Honeycomb Acoustic Insert Structure for Low-Frequency Noise Attenuation
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Solution Overview
Problem
Existing sound-attenuating systems for aircraft engines struggle to effectively reduce noise in the lower frequency range without increasing honeycomb cell depth or weight, limiting their adaptability to different frequency ranges.
Innovation Solution
A composite component with acoustic insert bodies having a cohesive surface that encircles or crosses the main axis, subdividing honeycomb cells into multiple cavities to deflect sound waves, thereby increasing resonator length and reducing honeycomb thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the depth of honeycomb cells is increased to achieve sound attenuation in the lower frequency range, then sound attenuation performance is improved, but weight and component dimensions increase
Solution Approach 1:
The honeycomb cell is segmented into multiple acoustic chambers by inserting acoustic septa that divide the cell into two or more separate chambers. This segmentation increases the effective resonator length without increasing the overall honeycomb depth, thereby improving low-frequency sound attenuation while maintaining compact dimensions and reducing weight.
Solution Approach 2:
The acoustic septa extend in the radial direction (across the width of the honeycomb cell) rather than only in the depth direction. This dimensional change allows the resonator length to be increased laterally instead of deepening the cell, achieving the same acoustic effect with reduced thickness and weight.
2Object-affected harmful factors
If the depth of honeycomb cells is increased to achieve sound attenuation in the lower frequency range, then sound attenuation performance is improved, but component dimensions increase
Solution Approach 1:
The honeycomb cell is segmented into multiple acoustic chambers by inserting acoustic septa that divide the cell into two or more separate chambers. This segmentation increases the effective resonator length without increasing the overall honeycomb depth, thereby improving low-frequency sound attenuation while maintaining compact dimensions and reducing weight.
Solution Approach 2:
The acoustic septa extend in the radial direction (across the width of the honeycomb cell) rather than only in the depth direction. This dimensional change allows the resonator length to be increased laterally instead of deepening the cell, achieving the same acoustic effect with reduced thickness and weight.
3Object-affected harmful factors
If conventional acoustic inserts are used to increase resonator length, then sound attenuation in lower frequencies is improved, but adaptability to different frequency ranges is limited
Solution Approach 1:
The position, orientation, and dimensions of the acoustic septa can be varied to adapt the resonator characteristics to different frequency ranges. By adjusting the length, position, and configuration of the septa, the same honeycomb structure can be optimized for different frequency attenuation requirements, enhancing versatility.
Solution Approach 2:
Different acoustic septa can be inserted into different honeycomb cells with varying local characteristics (different lengths, positions, and configurations) to create a distributed acoustic system that covers a broader frequency range. This local variation in septa design enables the structure to adapt to multiple frequency attenuation needs.
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 allows for significant sound attenuation in lower frequencies with reduced honeycomb thickness, enhancing adaptability to various frequency ranges while maintaining a lightweight and compact design.
Implementation Method 1
The honeycomb cells of the honeycomb core here act as acoustic resonators in the manner of a Helmholtz resonator, attenuating or reducing the sound.
Implementation Method 2
The insert body has been or is arranged in a respective honeycomb cell or inserted in a respective honeycomb cell in such a way that the main axis of the insert body runs in the depth direction of said honeycomb cell... the cohesive surface of the insert body has surface regions, spaced from one another in the axial direction or in the direction of the main axis, which face one another and overlap, in particular are aligned with one another, in a projection onto a plane lying perpendicular to the main axis in order to demarcate a passage for sound waves between these surface regions
Data Source
AI summary
A sound-attenuating composite component comprising a honeycomb and in each case at least one insert body in at least some honeycomb cells, and a production method therefor. The respective insert body has a main axis, a first end, a second end, and a cohesive surface and is inserted with the main axis in the direction of the honeycomb depth. The cohesive surface has surface regions spaced from one another in the axial direction and which face one another and overlap in a projection onto a plane lying perpendicular to the main axis in order to demarcate a passage for sound waves in the axial direction. The course of the cohesive surface through these surface regions from the first end to the second end encircles and/or repeatedly crosses the main axis.