Multi-layer acoustic linings
AssigneeROLLS-ROYCE plc
InventorJohn F. Chapman
Life of this patent
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Abstract
A multi-layer acoustic lining is of the type having core compartments rendered effective as Helmholtz resonators by means of resonator necks projecting from the core facing layer into the core compartments. In order to broaden the frequency response, those ends of the resonator necks which project into the core compartments are bevelled so as to give the necks a less well defined length. The acoustic lining is particularly for application to the jet pipe or fan duct of a turbofan aeroengine.
Claims5
For a fluid-flow duct in a gas turbine engine, a multi-layer acoustic lining comprising an air-impermeable backing layer, a compartmented-airspace core structure, a core facing layer overlying said core structure and incorporating apertures having predetermined cross-sections through which sound energy can enter the core, and tube-like Helmholtz resonator necks having bodies with cross-sections substantially the same as the cross-sections of said apertures which extend from said apertures into said core structure such that an end of each resonator neck is situated within a core compartment and spaced from walls thereof to thereby render core compartments effective as Helmholtz resonators;
- wherein the improvement is that said end of each resonator neck within said core structure is a biased configuration such that said end lies in a plane extending at an acute angle with the body of said neck.
Dependencies are inferred from the claim text.