Fan inlet diffuser housing for an air cycle machine system
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Solution Overview
Problem
Air cycle machine systems in aircraft face reduced performance due to heat exchanger clogging, which affects fan rotor efficiency and surge limits, and there is a need for a lightweight yet structurally robust fan inlet diffuser housing that maintains system performance under off-design conditions.
Innovation Solution
A fan inlet diffuser housing formed from composite materials with specific reinforcement patches and gap ratios, including an air cycle machine end reinforcement patch and bypass end reinforcement patch, along with an ejector gap width ratio, to enhance structural integrity and airflow recirculation, is designed to address the clogging issue and maintain performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the housing is made from composite materials to reduce weight, then weight is reduced, but structural integrity may be compromised
Solution Approach 1:
The patent applies local quality by implementing reinforcement patches at specific locations (transition regions between heat exchanger interface portion and ejector/bypass housing portions) rather than uniformly thickening the entire housing. This allows the housing to maintain lightweight composite construction while providing targeted structural reinforcement where stress concentrations occur during heat exchanger clogging events.
Solution Approach 2:
The patent utilizes composite materials for the housing body, combining lightweight properties with enhanced structural characteristics through the integration of reinforcement patches. This approach resolves the contradiction by using composite construction to achieve both weight reduction and improved strength where needed.
2Quantity of substance
If the fan rotor operates closer to its surge limit to maintain flow when heat exchanger is clogged, then flow volume is maintained, but performance under off-design conditions deteriorates
Solution Approach 1:
The patent implements a dynamic airflow path shape that can adapt to different operating conditions. The variable cross-sectional area along the airflow path allows the system to optimize flow characteristics dynamically, enabling the fan rotor to operate closer to its surge limit when needed while maintaining acceptable performance under off-design conditions through the geometric adaptation of the diffuser housing.
3Strength
If reinforcement patches are added to enhance structural integrity, then strength is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the reinforcement strategy into discrete patches located at specific transition regions rather than creating a complex uniformly reinforced structure. This segmented approach to reinforcement maintains relative structural simplicity while providing targeted strength enhancement where most needed.
Data Source
AI summary
A fan inlet diffuser housing includes a housing body of composite material and includes a heat exchanger interface portion positioned between an ejector housing portion and a bypass housing portion. A first transition region is formed between the heat exchanger interface portion and the ejector housing portion including an air cycle machine end reinforcement patch proximate to a heat exchanger interface. The air cycle machine end reinforcement patch includes a first patch thickness and a second patch thickness, and a ratio of the first patch thickness to the second patch thickness is between 2.02 and 3.11. An ejector is formed having an ejector gap width between a nozzle portion and a diffuser portion within the ejector housing portion of the housing body. The diffuser portion has a downstream ejector gap width, and a ratio of the downstream ejector gap width to the ejector gap width is between 4.62 and 5.01.