Gas Turbine Oil Scavenging Ejector for Bearing Cavity
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Solution Overview
Problem
Existing gas turbine engine oil scavenging systems face limitations in scavenging suction, particularly in certain operating conditions such as engine starting and quick deceleration, where additional suction is required without the need for additional equipment or increased pump size.
Innovation Solution
Incorporating an ejector with an air/oil path connected to the bearing cavity and a nozzle receiving compressed air, which entrains surrounding fluid to enhance suction, potentially using the air starter's compressed air or the engine's compressor air as the source, allowing for selective activation and deactivation based on operational needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump size is increased to improve scavenging suction, then oil drainage efficiency is improved, but device complexity and weight increase
Solution Approach 1:
An ejector is introduced as an intermediary device between the bearing cavity and the pump. The ejector uses compressed air from the air starter to create a vacuum effect that enhances oil suction from the bearing cavity, while the pump itself remains unchanged in size. This mediator approach allows improved scavenging performance without increasing pump dimensions or complexity.
Solution Approach 2:
The invention utilizes pneumatic principles by employing compressed air through the ejector mechanism. The high-pressure air from the air starter is directed through the ejector nozzle, creating a low-pressure zone that draws oil from the bearing cavity. This pneumatic assistance enhances the mechanical pump's capability without requiring the pump to be larger or more complex.
2Productivity
If additional equipment is added to improve scavenging suction, then oil drainage efficiency is improved, but device complexity and maintenance costs increase
Solution Approach 1:
The air starter serves multiple functions: it provides compressed air for engine starting and simultaneously supplies compressed air to the ejector for enhanced oil scavenging. By making the air starter multi-functional, the system improves scavenging performance without adding dedicated new equipment, thereby avoiding increased complexity and maintenance requirements.
Solution Approach 2:
The invention merges the air starter's compressed air output with the oil scavenging system through the ejector. Instead of adding separate compression equipment, the system combines the existing air starter's functionality with the scavenging requirement, creating an integrated solution that avoids additional equipment and associated maintenance costs.
3Productivity
If the pump size is increased to improve scavenging suction, then oil drainage efficiency is improved, but weight increases
Solution Approach 1:
The ejector acts as a lightweight intermediary that amplifies the scavenging effect without adding significant weight. By using the ejector to create vacuum assistance, the system achieves improved oil drainage while keeping the pump (and thus the moving weight) at its original, lighter size.
Solution Approach 2:
The pneumatic ejector system provides a lightweight alternative to mechanical pump enlargement. Compressed air, being weightless, is used to create the suction effect, allowing improved scavenging performance without increasing the weight of mechanical components like the pump.
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 provides enhanced scavenging suction in various operating conditions, including engine starting and quick deceleration, without the need for additional equipment or increased pump size, thereby improving oil drainage efficiency and reducing weight and maintenance costs.
Implementation Method 1
the compressed air exiting the nozzle entraining surrounding fluid in the air/oil path and thereby causing suction at the bearing cavity
Data Source
AI summary
The gas turbine engine can have a bearing cavity, an ejector having an air/oil path fluidly connected to the bearing cavity, and a nozzle fluidly coupled with the air/oil path, the nozzle connected to a compressed air source.