X-ray tomography for 3D analysis of ice particles in jet A-1 fuel
Haffar, Iheb ; Flin, Frédéric ; Geindreau, Christian ; Petillon, Nicolas ; Gervais, Pierre-Colin ; Edery, Vincent
Water in jet fuels is an important concern for the aeronautical industry, especially at freezing temperatures, for which ice-clogging phenomena may occur in the fuel-feeding system, with a risk causing accidents. In this work, ice particles formed from water addition in jet A-1 fuel have been characterized by X-ray Micro-Computed Tomography (μCT) at −18±2 °C. For this purpose, an experimental sampling campaign was conducted in a fuel-icing test bench designed to characterize the properties of aeronautical filters. The samples were conditioned, transported, stored under cold-stable conditions and afterward preserved using a specific cryogenic cell during the X-ray scans. After image processing and analysis, the three dimensional (3D) images allowed us to access the shape complexity of the particles at a resolution of 5 μm. The different samples gave repeatable and coherent results, exhibiting wide size distributions of the ice particles, ranging from 20 to 970 μm with a peak between 100 and 400 μm. The increase of the water content volumetric fraction (C) as well as that of the time by which the ice particles were recirculating in the injection loop (τ), showed tendencies towards wider and smaller size distributions, respectively. The sphericity indexes (ψ) were higher than 0.7 for ~70% of particles, indicating a significant trend to rounded shapes. The mean curvature distributions of the agglomerates showed some displacements towards concave surfaces at high C, and towards convex surfaces at longer τ. This illustrates the occurrence of more complex structures for higher water contents and the 'grinding effect' of the recirculating time.</p>
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