Active De-Aerator Impeller Support for Stable Air-Oil Separation
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Solution Overview
Problem
Aircraft engine lubrication systems face challenges in effectively separating air from oil due to rotor vibrations caused by turbulent air-oil mixtures, which existing de-aerators struggle to manage efficiently.
Innovation Solution
An active de-aerator is integrated with an oil pump, featuring an impeller with dual journal bearings and a specific housing configuration to stabilize the impeller and reduce vibrations, utilizing centrifugal forces to separate air from oil and return de-aerated oil back to the lubrication system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a de-aerator is used to remove air from the oil, then the air content in the lubricating oil is reduced, but rotor vibrations increase due to turbulent flow of mixed oil and air
Solution Approach 1:
The de-aerator is segmented into multiple functional zones: an inlet zone for receiving air-oil mixture, a separation zone with centrifugal elements for air-oil separation, and an outlet zone for discharging separated phases. This segmentation allows turbulent mixing to occur in controlled zones while maintaining stability in other zones, resolving the contradiction between effective air removal and vibration stability.
Solution Approach 2:
The de-aerator incorporates dynamic elements such as rotating centrifugal separators and adjustable flow control mechanisms that adapt to varying operating conditions. These dynamic components optimize the separation process while dampening vibrations, allowing the system to maintain stability across different air content levels and flow rates.
2Stress or pressure
If compressed air is used to pressurize the bearing cavity, then the bearing cavity pressure is increased, but air becomes mixed with the oil increasing air content
Solution Approach 1:
The de-aerator extracts air from the oil stream using centrifugal separation forces. The separated air is removed from the system while the de-aerated oil is returned to the lubrication circuit, effectively taking out the harmful air component that was introduced during bearing cavity pressurization.
Solution Approach 2:
The de-aerator acts as an intermediary device between the bearing cavity pressurization system and the lubrication system. It mediates the conflict by accepting air-oil mixture from one system and delivering de-aerated oil to the other, preventing air contamination while maintaining pressurization functionality.
3Quantity of substance
If the de-aerator processes turbulent air-oil mixture, then air separation is achieved, but the de-aerator is subject to rotor vibrations
Solution Approach 1:
The de-aerator incorporates vibration damping elements and shock-absorbing mounting structures that are installed beforehand to cushion against the turbulent forces generated during air-oil separation. This prior cushioning protects the rotor assembly from excessive vibrations while maintaining separation efficiency.
Solution Approach 2:
The de-aerator design converts the harmful turbulent flow into a beneficial centrifugal force that enhances air-oil separation. The turbulence that would normally cause vibrations is harnessed to create rotational motion in the centrifugal separator, improving separation efficiency while the vibrations are managed through damping mechanisms.
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 active de-aerator effectively reduces air content in the lubricating oil, enhancing the stability and efficiency of the lubrication system by minimizing vibrations and ensuring consistent lubrication, thereby improving the performance and longevity of aircraft engine components.
Implementation Method 1
utilizing centrifugal forces to separate air from oil
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
An active de-aerator (130) for an aircraft engine (10) is provided, with a housing (H) having an air-oil inlet (130a), an oil outlet (130b) and an air outlet (130c). An impeller (132) is received within and rotatable relative to the housing (H) about a central axis (A). The active de-aerator (130) has a first journal bearing (JB1) on a first side of the impeller (132) for rotatably supporting the impeller (132) relative to the housing (H) and a second journal bearing (JB2) on a second side of the impeller (132) for rotatably supporting the impeller (132) relative to the housing (H), the second side being opposite the first side.