Ram Outlet Header Stiffener Thickness Ratios
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Solution Overview
Problem
Aircraft environmental control systems face challenges in supporting a wide range of temperature and pressure combinations while maintaining structural integrity and controlling weight, particularly during varying loading conditions such as burst, buckling, and pressure cycling.
Innovation Solution
A ram outlet header is designed with a composite material structure incorporating multiple stiffeners and varying thickness regions, along with specific ratios between these stiffeners, to enhance structural integrity and reduce buckling, and is coupled to a heat exchanger assembly and fan housing through mounting flanges and necks, providing a robust and efficient air flow path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ram outlet header uses a composite material structure with multiple stiffeners and varying thickness regions, then structural integrity and resistance to buckling are improved, but manufacturing complexity increases
Solution Approach 1:
The ram outlet header is divided into multiple sections with different thickness requirements. The body includes a first thickness region and the mounting flange includes a second thickness region, allowing each section to be optimized for its specific functional requirements while maintaining overall structural integrity.
Solution Approach 2:
Different regions of the ram outlet header are assigned different thicknesses based on their specific structural needs. The mounting flange has a greater thickness than the body to provide enhanced mounting strength, while the body thickness is optimized for pressure containment, achieving local optimization without unnecessary weight elsewhere.
2Stability of the object's composition
If the ram outlet header uses a composite material structure with multiple stiffeners and varying thickness regions, then resistance to buckling is improved, but weight increases
Solution Approach 1:
The structure is segmented into regions with different thickness requirements. Stiffeners are strategically placed only where needed to prevent buckling, such as at the mounting flange and in the body, rather than uniformly throughout, reducing unnecessary weight while maintaining buckling resistance.
Solution Approach 2:
The ram outlet header utilizes composite materials that combine different properties to achieve high strength-to-weight ratio. The composite construction allows for tailored mechanical properties in different regions, providing buckling resistance and structural integrity while minimizing overall weight compared to solid metal constructions.
3Reliability
If the ram outlet header uses a composite material structure with multiple stiffeners and varying thickness regions, then support for temperature and pressure combinations is improved, but manufacturing precision requirements increase
Solution Approach 1:
The ram outlet header is constructed with segmented thickness regions and integrated stiffeners that are formed as part of the composite structure. This segmentation allows for standardized manufacturing of individual components with controlled tolerances, which are then assembled together, reducing the overall manufacturing precision requirements compared to a monolithic structure.
Solution Approach 2:
Composite materials provide inherent tolerance to temperature and pressure variations through their material properties. The composite construction allows for thermal expansion and pressure cycling without requiring extremely tight manufacturing tolerances, as the material itself accommodates these variations while maintaining structural integrity.
Data Source
AI summary
A ram outlet header includes a ram outlet header body. A ram air fan mounting neck and a ram air fan mounting flange are configured to couple the ram outlet header to a ram air fan housing. A heat exchanger mounting flange is configured to couple the ram outlet header to a heat exchanger assembly. A lower face includes a first stiffener. A mid-section includes a second stiffener, a third stiffener, and a fourth stiffener. The ram air fan mounting flange is positioned between the lower face and the mid-section. A ratio of thickness of the second stiffener to the third stiffener is between 1.04 and 1.16, and a ratio of thickness of the fourth stiffener to the third stiffener is between 1.04 and 1.16.