Gas Turbine Oil Tank Offset Outlets for Bearing Lubrication Warning
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Solution Overview
Problem
Existing gas turbine engines with a single oil circuit are prone to undesirable oil flow reductions, which can lead to gearbox failure and hazardous conditions due to insufficient lubrication, especially during extended periods or windmill conditions, as they lack a reliable mechanism to maintain oil supply to journal bearings.
Innovation Solution
A gas turbine engine design incorporating two oil circuits with offset outlets in the oil tank, ensuring that the second oil circuit generates a low oil pressure warning before the first circuit is affected, thereby providing a redundant oil supply to journal bearings and preventing premature failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single oil circuit is used to feed and scavenge oil to all users in the engine, then the system complexity is reduced, but the reliability of oil supply to journal bearings deteriorates under failure conditions
Solution Approach 1:
The oil system is segmented into two independent oil circuits (first oil circuit and second oil circuit) that separately feed oil to the journal bearings. This segmentation allows one circuit to continue supplying oil even if the other fails, thereby maintaining reliability while managing system complexity through modular design
Solution Approach 2:
The offset outlet arrangement in the oil tank is designed to trigger a warning signal in advance when oil levels drop, before complete oil supply failure occurs. This preliminary warning action gives operators time to respond before the system fails, preventing catastrophic bearing damage
2Reliability
If offset outlets are positioned at different heights in the oil tank, then early warning of low oil levels is achieved, but the device complexity increases
Solution Approach 1:
The offset outlets are positioned at different heights to create different oil pressure conditions at various oil levels. When oil drops below the higher outlet, pressure differential triggers the warning signal. This uses gravitational potential energy differences to create the warning function without additional complex sensing mechanisms
Solution Approach 2:
The oil system uses its own oil pressure and level conditions to automatically trigger the warning signal through the offset outlet arrangement. No external sensors or complex control systems are needed - the system self-monitors and self-alarms based on its operational parameters
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 design ensures that the pilot receives a timely warning of low oil levels, allowing for proactive action to prevent oil supply loss to journal bearings, thereby minimizing the risk of gearbox failure and maintaining engine safety during critical conditions.
Implementation Method 1
The offset outlet of the second oil circuit is positioned higher in the oil tank than the offset outlet of the first oil circuit feeding solely to the unit when the oil tank is in its installation position in the gas turbine engine during a level flight of an aircraft comprising the gas turbine engine
Data Source
AI summary
A gas turbine engine for an aircraft including a unit supplied with oil from a first oil circuit and a second oil circuit. The first oil circuit and the second oil circuit each are fluidly coupled with at least one inlet and with at least one outlet of the unit and with at least one inlet and with at least one outlet of an oil tank. The first oil circuit and the second oil circuit are configured to receive oil from the oil tank and to direct the received oil to the unit. The oil tank is incorporating offset outlets to each of the oil circuits. The offset outlet of the second oil circuit is positioned higher in the oil tank than the offset outlet of the first oil circuit.