Centrifugal Pump Impeller Density Measurement via Head-Curve Relation
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Solution Overview
Problem
Accurate measurement of aircraft fuel density is challenging due to temperature variations, pressure changes, and vibrations experienced during flight, which can affect the precision of fuel metering in aircraft engines.
Innovation Solution
A system that simultaneously pumps and measures the density of aircraft fuel using a centrifugal pump with a single impeller, where the rotational frequency, flow rate, and pressure differences are used to determine fuel density based on an empirically-determined head-curve relation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate density measurement device is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the density measurement function with the existing fuel pump by using the pump impeller as a rotating sensor. The impeller's rotational characteristics change with fuel density, allowing density measurement without adding a separate measurement device. This merging approach maintains measurement precision while avoiding increased system complexity.
Solution Approach 2:
The fuel pump impeller is designed to serve dual purposes: maintaining its primary function of pumping fuel while simultaneously acting as a sensor for density measurement. By making the impeller universal, the system eliminates the need for dedicated measurement equipment, thereby resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If multiple separate sensors are added for measuring density parameters, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent merges multiple measurement functions (density, flow rate, pressure) into a single integrated system using the pump impeller. This consolidation allows the system to maintain high measurement precision while simplifying operation, as users interact with one unified system rather than multiple separate sensors requiring individual calibration and operation.
3Productivity
If a centrifugal pump is used for both pumping and density measurement, then productivity is improved, but measurement precision may worsen due to vibrations and pressure changes
Solution Approach 1:
The patent converts the harmful effects of vibrations and pressure changes into beneficial measurement signals. The impeller's rotational frequency and differential pressure measurements are specifically designed to capture density information while compensating for the effects of vibrations and pressure variations. This approach allows the system to maintain productivity while improving measurement precision by utilizing the pump's operational dynamics rather than fighting against them.
Solution Approach 2:
The system incorporates feedback mechanisms where the measured rotational frequency and differential pressure are continuously monitored and used to calculate fuel density. This feedback loop allows the system to compensate for vibrations and pressure changes in real-time, maintaining measurement precision while the pump operates at full productivity.
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 allows for accurate and simultaneous pumping and density measurement of aircraft fuel, effectively addressing the challenges of temperature and pressure variations, and ensuring precise fuel metering for aircraft engines.
Implementation Method 1
Aircraft fuel is pumped by a centrifugal pump having an impeller
Implementation Method 2
Density of the aircraft fuel is determined based on an empirically-determined head-curve relation corresponding to the centrifugal pump. The head-curve relation is empirically determined during a characterization phase. The empirically-determined head-curve relation relates the density of the aircraft fuel to the rotational frequency, the flow rate, and the pressures at the two different points.
Data Source
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AI summary
Apparatus and associated methods relate to simultaneously pumping and measuring density of an aircraft fuel. The aircraft fuel is pumped by a centrifugal pump (22) having an impeller (32). A rotational frequency of the impeller is determined while the centrifugal pump is pumping the aircraft fuel. Flow rate of the aircraft fuel through the centrifugal pump is sensed. Pressure of the aircraft fuel is measured at two different points within or across the centrifugal pump or a differential pressure is measured between the two different points while the centrifugal pump is pumping the aircraft fuel. Density of the aircraft fuel is determined based on an empirically-determined head-curve relation corresponding to the centrifugal pump. The head-curve relation is empirically determined during a characterization phase. The empirically-determined head-curve relation relates the density of the aircraft fuel to the rotational frequency, the flow rate, and the pressures at the two different points.