Vented Buffer Air Supply for Intershaft Seal Pressure Control
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Solution Overview
Problem
Conventional seals in gas turbine engines, particularly those used for intershaft sealing, face degradation and operational issues due to pressure imbalances between low and high pressure compressor sources, leading to potential oil leakage and reduced service lifetime.
Innovation Solution
Incorporating a meter, such as a venturi tube or orifice plate, to regulate air pressure and mass flow across seals, allowing the use of commercially available seals while managing pressure drops and environmental changes, and exhausting excess air to a low-pressure location to prevent seal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air from low pressure compressor is used as buffer air source, then seal buffering function is provided, but pressure imbalance causes air flow across seals leading to seal degradation and reduced service lifetime
Solution Approach 1:
The patent changes the pressure parameter of the buffer air by selecting a different source (high pressure compressor or intermediate pressure stage) and using a metering device to control and equalize the pressure, thereby resolving the pressure imbalance that caused seal degradation
Solution Approach 2:
A metering device is introduced as an intermediary component between the air source and the seal buffer passage. This device controls and regulates the air flow and pressure, preventing direct uncontrolled flow across the seals that led to degradation
2Stress or pressure
If high pressure compressor air is used as buffer air source, then sufficient buffering pressure is achieved, but excessive pressure increases risk of oil leakage from bearing compartment
Solution Approach 1:
The patent precisely controls the pressure parameter of buffer air by using a metering device to reduce the high pressure from the high pressure compressor to an optimal level, maintaining sufficient buffering pressure while preventing excessive pressure that would cause oil leakage
Solution Approach 2:
The system incorporates pressure sensing and metering control that responds to pressure conditions in the seal buffer passage, automatically regulating air flow to maintain pressure within safe operating limits and prevent oil leakage
3Stress or pressure
If uncontrolled air flow across seals is allowed, then pressure equalization between compressor stages is achieved, but seal performance degrades and operational stability is reduced
Solution Approach 1:
The metering device serves as an intermediary that mediates between the high pressure air source and the seal buffer passage, providing controlled pressure equalization that maintains stability while achieving the necessary pressure balancing function
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
This solution enhances seal performance by maintaining optimal pressure levels, reducing leakage, and extending seal lifetime, thereby ensuring stable engine operation and preventing oil leakage.
Implementation Method 1
Incorporating a meter, such as a venturi tube or orifice plate, to regulate air pressure and mass flow across seals
Implementation Method 2
Incorporating a meter, such as a venturi tube or orifice plate, to regulate air pressure and mass flow across seals
Data Source
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AI summary
Aspects of the disclosure are directed to a system (300) associated with an engine having a central longitudinal axis (202), comprising: a first shaft (214) axially extend along the central longitudinal axis (202), a second shaft (220) coaxial with the first shaft (214), a first air seal (330b) that seals between the first shaft (214) and the second shaft (220) at a first axial location (B), a second air seal (330c) that seals between the first shaft (214) and the second shaft (220) at a second axial location (C), a high pressure compressor section (228-2) that provides air to the first air seal (330b) and the second air seal (330c), at least one buffer passage (302-2), and a meter (328) connected to the buffer passage (302-2) that exhausts a portion of the air.