Double-Walled Aircraft Air Pipe for Ice-Free Airflow

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Solution Overview

Problem

Aircraft environmental control system air pipes are prone to icing, which can lead to ice fragmentation and reduced airflow due to ice buildup, necessitating a solution to maintain optimal temperatures and prevent ice formation.

Innovation Solution

A double-walled pipe with an annular gap for circulating a temperature-controlled fluid, formed through additive manufacturing processes like direct metal laser sintering, featuring helical or pillar-based flow passages to ensure uniform heat distribution and pipe strength, while allowing for material flushing to prevent contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If air pipes are cooled to transport air in the environmental control system, then air supply function is achieved, but ice build-up occurs on the inner surface reducing airflow

Engineering Contradiction:
Improveair pipe temperatureVSAvoidairflow reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The air pipe is segmented into a double-walled structure with an inner wall bounding the air flowpath and an outer wall radially spaced from the inner wall, creating an annular gap. This segmentation allows independent temperature control of the pipe wall without affecting the air flowpath directly, preventing ice build-up while maintaining cooling function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A temperature-controlled fluid is introduced as an intermediary substance circulating through the annular gap between inner and outer walls. This mediator transfers heat to the inner wall surface, preventing ice formation on the air-facing surface while allowing the pipe to maintain its cooling function for avionics and cabin.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If ice build-up occurs on the inner surface, then cooling function is achieved, but inner diameter reduction causes airflow restriction

Engineering Contradiction:
Improvecooling temperatureVSAvoidairflow volume
Core Design Contradiction:
TemperatureVSVolume of moving object

Solution Approach 1:

The double-walled structure segments the cooling function from the air transport function. The inner wall maintains low temperature for cooling avionics and cabin air, while the annular gap provides a thermal buffer zone where temperature-controlled fluid prevents ice encroachment into the air flowpath, preserving the inner diameter and airflow volume.

Inventive Principle:
Principle #1Segmentation

3Reliability

If double-walled pipe structure is implemented, then ice prevention is achieved, but manufacturing complexity increases

Engineering Contradiction:
Improveice prevention reliabilityVSAvoidpipe structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The double-walled pipe with annular gap flow passages is manufactured as a single integrated component using additive manufacturing technology. This merging of the inner wall, outer wall, and flow passage structure into one monolithic part eliminates the need for separate manufacturing and assembly of multiple components, reducing manufacturing complexity despite the sophisticated geometry.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Traditional mechanical manufacturing methods (such as nesting separate pipes or complex machining) are replaced with additive manufacturing processes. This substitution enables the creation of the complex double-walled structure with internal flow passages as a single printed component, dramatically simplifying the manufacturing process while maintaining design complexity for ice prevention functionality.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If additive manufacturing process is used, then production efficiency is improved, but material flushing requirements increase

Engineering Contradiction:
Improveproduction efficiencyVSAvoidmaterial flushing ease
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The flow passages are designed with built-in flushing capability during the additive manufacturing process. Unused support material or powder can be flushed through the passages after printing using pneumatic or hydraulic pressure, ensuring the passages are clear before operation. This preliminary flushing action is integrated into the manufacturing workflow, maintaining high productivity while addressing material removal requirements.

Inventive Principle:
Principle #10Preliminary action

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 prevents ice buildup by maintaining optimal temperatures within the air pipes, ensuring consistent airflow and structural integrity, while reducing production costs and weight through optimized design and material usage.

Implementation Method 1

a temperature-controlled fluid is circulated to control the temperature of the inner wall

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The additive manufacturing process may be a direct metal laser sintering process

Methodology Applied
Scientific EffectDirect metal laser sintering: Selective Laser Sintering

Implementation Method 3

The additive manufacturing process may be an electron beam sintering process

Methodology Applied
Scientific EffectElectron beam sintering: Electron Beam

Implementation Method 4

The additive manufacturing process may be a wire arc additive manufacturing process

Methodology Applied
Scientific EffectWire arc additive manufacturing: Electric Arc

Data Source

PatentEP3290766B1Aircraft environmental control system with double-walled pipe and method
Publication Date: 2021.03.03 MICROTECHNICA SRL
  • EP3290766B1 patent drawingFigure 1~3
  • EP3290766B1 patent drawingFigure 4~5

AI summary

A double-walled pipe 10 includes an inner wall 16, which bounds a flowpath for a first fluid such as air, an outer wall 18 radially spaced from the inner wall 16 so that there is an annular gap 20 between the inner wall 16 and the outer wall 18; and walls 30 extending in the annular gap 20 between the inner wall 16 and the outer wall 18, such that flow passages 32 are formed in the annular gap 20, through which a temperature-controlled fluid can be circulated to control the temperature of the inner wall. The double-walled pipe 10 is formed by an additive manufacturing process. The walls 30 may be helical walls, defining helical flow passages.