Hybrid Electric Descent Control for Single-Engine Thrust Balance
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Solution Overview
Problem
Operating an aircraft with a single engine during descent can create a yawing moment that requires compensation, and the non-operational engine may need time to support starting or relighting if the fuel-burning engine shuts off unexpectedly.
Innovation Solution
A hybrid electric single engine descent power extraction control system that uses a combination of gas turbine engines and electric machines to manage power distribution and thrust balancing, allowing one engine to operate electrically while the other combusts fuel, thereby reducing fuel consumption and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If one engine is operated in fuel-burning mode during descent, then fuel consumption is reduced, but a yawing moment is created that requires compensation
Solution Approach 1:
The patent applies asymmetry by operating one engine in fuel-burning mode while the other operates in electric mode, creating an asymmetric propulsion configuration that reduces overall fuel consumption. The asymmetric thrust is compensated through differential thrust control and aerodynamic surfaces to maintain aircraft stability.
Solution Approach 2:
The patent uses the non-fuel-burning engine operating in electric mode as a counterbalancing element. By controlling the electrically-driven engine to produce compensating thrust, it offsets the yawing moment generated by the fuel-burning engine, thereby maintaining aircraft stability without requiring additional fuel consumption.
2Loss of energy
If one engine is shut off during descent, then fuel consumption is reduced, but the non-operational engine needs time to support starting or relighting
Solution Approach 1:
The patent applies preliminary action by maintaining the non-fuel-burning engine in a rotated state during descent, rather than shutting it off completely. This preliminary maintenance of rotational state ensures that the engine is ready for rapid relighting if needed, eliminating the delay that would occur if the engine had to be restarted from a stationary state.
Solution Approach 2:
The patent maintains continuous useful action by keeping the non-fuel-burning engine rotating during descent, even though it is not producing thrust. This continuous rotation preserves the engine's operational readiness and thermal state, enabling immediate relighting if required, thus maintaining reliability without continuous fuel consumption.
3Stability of the object's composition
If power is extracted from the fuel-burning engine to drive the non-fuel-burning engine, then thrust balancing is improved, but fuel consumption increases
Solution Approach 1:
The patent applies feedback by continuously monitoring the thrust output of both engines and adjusting the power extraction from the fuel-burning engine accordingly. The control system optimizes the amount of power extracted to maintain thrust balance while minimizing the impact on fuel consumption, using feedback from thrust sensors and engine performance parameters.
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 system reduces fuel consumption during descent, mitigates yawing moments by maintaining engine rotation and thermal efficiency, and improves engine restarting capabilities by keeping components rotating.
Implementation Method 1
a gas turbine engine (20) can include a low speed spool (30) configured to drive rotation of a fan (42), a high speed spool (32) configured to drive rotation of a compressor section
Implementation Method 2
a shaft (50) configured to rotate about a longitudinal axis of the gas turbine engine (20), an electric machine (12B) configured to extract rotational power from the high speed spool (32)
Data Source
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AI summary
A system of a hybrid aircraft includes a first gas turbine engine, a second gas turbine engine, and a controller. The first gas turbine engine includes a first low spool electric machine (12A) and a first high spool electric machine (12B). The second gas turbine engine includes a second low spool electric machine (12A) and a second high spool electric machine (12B). The controller is operable to determine an operating mode of the hybrid aircraft and control power extraction from either or both of the first low spool electric machine (12A) and the first high spool electric machine (12B) while a single engine descent mode is active. Electric power is provided to either or both of the second low spool electric machine (12A) and the second high spool electric machine (12B) while the single engine descent mode is active to balance thrust between the first gas turbine engine and the second gas turbine engine.