Gas Turbine Starter Motor Dwelling Speed Control
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Solution Overview
Problem
Gas turbine engines used in auxiliary power units face increased likelihood of start failure at high altitudes and cold temperatures due to flame-out issues, as existing start sequences do not effectively manage engine speed and combustor warm-up.
Innovation Solution
The method involves controlling the starter motor speed to maintain the gas turbine engine at a dwelling speed until a predetermined combustor warm-up is achieved, as indicated by an increase in Exhaust Gas Temperature (EGT), thereby preventing flame-out and ensuring successful ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the starter motor accelerates the engine quickly to self-sustaining speed, then the start sequence is faster and more productive, but the engine is more likely to flame-out under adverse conditions
Solution Approach 1:
The system performs preliminary combustion stabilization by maintaining dwelling speed after light-off until a predetermined magnitude of combustor warm-up is achieved. This preliminary action ensures the combustion process is stable before accelerating the engine, preventing flame-out during the transition to self-sustaining speed.
Solution Approach 2:
The starter motor speed is dynamically controlled through three phases: acceleration to dwelling speed, maintenance at dwelling speed during warm-up, and then acceleration to self-sustaining speed. This dynamic speed control adapts to the combustion state, ensuring reliability during critical phases while maintaining productivity.
2Loss of time
If the engine is accelerated rapidly after ignition, then the time to reach operational speed is reduced, but the combustor cannot warm-up sufficiently leading to flame-out
Solution Approach 1:
The system performs preliminary combustion stabilization by maintaining dwelling speed after light-off until a predetermined magnitude of combustor warm-up is achieved. This preliminary action ensures the combustion process is stable before accelerating the engine, preventing flame-out during the transition to self-sustaining speed.
Solution Approach 2:
The dwelling speed maintenance phase continues continuously until the combustor achieves sufficient warm-up, ensuring uninterrupted heat accumulation in the combustor. This continuous useful action prevents temperature drop that would cause flame-out, while the subsequent acceleration minimizes total time loss.
3Productivity
If the starter motor is disengaged immediately after light-off, then the start sequence is shorter, but the engine speed is insufficient to maintain combustion
Solution Approach 1:
The system performs preliminary combustion stabilization by maintaining dwelling speed after light-off until a predetermined magnitude of combustor warm-up is achieved. This preliminary action ensures the combustion process is stable before accelerating the engine, preventing flame-out during the transition to self-sustaining speed.
Solution Approach 2:
The controller monitors combustion parameters to determine when predetermined magnitude of combustor warm-up is achieved, then transitions the starter motor from dwelling speed maintenance to acceleration mode. This feedback-based control ensures combustion stability is achieved before speed increase, balancing productivity and reliability.
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 significantly reduces start failures in adverse conditions by maintaining engine stability through controlled warm-up, allowing for reliable ignition and transition to self-sustaining operational speed, even at high altitudes and cold temperatures.
Implementation Method 1
controlling a speed of a starter motor during a start sequence to drive a gas turbine engine at a dwelling speed
Implementation Method 2
the combustor section burns fuel in a high pressure environment
Implementation Method 3
The burning fuel in the combustor section heats the air prior to communication through the turbine section
Data Source
AI summary
A method of starting a gas turbine engine includes maintaining the gas turbine engine at the dwelling speed after light-off until a predetermined magnitude of combustor warm-up is determined then increasing the speed of the starter motor to accelerate the gas turbine engine after the predetermined magnitude of combustor warm-up is achieved.