Oblique Polyhedral Cellular Acoustic Liners for Turbomachines
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Solution Overview
Problem
Existing acoustic liners for turbomachines, such as turbofan engines, face challenges in minimizing size and weight while effectively attenuating a wide range of sound frequencies, often requiring complex and costly structures with additional cellular layers or thicker core layers, which increase weight and complexity.
Innovation Solution
The use of oblique polyhedral cellular structures combined with parallel polyhedral cells in acoustic liners, providing a continuous degree of freedom acoustic treatment, which allows for efficient sound attenuation across various frequencies with a reduced size and weight profile, achieved by configuring the core layer with oblique and parallel polyhedral cells that converge or diverge at specific angles and proportions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deeper cellular structures are used to attenuate low frequency sound, then acoustic damping performance is improved, but the size and weight of the acoustic liner increases
Solution Approach 1:
The patent applies asymmetry by using oblique polyhedral cells with non-uniform depth distributions and varying orientations throughout the liner structure. This asymmetric configuration allows different regions to resonate at different frequencies, providing broadband noise attenuation without requiring uniform increases in overall liner depth, thereby reducing weight while maintaining acoustic performance.
Solution Approach 2:
The patent transitions from traditional two-dimensional honeycomb structures to three-dimensional oblique polyhedral cellular structures with varying depths and orientations. This dimensional complexity enables the liner to address multiple sound frequencies simultaneously within a compact thickness, avoiding the weight penalty of deeper uniform structures.
2Reliability
If additional cellular layers are added to address different frequencies, then acoustic attenuation across frequency range is improved, but device complexity increases
Solution Approach 1:
The patent segments the acoustic liner into multiple oblique polyhedral cell layers with different orientations and depth characteristics. Each segment targets specific frequency ranges, and the segmented structure allows for modular design and manufacturing while achieving broadband attenuation performance that would otherwise require complex multi-layer configurations.
Solution Approach 2:
Different regions of the acoustic liner incorporate oblique polyhedral cells with locally optimized properties including varying orientations, depths, and densities. This local quality variation enables each region to be tuned for specific frequency attenuation needs, providing comprehensive broadband coverage without requiring a uniformly complex structure throughout.
3Adaptability or versatility
If variable depth cellular structures are used to provide different resonant cavity volumes, then acoustic treatment for multiple frequencies is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The oblique polyhedral cellular structures are pre-formed with specific depth variations and orientations during the manufacturing process rather than requiring post-production customization. This preliminary action embeds the frequency-tuning characteristics directly into the structure during fabrication, simplifying manufacturing compared to methods requiring assembly of individually tuned components.
Solution Approach 2:
The patent employs composite cellular structures combining different polyhedral cell types, materials, and configurations within a single integrated liner assembly. This composite approach achieves multi-frequency attenuation capabilities that would require multiple separate components, thereby reducing manufacturing complexity while maintaining versatility across frequency ranges.
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 enhances the acoustic damping and attenuation performance by increasing the surface area relative to volume, improving noise reduction efficiency while minimizing the size and weight of the acoustic liners, thus addressing the limitations of previous technologies.
Implementation Method 1
The solid back sheet is substantially impervious to sound waves, thereby allowing the cellular structure or cells to act as acoustic resonators
Implementation Method 2
acoustic structures that include oblique polyhedral cellular structures, including cellular structures providing continuous degree of freedom acoustic treatments
Data Source
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AI summary
The present disclosure provides acoustic structures 118 and related systems and methods which may be used to dampen or attenuate sound waves, including, for example, noise generated by or emanating from various aspects or components of turbomachines such as turbine engines 100. These acoustic structures 118 include oblique polyhedral cellular structures 200, including converging polyhedral cells 212 and diverging polyhedral cells 214, and related systems and methods of making and using such acoustic structures.