Aircraft Turbomachine Ejection Cone Assembly With Curved Acoustic Boxes

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Solution Overview

Problem

Existing aircraft turbomachine exhaust cones with acoustic boxes are not well-suited for absorbing low-frequency noise and are not compatible with ceramic matrix composite materials, and the brazing attachment is not suitable for all materials, leading to issues with thermal expansion and mechanical strength.

Innovation Solution

An assembly for the exhaust cone featuring first and second partitions that form acoustic boxes with curved shapes and fixed by offset fixing members, allowing for larger volumes and improved noise absorption, thermal expansion management, and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional acoustic boxes with straight partitions and brazing attachment are used, then the structure is simple to manufacture, but the noise absorption effectiveness for low-frequency noise is insufficient

Engineering Contradiction:

Improveease of manufactureVSAvoidnoise absorption effectiveness

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The partitions are designed with curved surfaces instead of straight lines, creating arcuate acoustic boxes that improve low-frequency noise absorption while maintaining manufacturing feasibility through standardized curved panel components

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The acoustic box volume is increased from small conventional dimensions to larger volumes of several liters, and the partition geometry is changed from straight to curved, fundamentally altering the acoustic properties to enhance low-frequency noise absorption effectiveness

Inventive Principle:

Principle #35Parameter changes

2Strength

If brazing attachment is used to join partitions to the first wall, then the assembly is strong, but it is not suitable for ceramic matrix composite materials and materials with different thermal expansion coefficients

Engineering Contradiction:

Improvemechanical strengthVSAvoidmaterial compatibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

A mechanical fastening system with offset fixing members is introduced as an intermediary connection method between partitions and the first wall, replacing direct brazing and enabling compatibility with ceramic matrix composite materials and materials having different thermal expansion coefficients

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical bonding method of brazing is replaced with a mechanical fastening system using fixing members that physically secure the partitions to the first wall through friction and geometric interlocking, eliminating material compatibility constraints

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Volume of moving object

If conventional small-volume acoustic boxes are used, then the exhaust cone structure is compact, but the noise absorption capacity is limited

Engineering Contradiction:

Improveacoustic box volumeVSAvoidstructural complexity

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The exhaust cone is segmented into multiple acoustic boxes arranged in circumferential rows, with each box formed by curved partitions that can be manufactured as standardized modules and assembled systematically to achieve large total volume without excessive structural complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The acoustic boxes are arranged in multiple circumferential rows around the exhaust cone, utilizing the circumferential dimension to increase total acoustic volume while maintaining a compact axial profile and balanced structural complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effectively absorbs low-frequency noise, manages thermal expansion, and enhances mechanical strength, improving the performance and durability of the exhaust cone.

Implementation Method 1

acoustic boxes for attenuating the noise produced by the combustion of the gases and/or the rotation of the different turbine stages

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentEP4441355B1Assembly for an ejection cone of an aircraft turbomachine

Publication Date: 2025.09.10 SAFRAN NACELLES

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AI summary

The invention relates to an assembly (10) for an ejection cone of an aircraft turbomachine, comprising a first annular wall (11) and a plurality of first partitions (12) and of second partitions (13) extending substantially perpendicularly from the first wall (11), the first partitions (12) additionally extending wholly in the axial direction and the second partitions (13) extending wholly in a circumferential direction between the adjacent pairs of first partitions (12) and being curved partitions comprising at least one arcuate portion (25a, 25b) in the axial direction upstream or downstream, the first wall (11), the first partitions (12) and the second partitions (13) additionally defining between them a plurality of acoustic boxes (21) distributed around the first wall (11).