Aircraft Friction Disk Cooling and Inert Gas Oxidation Control
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Solution Overview
Problem
Aircraft friction disks in braking assemblies undergo oxidation due to high temperatures generated during braking, reducing their usable life, as existing materials like carbon-carbon composites are susceptible to oxidation despite their heat resistance.
Innovation Solution
A system that includes a torque tube forming part of a coolant loop to transfer heat from friction disks and delivers inert fluid, such as a nitrogen-enriched air stream, to reduce oxygen concentration around the disks, thereby mitigating oxidation. The system also limits convective ambient airflow using a solid wheel portion and heat shield to further decrease oxidation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If carbon-carbon composite materials are used for friction disks to withstand high temperatures, then heat resistance is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent introduces an inert fluid (nitrogen or nitrogen-enriched air) delivery system that supplies inert gas to the friction disk environment during braking. This creates a localized inert atmosphere that prevents oxidation of the carbon-carbon composite material while allowing the material to maintain its heat resistance properties. The inert fluid delivery means includes conduits and nozzles positioned to direct inert gas onto the friction surfaces.
2Temperature
If carbon-carbon composite materials are used for friction disks, then heat withstand capability is improved, but usable life deteriorates due to oxidation
Solution Approach 1:
By maintaining a continuous supply of inert fluid during braking operations, the system protects the friction disks from oxidative degradation throughout their service life. This extends the usable life of the carbon-carbon composite disks by preventing the chemical degradation that would otherwise occur at elevated temperatures.
Solution Approach 2:
The inert fluid acts as an intermediary substance between the friction disk and the ambient oxygen-rich environment. It forms a protective barrier that allows the friction disk to operate at high temperatures without direct exposure to oxygen, thereby extending its operational life.
3Temperature
If cooling systems are implemented to reduce friction disk temperature, then oxidation rate is reduced, but device complexity increases
Solution Approach 1:
The patent combines the inert fluid delivery system with the existing braking assembly structure. The conduits and nozzles for inert gas delivery are integrated into the torque tube and brake caliper components, rather than adding separate cooling infrastructure. This merging approach reduces overall system complexity while achieving temperature and oxidation control.
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 combination of liquid cooling and inert fluid delivery significantly reduces the extent and rate of oxidation, extending the life of friction disks by lowering temperature and oxygen exposure.
Implementation Method 1
a torque tube, with the torque tube defining at least a portion of the coolant loop
Implementation Method 2
circulating a liquid coolant to the braking assembly to transfer heat from the friction disk
Implementation Method 3
delivery of the inert fluid to the braking assembly via the conduit supplants oxygen in a vicinity of the friction disk to reduce oxidation of the friction disk
Implementation Method 4
the source of the inert fluid may comprise a membrane configured to separate air into a nitrogen-enriched air stream and an oxygen-enriched air stream
Implementation Method 5
the wheel assembly is configured to limit convective ambient airflow around the friction disk of the braking assembly
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A system, and associated method, for reducing oxidation of a friction disk may include a braking assembly (320) comprising the friction disk and a coolant loop (712) coupled to the braking assembly, with the coolant loop being configured to circulate liquid coolant from the braking assembly. That is, the coolant loop may be configured to reduce the temperature of the braking assembly, thus reducing the rate/extent of oxidation of the friction disks and potentially enabling the concentration of oxygen around the braking assembly to be reduced.