Turbine Fuel Flow Threshold Adjustment via Density Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fuel flow rate estimation methods in turbine engines are inaccurate due to assumptions about fuel density and measurement uncertainties, leading to potential compressor surging or burnout during transient operations.
Innovation Solution
A method and device that adjust fuel flow rate threshold values by comparing estimates from both a fuel metering device and a more accurate estimator device, using a weighting factor to correct for inaccuracies, thereby improving acceleration and deceleration margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel density is assumed constant based on reference conditions, then the fuel flow rate estimation simplifies calculation, but measurement precision deteriorates due to not accounting for fuel nature changes, temperature variations, and density dispersion
Solution Approach 1:
The patent changes the parameter from a constant reference density to a variable density that adapts to actual fuel conditions. The system monitors fuel temperature and uses this information to adjust the density value dynamically, allowing the estimation to account for temperature variations and fuel nature changes while maintaining calculation feasibility
Solution Approach 2:
The patent implements a feedback mechanism where the estimated fuel flow rate is continuously compared against actual measurements or constraints. The system uses this feedback to refine the density assumption and adjust the fuel metering valve position, creating a closed-loop control that improves accuracy over time while maintaining operational simplicity
2Productivity
If the fuel mass flow rate is underestimated by the fuel metering device, then the acceleration margin is overestimated allowing faster acceleration, but reliability worsens due to risk of compressor surging
Solution Approach 1:
The patent applies preliminary anti-action by introducing a safety margin or correction factor to the fuel flow rate estimation before using it for control decisions. This pre-adjustment compensates for potential underestimation, ensuring that even if the raw estimation is optimistic, the corrected value provides adequate protection against compressor surging while still enabling good acceleration performance
Solution Approach 2:
The system prepares for potential failures by building in a cushion of safety through conservative estimation adjustments. The fuel metering device is calibrated or adjusted to account for worst-case scenarios, providing a buffer that prevents compressor surging even when operating conditions deviate from expectations, thereby protecting reliability without significantly sacrificing acceleration capability
3Productivity
If the fuel mass flow rate is overestimated by the fuel metering device, then the deceleration margin is overestimated allowing controlled deceleration, but reliability worsens due to risk of turbojet burnout
Solution Approach 1:
The patent uses feedback mechanisms to monitor actual fuel consumption and engine parameters during deceleration. When the system detects that the estimated fuel flow rate may be excessively high, it adjusts the fuel metering valve to reduce fuel delivery, preventing burnout conditions while maintaining smooth deceleration control through continuous monitoring and adjustment
Data Source
AI summary
A method of adjusting a fuel flow rate in a turbine engine propelling an aircraft, including: obtaining a first estimate of a flow rate of fuel injected into a combustion chamber of the turbine engine propelling an aircraft and as delivered by a fuel metering device of the turbine engine; obtaining a second estimate of the fuel flow rate, which second estimate is more accurate than the first estimate for at least one range of fuel flow rate values and being delivered by an estimator device having a flow meter; and adjusting the fuel flow rate threshold value with help of a difference evaluated between the first estimate and the second estimate, the threshold value being for use in an open loop for regulating the turbine engine.