Multilayer Shroud for Aerospace Duct Structural Support
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Solution Overview
Problem
Existing aircraft ducts fail to provide adequate structural support and leak detection accuracy due to insulation rotation and inadequate containment of heated, pressurized gases, especially at high temperatures and pressures.
Innovation Solution
A duct system featuring a multilayer shroud with a metallic inner layer and polymeric outer layer, affixed to a primary duct member with closeout collars to prevent rotation and gas leakage, and incorporating standoffs for leak detection systems to ensure accurate gas direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single metal duct tube is used with traditional insulation wrapping, then thermal insulation is provided, but structural support is insufficient and rotation occurs
Solution Approach 1:
The patent applies composite materials by combining a metallic inner layer (providing structural strength and thermal resistance) with a polymeric outer layer (providing enhanced insulation and protection). This composite shroud structure simultaneously addresses both thermal insulation requirements and structural support needs, preventing the rotation issues experienced with traditional flexible insulation wraps.
2Temperature
If traditional insulation wrapping is used, then thermal protection is achieved, but rotation about the duct occurs during service
Solution Approach 1:
The patent employs a flexible shroud structure that can conform to the duct geometry while maintaining positional stability. The metallic inner layer provides a stable, non-rotating framework that prevents the shroud from rotating about the duct, while still allowing for thermal expansion and contraction. This resolves the contradiction between flexibility for thermal protection and stability to prevent rotation.
3Ease of manufacture
If insulation is not tightly affixed to the duct, then installation is easier, but gas leakage and misdirection of leaking gases occur
Solution Approach 1:
The patent introduces an intermediary mechanism (the metallic inner layer with attachment features) that mediates between the shroud and the duct. This intermediary provides a reliable attachment interface that ensures gas containment while maintaining ease of installation. The metallic layer acts as a stable substrate that can be reliably attached to the duct, preventing gas leakage without complicating the installation process.
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 provides structural support and prevents insulation rotation, ensuring accurate leak detection and containment of high-pressure gases, enhancing safety and reliability in aerospace applications.
Implementation Method 1
a multilayer shroud (24)... with a metallic inner layer positioned at the inner surface; and a polymeric outer layer, bonded to the outer surface of the metallic inner layer
Data Source
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AI summary
A duct section and system, including a laminated shroud, acting as a secondary duct, for aerospace and other applications, and a method for constructing same. The duct structure incorporates a metallic primary duct tube, with a laminated shroud surrounding the primary duct tube and separated therefrom by an annular gap. The laminated shroud includes a metallic inner layer and a polymeric outer layer. Preferably, the thin metallic layer is a corrosion resistant material such as corrosion resistant stainless steel or titanium. In one embodiment of the invention, the outer polymeric layer is a polyimide material, such as polyimide resin-impregnated fiberglass cloth.