Gas Turbine Engine Fuel Flow Schedule Optimization
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Solution Overview
Problem
Current gas turbine engine start and restart processes face challenges in optimizing fuel and acceleration schedules, leading to inefficient engine starts and potential issues like compressor stall, overheating, or flameout, especially when transitioning from cold to hot conditions or varying aircraft speeds.
Innovation Solution
A method and system that estimate the compressor inlet recovered pressure by combining aircraft speed and engine rotational speed components, allowing for a tailored fuel flow schedule to optimize engine starts and prevent flameout, using characterization data and a computing device to select the appropriate fuel flow schedule based on estimated pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a compromise fuel and acceleration schedule is used to simplify control, then device complexity is reduced, but engine start efficiency and reliability deteriorate
Solution Approach 1:
The fuel flow schedule is made dynamic by selecting from multiple pre-defined schedules based on real-time aircraft speed and engine rotational speed conditions. The system transitions from a static compromise schedule to a dynamic adaptive schedule that optimizes engine start reliability for each specific operating condition without requiring complex real-time calculations.
Solution Approach 2:
The invention changes the parameter of fuel flow schedule selection based on aircraft speed and engine rotational speed. By using these parameters to index into a lookup table of pre-optimized schedules, the system achieves high reliability without the complexity of real-time fuel flow optimization algorithms.
2Reliability
If aircraft speed is limited for engine restart, then compressor stall is avoided, but productivity is reduced
Solution Approach 1:
The system dynamically adjusts the fuel flow schedule based on aircraft speed and engine rotational speed, allowing engine restart capability across the full flight envelope. Instead of imposing a static speed limit, the adaptive scheduling enables safe restarts at various speeds by optimizing fuel delivery for each condition, thus maintaining productivity while ensuring compressor stability.
3Reliability
If high acceleration is used for hot engine restart, then flameout is prevented, but compressor stall risk increases
Solution Approach 1:
The invention applies local quality by selecting different fuel flow schedules optimized for specific operating conditions. For hot engine restarts, the system identifies the appropriate schedule based on aircraft speed and rotational speed, delivering locally optimized fuel quantities that prevent flameout without excessively increasing compressor stall risk, rather than using a uniformly high acceleration approach.
4Ease of operation
If a single compromise fuel schedule is used for all conditions, then ease of operation is improved, but time to idle increases
Solution Approach 1:
The system uses dynamic selection from multiple pre-optimized fuel schedules based on aircraft speed and engine rotational speed. This approach maintains ease of operation through automated schedule selection while significantly reducing time to idle compared to a single compromise schedule, as each schedule is pre-optimized for its specific operating range.
Data Source
AI summary
Herein provided are methods and systems for setting a fuel flow schedule for starting a gas turbine engine of an aircraft. Aircraft speed and engine rotational speed are obtained. A compressor inlet recovered pressure is estimated by combining a first component influenced by the aircraft speed and a second component influenced by the engine rotational speed, and a fuel flow schedule is selected for engine start in accordance with the estimated compressor inlet recovered pressure.