Buffer Air System for Turbine Bearing Compartment
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Solution Overview
Problem
Existing turbine engine systems face challenges in providing buffer air at reduced pressures without disrupting continuous high-pressure air supply to bearing compartments, affecting internal air system functions.
Innovation Solution
The design incorporates a structured assembly with a rotating and stationary structure, featuring a buffer cavity, low pressure cavity, and high pressure cavity, where the buffer cavity surrounds the bearing compartment, and the low pressure cavity directs leakage air and buffer air into a vent line, regulated by a valve to manage airflow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffer air is provided at high pressure, then buffer air can effectively surround the bearing compartment, but other internal air system functions requiring continuous high pressure air supply are disrupted
Solution Approach 1:
The air system is segmented into multiple cavities (buffer cavity, low pressure cavity, high pressure cavity) with separate air supply paths. The buffer cavity receives buffer air at reduced pressure from the low pressure cavity, while the high pressure cavity maintains high pressure air supply for other functions. This segmentation allows buffer air to be provided at reduced pressure without disrupting other internal air system functions that require continuous high pressure air supply.
2Loss of energy
If buffer air pressure is reduced, then parasitic losses and pressure forces on seal devices are minimized, but buffer air supply capability is reduced
Solution Approach 1:
The low pressure cavity acts as an intermediary between the buffer air source and the bearing compartment. It receives buffer air at reduced pressure and directs it to the bearing compartment through the buffer cavity, while maintaining a pressure gradient that minimizes parasitic losses and pressure forces on seal devices. The vent line with valve provides controlled pressure management in this intermediary zone.
3Ease of operation
If a complex multi-cavity structure is implemented, then pressure management and air flow control are improved, but device complexity increases
Solution Approach 1:
The cavities are arranged in a nested configuration where the buffer cavity surrounds the bearing compartment, the low pressure cavity surrounds the buffer cavity, and the high pressure cavity surrounds the low pressure cavity. This nested structure allows multiple pressure zones to coexist in a compact arrangement, improving pressure management while limiting the increase in overall device complexity through efficient spatial utilization.
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 configuration effectively reduces pressure within the buffer and low pressure cavities, minimizing parasitic losses and pressure forces on seal devices, enhancing engine efficiency and maintaining essential air system functions.
Implementation Method 1
The bearing compartment wall may include: a sidewall radially between and forming the bearing compartment and the buffer cavity; a first endwall projecting radially inward from the sidewall, the first endwall axially between and forming the bearing compartment and the buffer cavity; and a second endwall projecting radially inward from the sidewall, the second endwall axially between and forming the bearing compartment and the buffer cavity.
Implementation Method 2
The assembly may also include: a first seal device sealing a gap between the first endwall rim and the rotating structure; and/or a second seal device sealing a gap between the second endwall rim and the rotating structure.
Data Source
AI summary
An assembly is provided for a turbine engine. This assembly includes a rotating structure rotatable about an axis, a stationary structure and a bearing. The stationary structure forms a bearing compartment, a buffer cavity, a low pressure cavity and a high pressure cavity with the rotating structure. The buffer cavity surrounds the bearing compartment. The low pressure cavity surrounds the buffer cavity. The high pressure cavity surrounds the low pressure cavity. The bearing is within the bearing compartment. The bearing rotatably couples the rotating structure to the stationary structure.