Turbofan Engine Electric Machine Radial Placement
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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 sizing that allows for a more compact engine configuration, 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 achieved, but specific thrust is reduced and specific fuel consumption is increased
Solution Approach 1:
The patent extracts the cooling function from the bypass air stream by introducing a separate cooling air intake. This allows the bypass air to be dedicated solely to cooling the heat exchanger without being mixed with the core engine airflow, thereby preserving thrust performance while achieving effective cooling.
Solution Approach 2:
The patent segments the airflows into distinct paths: a dedicated cooling air intake for the heat exchanger, a separate bypass air stream for cooling, and the core engine airflow for thrust generation. This segmentation prevents interference between cooling requirements and thrust generation, resolving the contradiction between cooling effectiveness and specific thrust.
2Temperature
If bypass air or compressor offtake is used as cooling medium, then cooling is provided, but surge margin is reduced
Solution Approach 1:
The cooling function is extracted from the core engine airflow path by using a separate cooling air intake. This ensures that the bypass air and cooling air do not interfere with the core engine's surge margin, allowing the engine to maintain its reliability while providing effective cooling to the heat exchanger.
3Power
If electric machine is added downstream of fan assembly, then electrical power generation is enabled, but axial length increases
Solution Approach 1:
The patent positions the electric machine radially outward from the core engine components, utilizing the radial space between the fan assembly and the engine case. This dimensional transition from axial to radial placement allows electrical power generation capability to be added without increasing the axial length of the engine.
4Volume of moving object
If compact engine configuration is achieved through optimized fan axis angle, then packaging efficiency is improved, but design complexity increases
Solution Approach 1:
The patent optimizes the fan axis angle as a key geometric parameter to achieve compact packaging. By carefully selecting and adjusting this angular parameter, the engine components are arranged to maximize packaging efficiency. While this introduces design complexity, the parameter-based approach provides a systematic method for achieving the desired compact configuration.
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 reduced propulsive efficiency losses and improved packaging, enabling easier integration into aircraft while maintaining performance.
Implementation Method 1
a fan assembly, a compressor module, and a turbine module, with a first electric machine being positioned downstream of the fan assembly and being rotationally connected to the turbine module
Implementation Method 2
conventional gas turbine engines face performance issues due to the use of bypass air or compressor offtakes as cooling mediums
Implementation Method 3
heat exchangers to cool a variety of fluids including inter alia air, fuel and oil
Data Source
AI summary
An gas turbine engine for an aircraft includes, in axial flow sequence, a compressor module, a combustor module, and a turbine module, together with a first electrical machine rotationally connected to the turbine module. The combustor module has a combustor volume V (cm3). In use, at a full power condition, the gas turbine engine has a maximum corrected core flow Q (m3/sec), and a ratio T of:T=(Maximum Corrected Core Flow=Q)(Combustor volume=V)is in a range of between 450 and 2,500.