Gas Turbine Thrust Control Using Variable Trim
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Solution Overview
Problem
Gas turbine engines face variations in thrust output and operating temperatures due to manufacturing tolerances and component deterioration, leading to inefficient operation and reduced lifespan, as existing control systems cannot tailor nominal schedules effectively on an engine-by-engine basis.
Innovation Solution
A system with sensors measuring engine parameters and a processor determining variance values to adjust operating demands, allowing for a variable trim mode that reduces operating temperatures in hotter engines without affecting thrust levels, using a controller to modify engine thrust based on these adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If predetermined engine model control schedules are used for all engines, then control system simplicity is maintained, but engine-by-engine optimization is lost resulting in excess thrust and higher operating temperatures
Solution Approach 1:
The system performs preliminary characterization of each engine during factory testing to determine its specific performance parameters. This advance preparation allows the control system to later apply pre-calculated trim values without requiring complex real-time analysis, thus achieving engine-by-engine optimization while maintaining operational simplicity.
Solution Approach 2:
The system creates individualized control profiles for each engine based on factory test data, effectively copying the optimal control strategy tailored to each specific engine's characteristics. These copied profiles are then stored and applied during operation, eliminating the need for complex real-time decision-making while achieving customization.
2Reliability
If minimum thrust engine schedules are used to ensure all engines meet thrust requirements, then reliability is improved, but operating temperatures increase and fuel consumption rises
Solution Approach 1:
The system applies different control strategies to different engines based on their individual characteristics. Instead of using a uniform conservative schedule for all engines, each engine receives a customized trim value that optimizes its specific operating parameters, allowing some engines to operate at lower temperatures while still meeting thrust requirements.
Solution Approach 2:
The system modifies the control parameter (thrust setting) by applying engine-specific trim values that adjust the operating point for each engine. This parameter adjustment allows engines to operate at optimized temperatures rather than the conservative high-temperature schedules required by minimum-thrust approaches.
3Reliability
If engines operate at higher thrust levels to compensate for component variations, then thrust margin is improved, but operating temperatures increase causing faster deterioration
Solution Approach 1:
The system uses factory test data to provide feedback about each engine's actual performance characteristics. This feedback information is used to calculate appropriate trim values that ensure each engine operates within optimal parameters, maintaining adequate thrust margins while avoiding excessive temperatures that would accelerate deterioration.
Data Source
AI summary
A method and systems for controlling a thrust output of a gas turbine engine are provided. The system includes a first sensor for measuring a first engine operating parameter, a second sensor for measuring a first engine condition parameter, and a processor programmed to determine an expected value of the first engine condition parameter and determine a first variance value using a difference between the expected value of the first engine condition parameter and the measured first engine condition parameter. The processor is further programmed to determine a trim value using the first variance value and a first engine operating parameter demand and to determine a modified operating parameter demand based on the nominal operating parameter demand and the determined trim value. The system also includes a controller coupled to the processor for controlling engine thrust based on the modified demand of the first engine operating parameter.