Brush Seal Oil Flow for Jet Engine Coking
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Solution Overview
Problem
Labyrinth seals in turbojet engines are inefficient due to excessive gas flow during high phases of flight, leading to reduced engine efficiency and increased oil leakage, while brush seals suffer from coking and wear issues.
Innovation Solution
A brush seal design where an oil flow is created along the strands to prevent degradation, with oil supply mechanisms to maintain freshness and lubrication, reducing coking and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If labyrinth seals are used with high gas flow rate, then oil leakage is reduced, but engine efficiency decreases and oil is carried out of the enclosure
Solution Approach 1:
The patent changes the physical parameters of the seal by transitioning from traditional labyrinth seals to brush seals with specific brush configuration, allowing optimal gas flow rates that maintain both oil tightness and engine efficiency across different flight phases
Solution Approach 2:
The seal design incorporates dynamic adaptation through brush seal elements that can adjust to varying operating conditions, maintaining effective sealing performance whether the engine is at idle or in high-power phases
2Reliability
If brush seals are used with low gas flow rate, then oil tightness is improved, but coking occurs on the fibers
Solution Approach 1:
The patent introduces oil as an intermediary substance that flows through the brush seal, serving dual functions: maintaining oil tightness and preventing coking by continuously renewing the oil film on the fibers, thus eliminating the harmful thermal degradation effect
Solution Approach 2:
The seal system performs self-maintenance through the continuous flow of oil that automatically renews itself as it passes through the brush seal, preventing accumulation of degraded oil and eliminating coking without external intervention
3Reliability
If brush seals are used with contact friction, then sealing effectiveness is improved, but wear reduces durability
Solution Approach 1:
The continuous oil flow through the brush seal provides automatic lubrication, reducing friction and wear on the fibers while maintaining contact with the rotating component, thus preserving sealing effectiveness over extended operational periods
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 improves the oil tightness and durability of the seal by maintaining oil freshness and lubrication, reducing coking and wear, thereby enhancing the seal's effectiveness and longevity.
Implementation Method 1
an oil flow is created along the strands of the brush seal, which ensures renewal of the oil on contact with them, since the latter is driven in motion along the strands
Implementation Method 2
the friction of the bristles on the track of the rotating part intended to be in contact with their ends causes their wear
Implementation Method 3
the gases are evacuated in 'oil separators' generally formed by radial chimneys made in the low pressure shaft and on the wall of which the oil is collected to be reinjected into the corresponding enclosure, by centrifugal effect
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a sealing device for a chamber (4, 5) that is formed of at least one rotary member (3, 15) and at least one static member (12, 13) of a jet engine (1) and is intended to contain a lubricating oil droplet suspension (h). The sealing device comprises at least one brush seal (14) that has juxtaposed strands (17) and is set up so as to ensure sealing between at least one rotary member (15) and at least one stationary member (12). Said device is characterized in that it comprises a means (12, 19, 25, 30) for recovering part of the oil suspended within the inner space (V) of the chamber (4, 5) and comprises a means (20, 22, 23, 24, 26) for delivering said recovered oil (h), said delivery means being set up so as to generate a flow of oil (h) along the strands (17) of said brush seal (14), said oil flow being oriented in the direction of the rotary member (3, 15). The brush seal (14) thus provides better resistance to coking.