Gas Turbine Buffer Manifold for Seal Pressure Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engines face challenges in maintaining effective sealing and lubrication within bearing compartments, particularly due to pressure imbalances that can lead to lubricant leakage and seal degradation, affecting the efficiency and longevity of the engine components.
Innovation Solution
A buffer system is introduced that utilizes a network of air and oil seals supported by a high-pressure air source from the high-pressure compressor, with an orifice plate to manage airflow and pressure, ensuring consistent pressurization and reducing pressure drop across seals, thereby maintaining efficient operation and extending seal life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-pressure air source is used to maintain pressure outside bearing compartments, then lubricant retention is improved, but pressure imbalances cause seal degradation and lubricant leakage
Solution Approach 1:
A buffer gas (typically air) is introduced into the intershaft compartment to act as an intermediary medium that balances pressure between the bearing compartments and the external environment. This buffer gas prevents direct exposure of seals to extreme pressure differentials while maintaining adequate pressure to prevent lubricant leakage, thereby reducing seal degradation while preserving lubricant retention.
Solution Approach 2:
The system dynamically adjusts the pressure parameters in the intersshaft compartment by controlling the flow of buffer gas through orifice plates and seals. By changing the pressure parameter in the buffer zone, the system optimizes the balance between preventing lubricant leakage (requiring higher pressure) and preventing seal degradation (requiring moderate pressure), thus resolving the contradiction.
2Loss of substance
If pressure is increased outside bearing compartments to retain lubricant, then lubricant leakage is reduced, but pressure drop across seals increases causing seal degradation
Solution Approach 1:
The engine interior is segmented into distinct pressure zones: high-pressure bearing compartments containing lubricant, a intermediate-pressure intersshaft buffer compartment, and lower-pressure external regions. This segmentation allows each zone to operate at optimal pressure levels, preventing lubricant leakage in bearing compartments while protecting seals from excessive pressure differentials.
Solution Approach 2:
The buffer gas in the intersshaft compartment serves as a cushioning medium that absorbs and moderates pressure fluctuations before they reach the seals. This beforehand cushioning prevents sudden pressure spikes from directly impacting seals, thereby extending seal life while maintaining adequate pressure for lubricant retention.
3Stability of the object's composition
If buffer gas flow is increased to maintain pressurization, then consistent pressure is achieved, but pressure drop across seals increases
Solution Approach 1:
Orifice plates are pre-positioned in the buffer gas flow path to control and regulate pressure before the gas reaches the seals. These orifice plates create a controlled pressure differential that maintains consistent pressure in the buffer zone while limiting the pressure drop across seals, thus achieving stable pressurization without excessive seal stress.
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 buffer system effectively retains lubricant within bearing compartments, reduces seal degradation, and maintains consistent pressurization, enhancing the operational efficiency and longevity of gas turbine engine components.
Implementation Method 1
A pressure outside of a bearing compartment that contains the bearings is typically maintained at a higher pressure than the pressure within the bearing compartment to assist in retaining the lubricant within the bearing compartment
Implementation Method 2
A buffer system is introduced that utilizes a network of air and oil seals supported by a high-pressure air source from the high-pressure compressor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A gas turbine engine includes a buffer manifold (244) in an intershaft region (240). The buffer manifold (244) is configured to direct a flow of air (266) between a first air seal (230b) and a first oil seal (234c), and to direct another flow of air (268) between a second air seal (230c) and a second oil seal (234c).