Method of manufacturing a sound absorbing panel
The present disclosure provides a method of manufacturing a sound absorbing panel in which a reflective wall on one of faces of a set of sound absorbing cells. In particular, a passage on a portion of a thickness (E) of the set of sound absorbing cells is formed on an opposite face of the one of the faces, while the passage forming a main channel for a communication between sound absorbing cells and for a circulation of a de-icing fluid.
1. A method of manufacturing a sound absorbing panel in which a reflective wall on at least a portion of one of faces of a set of sound absorbing cells is provided, wherein on an opposite face of said one of the faces at least one passage on a portion of a thickness (E) of said set of sound absorbing cells is formed, said at least one passage forming at least one main channel through which the sound absorbing cells communicate with each other and a de-icing fluid circulates through the sound absorbing cells, wherein the set of sound absorbing cells is formed by expanding at least two sheets bonded together in reduced bonding areas (Z′) forming a partial bonding along an entire length of adjacent webs of the cells, such that upon expansion of said at least two sheets, said at least one passage is formed, thereby forming said at least one main channel of fluid communication between the sound absorbing cells for circulation of the de-icing fluid.
2. The method of manufacturing a sound absorbing panel according to claim 1 , wherein metal strips are fixed over at least a portion of an inner wall or an outer wall of the sound absorbing panel, in a direction substantially transverse to that of the main channel direction.
3. The method of manufacturing a sound absorbing panel according to claim 1 , wherein said set of sound absorbing cells comprises an alveolar core structure comprising a plurality of alveolar cells.
4. The method of manufacturing a sound absorbing panel according to claim 1 , wherein the set of sound absorbing cells is formed by expanding at least two sheets bonded together in bonding alternating zones (Z).
5. The method of manufacturing a sound absorbing panel according to claim 1 , wherein upon expansion of said at least two sheets, secondary channels are formed substantially transverse to said at least one main channel.
6. The method of manufacturing a sound absorbing panel according to claim 1 , wherein one machines on one of the faces of the set of the sound absorbing cells at least one groove forming said at least one passage.
7. The method of manufacturing a sound absorbing panel according to claim 6 , wherein said at least one groove is profiled in a length direction or in a width direction of the set of the sound absorbing cells.
8. The method of manufacturing a sound absorbing panel according to claim 6 , wherein said at least one groove is profiled inclined with respect to a length or a width of the set of sound absorbing cells.
9. The method of manufacturing a sound absorbing panel according to claim 1 , wherein the set of sound absorbing cells comprises a sound open-cell foam.
10. A sound absorbing panel made by the method of manufacturing according to claim 1 .
11. A nacelle for aircraft turbojet engine comprising an upstream section forming an air inlet lip of an air flow “F” to mitigate acoustically, a middle section and a downstream section, wherein at least one section of said nacelle comprises at least one sound absorbing panel according to claim 10 .
12. The nacelle for an aircraft turbojet engine according to claim 11 , wherein the sound absorbing panel is fixed in an outer part of the air inlet lip, and said nacelle comprises a de-icing device adapted to track a de-icing fluid from an inlet conduit to a discharge chamber of said de-icing fluid through at least one main channel of communication between said sound absorbing cells.