Gas Turbine Fuel Flow Control via Differential Pressure Feedback
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Solution Overview
Problem
Existing fuel flow estimation and control systems in gas turbine engines rely heavily on the accuracy of pressure regulating valves, which can be non-ideal, leading to inaccuracies in fuel flow measurement and control.
Innovation Solution
A method that estimates fuel flow by determining differential pressure errors and correcting for them using a bypass fuel flow, metering valve position, and other system parameters, allowing for more accurate fuel flow control independent of pressure regulating valve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the metering valve position is used to determine fuel flow by referencing known fuel flow rates, then the fuel flow measurement is simple to implement, but the measurement precision deteriorates due to reliance on ideal pressure regulating valve accuracy
Solution Approach 1:
The system introduces a feedback mechanism by continuously monitoring the actual differential pressure across the metering valve and comparing it to the ideal differential pressure. The controller adjusts the fuel flow command based on the differential pressure error, creating a closed-loop control system that compensates for pressure regulating valve inaccuracies and improves measurement precision while maintaining implementation simplicity.
Solution Approach 2:
The invention replaces the purely mechanical reference-based fuel flow determination method with an electronic control system that uses differential pressure sensors and a controller to calculate and adjust fuel flow commands. This substitution of mechanical reference systems with electronic sensing and computation enables more precise measurements while keeping the system relatively simple to implement.
2Device complexity
If the differential pressure across the metering valve is assumed to be accurate with an ideal pressure regulating valve, then the system complexity is reduced, but the reliability deteriorates due to non-ideal pressure regulating valve performance
Solution Approach 1:
The system implements feedback by continuously measuring the actual differential pressure across the metering valve and using this information to correct fuel flow commands. The controller compares actual differential pressure with ideal differential pressure and adjusts the fuel flow accordingly, creating a self-correcting system that maintains reliability without significantly increasing complexity.
Solution Approach 2:
The invention changes the operating parameter from assuming ideal differential pressure to actually measuring and using the real differential pressure value. By transitioning from an idealized parameter assumption to a measured parameter approach, the system achieves higher reliability while maintaining manageable complexity through electronic computation.
3Ease of operation
If the pressure regulating valve accuracy is relied upon for fuel flow control, then the control precision is maintained with simple methods, but the measurement precision deteriorates when the pressure regulating valve is non-ideal
Solution Approach 1:
The system uses feedback by measuring the actual differential pressure across the metering valve and using this measurement to correct the fuel flow estimation. The controller continuously adjusts the fuel flow command based on the differential pressure error, maintaining control simplicity through electronic computation while dramatically improving measurement precision by eliminating reliance on pressure regulating valve accuracy.
Solution Approach 2:
The invention replaces the mechanical reliance on pressure regulating valve accuracy with electronic differential pressure sensing and computation. By substituting the mechanical assumption of ideal valve performance with electronic measurement and calculation, the system achieves high measurement precision while keeping the control method simple to operate.
Data Source
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AI summary
A system and methods of estimating and controlling fuel flow in a gas turbine engine (20) are disclosed. The system and methods include providing a metering valve (112) and a pressure regulating valve (122). The system and methods further include determining a differential pressure error (216) of the pressure regulating valve (122) based on a metering valve inlet pressure (220), a discharge pressure (222), and a bypass fuel flow (218) and determining a metering valve fuel flow (230) based on a metering valve position (212) and the differential pressure error (216).