Abstract: An internal duct of an aircraft engine pod may include a fan and a tubular air intake having a first acoustic attenuation internal tubular piece. The first acoustic attenuation internal tubular piece is acoustically homogeneous, is of the resonator type, and has no internal assembly fish-plate. Additionally, the internal duct may include a tubular fan casing and a tubular transition part for connecting the air intake to the fan casing. An internal face of the tubular transition part is acoustically homogeneous also. Moreover, the internal face of the first acoustic attenuation internal tubular piece and the internal face of the tubular transition part are disposed in aerodynamic continuity.

Abstract: A process for the production of a panel (9) with a fitted acoustically resistive layer, including at least one central core with porous structure bounded on one side by a structural layer covered with a porous acoustically resistive layer and, on the other side, by a total acoustical reflector, in which, successively, acoustically resistive strips are laid down to form the layer on a mold (M) shaped like the panel to be obtained, the structural layer is emplaced, the core of porous structure is emplaced, the total reflector is emplaced, then the mold (M) is withdrawn from the panel. When laying down on the mold (M) the acoustically resistive layer, the porosity of this latter is locally adapted to correspond with the characteristics of the sonic wave at the point of impact, the correlation between characteristics and impact region being previously determined by conventional acoustical techniques applied to a test panel identical to that to be produced.

Abstract: Aircraft engine pod with acoustic attenuation.

Abstract: Noise reduction sandwich panel, notably for an aircraft turbojet engine. In order to produce a noise reduction sandwich panel having a structure with two degrees of freedom, inserted separative components (20) are placed into the hexagonal cells (16) of the unique waffle core of the panel. More specifically, the separative components (20) have an substantially circular external peripheral edge, which allows them to be easily assembled, in spite of the deformations of the walls (18) of the cells (16) due to manufacturing tolerances and to the optional forming of the waffle core. Advantageously, several separative components (20) are supported by a same positioning unit (22), which then allows relative displacement between the separative components.

Abstract: A process for the production of an acoustical attenuating panel comprises emplacing on a mold a layer (1′a) with structural properties constituted by filaments (7, 8) pre-impregnated with a thermoplastic or thermosetting resin, by draping, winding or wrapping, such that the layer has an open surface quantity of about 30% of the total surface of the exposed layer, emplacing from above the layer with structural properties a layer (1′b) with acoustical properties constituted by a microporous cloth of a thickness of about one tenth of that of the layer with structural properties, then emplacing a cellular structure (2) and a reflector (3) with if desired the addition of an adhesive (5, 6) between the components, at least one step of baking in an autoclave being practiced at the end of at least one of the above-mentioned emplacing steps.

Abstract: The object of the invention is a process for the production of a panel (9) with a fitted acoustically resistive layer, of the type comprising at least one central core with porous structure bounded on one side by a structural layer covered with a porous acoustically resistive layer and, on the other side, by a total acoustical reflector, in which, successively, acoustically resistive strips are laid down to form said layer on a mold (M) shaped like the panel to be obtained, said structural layer is emplaced, said core of porous structure is emplaced, said total reflector is emplaced, then the mold (M) is withdrawn from the panel, characterized in that the course of laying down on the mold (M) the acoustically resistive layer, the porosity of this latter is locally adapted to correspond with the characteristics of the sonic wave at the point of impact, the correlation between characteristics and impact region being previously determined with the help of conventional acoustical techniques applied to a test pane

Abstract: Noise reduction sandwich panel, notably for an aircraft turbojet engine.

Abstract: An acoustically resistive layer comprises at least one layer (12) of acoustic damping cloth and a reinforcing material comprising a sheet (14, 114, 214, 314) of filaments (16) secured to the acoustically damping cloth. The filaments (16) are disposed unidirectionally, bidirectionally or multidirectionally. A process for producing such an acoustically resistive layer, comprises positioning an acoustically damping cloth (12) on a mold (18) having the shape of the layer to be obtained, and disposing on this acoustically damping cloth filaments (16) impregnated with a binder by filamentary winding, and then withdrawing the layer thus obtained from the mold, or by laying with application of pressure, and withdrawing the layer thus obtained from the mold.