Turbofan Thrust Fault Detection Using Transient Phase Modeling
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Solution Overview
Problem
Current methods for monitoring thrust in turbojet engines are hindered by latency issues during transient phases, making it impossible to detect thrust faults in real time, which delays the activation of safety systems.
Innovation Solution
A method that uses filtering functions and transient phase models to compare setpoint and actual thrust values, allowing for immediate detection of thrust faults by correlating modeled and actual thrust during transient phases, and adjusts alarm thresholds based on auxiliary conditions to enhance sensitivity and avoid false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct comparison of setpoint thrust and actual thrust is performed during transient phase, then detection speed is improved, but measurement precision deteriorates due to latency
Solution Approach 1:
The system performs preliminary actions by measuring multiple parameters (N1 speed, EPR, ambient conditions) and pre-processing this data during the transient phase before a fault occurs. The filtering function and transient phase model are prepared in advance to process thrust comparisons, enabling rapid detection once the fault occurs while accounting for the transient dynamics characteristics.
Solution Approach 2:
The patent introduces intermediary elements including a filtering function that processes the raw thrust comparison signal, and a transient phase model that mediates between the setpoint and actual thrust values. These intermediaries smooth out the latency effects and provide a more accurate basis for fault detection during transient operations.
2Measurement precision
If filtering function is applied to model transient phase delay, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes parameters by introducing a filtering function with specific time constants that are optimized to match the transient phase characteristics of the engine. The filtering parameters are selected to accurately represent the engine's dynamic response without over-complicating the system. Additionally, the system adapts parameters based on operating conditions such as ambient temperature and pressure.
3Measurement precision
If alarm threshold is lowered to increase sensitivity, then detection precision is improved, but false alarms increase
Solution Approach 1:
The system implements dynamic alarm thresholds that adapt based on the engine's operating state and transient phase characteristics. During transient operations, the threshold is dynamically adjusted to account for expected variations, preventing false alarms. When the engine is in steady state, the threshold becomes more sensitive to detect actual faults. This dynamic adaptation maintains high detection precision while minimizing false alarms.
Solution Approach 2:
The system uses feedback mechanisms where the transient phase model and filtering function continuously monitor the difference between setpoint and actual thrust. This feedback loop allows the system to learn normal transient behavior patterns and distinguish them from actual faults, adjusting the effective threshold dynamically based on observed behavior rather than using a fixed threshold.
Data Source
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AI summary
The invention relates to a method for monitoring a thrust fault of a turbofan during a modification of the thrust setting (NCONS) of said turbofan, said method comprising a step of processing the thrust setting (NCONS) by means of a filtering function and a transient-phase model such as to obtain a modelled thrust (NMOD), a step of comparing said modelled thrust (NMOD) to the actual thrust (NEFF) such as to determine a thrust difference (∆), a step of comparing said thrust difference (∆) to an alarm threshold (S); and a step of emitting an alarm in the event of exceeding said alarm threshold (S), wherein at a given iteration, in which the prior modelled thrust is known, the transient-phase model provides a time constant in accordance with the prior modelled thrust, and the filtering function provides a modelled thrust (NMOD) in accordance with the time constant obtained, the prior modelled thrust and the thrust setting (NCONS).