Acoustic Liner Internal Separator Structures for Noise Reduction
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Solution Overview
Problem
Conventional acoustic panels in aircraft engines are inefficient in attenuating broadband noise, particularly with the shift towards lower sound frequencies from higher bypass turbofan engines, and they often require thicker, heavier designs that increase aerodynamic drag and reduce engine performance.
Innovation Solution
The introduction of internal separator structures within the acoustic panels, such as hourglass and frusto-conical shapes, which divide cavities into multiple fluid volumes, allowing for tailored sound attenuation across a broader frequency range by adjusting the neck width and volume ratios, thereby improving noise reduction efficiency with reduced thickness and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional acoustic panels are used to attenuate broadband noise, then noise reduction is achieved, but the panel thickness and weight increase, leading to increased aerodynamic drag and reduced engine performance
Solution Approach 1:
The cavity is divided into multiple sub-cavities using internal separator structures (such as hourglass or frusto-conical shapes), which segment the acoustic treatment space. This segmentation allows each sub-cavity to be optimized for different frequency ranges, improving broadband noise attenuation efficiency without requiring increased overall panel thickness or weight.
2Object-affected harmful factors
If conventional acoustic panels are used to attenuate broadband noise, then noise reduction is achieved, but the panel thickness increases, leading to increased aerodynamic drag and reduced engine performance
Solution Approach 1:
The cavity is divided into multiple sub-cavities using internal separator structures (such as hourglass or frusto-conical shapes), which segment the acoustic treatment space. This segmentation allows each sub-cavity to be optimized for different frequency ranges, improving broadband noise attenuation efficiency without requiring increased overall panel thickness or weight.
3Object-affected harmful factors
If conventional acoustic panels are used to attenuate broadband noise, then noise reduction is achieved, but aerodynamic drag increases, reducing engine performance
Solution Approach 1:
The cavity is divided into multiple sub-cavities using internal separator structures (such as hourglass or frusto-conical shapes), which segment the acoustic treatment space. This segmentation allows each sub-cavity to be optimized for different frequency ranges, improving broadband noise attenuation efficiency without requiring increased overall panel thickness or weight.
4Object-affected harmful factors
If internal separator structures are introduced to improve sound attenuation efficiency, then noise reduction across broader frequency range is achieved, but device complexity increases
Solution Approach 1:
The internal separator structures modify the acoustic parameters (volume, neck width, resonance frequency) of each sub-cavity to optimize broadband noise attenuation. By adjusting these parameters, the panel achieves superior sound attenuation efficiency across multiple frequency ranges while maintaining a manageable structural complexity through standardized separator designs.
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 use of internal separator structures in acoustic panels provides a more efficient and linear sound attenuation profile, effectively reducing noise across a wider frequency range, optimizing engine performance by minimizing size and aerodynamic drag while maintaining or improving noise reduction capabilities.
Implementation Method 1
The introduction of internal separator structures within the acoustic panels, such as hourglass and frusto-conical shapes, which divide cavities into multiple fluid volumes, allowing for tailored sound attenuation across a broader frequency range by adjusting the neck width and volume ratios
Implementation Method 2
Acoustic attenuation panels generally have a sandwich structure that includes sheets enclosing a cellular honeycomb-type inner structure
Data Source
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AI summary
An acoustic liner 100, 200, 300 can include a support layer 110, 210 with a set of partitioned cavities 120, 220, 320 defining a set of cells with open faces 122, a first facing sheet 131, 231 operably coupled to the support layer 110, 210 such that the first facing sheet 131, 231 overlies and closes the open faces 122, and a set of internal separator structures 150, 250, 350 within at least some of the set of partitioned cavities 120, 220, 320.