Cellular Core with Vertical Stiffeners for Low Frequency Noise Attenuation
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Solution Overview
Problem
Aircraft gas turbine engines generate relatively low frequency noise, which existing acoustic panels struggle to attenuate effectively due to space constraints and structural integrity limitations, while also requiring formability during manufacturing without degrading performance.
Innovation Solution
The acoustic panel features a cellular core with vertical stiffeners configured as structural flanges, baffles, and septums arranged in a corrugated configuration, allowing for vertical bending and increased surface area, which enhances noise attenuation of low frequency noise without increasing panel thickness and maintains structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the acoustic panel is increased to tune resonating chambers for low frequency noise, then noise attenuation performance is improved, but space constraints are violated and device dimensions increase
Solution Approach 1:
The patent introduces vertical stiffeners that extend in the thickness direction (z-axis) to provide structural support, while the resonating chambers are configured to achieve low frequency attenuation without proportionally increasing overall panel thickness. This dimensional differentiation allows acoustic performance improvement without linearly increasing panel thickness.
Solution Approach 2:
The acoustic panel employs a composite structure combining perforated face skin, solid back skin, and cellular core with vertical stiffeners. This composite configuration integrates multiple functional elements (acoustic attenuation, structural support, formability) within a optimized thickness, achieving low frequency noise attenuation without excessive thickness increase.
2Object-affected harmful factors
If the panel thickness is increased to improve low frequency noise attenuation, then acoustic performance is improved, but structural integrity requirements become more difficult to meet without additional support
Solution Approach 1:
The cellular core is segmented into multiple cavities by vertical stiffeners, baffles, and septums. This segmentation creates a structured framework that provides structural integrity while maintaining the acoustic attenuation function. The vertical stiffeners act as internal support elements that reinforce the panel structure without requiring excessive thickness.
Solution Approach 2:
The composite structure integrates the cellular core with vertical stiffeners that provide both acoustic functionality and structural reinforcement. This composite design achieves enhanced structural integrity within the constrained thickness, addressing both acoustic performance and strength requirements simultaneously.
3Object-affected harmful factors
If the panel configuration is modified to improve noise attenuation, then acoustic performance is improved, but formability during manufacturing deteriorates
Solution Approach 1:
The vertical stiffeners are designed with controlled flexibility to enable the panel to be formed into curved surfaces during manufacturing. The stiffener configuration allows temporary deformation during forming operations while maintaining structural integrity during service. This dynamic behavior enables both improved acoustic performance and manufacturability.
Solution Approach 2:
The panel design incorporates parameters that balance formability and acoustic performance, such as the spacing, thickness, and configuration of vertical stiffeners. These parameters can be adjusted to optimize both manufacturability (formability) and acoustic attenuation performance, allowing the panel to be formed during manufacturing while achieving the desired low frequency 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 while maintaining or improving structural integrity and allowing for formability during manufacturing, addressing the limitations of previous acoustic panels.
Implementation Method 1
The vertical stiffener may be configured to enable vertical bending of the wall
Implementation Method 2
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
Implementation Method 3
One or more perforations in the first skin may be fluidly coupled with the bore
Data Source
Figure 1
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Figure 4
AI summary
A structural panel (20) may be configured for attenuating noise. This panel (20) includes a first skin (22), a second skin (24) and a core (26) forming a plurality of cavities (42) vertically between the first skin (22) and the second skin (24). The core (26) may include a wall (36) connected to and extending vertically between the first skin (22) and the second skin (24). The wall (36) may be laterally between and fluidly separate at least a first of the cavities (42) from a second of the cavities (42). The wall (36) may include a vertical stiffener (50). One or more perforations (30) in the first skin (22) may be fluidly coupled with the first of the cavities (42).