Hybrid Electric Hydrogen Fuel Cell Engine with Variable Flowpath
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Solution Overview
Problem
Conventional aircraft propulsion systems face inefficiencies and increased carbon emissions due to the need for large fuel cells and batteries during takeoff and climb, and hydrogen combustion can degrade gas turbine engines, necessitating a more efficient propulsion system with reduced carbon emissions.
Innovation Solution
A hybrid electric propulsion system incorporating a fuel cell and a gas turbine engine, with a variable flowpath geometry that bypasses the combustor during non-combustor modes, utilizing electric motors to drive compressors and a fuel cell to generate power, and a sprag clutch system to manage power transfer between the turbine and compressors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional parallel hybrid engines are used with large fuel cells and batteries to handle takeoff and climb power outputs, then sufficient power is provided for all flight phases, but device complexity and weight increase significantly
Solution Approach 1:
The propulsion system is segmented into distinct combustion mode and non-combustion modes, with the combustor operating only when needed for high power demands during takeoff and climb, while the fuel cell handles other flight phases independently
Solution Approach 2:
The fuel cell serves multiple functions: it generates electricity during cruise and descent, provides auxiliary power during takeoff and climb without requiring large batteries, and eliminates the need for a separate battery system while maintaining sufficient power for all flight phases
2Power
If hydrogen is burned continuously in a conventional gas turbine engine to provide power, then sufficient thrust is generated for all flight operations, but turbine degradation occurs and reliability decreases
Solution Approach 1:
The combustor operates periodically only during high power demand phases (takeoff and climb) rather than continuously, allowing the turbine to rest and cool during cruise and descent phases, thereby reducing thermal degradation and extending turbine life
Solution Approach 2:
The fuel cell acts as an intermediary power source that can independently generate electricity during cruise and descent, reducing or eliminating the need for continuous combustor operation and thereby protecting the turbine from excessive wear
3Object-generated harmful factors
If conventional electric propulsors are used during cruise and descent, then carbon emissions are reduced, but sufficient power may not be available without large fuel cells and batteries
Solution Approach 1:
The fuel cell serves itself by generating electricity during cruise and descent phases when combustion is not needed, providing self-sufficient power for these phases without requiring external battery storage systems
Solution Approach 2:
The system changes operational parameters by switching between combustion mode (high power demand) and non-combustion mode (lower power demand), with the fuel cell adapting its output to match the varying power requirements of different flight phases
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 achieves efficient thrust generation with reduced carbon emissions by optimizing power usage between combustion and electric modes, minimizing turbine wear, and providing sufficient power for takeoff and cruise phases.
Implementation Method 1
a fuel cell connected to the HP electric motor, the fuel cell configured to react the second compressed air with the fuel to generate HP electric power
Implementation Method 2
a combustor positioned downstream of the second compressor to receive the second compressed air outputted from the second compressor, the combustor outputting a first exhaust gas formed from a fuel burned with the second compressed air
Implementation Method 3
a turbine positioned downstream of the combustor to receive the first exhaust gas
Data Source
AI summary
A hybrid engine including features to meet aircraft thrust, passenger airflow, and fuel cell requirements. The engine includes a combustor burning the same fuel as the fuel cell. The engine has electric motors to utilize the power output of the fuel cell. The engine shafts have sprags to allow motors to drive the compressors and over run the turbines. The engine has variable flowpath geometry to bypass the combustor.