Septumized Acoustic Panel for Wideband Noise Attenuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acoustic panels for high bypass aircraft engines are either expensive to fabricate or limited in their ability to attenuate sound over a wide range of frequencies, and current solutions do not efficiently optimize impedance and dampening functions.
Innovation Solution
An acoustic panel with a septumized core and a perforated, linear acoustic facesheet that separates impedance and dampening functions, using automated fiber placement and out-of-autoclave processing to achieve efficient sound attenuation across a wide range of frequencies and sound pressure levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If only a septum in the core is used to dampen incoming acoustic waves, then the fabrication cost is reduced, but the ability to attenuate acoustic waves over a wide range of frequencies is limited
Solution Approach 1:
The acoustic panel is divided into functionally distinct segments: a core with septums for dampening and a separate linear acoustic facesheet for impedance control. This segmentation allows each component to be optimized for its specific function, enabling wide frequency attenuation while maintaining economical fabrication through specialized manufacturing processes for each segment.
Solution Approach 2:
The invention combines different material systems - the core structure with septums and the linear acoustic facesheet made through automated fiber placement. This composite approach integrates materials with complementary acoustic properties, achieving broad frequency range attenuation that neither component could achieve alone.
2Reliability
If a layer of acoustic material is placed on one side of the inner skin to reduce acoustic wave amplitude, then the impedance function is improved, but the frequency range of attenuation remains relatively narrow
Solution Approach 1:
The linear acoustic facesheet is positioned specifically at the interface where acoustic waves first enter the core, creating a localized zone of optimized impedance control. This local quality enhancement at the critical interface enables effective impedance matching across a broad frequency range without requiring uniform acoustic material distribution throughout the entire panel.
Solution Approach 2:
The linear acoustic facesheet utilizes materials and结构设计 that provide impedance control characteristics varying smoothly across frequency, unlike traditional discrete acoustic layers. This parameter optimization enables the facesheet to maintain effective impedance function across a wide frequency spectrum rather than being tuned to specific frequency bands.
3Reliability
If individual septums are used in core cells, then the dampening function is achieved, but the fabrication time and cost increase
Solution Approach 1:
The manual or complex mechanical process of installing individual septums into core cells is replaced by an automated fiber placement process that directly forms the linear acoustic facesheet with integrated dampening functionality. This substitution of manufacturing methodology dramatically reduces fabrication time and cost while maintaining the dampening function through the combined action of the facesheet and core structure.
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 enables the economical fabrication of acoustic panels that effectively attenuate sound over a wide range of frequencies and sound pressure levels, optimizing impedance and dampening functions for improved noise reduction in aircraft engines.
Implementation Method 1
A linear acoustic facesheet on the second side of the core includes a layer of linear material that responds substantially the same to the acoustic waves over a range of acoustic wave frequencies and sound pressure levels
Implementation Method 2
a septum is present within the core between said first and second sides of the core
Implementation Method 3
The placement of septums in the cells of the honeycomb core form cavities that act as Helmholtz resonators which attenuate the sound/noise caused by high speed airflow into the inlets of the engine nacelles
Implementation Method 4
Sound entering the cells of the core is dampened by the septum and reflected by the outer skin to partially cancel the incoming sound over a range of frequencies
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An acoustic panel (10) for sound attenuation employs a septumized cellular core (12) sandwiched between a backsheet (26) and a linear acoustic facesheet (30). The linear acoustic facesheet employs a linear material layer (34) that impedes acoustic waves entering the core substantially linearly over a wide range of frequencies and sound of pressure levels.