Aircraft Propulsion Acoustic Panel Cell Rows for Curved-Skin Attenuation
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Solution Overview
Problem
Existing acoustic panels for aircraft propulsion system exhaust sections require improvements in attenuation efficiency and structural integrity, particularly in handling varying acoustic frequencies and maintaining consistent attachment to curved surfaces.
Innovation Solution
The method involves forming an acoustic panel assembly with a plurality of cell rows, each comprising transverse, longitudinal, and oblique panels, which are cut and folded from sheets to fit an inner skin, and attached using tabs to ensure consistent attachment and reduced stress points, enhancing acoustic core integrity and frequency attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional acoustic panel configurations are used, then basic acoustic attenuation is achieved, but attenuation efficiency for varying acoustic frequencies and structural integrity at curved surfaces are insufficient
Solution Approach 1:
The acoustic panel is divided into multiple cell rows, each containing multiple cells with specific geometric configurations. Each cell includes transverse panels, longitudinal panels, and oblique panels arranged to form resonant cavities that target specific acoustic frequencies. This segmentation allows the panel to achieve broad-spectrum attenuation by combining multiple resonant structures, thereby improving acoustic attenuation efficiency without excessive overall complexity.
Solution Approach 2:
Different regions of the acoustic panel are designed with locally optimized geometries. The oblique panels are specifically configured with attachment tabs positioned to engage with the curved inner skin at optimal locations, creating local quality variations that enhance both acoustic performance and structural attachment. Each cell's specific geometry is tailored to contribute to overall attenuation while maintaining structural integrity at critical attachment points.
2Area of stationary object
If acoustic panels are attached to curved surfaces, then coverage is achieved, but stress concentration occurs at attachment points reducing structural integrity
Solution Approach 1:
The attachment system is segmented into multiple discrete attachment tabs distributed across different cells rather than relying on a single continuous attachment mechanism. This segmentation distributes the mechanical stress across multiple localized points, preventing stress concentration at any single attachment location while maintaining comprehensive surface coverage through the distributed tab configuration.
Solution Approach 2:
The attachment tabs are strategically positioned at specific locations on the oblique panels where local geometric features optimize both attachment effectiveness and stress distribution. The tabs are designed with specific dimensions and orientations that match the curved surface geometry, creating locally optimized attachment points that maximize coverage while minimizing stress concentration effects.
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 improves acoustic panel performance by reducing stress at attachment points, increasing transverse shear modulus, and enhancing attenuation of various acoustic frequencies while ensuring robust attachment to curved surfaces.
Implementation Method 1
acoustic panels configured for attenuating acoustic energy
Implementation Method 2
each cell of the plurality of cells includes a first transverse panel, a first longitudinal panel, a second longitudinal panel, and an oblique panel
Data Source
AI summary
A method for forming an acoustic panel assembly for an aircraft propulsion system is provided that includes: forming a plurality of cell rows of an acoustic core by, for each cell row of the plurality of cell rows, cutting and folding a sheet to form each cell row with a plurality of cells, and each cell includes a first transverse panel, first and second longitudinal panels and an oblique panel, and the first and second longitudinal panels extend transversely from the first transverse panel; positioning the cell rows on an inner skin extending circumferentially about an axial centerline; attaching the longitudinal panels of a cell to the oblique panel of that cell, and attaching each cell row of the plurality of cell rows to at least one other cell row to form the acoustic core.