Pinched Airflow Nozzle for Aircraft Cabin Noise Reduction

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Solution Overview

Problem

Existing aircraft cabin air distribution systems face challenges in providing a desired volumetric conditioned airflow rate while minimizing noise, airflow recirculation, and separation downstream of the nozzle inlet, primarily due to noise generation from airflow restrictors and abrupt changes in the airflow path.

Innovation Solution

The apparatus features a nozzle housing with a smooth contour airflow passage defined by opposing sidewalls, front, and back walls, where the thickness and width of cross-sections gradually decrease from the inlet to the outlet, reshaping the airflow path to reduce noise and recirculation, and incorporating a vane for structural support and airflow directionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If airflow restrictors such as orifices, airflow straighteners and nozzle directional vanes are used to obtain desired velocity at nozzle outlet, then the airflow velocity at head level is improved, but noise generation increases and is transmitted into the passenger cabin

Engineering Contradiction:

Improveairflow velocity at head levelVSAvoidnoise generation

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent applies curvature by replacing abrupt angular changes in the airflow path with smooth curved surfaces. The airflow passage features rounded corners and continuous curved transitions instead of sharp edges, which eliminates turbulence and noise generation while maintaining the desired airflow velocity distribution at the nozzle outlet.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the geometric parameters of the airflow passage by eliminating abrupt changes and using gradual transitions. The cross-sectional area varies smoothly along the flow direction, and the passage walls feature continuous curvature rather than sharp angles, which reduces noise while preserving airflow velocity.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If abrupt changes in airflow path are used upstream of nozzle outlet, then device complexity is reduced, but noise generation and airflow separation increase

Engineering Contradiction:

Improveairflow passage structureVSAvoidnoise generation and airflow separation

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces abrupt angular changes with smooth curved surfaces throughout the airflow passage. The rounded corners and continuous curvature eliminate turbulence and noise generation while maintaining relatively simple device geometry, thus resolving the contradiction between complexity and harmful factors.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Ease of manufacture

If traditional nozzle designs with abrupt changes are used, then manufacturing is simpler, but airflow recirculation and separation downstream of nozzle inlet increase

Engineering Contradiction:

Improvenozzle housing fabricationVSAvoidairflow pattern stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent uses smooth curved surfaces and rounded transitions in the airflow passage that eliminate recirculation zones and flow separation. These curved geometries can be manufactured using modern molding or machining techniques, balancing manufacturing ease with improved airflow stability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the geometric parameters by implementing gradual area variations and smooth transitions instead of abrupt changes. This eliminates unstable flow patterns and recirculation zones while maintaining manufacturability through continuous surface geometries.

Inventive Principle:

Principle #35Parameter changes

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 effectively reduces noise levels, minimizes airflow recirculation and separation, and provides a uniform three-dimensional airflow pattern for improved thermal comfort and air mixing within the aircraft cabin.

Implementation Method 1

reduce airflow separation downstream of the nozzle inlet

Methodology Applied

Scientific EffectFlow separation: Flow Separation

Implementation Method 2

Each of the plurality of cross-sections has a thickness between the front wall and the back wall that is greater at side edges of both the front wall and the back wall than at the centerline

Methodology Applied

Scientific EffectVenturi effect: Venturi Effect

Data Source

PatentUS11554868B2Three dimensional pinched airflow nozzle and methods for use thereof

Publication Date: 2023.01.17 THE BOEING CO

AI summary

Apparatus and methods for providing a desired volumetric conditioned airflow rate and for reducing noise level, airflow recirculation and airflow separation are disclosed. An example apparatus includes a nozzle housing having a pair of opposing sidewalls and a front and back wall that define an airflow passage. The airflow passage has a centerline extending between the inlet and the outlet and has a plurality of cross-sections taken perpendicular to the centerline that collectively define a smooth contour along a length of the airflow passage. The cross-sections each have a thickness between the front and back wall that is greater at side edges than at the centerline. The thickness of the cross-sections decreases along a length of at least a first portion of the nozzle housing. A width of each of the cross-sections between the sidewalls increases along the length of at least the first portion of the nozzle housing.