Compressed-Air Thermal Circuit for Aircraft Propulsion Cooling
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Solution Overview
Problem
Conventional thermal management systems for propulsion systems, such as geared turbomachines or variable pitch fans, face inefficiencies due to fan stream blockage and inadequate thermal load attenuation, particularly affecting reduction gearboxes and variable pitch fans, leading to reduced engine performance and efficiency.
Innovation Solution
A method and structure that extracts a flow of compressed fluid from a compressor section of a propulsion system, utilizing a turbine downstream of the compressor to generate output torque and adjust fluid flow through a variable area turbine nozzle (VATN) to drive a turbomachine, allowing independent adjustment of heat exchange fluid relative to operating conditions, and includes heat exchangers to manage thermal loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an air stream is used to provide thermal attenuation of fuel or lubricant, then thermal management is achieved, but fan stream blockage occurs reducing engine performance and efficiency
Solution Approach 1:
The patent extracts the thermal management function from the fan stream by introducing a separate cooling system that uses compressed air from the compressor section. This separates the thermal attenuation function from the propulsion function, allowing thermal management without blocking the fan stream and maintaining engine performance.
Solution Approach 2:
The patent introduces compressed air as an intermediary substance to transfer thermal energy from hot components (exhaust manifold, turbocharger) to the cooling system. This intermediary approach enables thermal management without directly using the fan stream, avoiding blockage while achieving temperature control.
2Temperature
If conventional cooling configurations are used, then thermal management is provided, but thermal loads from reduction gearboxes and variable pitch fans are inadequate
Solution Approach 1:
The patent creates a universal cooling system that can serve multiple thermal management needs including reduction gearboxes, variable pitch fans, and exhaust components. The system uses a common compressed air source and can be configured to cool different components, providing comprehensive thermal management for previously inadequately cooled elements.
3Loss of energy
If compressed fluid flow is extracted from compressor section, then work extraction is maximized, but system complexity increases
Solution Approach 1:
The patent makes the cooling system self-service by using compressed air that is already available from the compressor section. The system utilizes existing system resources (compressed air) to provide cooling, eliminating the need for separate compression systems and reducing overall complexity despite the additional cooling components.
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
Improves overall system and vehicle efficiency by maximizing work extraction from compressed fluid, enhancing heat transfer from lubricants and load devices, and allowing independent adjustability of cooling fluid flow, thereby optimizing thermal management.
Implementation Method 1
generating an output torque via expanding at least a portion of the flow of compressed fluid across a turbine operably connected to a driveshaft
Implementation Method 2
enhancing heat transfer from lubricants and load devices
Data Source
AI summary
A thermal management system for a propulsion system of an aircraft includes a fluid circuit configured to provide a flow of a compressed fluid from a compressor section of the propulsion system to, in serial flow order, a first turbine, a compressor, a second turbine, a thermal load, and an exhaust sink. A heat exchanger is disposed in a fan stream of the propulsion system at a location along the fluid circuit between the compressor and the second turbine. The fluid circuit extends through and is in thermal communication with the heat exchanger.