Acoustic Panel 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 there is a need for panels with improved structural integrity while maintaining or reducing space usage.
Innovation Solution
The acoustic panel design features a perforated face skin, a solid back skin, and a cellular core with baffles, septa, and stiffeners that form resonance chambers with a minimum length extending between the skins, and includes stiffeners projecting into cavities to enhance structural rigidity and noise attenuation without increasing panel thickness.
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
Solution Approach 1:
The patent transitions from traditional parallel resonating chambers to longitudinally extending resonance chambers that follow the diagonal path from perforated skin through the core to the back skin. This dimensional reorientation allows the resonance chamber length to exceed the panel thickness, enabling low-frequency noise attenuation without increasing panel thickness.
Solution Approach 2:
The core is segmented into multiple cells with baffles and septa that create distinct resonance pathways. Each cell contains stiffeners that further subdivide the space, allowing multiple resonance chambers to be packed into the available thickness while maintaining structural integrity.
2Strength
If stiffeners are added to increase structural integrity, then structural rigidity is improved, but space for resonance chambers is reduced
Solution Approach 1:
Stiffeners are strategically positioned within specific regions of the core rather than uniformly distributed. They are placed to provide maximum structural reinforcement at critical locations while minimizing intrusion into the resonance chamber volumes, allowing localized strengthening without globally reducing acoustic performance.
3Object-affected harmful factors
If the resonance chamber length is increased for low frequency attenuation, then noise attenuation at low frequencies is improved, but panel thickness must increase
Solution Approach 1:
The resonance chambers are configured to extend diagonally through the core at an angle rather than parallel to the panel faces. This angular orientation allows the effective resonance path length to be longer than the panel thickness, achieving low-frequency attenuation capability without increasing the panel's external dimensions.
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 by forming longer resonance chambers and increasing structural integrity, allowing for efficient noise reduction within the same or reduced space as legacy designs.
Implementation Method 1
The first cavity may form a resonance chamber having a minimum length that extends between the perforated first skin and the second skin
Data Source
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AI summary
An acoustic panel is provided that includes a perforated first skin, a second skin and a core. The core includes a first wall, a second wall and a stiffener. The core forms a plurality of cavities that extend vertically between the perforated first skin and the second skin and that extend laterally between the first wall and the second wall. The plurality of cavities include a first cavity. The stiffener projects partially into the first cavity and is connect to the first wall and the second wall.