Acoustic Panel Sidewall Stringers for Low-Frequency Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft gas turbine engines generating relatively low frequency noise pose a challenge for acoustic panels due to space constraints, requiring effective noise attenuation without increasing panel thickness, while also simplifying assembly, complexity, and cost.
Innovation Solution
The acoustic panel features a cellular core with a corrugated body, top, and bottom stringer bodies, forming an open cavity structure with extended resonance chambers that allow for low-frequency noise attenuation without increasing the panel's vertical thickness, using materials like metals, polymers, or fiber-reinforced composites, and employing manufacturing methods such as welding or mechanical fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the core thickness is increased to tune resonating chambers for low frequency noise, then noise attenuation performance is improved, but panel thickness increases which violates space constraints
Solution Approach 1:
The patent introduces stringer bodies that extend in the longitudinal direction (along the flow of sound waves) to create extended resonance chambers. This transforms the resonance chamber geometry from a simple thickness-based dimension to a multi-dimensional structure, allowing low frequency noise attenuation without increasing panel thickness in the vertical direction.
Solution Approach 2:
The resonance chambers are segmented into multiple sections by dividing them into a first section and a second section with different cross-sectional areas. This segmentation allows the chambers to maintain compact vertical dimensions while achieving the effective acoustic length needed for low frequency noise attenuation through the longitudinal extension.
2Object-affected harmful factors
If traditional acoustic panel configurations are used, then noise attenuation is achieved, but assembly complexity and manufacturing cost increase
Solution Approach 1:
The stringer bodies are integrated directly into the cellular core structure, merging the structural support function with the acoustic resonance function. This integration eliminates the need for separate assembly steps for stringers and core, reducing manufacturing complexity and cost while maintaining effective noise attenuation.
3Object-affected harmful factors
If traditional acoustic panel configurations are used, then noise attenuation is achieved, but manufacturing cost increases
Solution Approach 1:
The stringer bodies serve dual functions: providing structural support to the panel and creating the extended resonance chambers for acoustic attenuation. This multi-functionality reduces the need for additional components and assembly operations, thereby lowering manufacturing cost while achieving effective noise attenuation.
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
This configuration effectively attenuates low-frequency noise without increasing panel thickness, reduces assembly complexity and cost, and allows for efficient noise reduction in aircraft propulsion systems, including turbofan and turbojet systems.
Implementation Method 1
The honeycomb core includes a plurality of resonating chambers. These resonating chambers are tuned by selecting a desired chamber length and, thus, core thickness that corresponds to a specific target frequency of noise to be attenuated.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A panel is provided for attenuating noise. This panel includes a porous first skin, a second skin and a core (26), which is connected between the porous first skin and the second skin. The core (26) includes a corrugated body (42) and a plurality of stringer bodies (44). The corrugated body (42) includes a plurality of corrugations (48) configured from at least a plurality of baffles (52) and a plurality of porous septums (54). Each of the corrugations (48) includes a respective one of the baffles (52) and a respective one of the porous septums (54). A first of the corrugations (48) forms a first channel (78) that extends laterally between a first of the baffles (52) and a first of the porous septums (54). The stringer bodies (44) are spaced longitudinally along the first channel (78). Each of the stringer bodies (44) includes a first sidewall (82) disposed within the first channel (78) and configured to fluidly isolate longitudinally adjacent portions of the first channel (78) from one another.