Adaptive Fuel Flow Estimation with Meter Feedback
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Solution Overview
Problem
Existing fuel systems for gas turbine engines face challenges in accurately determining fuel flow over a long period due to the difficulty in characterizing the relationship between the metering valve position and fuel flow, especially with latency and accuracy issues in flow meter feedback.
Innovation Solution
A method is introduced to determine a correction factor for fuel flow by using feedback from a mass flow meter, which is applied to the nominal fuel flow based on the metering valve stroke, allowing for adaptive learning of the stroke-to-flow relationship and diagnosing system problems, with weighting and trending mechanisms to refine the estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel flow is determined using metering valve position alone, then the system is simple to operate, but measurement precision deteriorates over time due to difficulty in characterizing the valve-flow relationship
Solution Approach 1:
The system uses feedback from a mass flow meter to continuously correct and refine the fuel flow measurement. The mass flow meter provides actual fuel flow data that is compared with the nominal fuel flow calculated from valve position, and the difference is used to update a correction factor. This feedback mechanism maintains measurement precision over time by adapting to valve characterization drift and changes.
Solution Approach 2:
The system dynamically changes the parameter used for fuel flow determination from a static valve position-based calculation to a dynamic correction factor that incorporates actual mass flow meter readings. The correction factor is updated based on operational data, transforming the fuel flow determination from a fixed relationship to an adaptive parameter that maintains accuracy across different operating conditions and over time.
2Measurement precision
If a mass flow meter is added to provide feedback, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system implements self-service by using the mass flow meter feedback to automatically correct and update the fuel flow measurement without requiring manual intervention or complex external calibration systems. The correction factor is continuously updated based on the difference between actual and nominal fuel flow, allowing the system to self-calibrate and maintain precision autonomously.
Solution Approach 2:
The patent replaces complex mechanical characterization methods with an electronic/digital approach. Instead of relying on complex mechanical valve flow coefficients that are difficult to characterize, the system uses electronic sensing from the mass flow meter and computational correction factors to achieve precise fuel flow measurement, substituting mechanical complexity with electronic measurement and calculation.
3Adaptability or versatility
If the correction factor is updated continuously, then adaptability improves, but loss of time increases due to processing requirements
Solution Approach 1:
The system applies partial action by updating the correction factor selectively at specific intervals or under specific conditions rather than continuously. The correction factor is updated based on operational regimes and when significant deviations are detected, rather than performing constant computational updates. This approach maintains adaptability while reducing processing time and computational overhead.
Data Source
AI summary
According to an aspect, a correction factor for a fuel flow of a fuel system of an engine is determined. A nominal fuel flow is determined based on a metering valve stroke. The correction factor is applied to the nominal fuel flow to produce an estimated fuel flow to control combustion in the engine.