Turbomachine Ejection Cone Assembly for Low-Frequency Absorption
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Solution Overview
Problem
Existing aircraft turbomachine ejection cones have limitations in noise absorption, particularly for low-frequency noise, and are not well-suited for materials like ceramic matrix composites, with soldered attachments failing to accommodate differential thermal expansion.
Innovation Solution
The ejection cone design features bent partitions with arched portions and a patterned arrangement, combined with offset attachment members, to enhance noise absorption and mechanical strength, using materials that withstand high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If straight partitions are used to form acoustic enclosures, then the structure is simple to manufacture, but low-frequency noise absorption is insufficient
Solution Approach 1:
The patent applies curvature by replacing straight partitions with bent partitions that have arched portions. The arched portions of the bent partitions create curved surfaces that are more effective at absorbing low-frequency noise compared to straight partitions, while maintaining manufacturability through standardized bending processes
2Ease of manufacture
If soldering is used to attach partitions to the first wall, then the attachment process is simple, but the structure cannot accommodate differential thermal expansion
Solution Approach 1:
The patent introduces attachment members as intermediary elements between the partitions and the first wall. These attachment members serve as a mediator that accommodates differential thermal expansion between different materials, replacing direct soldering while maintaining secure attachment
Solution Approach 2:
The patent changes the attachment method from rigid soldering to a more flexible system using attachment members that can accommodate parameter changes due to thermal expansion. This allows the structure to adapt to different material combinations and thermal conditions
3Volume of stationary object
If small-volume acoustic enclosures are used, then the device fits within space constraints, but noise absorption effectiveness is limited
Solution Approach 1:
The bent partitions with arched portions create acoustic enclosures with curved geometries that improve noise absorption effectiveness within the same volume compared to straight partitions, allowing better noise control without increasing overall device volume
4Temperature
If ceramic matrix composite materials are used, then high-temperature resistance is improved, but traditional soldered attachment fails
Solution Approach 1:
The attachment members serve as an intermediary that bridges ceramic matrix composite materials with metal partitions, enabling the use of high-temperature resistant ceramics while maintaining manufacturability through mechanical attachment instead of soldering
Solution Approach 2:
The patent employs composite construction by combining ceramic matrix composite materials for the first wall with metal partitions and attachment members, creating a multi-material system that leverages the high-temperature resistance of ceramics while maintaining ease of manufacture through standardized attachment components
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 design effectively absorbs low-frequency noise and withstands thermal stresses, improving mechanical strength and adaptability to various materials.
Implementation Method 1
the first wall, the first partitions and the second partitions define therebetween a plurality of acoustic enclosures distributed around the first wall
Implementation Method 2
the attachment by soldering provided between the partitions and the first wall is not adapted to the use of different materials for the partitions and the first and second walls and to the absorption of forces generated by differential thermal expansion
Data Source
AI summary
An assembly for an ejection cone of an aircraft turbomachine, including a first annular wall and a plurality of first partitions and of second partitions extending substantially perpendicularly from the first wall, the first partitions additionally extending wholly in the axial direction and the second partitions extending wholly in a circumferential direction between the adjacent pairs of first partitions and being curved partitions including at least one arcuate portion in the axial direction upstream or downstream, the first wall, the first partitions and the second partitions additionally defining between them a plurality of acoustic boxes distributed around the first wall.