Acoustic Absorbent Assembly with Nested Tubes and Honeycomb
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Solution Overview
Problem
Existing acoustically absorbent materials for aircraft engines are effective for specific acoustic frequencies but are complex to manufacture and do not provide broad-band attenuation.
Innovation Solution
A multi-layer assembly comprising a first and second panel with holes, an intermediate panel with through-holes and tubes, and honeycomb structures between the panels, where the intermediate panel and tubes are made of acoustically rigid materials, forming Helmholtz and quarter-wave resonators for broad-band frequency attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional honeycomb structures or truncated cones are used for acoustic attenuation, then specific acoustic frequencies are effectively attenuated, but the device complexity increases and manufacturing becomes difficult
Solution Approach 1:
The assembly is divided into multiple functional layers: first panel with holes, intermediate panel with through-holes, and second panel with holes. Each layer serves a specific acoustic function, allowing independent optimization of each segment while achieving broad-band attenuation collectively. This segmentation reduces the complexity of designing a single complex structure.
Solution Approach 2:
Tubes are nested within the honeycomb structures, with tube ends positioned inside the hexagonal cells. The intermediate panel with through-holes is nested between the two honeycomb structures. This nesting arrangement integrates multiple functional elements (tubes for low-frequency attenuation, honeycomb for high-frequency attenuation) into a compact unified structure.
2Reliability
If traditional honeycomb structures or truncated cones are used for acoustic attenuation, then specific acoustic frequencies are effectively attenuated, but the ease of manufacture decreases
Solution Approach 1:
The assembly consists of discrete layers (first panel, intermediate panel, second panel) and standardized components (honeycomb structures, tubes) that can be manufactured independently using conventional processes, then assembled together. This segmentation allows each component to be optimized for its specific manufacturing process.
Solution Approach 2:
The honeycomb structures serve dual functions: providing structural support and acting as acoustic absorbers for high-frequency noise. The tubes provide both structural support and function as resonators for low-frequency attenuation. This multi-functionality reduces the number of separate components needed, simplifying manufacturing.
3Reliability
If single-frequency acoustic absorbers are used, then specific frequencies are attenuated effectively, but the adaptability to handle multiple acoustic frequencies is limited
Solution Approach 1:
The acoustic spectrum is segmented into different frequency ranges, with each layer targeting specific bands. The tubes with varying lengths address low-frequency ranges, while the honeycomb structures address high-frequency ranges. This segmentation of the frequency spectrum allows each component to be optimized for its target band while collectively providing broad-band attenuation.
Solution Approach 2:
Different regions of the assembly have different acoustic properties tailored to specific frequency ranges. The tubes with varying lengths create local resonant frequencies for different low-frequency bands, while the honeycomb cell structures provide localized absorption for high frequencies. This local optimization of acoustic properties enables broad-band performance.
4Adaptability or versatility
If complex multi-structure assemblies are used for broad-band attenuation, then multiple acoustic frequencies can be attenuated, but the device complexity increases
Solution Approach 1:
The tubes are nested within the honeycomb structures, with tube ends positioned inside the hexagonal cells. The intermediate panel is nested between the two honeycomb structures. This nesting integrates multiple functional elements into a compact unified structure, reducing overall assembly complexity.
Solution Approach 2:
The assembly merges two distinct acoustic absorption mechanisms (Helmholtz resonators via tubes and quarter-wave resonators via honeycomb structures) into a single integrated unit. The panels and honeycomb structures are combined to form a unified assembly that provides both low-frequency and high-frequency attenuation simultaneously.
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 assembly achieves easy manufacturing and effective broad-band attenuation of acoustic frequencies, with adjustable tube lengths and materials ensuring flexibility and efficiency.
Implementation Method 1
the first structure (112), with the first panel (102), the intermediate panel (110) and the tubes (130) form a Helmholtz resonator that attenuates the acoustic low frequencies
Implementation Method 2
The second structure (114), with the second panel (104) and the intermediate panel (110) form a quarter-wave resonator that attenuates the acoustic high frequencies
Implementation Method 3
The intermediate panel (110), the second panel (104) and the tubes (130) are produced from acoustically rigid materials
Data Source
AI summary
An assembly constituting an acoustically absorbent material and including a first panel, a second panel pierced with holes, an intermediate panel pierced with through-holes and arranged between the first panel and the second panel, a first structure between the first panel and the intermediate panel and including first cages, a second structure between the second panel and the intermediate panel and including second cages, and for each through-hole of the intermediate panel, a tube opening out at the two ends thereof, where one of the ends of the tube is fixed to the intermediate panel at the through-hole, and where the other end of the tube is accommodated inside a first cage. Such an assembly makes it possible to obtain broad-band attenuation and is easy to manufacture.