Hybrid-Electric Engine Shutdown Support for In-Flight Relight
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Solution Overview
Problem
Conventional commercial aircraft propulsion systems face challenges in efficiently managing in-flight engine shutdowns, leading to significant speed decay and the need for oversizing components to relight at low rotational speeds, which affects engine performance and efficiency.
Innovation Solution
A hybrid electric propulsion system is employed, utilizing an electric machine coupled to the low or high pressure system of the engine, or both, to provide immediate torque and reduce speed decay during in-flight shutdowns, allowing for relighting at higher rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional propulsion systems are used without hybrid electric components, then the system structure remains simple, but engine speed decays significantly during in-flight shutdown making relighting difficult
Solution Approach 1:
The patent combines a conventional gas turbine engine with a hybrid electric propulsion system, merging the mechanical propulsion function with electric power assistance. The electric machine is integrated with the engine's high-pressure or low-pressure system, creating a unified propulsion system that leverages both conventional and electric power sources to maintain engine speed during shutdown and enable reliable relighting.
2Loss of time
If the engine shutdown duration is extended to allow for diagnostic procedures, then troubleshooting can be performed, but engine speed decays further making relighting even more difficult
Solution Approach 1:
The patent applies preliminary anti-action by having the electric machine ready to provide compensating power before speed decay becomes problematic. Upon detecting an engine shutdown, the electric machine immediately activates to counteract the natural speed decay, maintaining engine speed within a range that allows for extended diagnostic procedures without compromising relighting capability.
3Device complexity
If starter systems are removed to simplify the propulsion system, then device complexity is reduced, but the ability to initiate engine rotation and achieve relighting is compromised
Solution Approach 1:
The patent replaces the traditional mechanical starter system with an electric machine that provides both starting and speed maintenance functions. The electric machine substitutes the mechanical starter's role of initiating engine rotation and extends its function to maintain engine speed during shutdown, eliminating the need for a separate starter system while enhancing relighting capability.
4Speed
If electric power is added immediately upon detecting shutdown, then engine speed decay is minimized, but energy consumption increases
Solution Approach 1:
The patent applies partial action by providing electric power at the precise moment it is needed - immediately upon detecting engine shutdown - rather than continuously. The electric machine delivers power selectively during the critical shutdown period when speed maintenance is essential for relighting, avoiding unnecessary energy consumption during normal operation or extended ground-based diagnostics.
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 hybrid electric propulsion system maintains engine rotational speed during shutdowns, reducing speed decay and enabling efficient relighting, thereby improving engine restart capabilities and overall system efficiency.
Implementation Method 1
an electric machine coupled to one of the high pressure system or low pressure system... adding power to the gas turbine engine through the electric machine
Data Source
AI summary
A method for operating a hybrid-electric propulsion system of an aircraft is provided. The hybrid-electric propulsion system includes a gas turbine engine having a high pressure system, a low pressure system, and an electric machine coupled to one of the high pressure system or low pressure system. The method includes receiving data indicative of an actual or anticipated in-flight shutdown of the gas turbine engine; and adding power to the gas turbine engine through the electric machine in response to receiving data indicative of the actual or anticipated in-flight shutdown of the gas turbine engine.