Lipskin Assembly Noise Attenuation via Segmented Core
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Solution Overview
Problem
Conventional lipskin assemblies for jet engines face challenges in noise attenuation due to the high cost and time required for precise formation of small perforations, which limits their acoustic performance and structural integrity.
Innovation Solution
A noise attenuating lipskin assembly is designed with a linear facesheet coupled between an acoustic core and a lipskin, featuring a plurality of openings that form tortuous paths for heated air transpiration, reducing the need for extensive perforation formation in the lipskin and allowing for larger openings while maintaining structural integrity, and utilizing a combination of acoustic cores with varying thicknesses to enhance noise damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small perforations are formed densely in the lipskin to improve noise attenuation, then acoustic performance is improved, but manufacturing cost and time increase prohibitively
Solution Approach 1:
The lipskin assembly is divided into multiple functional layers: a lipskin layer with fewer openings, a core layer with noise attenuating structure, and a backsheet layer. This segmentation allows each layer to contribute differently to noise attenuation, reducing the need for excessive perforations in the lipskin while maintaining acoustic performance.
Solution Approach 2:
A core layer is introduced as an intermediary between the lipskin and the backsheet. This core layer contains the noise attenuating structure and works in conjunction with the lipskin openings to achieve effective noise attenuation without requiring the lipskin itself to have dense perforations, thereby reducing manufacturing complexity.
2Reliability
If the lipskin has high porosity to improve noise attenuation, then acoustic performance is improved, but structural strength decreases
Solution Approach 1:
The noise attenuation function is segmented from the lipskin structure and placed in a separate core layer. This allows the lipskin to maintain its structural integrity with fewer and larger openings, while the core layer provides the noise attenuation function through its internal structure.
Solution Approach 2:
The lipskin assembly uses a composite structure combining the lipskin material, core material, and backsheet material. This composite construction allows optimization of each layer for its specific function: the lipskin for structural strength, the core for noise attenuation, and the backsheet for additional support.
3Reliability
If extensive perforation formation is performed on the lipskin to improve noise attenuation, then acoustic performance is improved, but manufacturing complexity increases
Solution Approach 1:
The noise attenuation function is segmented into a separate core layer with its own internal structure, rather than relying solely on lipskin perforations. This segmentation simplifies lipskin manufacturing while maintaining acoustic performance through the combined structure.
Solution Approach 2:
The noise attenuating structure is extracted from the lipskin and placed in a separate core layer. This extraction eliminates the need for complex perforation formation in the lipskin, as the noise attenuation function is now provided by the core's internal structure working in conjunction with fewer, simpler openings.
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 results in a lightweight, efficient, and cost-effective engine nacelle with improved noise attenuation and structural rigidity, reducing manufacturing complexity and excrescence drag, while maintaining ice prevention capabilities.
Implementation Method 1
sound waves generated inside the engine propagate forward and enter the cells of the honeycomb core through the lipskin and reflect from the backsheet at a phase different from the entering sound waves to facilitate damping the incoming sound waves and attenuating the overall noise level
Implementation Method 2
Heated air flows through the perforated backsheet, into the core, and transpires through the perforated lipskin to prevent ice from forming on the nacelle
Data Source
AI summary
An acoustic assembly includes a backsheet including a plurality of perforations defined therethrough and an acoustic core coupled to the backsheet. The acoustic core includes a plurality of channels defined therethrough that are configured to be in flow communication with the plurality of perforations. The acoustic assembly also includes a linear facesheet coupled to the acoustic core, wherein the linear facesheet includes a plurality of apertures configured to be in flow communication with the plurality of channels. A lipskin is coupled to the linear facesheet, wherein the lipskin includes a plurality of openings configured to be in flow communication with the plurality of apertures.