Aircraft Propulsion Bleed-Air Restart to Reduce Engine Shaft Load
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Solution Overview
Problem
Aircraft propulsion systems face increased power consumption and rotational load when engines are restarted after being stopped due to decreased engine temperature, necessitating high electric power for starter motors, especially during high load conditions like landing.
Innovation Solution
The system employs a bleed air mechanism to supply compressed air from an operational engine to the compression chamber of a stopped engine using a bleed air hole and pipe, allowing the stopped engine to restart without relying on a starter motor, thereby reducing the rotational load on the engine shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an engine is stopped for a long period of time to improve power generation efficiency, then power generation efficiency is improved, but the rotational load of the engine shaft increases when restarted
Solution Approach 1:
Compressed air is supplied to the compression chamber before the engine shaft starts rotating, creating a preliminary driving force that reduces the rotational load when the engine is restarted. This preliminary action of pre-charging the compression chamber with high-pressure air allows the engine to start more easily after being stopped for extended periods.
2Loss of energy
If an engine is stopped for a long period of time, then power generation efficiency is improved, but the starter motor power consumption increases
Solution Approach 1:
The compression chamber is pre-charged with compressed air from another operating engine before the stopped engine needs to restart. This preliminary action reduces the work required by the starter motor, thereby decreasing starter motor power consumption when restarting engines after extended stop periods.
3Loss of energy
If an engine is stopped for a long period of time, then power generation efficiency is improved, but the engine restart time increases
Solution Approach 1:
By pre-charging the compression chamber with compressed air before restart is needed, the engine can start more quickly without requiring the full startup sequence. This preliminary preparation of high-pressure air in the compression chamber significantly reduces the time required to restart the engine after being stopped for extended periods.
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 the rotational load on the engine shaft and shortens the engine restart time, minimizing power consumption and reliance on starter motors.
Implementation Method 1
a compressor (62-1) that compresses air; a compression chamber (64-2) into which the compressed air is supplied
Implementation Method 2
a bleed air pipe (72-1) that extends from the bleed air hole (71-1) to the compression chamber (64-2) of the other gas turbine engine (60-2); a bleed air valve (73-1) that is provided in the bleed air pipe (72-1)
Data Source
AI summary
An aircraft propulsion system capable of reducing a rotational load of an engine shaft is provided. An aircraft propulsion system includes a plurality of engines (60-1 and 60-2) and a controller (100). When a flight state is a first state, the controller (100) causes some of the plurality of engines (60-1 and 60-2) to operate while stopping the remaining engine. At least one engine (60-1) of the plurality of engines (60-1 and 60-2) includes a bleed air hole (71-1), a bleed air pipe (72-1), and a bleed air valve (73-1). When causing the engine (60-2) which has stopped to start up again, the controller (100) opens a bleed air valve (73-1) in the engine (60-1) which is in operation and supplies compressed air of the compressor (62-1) to the compression chamber (64-2) of the engine (60-2) which has stopped.