Aircraft Acoustic Panel Structure for Thin Low-Frequency Absorption
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Solution Overview
Problem
Conventional acoustic panels struggle to effectively absorb low-frequency sound frequencies due to the need for large cavities, leading to thick panels that are not suitable for aeronautical applications.
Innovation Solution
A sound insulation device with a specific alveolar structure comprising a first sheet with perforations, a second solid sheet, and a sound insulation covering formed by the abutment of longitudinal strips, featuring quarter-wave and Helmholtz cavities with sacrificial portions to maintain acoustic permeability and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional acoustic panels use small-sized cavities, then the panel thickness is reduced, but the ability to absorb low-frequency sounds is lost
Solution Approach 1:
The acoustic panel is divided into multiple functional layers: a first alveolar layer with small cavities for high-frequency absorption, and a second alveolar layer with larger cavities for low-frequency absorption. This segmentation allows each layer to specialize in different frequency ranges, achieving broad-spectrum sound absorption without requiring the entire panel to be thick.
Solution Approach 2:
The invention transitions from a single-layer structure to a multi-layer structure, adding the dimension of layering. By stacking alveolar layers with different cavity characteristics, the panel achieves both thin profile and effective low-frequency absorption capabilities that would be impossible in a single layer.
2Object-affected harmful factors
If the first sheet is perforated to improve acoustic permeability, then sound insulation performance is improved, but the structural integrity of the panel is compromised
Solution Approach 1:
The panel structure implements local quality by having the first sheet perforated only in specific regions where acoustic permeability is needed, while other regions maintain solid structure for strength. The perforations are strategically placed to allow acoustic wave passage while preserving overall panel integrity.
Solution Approach 2:
The invention uses a composite structure combining perforated and solid regions within the first sheet, and combines different alveolar layers with distinct properties. This composite approach allows the panel to simultaneously achieve acoustic permeability where needed and structural strength where required.
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 device effectively treats low-frequency sound frequencies while maintaining structural integrity and reducing panel thickness, enhancing acoustic performance in aircraft nacelles.
Implementation Method 1
at least one cavity which is open in the region of the first sheet and of which a cross section gradually reduces between the first sheet and the second sheet until the cavity is closed, called the quarter-wave cavity
Implementation Method 2
a first abutment of two walls, respectively of the first strip and of the second strip, in contact with each other, such that a passage is formed between the cavity and another cavity, the other cavity, called the Helmholtz cavity
Data Source
AI summary
A sound insulation device comprising at least one cavity, called a quarter-wave cavity, a first abutment of two walls, respectively of a first strip and a second strip, in contact with each other, so that a passage is provided between the cavity and another cavity. The other cavity, called a Helmholtz cavity, is closed by an edge closure, a second joining of two walls, respectively of the first strip and the second strip, in contact with one another. Each of the walls of the first and second abutments include a portion arranged along the closing edge of the Helmholtz cavity, called the sacrificial portion and form the end of the covering.