Seamless acoustic liner
AssigneeGKN Aerospace Services Limited
InventorArmando Vavalle
Life of this patent
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Abstract
The invention relates to a method of manufacturing a composite acoustic panel employed in an inlet passage of a gas turbine engine (1). The acoustic panel comprises a permeable face-layer (8), an impermeable backing sheet (9) and a sound absorbing layer (10) disposed therebetween. The method comprises a double polymerisation process for the face-layer and the remainder of the acoustic panel and finally a perforation step to perforate the face-layer according to a pre-determined perforation distribution (11.1, 11.2, 11.3, 11.4, 11.5).
Claims35
A method of manufacturing a composite acoustic panel comprising a
- permeable face-layer, an impermeable backing sheet and a sound absorbing layer disposed therebetween,
- the method comprising the steps of:
- laying-up a composite material laminate to form a face-layer;
- polymerising said laminate to form a substantially continuous face-layer at a first polymerisation pressure of approximately atmospheric pressure or at a pressure greater than atmospheric pressure;
- laying-up of a sound absorbing layer onto the polymerised face-layer;
- laying-up a composite material laminate onto the sound absorbing layer to form a backing layer;
- polymerising the entire composite acoustic panel at a second polymerisation pressure;
- and
- perforating the face-layer at a plurality of positions and to a pre-determined depth.
A method of perforating a face-sheet of a composite acoustic panel with a predetermined perforation distribution pattern, said panel comprising a seamless face-layer, an impermeable backing sheet and a sound absorbing layer disposed therebetween,
- the method comprising the steps of:
- A—aligning a perforating apparatus relative to the seamless face-sheet at a first perforating position;
- B—activating the perforating apparatus to form at least one perforation through the face sheet;
- C—moving the acoustic panel and the perforating apparatus relative to one another by a predetermined amount to align the perforating apparatus with a subsequent perforation position;
- and
- D—repeating steps B and C until the desired perforation distribution is achieved, and wherein the penetrations extend into the sound absorbing layer to a maximum depth corresponding to the position of the septum where the septum tail extends toward the backing-layer or to a maximum depth corresponding to the position of the septum tail where the septum extends towards the face-layer, and
- the perforations are arranged to coincide with at least one wall of the cells of the sound absorbing layer defining a boundary between adjacent cells.
(canceled)
(canceled)
A method of perforating an acoustic panel, said panel comprising a substantially continuous face-layer, an impermeable backing layer and a honeycomb sound absorbing layer disposed therebetween, said layer comprising a plurality of discrete cells, the method comprising the steps of:
- A—pre-determining a perforation depth h according to:
- h=t+∈ where h is the total perforation depth
- t is the thickness of the facesheet
- ∈ is the perforation depth into the sound absorbing layer
- B—pre-determining a perforation spacing and distribution pattern for the face-layer surface;
- C—aligning a perforating apparatus with the face-layer;
- D—perforating the face-layer to the predetermined perforation depth h;
- E—moving the acoustic panel relative to the perforating apparatus to align the perforating apparatus with a subsequent perforation position;
- and
- F—repeating steps D and E until a desired portion of the face-layer has been perforated.
(canceled)
(canceled)
Dependencies are inferred from the claim text.