Aft Electric Machine Cooling in Reverse-Flow Gas Turbines
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Solution Overview
Problem
Existing gas turbine engines with reverse flow configurations face challenges in integrating auxiliary components like electric machines efficiently, particularly due to heat management and packaging constraints.
Innovation Solution
The electric machine is positioned aft of the core turbine engine, coupled to the low-pressure shaft, and utilizes the intake channel airflow for heat exchange, allowing for tighter packaging and effective cooling through conduction and convection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electric machine is integrated into the reverse flow gas turbine engine, then the power density and engine performance are improved, but the heat management becomes more difficult due to the high temperatures in the reverse flow configuration
Solution Approach 1:
The electric machine is extracted from the traditional accessory gearbox location and positioned in the tail cone section of the engine, separating it from the high-temperature core turbine area. This spatial extraction allows the electric machine to utilize cooler airflow from the intake channel while still being driven by the low-pressure shaft, thereby improving heat management while maintaining power density.
Solution Approach 2:
The intake channel airflow serves as an intermediary cooling medium between the electric machine and the high-temperature engine core. The airflow is directed through the tail cone section where it absorbs heat from the electric machine through conduction and convection, effectively managing thermal loads without requiring additional cooling systems.
2Volume of moving object
If the electric machine is positioned aft of the core turbine engine, then the packaging is tighter and space is optimized, but the heat exposure from the reverse flow configuration increases
Solution Approach 1:
The electric machine is positioned in the tail cone section, utilizing the axial dimension of the reverse flow configuration to its advantage. The intake channel airflow moves axially through the tail cone, creating a natural convection current that passes through or near the electric machine, providing cooling while maintaining compact packaging in the radial direction.
Solution Approach 2:
The reverse flow configuration's own airflow serves the dual purpose of driving the low-pressure shaft (which drives the electric machine) and cooling the electric machine. The system uses its inherent airflow to provide thermal management, eliminating the need for separate cooling systems and enabling tighter packaging.
3Reliability
If the electric machine utilizes intake channel airflow for heat exchange, then the cooling effectiveness is improved, but the complexity of integrating the heat exchange system increases
Solution Approach 1:
The heat exchange function is merged with the existing intake channel airflow path. The intake channel, which already exists to supply air to the compressor, is extended or modified to also flow through the tail cone section where the electric machine is located. This combines the cooling function with the existing airflow system, improving cooling effectiveness without adding separate complex heat exchange components.
Solution Approach 2:
The intake channel airflow serves multiple functions: it provides oxygen for combustion, drives the low-pressure shaft (and thus the electric machine), and cools the electric machine through heat exchange in the tail cone section. This multi-functionality reduces the need for additional dedicated cooling systems, simplifying overall integration while maintaining high cooling effectiveness.
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 configuration enhances heat management, enabling higher power density and improved engine performance by allowing the electric machine to operate efficiently while withstanding high temperatures.
Implementation Method 1
utilizes the intake channel airflow for heat exchange, allowing for tighter packaging and effective cooling through conduction and convection
Implementation Method 2
utilizes the intake channel airflow for heat exchange, allowing for tighter packaging and effective cooling through conduction and convection
Data Source
AI summary
An aircraft engine assembly includes a gas turbine engine having an intake channel configured to receive an incoming flow of air and form an intake flow of air, the intake channel configured to turn the received incoming flow of air from an incoming flow direction to a first axial direction of the gas turbine engine, the incoming flow direction reverse of the first axial direction, and an electric machine coupled with the low pressure shaft and located at the aft end of the gas turbine engine proximate the intake channel, the electric machine in heat exchange communication with the intake flow of air such that the electric machine transfers heat to the incoming flow of air within the intake channel when the electric machine is operated.