Segmented Heat Shield Barriers Suppress Exhaust Gas Heat Flow
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Solution Overview
Problem
Aircraft heat shields face challenges with buckling due to thermal expansion and exposure to hot exhaust gases, particularly in larger aircraft where the distance between frame members is greater, leading to inefficiencies in thermal insulation and structural integrity.
Innovation Solution
A segmented heat shield design featuring barriers with close-out frames and thermal insulation layers positioned on the underside, allowing for thermal expansion and redirecting exhaust gas flow to minimize heat transfer and exposure, while using superplastic forming for the skin segments to enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between adjacent frame members is increased for larger aircraft, then the heat shield can cover larger areas, but the skin panels become susceptible to buckling under thermal stress
Solution Approach 1:
The heat shield skin is divided into multiple segments between adjacent frame members, with expansion joints allowing independent movement. This segmentation prevents buckling by enabling each panel to expand and contract independently under thermal stress while maintaining overall structural integrity across large areas.
2Object-affected harmful factors
If thermal insulation material is used to reduce heat transfer, then the protection against exhaust gases is improved, but the thermal insulation material is exposed to direct exhaust gas flow increasing heat exposure
Solution Approach 1:
A barrier wall is introduced as an intermediary structure between the exhaust gas flow and the thermal insulation material. This barrier redirects exhaust gases away from the insulation, reducing direct thermal exposure while maintaining the insulation's protective function. The barrier acts as a mediator that protects the insulation layer from harmful direct exposure.
3Ease of manufacture
If the heat shield is designed as a single integrated structure, then manufacturing is simpler, but thermal expansion causes structural stress and potential failure
Solution Approach 1:
The heat shield is designed with segmented skin panels and expansion joints that allow each segment to expand and contract independently. This segmentation maintains structural integrity under thermal cycling while still allowing for relatively simple manufacturing of individual segments that can be assembled into the complete heat shield structure.
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 design effectively reduces thermal stresses, prevents buckling, and optimizes thermal insulation by allowing for independent expansion of segments, thereby enhancing the heat shield's ability to shield against exhaust gases without compromising structural integrity.
Implementation Method 1
the gap allowing thermal expansion and contraction of the segments
Implementation Method 2
the barriers suppress heat flow between the thermal insulation layers
Data Source
AI summary
An aircraft structure including a heat shield. A heat shield including an interior; a skin enclosing the interior; a plurality of barriers attached in the interior to the skin, each of the barriers spaced to separate a plurality of thermal insulation layers disposed in the interior; and wherein the barriers suppress heat flow between the thermal insulation layers.