Seamless acoustic liner

摘要

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).

主权项

1. 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 first composite material laminate to form a face-layer; subjecting said first laminate to a first polymerisation cycle 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, the sound absorbing layer comprising a plurality of discrete cells defined by cell walls; laying-up a second composite material laminate onto the sound absorbing layer to form a backing sheet; subjecting the entire composite acoustic panel to a second polymerisation cycle at a second polymerisation pressure; and perforating the face-layer at a plurality of positions and to a pre-determined depth, wherein the perforations range in diameter from 50 microns to 1.6 mm and are arranged to coincide with and penetrate at least one of the cell walls of the sound absorbing layer thereby connecting two adjacent cells.