Clutched Shaft Coupling for Rapid Gas Turbine Start
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Solution Overview
Problem
Existing starter systems for gas turbine engines in hybrid electric engines face limitations in reducing start-times, requiring larger components and are not viable for free-turbine type power turbines, leading to inefficiencies and durability issues.
Innovation Solution
A starter system that includes a clutch mechanism to couple a low-pressure shaft to a high-pressure shaft, allowing the electric machine to act as a starter motor, and automatically disengaging when the high-pressure shaft exceeds the low-pressure shaft's rotational speed, eliminating the need for separate starter motors and batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the starter motor is enlarged to reduce start-times, then the start-time is reduced, but the device complexity and component size increase
Solution Approach 1:
The main generator is designed to perform dual functions: serving as the primary power generation device during normal operation and as a starter motor during engine startup. By coupling the generator to the compressor shaft and controlling its operation mode, the system eliminates the need for a separate dedicated starter motor, thereby reducing component size and device complexity while maintaining fast start capabilities.
2Loss of time
If the high capacity battery and large generator are used to reduce start times, then the start-time is reduced, but the system is not viable for free-turbine type power turbines where the generator does not spin the compressor
Solution Approach 1:
The system employs dynamic control of the clutch engagement and generator operation modes to adapt to different engine configurations. For free-turbine type power turbines, the clutch is controlled to engage the generator to the compressor shaft during startup, enabling the generator to spin the compressor and achieve fast starts, thus making the system versatile across different turbine architectures.
3Loss of time
If separate starter motors and batteries are added to reduce start-times, then the start-time is reduced, but the device complexity increases
Solution Approach 1:
The system merges the function of the starter motor with the main generator, and integrates the starting function into the existing battery system. By combining these components and their functions, the system achieves fast start capability without adding separate dedicated starter motors and start batteries, thereby reducing overall device complexity.
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
Significantly reduces start-up time, improves turbine durability, and enhances altitude re-light characteristics by utilizing existing high-capacity batteries and generators efficiently.
Implementation Method 1
a clutch configured to selectively couple the low-pressure shaft to a high-pressure shaft of the gas turbine engine, wherein the clutch is configured, when engaged, to transfer mechanical power from the low-pressure shaft
Data Source
AI summary
A starter system for a gas turbine engine in, for example, a hybrid electric engine is provided. The hybrid electric engine may include the gas turbine engine, an electric machine, and an electrical energy storage. The starter system may include the electric machine, and a low-pressure shaft of the gas turbine engine may be mechanically coupled to a rotor of the electric machine. The electrical energy storage may electrically power the electrical machine and receive electrical power from the electrical machine. In addition, a clutch may selectively couple the low-pressure shaft to a high-pressure shaft of the gas turbine engine. The clutch may, when engaged, transfer mechanical power from the low-pressure shaft, which is mechanically coupled to the electric machine, to the high-pressure shaft. Further, the clutch may disengage if a rotational speed of the high-pressure shaft exceeds a rotational speed of the low-pressure shaft.