Hybrid-Electric Aircraft Propulsion System Acceleration Control
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Solution Overview
Problem
Conventional aircraft propulsion systems, such as turbofan jet engines, face inefficiencies in thrust management, leading to increased fuel consumption and premature wear due to suboptimal idle setpoints and clearance control in turbomachines, which affects acceleration and operational efficiency.
Innovation Solution
A hybrid-electric propulsion system that includes a turbomachine coupled with an electric machine and an electric energy storage unit, where computing devices manage fuel flow and clearance control to provide additional power to the turbomachine during acceleration, allowing for efficient and quick thrust increases while maintaining optimal operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the idle setpoint of turbofan jet engines is set higher to enable quick acceleration at takeoff, then the acceleration capability is improved, but fuel consumption increases and brake wear increases during taxiing
Solution Approach 1:
An electric machine is introduced as an intermediary to provide supplemental power during acceleration events. The electric machine assists the turbomachine during takeoff acceleration, enabling the engine to operate at a lower idle setpoint during taxiing while still achieving quick acceleration when needed. This mediator resolves the contradiction by decoupling the idle speed setting from the acceleration capability.
2Use of energy by moving object
If clearances within turbine sections are tightened to increase engine efficiency, then fuel efficiency is improved, but the ability to quickly increase power output deteriorates due to thermal expansion constraints
Solution Approach 1:
The electric machine serves as a mediator that compensates for the reduced power increase rate caused by tight clearances. During rapid acceleration events, the electric machine provides supplemental power, allowing the engine to maintain tight clearances for efficiency while achieving the required power increase through the combined effect of the engine and electric machine.
Solution Approach 2:
The system dynamically adjusts the clearance parameters based on operating conditions. During steady-state operation, clearances are maintained tight for efficiency. During rapid acceleration, the electric machine compensates for the lag in power response, effectively allowing the system to operate with tight clearances across a broader range of conditions without sacrificing acceleration capability.
3Loss of time
If the idle setpoint is set higher to enable quick acceleration, then the response time is improved, but harmful factors such as brake wear during taxiing increase
Solution Approach 1:
The electric machine acts as a mediator that provides acceleration assistance without requiring the turbomachine to operate at a high idle setpoint. This reduces the harmful effects of high idle operation during taxiing (such as brake wear from excessive thrust) while maintaining quick acceleration capability when the electric machine provides supplemental power during takeoff rolls.
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 enables efficient turbomachine operation by providing immediate power assistance during acceleration, reducing fuel consumption and minimizing wear on aircraft components, while maintaining efficient steady-state flight operations.
Implementation Method 1
providing electrical power to the electric machine to add power to the turbomachine, the propulsor, or both
Data Source
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AI summary
A hybrid-electric propulsion system (50) includes a propulsor (104), a turbomachine (102), and an electrical system, the electrical system including an electric machine (56) coupled to the turbomachine (102). A method for operating the propulsion system (50) includes operating at (302), by one or more computing devices, the turbomachine such that the turbomachine rotates the propulsor; receiving at (304), by the one or more computing devices, a command to accelerate the turbomachine while operating the turbomachine; and providing at (306), by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine, the propulsor, or both in response to the received command to accelerate the turbomachine.