Bearing Compartment Oil Drainback Assembly for Leak Recirculation
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Solution Overview
Problem
Gas turbine engines face issues with oil loss from bearing compartments due to seal system leaks, which can lead to performance degradation, imbalance, and contamination, affecting engine operation and durability.
Innovation Solution
An oil drainback assembly with a windage blocker and directional fitting is used to capture wept oil, directing it back into the oil-wetted zone through a recirculation zone created by offset walls, enhancing drainage and reducing oil egress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seal systems are used to retain oil within the bearing compartment, then oil retention is improved, but oil loss through seal leakage still occurs causing contamination and performance degradation
Solution Approach 1:
The invention captures the harmful leaked oil through the windage blocker and directional fitting, then redirects it back to the oil-wetted zone through drain passages. This converts the harmful leakage into a beneficial recirculation system that maintains lubrication while preventing contamination.
Solution Approach 2:
The windage blocker and directional fitting act as intermediary components between the oil-wetted zone and the seal system. They intercept oil that would otherwise leak harmful amounts into the turbine or compressor, providing a middle path for oil return.
2Productivity
If windage blocker with offset walls is introduced to create recirculation zone, then oil drainage efficiency is improved, but device complexity increases
Solution Approach 1:
The assembly is segmented into distinct functional components: the windage blocker with offset walls for creating recirculation, the directional fitting for guiding flow, and the drain passages for oil return. This segmentation allows each component to be optimized for its specific function while maintaining overall efficiency.
Solution Approach 2:
The offset walls of the windage blocker create an asymmetric geometry that generates the recirculation zone. This asymmetric design is crucial for producing the rotational flow pattern that enhances oil drainage efficiency without requiring additional mechanical components.
3Loss of substance
If directional fitting is used to direct oil into oil-wetted zone, then oil recirculation is improved, but manufacturing complexity increases
Solution Approach 1:
The directional fitting serves multiple functions: it directs oil flow into the oil-wetted zone, structural support for the assembly, and flow conditioning element. This multi-functionality reduces the need for separate components, simplifying manufacturing despite the complex flow requirements.
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 effectively recirculates wept oil, reducing oil consumption, preventing contamination, and maintaining engine performance by minimizing oil loss and ensuring efficient lubrication.
Implementation Method 1
creating a recirculation zone
Implementation Method 2
build head pressure for the oil to drain down the drain hole
Implementation Method 3
a pumping action due to the direction of rotation of the recirculation zone
Implementation Method 4
the rotationally fixed structure at least partially separates an oil-wetted zone from a non-oil-wetted zone in the bearing compartment
Data Source
Figure 1
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Figure 3
AI summary
A bearing compartment of a gas turbine engine includes a rotationally fixed structure (82) defined about an engine longitudinal axis (A); a gutter section (84) formed in the front support (82); an oil drainback assembly (100) mountable to the gutter section (84) to direct oil into a drain passage (118) to communicate oil from the gutter (84).