming capsules that extend into the cellular structure. At least one channel is provided at the apex of each capsule for the passage of acoustic waves. Such a panel effectively attenuates the noise of aircraft engines, in particular, the low frequencies. It is extremely easy to manufacture industrially, the capsular skin being able to be obtained by molding with polymerization in situ, the polymerizable material then adhering to the cellular structure while it polymerizes.
Abstract:
An anterior part of a nacelle of an aircraft propulsion assembly, which comprises an air intake lip, an outer panel extending an outer part of the air intake lip, an inner structure extending an inner part of the air intake lip, a front frame connecting the outer wall to the air intake lip or to the inner structure. The outer panel and the outer part of the air intake lip together form an outer wall of the anterior part. The front frame and the outer wall are connected to one another by assembly means located inside the anterior part. The anterior part constituted in this manner ensures laminar flow of the air on an outer surface of the anterior part and reduces drag. A nacelle of a propulsion unit, comprising an anterior part of this kind is also provided.
Abstract:
A strip-form acoustic material, the strip having a length in a longitudinal direction, a width in a transverse direction, a thickness and axial ends. At least one of the axial ends of the strip, in an end portion of the length of the strip, the strip of material is folded in a substantially transverse plane.
Abstract:
A production method for an acoustic panel comprising a step of producing a composite structure, a step of providing inserts, wherein each insert comprises a nozzle formed as a hollow cylinder with a through-bore and a cap comprising a base formed as a cylinder and a cover formed as a cone, and wherein the base is accommodated in the bore, a step of positioning the inserts in the composite structure by penetration of the cover into the composite structure so that the bore opens at one side and the other of the composite structure, a step of polymerizing during which the composite structure with the inserts is polymerized, a step of removing the caps, a first step of fixing a honeycomb structure to the polymerized composite structure, and a second step of fixing a rear skin to the honeycomb structure.
Abstract:
The invention relates to a wall made from a composite material comprising at least two layers of fibers (18, 18′) embedded in a resin matrix, a crack being able to spread in said wall in a direction of propagation, characterized in that it comprises at least one longilineal metal reinforcement (20), oriented in a direction secant to the direction of propagation, inserted between two layers of fibers (18, 18′) of the wall.
Abstract:
A cellular sound insulation structure and associated aircraft, a cell of which is provided with a diaphragm which includes a membrane having at least one orifice passing through a thickness of the membrane, and at least one tube surmounting the orifice and extending from a face of the membrane into one compartment of the cell, the tube comprising a free end, forming an acoustic outlet, which is positioned at a distance (p) from the base cross section of the cell. Also, a method for manufacturing such a cellular sound insulation structure, as well as to a tool for inserting a diaphragm into a cell. Such a cellular structure makes it possible to treat a wider acoustic frequency spectrum, and its acoustic dimensioning as well as its manufacture are simplified.
Abstract:
An acoustic panel for an aircraft nacelle air intake comprising a resistive skin perforated by noise absorption holes and a core against which the resistive skin extends, wherein the resistive skin has a smooth visible face and a castellated rear face with alternating ribs and grooves. The noise absorption holes are formed exclusively in the grooves, i.e., in a zone where the skin is less thick, which enables the holes to have a diameter that is both greater than the thickness of the skin and small enough not to have any impact on drag. The mechanical strength of the resistive skin provided by the ribs ensures that the lesser thickness of the resistive skin in the grooves does not render the resistive skin overly flexible.