Acoustic Panel Vertical Stiffeners Low-Frequency Noise
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Solution Overview
Problem
Aircraft gas turbine engines generating relatively low frequency noise pose a challenge for acoustic panels, as increasing thickness to tune resonating chambers for noise attenuation is limited by strict space constraints, necessitating a solution that maintains or reduces space usage while ensuring structural integrity and effective noise attenuation.
Innovation Solution
The acoustic panel features a cellular core with corrugations and stiffeners arranged to form open cavities, allowing for increased vertical thickness of the core without expanding the panel's overall dimensions, enabling effective noise attenuation of low-frequency noise through resonating chambers that maintain structural integrity.
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 attenuation, then noise attenuation performance is improved, but panel thickness and space usage increase
Solution Approach 1:
The patent introduces vertical stiffeners that extend through the core thickness, creating a three-dimensional structural framework. This vertical dimension allows the resonating chambers to be tuned for low-frequency noise while the stiffeners provide structural support that enables the use of thinner core materials, thus reducing overall panel thickness while maintaining noise attenuation effectiveness.
Solution Approach 2:
The patent employs a composite structure combining a cellular core material with integrated vertical stiffeners. This composite approach creates a hybrid structure where the cellular core provides acoustic attenuation functionality while the stiffener elements provide structural integrity, allowing the panel to achieve both low-frequency noise reduction and reduced thickness simultaneously.
2Length of stationary object
If the core thickness is decreased to reduce space usage, then space constraints are satisfied, but noise attenuation performance deteriorates
Solution Approach 1:
The patent applies local quality by concentrating structural reinforcement at specific locations through the vertical stiffeners rather than uniformly thickening the entire core. This localized approach allows the panel to maintain thin overall dimensions while providing enhanced structural support and acoustic performance at critical regions where the stiffeners are positioned.
3Strength
If vertical stiffeners are added to maintain structural integrity in thinner panels, then structural strength is improved, but device complexity increases
Solution Approach 1:
The vertical stiffeners serve multiple functions simultaneously: they provide structural reinforcement to maintain panel integrity, act as tuning elements for the resonating chambers to optimize noise attenuation, and serve as integration points for connecting the cellular core to the face and back skins. This multi-functionality reduces the need for separate components, thereby limiting the increase in overall device complexity.
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 the panel's thickness, ensuring the same or improved structural integrity and noise reduction performance compared to previous designs, while utilizing the same or less space.
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
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AI summary
A panel (20) for attenuating noise includes a core (26) having a first baffle (56), a second baffle (56), a first septum (58), a second septum (58) and a stiffener (50A). The core (26) forms first and second cavities (52A,B) vertically between a first skin (22) and a second skin (24), wherein the first and the second cavities (52A,B) are each fluidly coupled with perforations (34) in the first skin (22). The first cavity (52A) is formed laterally between the first baffle (56) and the second baffle (56) and has a first cross-sectional geometry. The first septum (58) is laterally between the first baffle (56) and the second baffle (56) and divides the first cavity (52A) into fluidly coupled sub-cavities. The second cavity (52B) is formed laterally between the second baffle (56) and the stiffener (50A) and has a second cross-sectional geometry that is at least approximately identical to the first cross-sectional geometry. The second septum (58) is laterally between the second baffle (56) and the stiffener (50A) and divides the second cavity (52B) into fluidly coupled sub-cavities.