Fuel Density Inference via Dielectric Constant Measurement
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Solution Overview
Problem
Existing fuel-gauging techniques for gas turbine engines are inaccurate due to variations in fuel density caused by differing environmental conditions within the engine, leading to inefficiencies in engine control.
Innovation Solution
A method and assembly that measure the dielectric constant of fuel at varying conditions using a multi-plate capacitor device within the fuel line, coupled with dielectric constant versus density characteristics obtained at a reference location, to infer fuel density accurately across different environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel density is measured using prior techniques (densitometer or dielectric constant measurement) at a location external to the engine, then the measurement process is simple, but the measurement accuracy is insufficient for precise engine control
Solution Approach 1:
The patent performs preliminary characterization of the relationship between dielectric constant and density at a first location (fuel tank) before actual engine operation. This pre-established relationship is then used to infer density at the second location (fuel metering valve) based on dielectric constant measurements, eliminating the need for complex direct density measurements during engine operation.
Solution Approach 2:
The patent uses dielectric constant as an intermediary parameter to determine fuel density. Instead of directly measuring density with complex equipment, the system measures the dielectric constant (a simpler electrical property) and uses the pre-established relationship to infer density, thus simplifying the measurement device while maintaining accuracy.
2Reliability
If fuel density is measured at the fuel tank location, then the measurement environment is stable and accessible, but the density value does not account for temperature and pressure variations within the engine
Solution Approach 1:
The patent replaces direct mechanical/physical density measurement with an electrical field-based dielectric constant measurement. This substitution allows for non-intrusive measurement at the fuel metering valve location within the engine, capturing the actual in-situ density conditions without mechanical interference or complex operation.
Solution Approach 2:
The patent measures a different physical parameter (dielectric constant) that can be easily obtained electrically, and then uses the pre-established relationship between dielectric constant and density to derive the density value. This parameter change enables measurement at the engine location while maintaining measurement reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides precise fuel density measurements, enabling efficient engine control by accounting for temperature and pressure variations, thus improving the accuracy of fuel mass flow calculations.
Implementation Method 1
measuring a dielectric constant of the fuel at a second location
Implementation Method 2
a first measurement of capacitance of the fuel can be obtained across the at least one gap
Data Source
AI summary
A method for accurately determining a density of a fuel includes obtaining dielectric constant versus density characteristics of the fuel at a first location and measuring a dielectric constant of the fuel at a second location. The environmental conditions at the second location differ from environmental conditions at the first location. Density of the fuel at the second location is inferred using the dielectric constant of the fuel at the second location and the dielectric constant versus density characteristics of the fuel at the first location.