Aircraft Acoustic Panel Combining Resonators for Wideband Attenuation
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Solution Overview
Problem
Existing acoustic panels for aircraft propulsion units face difficulties in manufacturing due to the complex operations of inserting tubes and arranging diaphragms in cellular structures to achieve noise absorption across a wide frequency band.
Innovation Solution
An acoustic panel design that combines two sets of resonators - quarter-wave and Helmholtz resonators - using superposed cellular structures with aligned perforations and adhesive layers, eliminating the need for tube insertion and diaphragm arrangement, and a simplified manufacturing method involving identification and assembly steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tubes are inserted into all cells of one cellular structure to combine quarter-wave and Helmholtz resonators, then noise absorption over a wide frequency band is achieved, but manufacturing complexity increases significantly
Solution Approach 1:
The patent merges the functions of quarter-wave resonators and Helmholtz resonators into a single integrated acoustic panel without requiring separate tube insertions. The cellular structure is designed so that adjacent cells with different cross-sectional areas directly provide both resonator types, eliminating the need for additional tubes and simplifying manufacturing while maintaining wide frequency band noise absorption.
Solution Approach 2:
The cellular structure is designed to perform multiple functions simultaneously. Each cell configuration serves dual purposes: cells with larger cross-sectional areas function as Helmholtz resonators while adjacent cells with smaller cross-sectional areas function as quarter-wave resonators. This multi-functionality is achieved through the inherent geometric variation in the cellular structure rather than through additional components.
2Adaptability or versatility
If diaphragms are inserted into cells to handle different frequency ranges, then noise absorption performance is improved, but the difficulty of incorporating and positioning diaphragms increases
Solution Approach 1:
The patent extracts the diaphragm component entirely from the design. Instead of inserting diaphragms into cells to create resonators, the invention uses the cellular structure's inherent geometric variation (different cross-sectional areas) to directly define both Helmholtz and quarter-wave resonator behaviors. This eliminates the manufacturing difficulty of incorporating and positioning diaphragms while maintaining the ability to handle different frequency ranges.
Solution Approach 2:
The cellular structure serves itself by using its own geometric variations to define resonator characteristics. The different cross-sectional areas of adjacent cells automatically create the necessary conditions for both Helmholtz and quarter-wave resonance without requiring additional components like diaphragms. The structure's own geometry provides the frequency differentiation capability.
3Reliability
If two cellular structures are separated by a partition with glass-fiber composite material, then acoustic performance is maintained, but manufacturing complexity increases due to multiple assembly steps
Solution Approach 1:
The patent merges what would traditionally be two separate cellular structures into a single integrated cellular structure. By using adjacent cells with different cross-sectional areas within one continuous structure, the design eliminates the need for partitions and glass-fiber composite materials, simplifying manufacturing while maintaining the acoustic performance benefits of having both resonator types.
Solution Approach 2:
The patent uses a single cellular structure material that provides both structural integrity and acoustic functionality. Instead of combining different materials (glass-fiber composites for partitions) to achieve acoustic performance, the invention relies on the geometric configuration and material properties of the unified cellular structure to deliver both structural and acoustic requirements.
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
Facilitates easier manufacturing with improved noise attenuation across a wide frequency range, reducing material mass and cost while maintaining high acoustic performance.
Implementation Method 1
The acoustic panel combines two sets of resonators: a set of quarter-wave resonators provided by the third cellular structure and a set of Helmholtz resonators provided by the first and second cellular structures
Implementation Method 2
The acoustic panel combines two sets of resonators: a set of quarter-wave resonators provided by the third cellular structure and a set of Helmholtz resonators provided by the first and second cellular structures
Implementation Method 3
a resistive skin comprising second perforations
Data Source
AI summary
An acoustic panel for an aircraft providing noise attenuation over a wide frequency band by combining two resonators, and acoustic panel manufacturing method. The acoustic panel includes a rear skin, a cellular structure, an intermediate layer including perforations, a cellular structure, a cellular structure and a resistive skin including perforations. The acoustic panel combines quarter-wave resonators with Helmholtz resonators to provide noise attenuation over a wide frequency range.