Turbine Bearing Buffer Air Venting for Parasitic Loss Reduction
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Solution Overview
Problem
Existing turbine engine systems face challenges in providing buffer air at reduced pressures without disrupting the continuous high-pressure air supply to bearing compartments, which can lead to inefficiencies and increased parasitic losses.
Innovation Solution
A method and assembly that combine buffer air with leakage air from a high-pressure cavity to a low-pressure cavity, using a venting system controlled by a valve to maintain buffer air pressure below a maximum threshold and leakage air flowrate above a minimum threshold, ensuring efficient operation and reduced pressure forces on bearing seal devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If buffer air pressure is reduced to decrease parasitic losses, then energy efficiency is improved, but the ability to maintain minimum leakage air flowrate across the buffer seal device deteriorates
Solution Approach 1:
The patent combines buffer air from the buffer cavity with leakage air from the high-pressure cavity to create combined air in the low-pressure cavity. This merging allows the system to utilize the pressure differential between cavities to maintain adequate flowrate across the buffer seal device while operating with reduced buffer air pressure overall, thereby decreasing parasitic losses while preserving reliability
Solution Approach 2:
The low-pressure cavity acts as an intermediary chamber that receives both buffer air and leakage air, combining them before venting to the pressure sink. This intermediary structure enables the system to balance pressure conditions to maintain minimum leakage air flowrate while allowing reduced buffer air pressure to reduce parasitic losses
2Reliability
If buffer air pressure is maintained high to ensure adequate leakage air flowrate, then reliability is improved, but energy efficiency deteriorates due to increased parasitic losses
Solution Approach 1:
The system dynamically manages air pressure by selectively venting combined air from the low-pressure cavity through a controllable valve. This dynamic control allows the system to maintain adequate leakage air flowrate when needed while reducing buffer air pressure to minimize parasitic losses during normal operation, optimizing the balance between reliability and energy efficiency
3Reliability
If a valve is added to control venting of combined air, then the ability to maintain pressure thresholds is improved, but device complexity increases
Solution Approach 1:
The control system monitors pressure conditions in the buffer cavity and low-pressure cavity, and automatically controls the valve to vent combined air when pressure thresholds are exceeded. This feedback mechanism maintains reliable pressure control while minimizing the need for complex manual intervention or oversized valve systems
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 effectively manages air pressure and flowrate within the turbine engine, reducing parasitic losses and maintaining optimal conditions for bearing seal devices, thereby enhancing engine efficiency and reliability.
Implementation Method 1
The combined air is vented to a pressure sink such that: a pressure of the buffer air within the buffer cavity is maintained at or below a maximum buffer air threshold; and a flowrate of the leakage air across the buffer seal device is maintained at or above a minimum leakage air threshold
Data Source
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AI summary
A method of operation is provided during which buffer air flows into a buffer cavity (124) in a turbine engine (20). The buffer cavity (124) surrounds a bearing compartment (100) in the turbine engine (20). Leakage air flows across a buffer seal device (150, 154) in the turbine engine (20). The buffer air and the leakage air are combined to provide combined air. The combined air is vented to a pressure sink (174) such that: a pressure of the buffer air within the buffer cavity (124) is maintained at or below a maximum buffer air threshold during operation of the turbine engine (20); and a flowrate of the leakage air across the buffer seal device (150, 154) is maintained at or above a minimum leakage air threshold during the operation of the turbine engine (20).