Flow Divider Valve Failure Detection in Gas Turbine Fuel Systems
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Solution Overview
Problem
Current systems fail to detect a failed flow divider valve in gas turbine engine fuel systems, leading to potential over-fueling and failure to start the auxiliary power unit (APU) due to inadequate fuel pressure buildup.
Innovation Solution
A method involving a fuel command to operate a fuel pump and metering valve to deliver fuel at a specific rate, calculating expected and actual fill times, and comparing actual fuel pressure values against expected values based on environmental signals to determine if the flow divider valve has failed in an open condition, triggering appropriate annunciation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flow divider valve fails in an open condition, then fuel flows continuously to the combustor, but fuel pressure does not build up in the manifold causing over-fueling and potential failure to start
Solution Approach 1:
The system implements feedback by continuously monitoring fuel pressure sensor readings and comparing them against expected pressure values calculated from the fuel delivery rate and manifold fill time. This closed-loop feedback mechanism enables automatic detection of flow divider valve failures without adding complex external monitoring equipment.
Solution Approach 2:
The fuel system performs self-diagnosis by using its own operational parameters (fuel delivery rate, manifold fill time, pressure sensor readings) to detect failures. The controller calculates expected pressure values and compares them with actual readings, allowing the system to identify flow divider valve failures using its existing components and operational data.
2Stress or pressure
If the manifold fill time is extended to ensure proper fuel distribution, then fuel pressure builds up adequately, but the APU may accelerate beyond the light-off window
Solution Approach 1:
The system dynamically adjusts the expected fuel pressure values based on the actual manifold fill time and fuel delivery rate. By calculating expected pressure as a function of these dynamic parameters, the system can accurately detect flow divider failures regardless of variations in fill time, whether extended or compressed.
Solution Approach 2:
The controller changes the reference parameter from a fixed pressure value to a dynamically calculated expected pressure value that accounts for variations in manifold fill time and fuel delivery rate. This parameter adaptation allows accurate failure detection across different operating conditions and time scales.
Data Source
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AI summary
The present disclosure relates generally to a method for determining a failure of a flow divider (82) within a fuel system (66), the method being performed by a controller (84) and comprising the steps of: delivering a fuel command, calculating an expected fill time, wherein the expected fill time is indicative of the time required to fill a known fuel manifold volume, determining whether the actual fill time is greater than or equal to an expected fill time; and determining whether an actual fuel pressure value is less than or equal to an expect fuel pressure value based at least in part on at least one environmental signal.