In granular media, topological features are known to determine the effective material properties ... more In granular media, topological features are known to determine the effective material properties and boundary behavior when interacting with other structural components. X-ray computed tomography results are reported on sphere packing structures in slender prismatic containers (X = 20, Y = Z = 80 mm), filled and vibrated with both monosized spheres (diameter d = 2.4 mm), Exp. (M), and polydisperse spheres (1 mm < d < 1.25 mm), Exp. (P). Packing structures were characterized by void fraction distributions, coordination numbers, contact angle distributions and Voronoi packing fractions. In (M), an almost perfect hexagonal dense packing exists in the total volume, associated with a packing fraction γ t≈0.68. In additional packing experiments, large γ t values were achieved as well. Although the d spread in (P) is relatively small, significantly different results are obtained: γ t≈0.62, regular structures are restricted to narrow wall zones and distributions in the container volum...
... b , L Giancarli c , G Le Marois d , A Li Puma c , Y Poitevin c , J Reimann e , J.-F Salavy c ... more ... b , L Giancarli c , G Le Marois d , A Li Puma c , Y Poitevin c , J Reimann e , J.-F Salavy c , J Szczepanski c , G Vella f and G ... Specifications for a DEMO and a power reactor equipped with a WCLL blanket and water-cooled divertor (hot divertor: coolant T max =320 °C; cold divertor ...
The reference concept of the EU water-cooled Pb-17Li DEMO blanket is essentially formed by a dire... more The reference concept of the EU water-cooled Pb-17Li DEMO blanket is essentially formed by a directly-cooled steel box having the function of Pb-17Li container and by a double-wall U-tube bundle, immersed in the liquid metal, in which the pressurised water-coolant flows. The structural material is martensitic steel. All blanket performances satisfy DEMO requirements, such as tritium breeding self-sufficiency, capability of
Abstract Computed tomography experiments were performed with mostly spherical particles in contai... more Abstract Computed tomography experiments were performed with mostly spherical particles in containers with concave, plane and convex walls. Regular pebble packings exist also close to convex cylindrical walls even if the cylinder-to-pebble diameter ratio is about 1, characteristic of thermocouples within the pebble bed. A model for arbitrary container shapes is proposed which predicts the inner packing factor based on the known total packing factor. With increasing vibration efficiency the total packing factor rises because the zones with structured packing increase. Depending on container dimensions, a structured packing can occur in the total pebble bed. Large packing factors are desirable, however, these pebble beds can probably no longer be considered as isotropic with respect to thermo-mechanic properties.
In granular media, topological features are known to determine the effective material properties ... more In granular media, topological features are known to determine the effective material properties and boundary behavior when interacting with other structural components. X-ray computed tomography results are reported on sphere packing structures in slender prismatic containers (X = 20, Y = Z = 80 mm), filled and vibrated with both monosized spheres (diameter d = 2.4 mm), Exp. (M), and polydisperse spheres (1 mm < d < 1.25 mm), Exp. (P). Packing structures were characterized by void fraction distributions, coordination numbers, contact angle distributions and Voronoi packing fractions. In (M), an almost perfect hexagonal dense packing exists in the total volume, associated with a packing fraction γ t≈0.68. In additional packing experiments, large γ t values were achieved as well. Although the d spread in (P) is relatively small, significantly different results are obtained: γ t≈0.62, regular structures are restricted to narrow wall zones and distributions in the container volum...
... b , L Giancarli c , G Le Marois d , A Li Puma c , Y Poitevin c , J Reimann e , J.-F Salavy c ... more ... b , L Giancarli c , G Le Marois d , A Li Puma c , Y Poitevin c , J Reimann e , J.-F Salavy c , J Szczepanski c , G Vella f and G ... Specifications for a DEMO and a power reactor equipped with a WCLL blanket and water-cooled divertor (hot divertor: coolant T max =320 °C; cold divertor ...
The reference concept of the EU water-cooled Pb-17Li DEMO blanket is essentially formed by a dire... more The reference concept of the EU water-cooled Pb-17Li DEMO blanket is essentially formed by a directly-cooled steel box having the function of Pb-17Li container and by a double-wall U-tube bundle, immersed in the liquid metal, in which the pressurised water-coolant flows. The structural material is martensitic steel. All blanket performances satisfy DEMO requirements, such as tritium breeding self-sufficiency, capability of
Abstract Computed tomography experiments were performed with mostly spherical particles in contai... more Abstract Computed tomography experiments were performed with mostly spherical particles in containers with concave, plane and convex walls. Regular pebble packings exist also close to convex cylindrical walls even if the cylinder-to-pebble diameter ratio is about 1, characteristic of thermocouples within the pebble bed. A model for arbitrary container shapes is proposed which predicts the inner packing factor based on the known total packing factor. With increasing vibration efficiency the total packing factor rises because the zones with structured packing increase. Depending on container dimensions, a structured packing can occur in the total pebble bed. Large packing factors are desirable, however, these pebble beds can probably no longer be considered as isotropic with respect to thermo-mechanic properties.
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