Aircraft Propulsion Acoustic Treatment With Nested Honeycomb Shapes
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Solution Overview
Problem
Conventional acoustic treatment devices for aircraft propulsion units face challenges in effectively attenuating low frequencies while maintaining a reduced footprint and adhering to mass and size constraints, particularly in UHBR architectures, and existing methods for enhancing low-frequency attenuation are limited by increased thickness, complex geometric control, and additional manufacturing steps.
Innovation Solution
An acoustic treatment device comprising a honeycomb structure with integrated protruding shapes, such as cones, and studs designed to fit into hollow cells, allowing for enhanced low-frequency attenuation without significant thickness increase, and featuring through holes for secure attachment to propulsion unit parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cavity height of the honeycomb structure is increased to attenuate low frequencies, then the acoustic attenuation performance at low frequencies is improved, but the thickness of the acoustic treatment device increases significantly
Solution Approach 1:
The patent inserts cones or other shaping elements inside the hollow cells of the honeycomb structure. These internal shapes are nested within the existing cell cavities, effectively increasing the acoustic path length and improving low-frequency attenuation without increasing the overall thickness of the device. The cones are positioned coaxially within selected cells to maximize acoustic treatment effectiveness while maintaining a compact profile.
Solution Approach 2:
The patent applies acoustic treatment selectively to specific cells rather than uniformly treating all cells. By choosing particular cells for cone insertion based on their position and acoustic function, the design optimizes low-frequency attenuation in critical areas while leaving other cells intact, thereby maintaining a reduced overall thickness.
2Ease of manufacture
If conventional manufacturing methods are used for acoustic treatment devices, then the manufacturing process is simple, but the geometric control precision and manufacturing adaptability are limited
Solution Approach 1:
The patent incorporates studs and through-holes directly into the shaping elements (cones) during their initial manufacturing process. This preliminary integration of attachment features eliminates the need for separate assembly operations to add mounting components, thereby maintaining manufacturing simplicity while achieving high geometric precision for both acoustic and attachment functions.
3Area of stationary object
If the footprint of the acoustic treatment device is reduced to meet space constraints, then the device fits within UHBR architecture constraints, but the acoustic treatment effectiveness at low frequencies deteriorates
Solution Approach 1:
The patent addresses the footprint-thickness trade-off by transitioning from a planar expansion approach to a three-dimensional utilization approach. Instead of increasing device area to improve acoustic treatment, the invention uses the internal volume of existing cells by inserting cones that extend along the thickness dimension. This allows effective low-frequency treatment within a compact footprint by exploiting the third dimension within the cell structures.
4Reliability
If studs are added to the shape structure for secure attachment, then the device fixation reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent combines the acoustic treatment function (cones) and the attachment function (studs with through-holes) into a single integrated shaping element. This merging of functions into one component eliminates the need for separate attachment hardware and assembly steps, thereby improving fixation reliability while avoiding increases in manufacturing 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
The solution provides effective low-frequency acoustic attenuation with a reduced footprint, ensuring compliance with space constraints and aerodynamic integrity, while simplifying the manufacturing process and reducing production costs.
Implementation Method 1
The acoustic performance of such a device is mainly related to its alveolar structure and, in particular, the frequency range in which the acoustic waves are attenuated by the device results in particular from the geometry and dimensions of the cells of the alveolar structure. In particular, in conventional acoustic treatment technologies, the length of the neck is small compared to the height of the cavity of the honeycomb structure.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
The invention relates to an acoustic treatment device for an aircraft propulsion assembly. The device comprises two skins, which enclose an acoustic structure. The acoustic structure comprises a cellular structure with hollow cells and a structure of shapes (413) with protruding shapes (415) which each engage in a different hollow cell of the cellular structure. The structure of shapes (413) additionally has stubs (417) designed to fit into the hollow cells of the cellular structure and to allow the acoustic treatment device to be fixed to a component of the aircraft propulsion assembly.