Acoustic Panel Corrugated Baffles 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 a perforated face skin, a solid back skin, and an open cavity structure with corrugated walls and undulating geometry, allowing for increased resonance chamber length without increasing core thickness, utilizing materials like metals, polymers, or fiber composites to enhance structural rigidity and noise attenuation.
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 effectiveness is improved, but space constraints are violated and panel thickness increases
Solution Approach 1:
The patent introduces corrugated baffles with wave-like geometries that extend resonating chambers in the longitudinal direction rather than increasing thickness in the vertical direction. This dimensional transformation allows the resonance chamber length to exceed the panel thickness, enabling low frequency noise attenuation while maintaining compact panel thickness.
Solution Approach 2:
The corrugated baffles feature curved, wave-like geometries with peaks and valleys that create extended resonating pathways. This curvature allows sound waves to travel longer distances through the resonating chambers without requiring increased panel thickness, effectively tuning the chambers for low frequency noise while maintaining space efficiency.
2Object-affected harmful factors
If the core thickness is increased to achieve effective noise attenuation, then acoustic performance is improved, but structural integrity may be compromised due to increased flexibility
Solution Approach 1:
The corrugated baffles with their curved, rigid geometries provide inherent structural stiffness that prevents panel flexing. The wave-like structures act as structural reinforcement, distributing loads and maintaining structural integrity while simultaneously creating the extended resonating pathways needed for effective noise attenuation.
Solution Approach 2:
The patent employs a composite structure combining the cellular core with corrugated baffles and skins, creating a multi-layered system where each component contributes both acoustic and structural functions. This composite architecture achieves both noise attenuation and structural rigidity without requiring increased thickness.
3Ease of manufacture
If traditional honeycomb core structure is used, then manufacturing is simplified, but resonance chamber length is limited by core thickness
Solution Approach 1:
The corrugated baffles transform the resonance chamber geometry from a simple thickness-dependent structure to a longitudinally extended structure. The wave-like patterns create multiple peaks and valleys that effectively multiply the resonating path length without increasing the distance between skins, maintaining manufacturing feasibility while achieving longer resonance chambers.
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, maintaining or improving structural integrity and space efficiency, enabling effective noise reduction in aircraft propulsion systems.
Implementation Method 1
The 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 2
an acoustic panel for attenuating noise generated by, for example, a gas turbine engine for an aircraft propulsion system
Data Source
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AI summary
A panel (20) for attenuating noise includes a core (26), which forms a plurality of cavities (54) vertically between a perforated first skin (22) and a second skin (24). The core (26) includes an array of corrugations that include a first baffle (62), a second baffle (62) and a first septum (64). The cavities (54) include a first cavity (54) that is formed longitudinally between the first baffle (62) and the second baffle (62) and is fluidly coupled with perforations (34) in the first skin (22). The first septum (64) extends from the first skin (22) and the first baffle (62) to the second skin (24) and the second baffle (62), and divides the first cavity (54) into fluidly coupled sub-cavities (54A, 54B). The first baffle (62) includes a lateral array of baffle ribs. The first septum (64) includes a lateral array of septum ribs that are laterally offset from the baffle ribs.