Turbofan Engine Electric Machine Cooling Integration
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Solution Overview
Problem
Conventional gas turbine engines face performance issues due to the use of bypass air or compressor offtakes as cooling mediums, leading to reduced specific thrust and increased specific fuel consumption, as well as reduced surge margin.
Innovation Solution
A turbofan gas turbine engine design with a specific fan axis angle and electric machine configuration that allows for a more compact engine layout, incorporating a first electric machine positioned downstream of the fan assembly and connected to the turbine module, and optimizing the placement of the electric machine within the compressor module to reduce axial length and enhance packaging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If bypass air or compressor offtake is used as cooling medium in heat exchanger, then cooling function is provided, but specific thrust is reduced and specific fuel consumption increases
Solution Approach 1:
The patent extracts the cooling function from the main engine airflow path by using dedicated cooling fans and separate heat exchangers. The cooling air is taken from ambient sources or engine exhaust rather than from the compressor bypass air, thereby separating the cooling subsystem from the propulsive airflow path and eliminating the negative impact on specific thrust.
Solution Approach 2:
The patent introduces electric machines as intermediaries to drive cooling fans independently. These electric machines can be powered by the turbine module or battery, acting as a mediator between the power source and the cooling system, allowing precise control of cooling airflow without affecting the main engine thrust production.
2Temperature
If bypass air or compressor offtake is used as cooling medium, then cooling function is provided, but surge margin is reduced
Solution Approach 1:
The cooling function is extracted from the compressor airflow path and provided through dedicated cooling fans driven by electric machines. This separation ensures that the compressor operates with its full airflow margin without being depleted by cooling demands, thereby maintaining surge margin and improving reliability.
3Length of moving object
If electric machine is positioned downstream of fan assembly and connected to turbine module, then compact layout is achieved, but space for component placement is reduced
Solution Approach 1:
The patent positions the electric machine in a radially outward location downstream of the fan assembly, utilizing the radial dimension rather than extending the axial length. This dimensional repositioning allows the electric machine to be integrated into the engine periphery where space is available, achieving a compact axial length while providing adequate space for component placement and maintenance access.
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 design results in a more compact and efficient turbofan engine with improved packaging and reduced propulsive efficiency losses, allowing for easier integration into aircraft while maintaining performance.
Implementation Method 1
a turbine module, with a first electric machine being positioned downstream of the fan assembly and being rotationally connected to the turbine module
Data Source
AI summary
A cooling system for an aircraft comprises a gas turbine engine, an ancillary apparatus, and a heat exchanger. The gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate an electrical power PEM1 (W). The heat exchanger is configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger, and a ratio S of:S=(Total Electrical Power Generated=PEM1)(Total Heat Energy Rejected to Airflow=Q)is in a range of between 0.50 and 5.00.