Defence and Security

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Browsing Defence and Security by Subject "'Aircraft'"

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    ItemOpen Access
    Characterization of water droplets size distribution in aviation turbine fuel: Ultrasonic homogeniser vs. High shear speed mixer
    (Cranfield University, 2022-06-24 10:10) Ugbeh, Judith
    Pumps, pressure drops across fittings, and flight operations (such as turning manoeuvres, take-off, and landing) are some of the many sources of turbulence mixing and shearing in aircraft fuel systems, therefore, making it an inevitable condition. Literature established that shearing conditions would influence the droplets and droplets size distribution in oil/water emulsion. So, low intensity shearing conditions could be beneficial as it promotes droplet coalescence, which could be a driving force for a weak emulsion. However, to date no experimental data shows the influence homogenising intensity and total water content has on dispersed water droplet size distribution (DSD) in aviation fuel. Therefore, to expand knowledge of improving quantification to the measurements of dispersed water droplets in aviation fuel, this study characterizes dispersed water droplets in aviation turbine fuel, varying available laboratory homogenising gadget and water content. Results presented shows that droplet count increases with water concentration and shearing effect. To provide more statistical evidence, kurtosis and skew values was calculated from the extrapolated data and compared with data from a hexanol/water mixture given that hexanol is likely to form a stable emulsion. Experimental results shows that the higher the homogenising intensity the more stable the emulsion is likely to be with a higher kurtosis and skew value close to that for the hexanol/water mixture.
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    ItemOpen Access
    Investigation of Water Droplet Size Distribution in Conventional and Sustainable Aviation Turbine Fuels
    (Cranfield University, 2022-06-24 10:13) Ugbeh, Judith; Carpenter, Mark; Okeke, Nonso
    Water droplet size variation has been established in the literature as an important variable that influences the behaviour and characteristics of water in fuel emulsion. However, with the growing demand for sustainable aviation fuels (SAF), no data is available that shows how these fuels will affect dispersed water droplets’ size and frequency distribution. To address this lack of knowledge, this study explores and presents experimental results on the characterization of dispersed water droplets in alternative fuel and conventional Jet A-1 fuel under dynamic conditions. The alternative fuels comprised of two fully synthetic fuels, two fuels synthesised from bio-derived materials and one bio-derived fuel. The data and statistics presented reveal that water droplet frequency and size distribution are sensitive to changes in fuel composition. Observations show that the evident transition of the droplet’s percentile over time in the cumulative frequency distribution could be attributed to droplets coalescence to form larger droplets. Mean droplet diameters between 3 and 6 µm were observed for all the fuels tested. With further analysis based on recommendations proposed in this work, the data may assist in providing insight to filter manufacturers.