Aircraft Return Air Bridge Noise Attenuation

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Solution Overview

Problem

Existing aircraft decompression panels and grilles allow sound waves to propagate into the cabin due to gaps and openings, generating noise, and may not have sufficient space to open during decompression events, leading to inefficiencies in air flow and noise attenuation.

Innovation Solution

A return air bridge system with an inboard portion coupled to the sidewall assembly and an outboard portion coupled to a structural member, featuring a noise-attenuating material and angled plate to direct air flow upward, creating a discrete air return path that mitigates sound waves and protects the sidewall assembly from foreign objects and passenger access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If decompression panels are positioned closer to the fuselage skin to gain cabin volume, then cabin volume is increased, but the panels do not have enough gap to swing open during decompression events

Engineering Contradiction:

Improvecabin volumeVSAvoidpanel opening capability

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The decompression panel system is divided into two independent components: a fixed grille that remains in place and a separate baffle that can be independently deployed. This segmentation allows the grille to stay close to the fuselage skin for maximum cabin volume while the baffle provides the necessary movement capability for decompression operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A baffle is introduced as an intermediary component between the fixed grille and the cargo bay. The baffle acts as a movable barrier that can be deployed to block air flow during normal operation and retracted during decompression, solving the conflict between close positioning and operational capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If openings and gaps are provided in decompression panels for air return flow, then air can flow through the panel, but sound waves can propagate from the space between fuselage and sidewall into the cabin

Engineering Contradiction:

Improveair return flowVSAvoidsound wave propagation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A flexible noise-attenuating material is applied to the baffle, allowing it to conform to the grille opening while providing acoustic attenuation. This flexible material covers the openings to block sound waves while still permitting air flow when the baffle is retracted during decompression events.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The baffle is constructed with noise-attenuating material that combines acoustic blocking properties with flow-permeable characteristics, creating a composite structure that simultaneously addresses both air return flow requirements and sound wave propagation prevention.

Inventive Principle:

Principle #40Composite materials

3Productivity

If louvers or multiple openings are provided in decompression grilles, then air can flow through the grille, but sound waves can propagate through the uncovered portion and louvers may generate sound

Engineering Contradiction:

Improveair flow through grilleVSAvoidnoise generation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

A flexible noise-attenuating material covers the louvers and openings in the grille, blocking sound waves from propagating through the openings while allowing air flow when the baffle is retracted. The flexible material conforms to the louver structure to provide effective acoustic attenuation.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The louvers, which could potentially generate noise when air flows past them, are covered with noise-attenuating material that converts the potential harmful noise generation into beneficial sound blocking, while still permitting necessary air flow during decompression events.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 return air bridge system reduces noise levels in the cabin by attenuating sound waves through a noise-attenuating material and directing them downward, while providing a separate air return path that is isolated from decompression flow, enhancing noise reduction and structural protection.

Implementation Method 1

The outboard portion comprises a plate configured to direct an air flow along the return air flow path upwardly with respect to the bottom edge of the sidewall assembly

Methodology Applied

Scientific EffectFluid flow direction:

Implementation Method 2

The return air bridge system reduces noise levels in the cabin by attenuating sound waves through a noise-attenuating material

Methodology Applied

Scientific EffectSound wave attenuation: Acoustic Absorption

Data Source

PatentUS10220931B2Sidewall panel assembly and return air bridge for use in an aircraft assembly

Publication Date: 2019.03.05 THE BOEING CO

AI summary

A return air bridge for use in an aircraft assembly includes an inboard portion configured to couple to a sidewall assembly at a bottom edge of the sidewall assembly and an outboard portion configured to couple to a structural member. The return air bridge also includes at least one support coupling the inboard portion to the outboard portion such that a return air flow path is defined between the inboard portion and the outboard portion. The outboard portion comprises a plate configured to direct an air flow along the return air flow path upwardly with respect to the bottom edge of the sidewall assembly.