Honeycomb Core W-Shaped Septa for Acoustic Attenuation
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Solution Overview
Problem
Conventional acoustic attenuation panels in turbomachines are limited in reducing height without compromising sound wave absorption capacity, as the length of the sound wave path within the cells is fixed and cannot be reduced without losing acoustic attenuation effectiveness.
Innovation Solution
The honeycomb core incorporates W-shaped septa with through orifices, allowing for increased path length of sound waves by offsetting orifices radially, enabling longer air passage paths within the same height, thus reducing panel dimensions and weight while maintaining or improving acoustic attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the height of the cells is reduced to make the panel thinner, then the panel becomes more compact and lighter, but the capacity to absorb sound waves is lost
Solution Approach 1:
The invention transforms the sound wave path from a straight vertical line (one dimension) to a zigzag path through offset septa (multiple dimensions). By introducing lateral offsets in the septa positions along the cell height, the sound wave must travel laterally between septa, effectively increasing the path length within the same vertical height constraint, thus resolving the contradiction between panel thickness and acoustic attenuation capacity
Solution Approach 2:
The invention replaces straight septa with curved or angled zigzag paths formed by offset septa. This curvature in the sound wave trajectory increases the path length without increasing the vertical height of the cell, allowing the panel to maintain reduced thickness while preserving acoustic attenuation effectiveness
2Reliability
If the length of the sound wave path in the cell is increased to improve acoustic attenuation, then lower frequencies can be attenuated, but the panel height must be increased
Solution Approach 1:
The invention utilizes lateral positioning (offset) of septa to create diagonal sound wave paths. By arranging septa at different lateral positions along the cell height, the sound wave travels a longer three-dimensional path (combining vertical and lateral components) within the same vertical height, enabling improved acoustic attenuation without increasing panel height
Solution Approach 2:
The invention nests multiple zigzag path segments within a single cell height by using multiple offset septa. Each septum creates a path segment, and the combination of multiple such segments within the same vertical space effectively packs more acoustic path length into the available height, similar to nesting structures
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 design allows for effective attenuation of lower noise frequencies with reduced panel height and weight, overcoming the limitations of conventional panels by increasing the path length of sound waves within the same core height, thereby enhancing acoustic performance and compactness.
Implementation Method 1
the capacity of the panel to absorb the sound waves is optimal for a conventional panel when the cells have a height corresponding approximately to a quarter of the wavelength k of the sound wave to be treated
Data Source
AI summary
A core for an acoustic attenuation panel extending between a first and a second end face, the core including a plurality of tubular polygonal cells having a main axis of extension between the end faces, each cell including an internal cavity delimited by lateral walls extending between the first and second end faces and opening out into each of the two end faces, the cells being expandable in a direction parallel to the end faces, each polygonal cell having septa extending transversely relative to the main axis and being offset there along, wherein each septum is folded in a W-shape at least between one of the lateral walls and another of the lateral walls and has a through orifice, the orifices of two consecutive septa being offset radially with respect to the main axis to form a baffle.