Hybrid Electric Propulsion System for Aircraft Gas Turbine Engine
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Solution Overview
Problem
Conventional helicopters experience minor cycle damage in their gas turbine engines due to frequent changes in power output demand during flight, leading to reduced engine lifespan.
Innovation Solution
A hybrid electric propulsion system that determines a baseline power output for the gas turbine engine and uses an electric machine and energy storage unit to adjust power output by adding or extracting power, thereby reducing the number of minor cycles and maintaining a consistent power level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas turbine engine frequently adjusts its rotational speed to meet varying power output demands, then the power output responsiveness is improved, but the engine experiences increased minor cycle damage and reduced lifespan
Solution Approach 1:
An electric machine is introduced as an intermediary component between the gas turbine engine and the load. The electric machine absorbs transient power demands and supplies power during deceleration, allowing the gas turbine engine to maintain a steady rotational speed while still meeting varying power output requirements. This mediator protects the engine from frequent speed adjustments and associated minor cycle damage.
Solution Approach 2:
The system changes the operating parameters of the gas turbine engine by maintaining a constant or near-constant rotational speed rather than allowing it to vary with power demands. The electric machine compensates for power fluctuations, enabling the engine to operate in a optimized parameter range that minimizes wear and extends lifespan while still meeting dynamic power requirements.
2Reliability
If the gas turbine engine maintains a constant baseline power output, then minor cycle damage is reduced, but the ability to quickly respond to sudden power demands is compromised
Solution Approach 1:
The electric machine is pre-charged with energy from the energy storage unit during periods when the gas turbine engine is operating at baseline power. This preliminary energy storage allows the electric machine to immediately supply additional power when sudden demands occur, enabling quick response without requiring the gas turbine engine to rapidly adjust its speed and avoid minor cycle damage.
3Reliability
If a hybrid electric propulsion system is implemented to reduce minor cycles, then engine lifespan is extended, but the device complexity increases
Solution Approach 1:
The electric machine serves multiple functions: it acts as a motor to supplement power during high demand, a generator to recover energy during deceleration, and an energy buffer to smooth out power fluctuations. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall system complexity while achieving the goal of extending engine lifespan.
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 approach reduces wear on the gas turbine engine, extends its useful life, and minimizes minor cycle damage by operating the engine at a baseline power level while using the electric system to meet varying power demands.
Implementation Method 1
an electric machine coupled to an output shaft of the gas turbine engine... providing power to the electric machine may help drive the output shaft of the gas turbine engine to increase an effective power output of the output shaft of the gas turbine engine
Implementation Method 2
extracting power from the electric machine may act as a drag on the output shaft of the gas turbine engine to reduce an effective power output of the output shaft of the gas turbine engine
Implementation Method 3
a hybrid electric propulsion system includes a gas turbine engine with an output shaft... an electric machine coupled to an output shaft of the gas turbine engine
Data Source
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AI summary
A hybrid electric propulsion system 100 includes a gas turbine engine 102 and an electric machine 162 coupled to the gas turbine engine 102. A method for operating the propulsion system 100 includes determining, by one or more computing devices 410, a baseline power output for the gas turbine engine 102; operating, by the one or more computing devices 410, the gas turbine engine 102 to provide the baseline power output; determining, by the one or more computing devices 410, a desired power output greater than or less than the baseline power output; and providing, by the one or more computing devices 410, power to, or extracting, by the one or more computing devices 410, power from, the gas turbine engine 102 using the electric machine 162 such that an effective power output of the gas turbine engine 102 matches the determined desired power output.