Monolithic Acoustic Panel for Aircraft Nacelle Inlet Noise
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Solution Overview
Problem
Aircraft engine noise reduction is challenging due to noise generated by the engine nacelle inlet area, where existing acoustic panels have non-acoustically treated areas for attachment and exposed fasteners that disrupt airflow, leading to noise amplification.
Innovation Solution
The development of monolithic, layered composite acoustic panels with a perforated film, sound attenuating core, and a structural layer with through-holes for fasteners, ensuring complete acoustic treatment and structural integrity, eliminating noise-generating discontinuities and projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If acoustic panels use separate panel halves joined with splice fittings and fasteners, then attachment to nacelle inlet is achieved, but noise is generated due to exposed fasteners and discontinuities in the smooth surface
Solution Approach 1:
The patent merges two separate acoustic panel halves into a single monolithic acoustic panel that forms a complete hoop shape. This eliminates the splice fitting and exposed fasteners that caused noise, while maintaining the necessary attachment capability through integrated through-holes in the structural layer.
Solution Approach 2:
The monolithic acoustic panel is constructed with segmented functional layers (acoustic treatment layer, core layer, structural layer) that are bonded together. This segmentation allows each layer to perform its specific function while forming an integrated whole that eliminates surface discontinuities.
2Strength
If acoustic panels have non-acoustically treated areas for attachment, then structural strength is provided, but noise attenuation is reduced in those areas
Solution Approach 1:
The acoustic panel applies acoustic treatment material to specific local areas where needed, rather than uniformly across the entire panel. The acoustic treatment layer is positioned to cover noise-generating surfaces, while through-holes are strategically placed in the structural layer for attachment, minimizing the impact on overall noise attenuation.
3Object-generated harmful factors
If a monolithic acoustic panel design is used to eliminate splice fittings, then noise from exposed fasteners is reduced, but manufacturing complexity increases
Solution Approach 1:
The monolithic acoustic panel is constructed as a composite structure with multiple functional layers (acoustic treatment layer, core layer, structural layer) bonded together. This composite construction allows the panel to be manufactured as a single integrated unit with embedded attachment features, eliminating the need for separate splice fittings while maintaining manufacturability through layered assembly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides effective noise attenuation around the entire nacelle inlet circumference, maintaining structural strength for secure attachment, and can be retrofitted to existing engines, reducing noise levels without the need for splice fittings and exposed fasteners.
Implementation Method 1
The acoustic panel is comprised of a perforated film, a sound attenuating core, and a structural layer
Data Source
AI summary
An acoustic, noise-attenuating panel for an aircraft engine nacelle inlet. The panel includes at least three layers: (a) a perforated film; (b) a sound attenuating core; and (c) a structural layer. The structural layer has through-holes adapted for receiving fasteners that are configured to engage structure of an engine nacelle. The structural layer is fabricated, at least at its ends, of a material sufficiently strong so that when fasteners are engaged in the through-holes in the layer's ends, the fasteners retain the acoustic panel in a nacelle inlet under conditions of use. Alternatively, or in addition, the structural layer ends may be reinforced at the through-holes with reinforcing strips.