Centrifugal Pump Fuel Density Measurement via Pressure Differential
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Solution Overview
Problem
Accurate measurement of aircraft fuel density is challenging due to temperature, pressure, and vibration variations during flight, which affect the energy content and thus the metering of fuel to aircraft engines.
Innovation Solution
A system utilizing a centrifugal pump with an impeller, speed sensing, and pressure sensing arrangements, along with a processor to calculate fuel density based on rotational frequency and pressure measurements at different radial distances from the impeller axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a centrifugal pump is used to pump aircraft fuel, then fuel can be delivered to the engine, but the pump's mechanical components experience wear and potential failure due to the fuel's chemical properties and operating conditions
Solution Approach 1:
The patent combines the fuel pumping function and density measurement function into a single integrated system. The centrifugal pump serves dual purposes: delivering fuel to the engine while simultaneously enabling density measurement through its mechanical components (impeller and housing). This integration eliminates the need for separate measurement apparatus that would introduce additional failure points, while maintaining reliable fuel delivery.
Solution Approach 2:
The pump's own mechanical components (impeller and housing) are utilized for density measurement rather than requiring external sensing equipment. The wear-resistant properties of these components ensure they can withstand the measurement process while continuing to perform their primary fuel delivery function, making the system self-sufficient and reducing component failure risks.
2Measurement precision
If density measurement is performed using traditional methods separate from the pump, then density can be measured, but the system complexity increases and measurement accuracy is compromised by flight conditions
Solution Approach 1:
The patent merges the density measurement function with the existing fuel pump system. By using the pump's impeller and housing as the measurement components, the system eliminates the need for separate density measurement apparatus. This integration reduces system complexity while improving measurement accuracy, as the measurement is performed on the actual fuel being pumped under real flight conditions rather than in a separate sampling process.
Solution Approach 2:
The centrifugal pump is designed to perform multiple functions: fuel delivery and density measurement. The impeller and housing serve both as pumping components and as the measurement chamber for density determination. This multi-functionality reduces the overall system complexity by eliminating dedicated measurement equipment while maintaining measurement accuracy through direct measurement of the pumped fuel.
3Productivity
If the pump operates at high speeds to deliver sufficient fuel flow, then productivity increases, but the mechanical stress on pump components increases leading to potential failure
Solution Approach 1:
The patent employs wear-resistant ceramic coatings on the impeller and housing surfaces. These coated components can withstand the high-speed operation and mechanical stress better than conventional materials. The ceramic coating acts as a protective layer that can be applied to standard pump components, providing enhanced durability without significantly increasing component complexity or cost.
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 system enables precise fuel metering by accurately determining fuel density, ensuring consistent energy delivery to aircraft engines despite flight conditions.
Implementation Method 1
a centrifugal pump, speed sensing and pressure sensing arrangements, and a processor. The centrifugal pump includes an impeller configured to pump the aircraft fuel
Implementation Method 2
The Pressure sensing arrangement is configured to measure pressure at two points within the centrifugal pump or a differential pressure between the two points
Implementation Method 3
The speed sensing arrangement is configured to determine a rotational frequency of the impeller while the centrifugal pump is pumping the aircraft fuel
Implementation Method 4
The processor is configured to calculate a density of the aircraft fuel based on the rotational frequency and either the two measured pressures or the measured differential pressure
Data Source
AI summary
Apparatus and associated methods relate to measuring density of aircraft fuel. The aircraft fuel is circumferentially pumped about an impeller axis by a centrifugal pump. Differential pressure of the aircraft fuel is measured between two different points within the centrifugal pump, each a different radial distance from an impeller axis. Rotational frequency of the impeller of the centrifugal pump is measured. Density of the aircraft fuel is calculated based on the rotational frequency and the differential pressure.