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Investigation of flow behaviour of homogeneous and heterogeneous ash slurries: fly and bottom ash Porici
Chára, Zdeněk ; Vlasák, Pavel ; Konfršt, Jiří
The flow behaviour of fly ash and bottom ash from fluidic combustion slurries was experimentally investigated for laminar, transitional and turbulent regimes with respect to the effect of solid concentration, particle size distribution and time and intensity of shearing in smooth stainless steel pipes of inner diameter of 26.8 and 36 mm. Volumetric concentration ranges from 20 to 32 %, slurry velocity reach value up to 5 m/s. It was demonstrated that turbulent shearing or addition of bottom ash results in the significant decrease of the apparent viscosity; also laminar/turbulent transition region was reached for lower flow velocity.
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Numerický 3D model kolize pevné částice s drsným dnem kanálu
Lukerchenko, Nikolay ; Chára, Zdeněk ; Vlasák, Pavel
The paper deals with 3D numerical model of the random process of rotating spherical particle-bed impact and rebound for saltation movement of a particle in channels with rough bed. The collision height and the contact point are defined as random variables of the collision process. The collision height depends on bed roughness. The contact point position depends on the irection of the particle velocity vector before the collision
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Použití "rovnic mělké vody" na proudění nenewtonských suspenzí
Hoření, Bohumír ; Chára, Zdeněk ; Vlasák, Pavel
The paper presents an attempt to use shallow water equations to solve a flow of non-Newtonian suspensions. Saint-Vennant set of equations of incompressible free surface flow in thin layers (frequently referred as "shallow water equations") forms a baseline for theoretical solution. The original set of equations established for Newtonian fluids is modified to solve also flow of non-Newtonian fluids with arbitrary rheological behaviour
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Transport hrubých částic v nenewtonovských suspenzích
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří
The paper deals with flow behaviour of slurries containing colloidal, clay, dust and also coarse-grained particles. The slurry flow behaviour changes form Newtonian to non-Newtonian in dependence on the solid phase concentration and composition, especially on the contents of colloidal particles. Flow behaviour of fluidic fly and bottom ash slurries, clay and sand slurries was experimentally investigated with respect to the solids composition, volumetric concentrationa and slurry velocity. The re-circulation pipe loop with smooth stainless steel pipes of the inner diameters D = 17.5, 26.8 and 36 mm was used for measuring the slurry flow parameters. Also the effect of time and intensity of shearing was studied for time dependent fluidic ash slurries
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Experimentální výzkum odporu rotačně se pohybující kulové částice
Lukerchenko, Nikolay ; Kvurt, Y. ; Chára, Zdeněk ; Vlasák, Pavel
Saltatory solid particles conveyed by fluid impact a channel bed from time to time. As a result of the collision the particles receive angular velocity, which gradually decreases with time. For numerical simulation of saltation it is necessary to know values of the drag rotation coefficient. In this paper experimental results of the rotating spherical particles moving in water are described. The rubber spherical balls with density near that of water were used; each of them was speeded up in a special chute that ensured that the particle rotated in a given plane. Values of the drag coefficient of the rotating spherical particle were determined in a dependence on rotation particle Reynolds number
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