Geared Architecture Heat Pipe Cooling
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Solution Overview
Problem
The integration of a geared architecture in gas turbine engines leads to thermal energy being transferred into the engine core flowpath via conduction, negatively impacting engine performance due to the use of fluids for both lubrication and cooling, which increases operational inefficiencies.
Innovation Solution
A thermal management system is introduced, comprising an evaporator portion acting as a heat spreader heat exchanger at the geared architecture and a condenser portion located in the fan bypass flowpath, with fluid pathways to convey heat transfer fluid between them, effectively exchanging thermal energy and reducing thermal energy transfer into the core flowpath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fluids are used for both lubrication and cooling in the geared architecture, then the system is simplified and fewer components are needed, but thermal energy is transferred into the engine core flowpath via conduction, negatively impacting engine performance
Solution Approach 1:
The fluid system is segmented into separate functions: a first fluid (oil) dedicated to lubrication and a second fluid (heat transfer fluid) dedicated to cooling. This is achieved by introducing a separate cooling circuit with an evaporator portion at the geared architecture and a condenser portion in the fan bypass flowpath, while the lubrication system continues to use oil through the geared architecture. This segmentation resolves the technical contradiction by eliminating thermal energy transfer to the core flowpath while maintaining both lubrication and cooling functions.
Solution Approach 2:
The cooling function is extracted from the lubrication fluid system. A separate cooling circuit is implemented using a heat transfer fluid that circulates through an evaporator at the geared architecture and a condenser in the fan bypass flowpath. This extraction removes the harmful thermal energy transfer to the core flowpath while preserving the lubrication function of the oil, resolving the contradiction between system simplicity and thermal management performance.
2Object-generated harmful factors
If a separate cooling system is introduced for the geared architecture, then thermal energy transfer to the core flowpath is reduced, but the device complexity increases
Solution Approach 1:
The cooling system is merged with the existing engine structure by utilizing the fan bypass flowpath as the condenser location. The heat transfer fluid condenses in the fan bypass flowpath, effectively combining the cooling function with the existing airflow path. This merging approach reduces the additional complexity by integrating the cooling system into the existing engine architecture rather than adding completely separate components.
Solution Approach 2:
The fan bypass flowpath serves multiple functions: it provides airflow for engine cooling and simultaneously serves as the condenser for the geared architecture cooling system. This multi-functionality reduces device complexity by utilizing existing engine components and flowpaths for dual purposes, eliminating the need for dedicated cooling components that would increase complexity.
3Device complexity
If oil is used for cooling in the geared architecture, then the cooling mechanism is simplified, but the operational efficiency decreases due to increased oil volume requirements
Solution Approach 1:
The mechanical cooling system using oil is replaced with a thermal management system using a dedicated heat transfer fluid in a closed-loop evaporator-condenser system. The heat transfer fluid circulates through the evaporator at the geared architecture and condenses in the fan bypass flowpath, replacing the need for oil-based cooling. This substitution improves operational efficiency by eliminating the need for large oil volumes while maintaining effective cooling, and the system complexity is managed through integration with existing engine structures.
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 system enhances engine performance by reducing the thermal impact on the core flowpath, minimizing the need for oil-based cooling and lubrication in the geared architecture, thereby improving operational efficiency and reducing oil volume requirements.
Implementation Method 1
configured to exchange thermal energy with the geared architecture via boiling of a volume of heat transfer fluid flowing therethrough
Implementation Method 2
a condenser portion located at a fan bypass flowpath of the gas turbine engine to reject thermal energy from the volume of heat transfer fluid into the fan bypass flowpath
Implementation Method 3
an inner plate in thermal contact with the geared architecture and an outer plate secured to the inner plate, the inner plate and the outer plate defining a plurality of fluid flow channels therebetween
Data Source
Figure 1
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AI summary
A thermal management system (72) for a geared architecture (48) of a gas turbine engine (20) includes an evaporator portion (74) located at the geared architecture (48) and configured to exchange thermal energy with the geared architecture (48) via boiling of a volume of heat transfer fluid flowing therethrough and a condenser portion (76) located at a fan bypass flowpath (B) of the gas turbine engine (20) to reject thermal energy from the volume of heat transfer fluid into the fan bypass flowpath (B). One or more fluid pathways (80) extend from the evaporator portion (74) to the condenser portion (76) to convey the volume of heat transfer fluid therebetween.