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Flow behaviour of highly concentrated slurries
Vlasák, Pavel ; Chára, Zdeněk
The paper describes results of experimental investigation of the highly concentrated fine-grained slurry. The flow behaviour of the slurry was experimentally investigated for the laminar and turbulent regimes with respect to the effect of solid concentration and flow velocity. The re-circulation pipe loop with smooth stainless steel pipe of the inner diameter D = 17.5 mm was used. Stony dust from Mistrovice quarry (d50 = 8 μm, ρs = 2 701 kg/m3) was used as a solid phase, water was used as a carrier liquid. Volumetric concentration and slurry velocity reached up to 44% and 6 m/s, respectively.
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Přechod z laminárního do turbulentního proudění pro zahuštěné nenewtonovské suspenze
Vlasák, Pavel ; Chára, Zdeněk
The paper deals with flow behaviour of fine-grained highly concentrated non-Newtonian slurries and their laminar/turbulent transition. The non-Newtonian slurry behaviour changes significantly if the laminar flow changes to the turbulent one. Results of experimental investigation of water mixtures of kaolin or fluidic ash in horizontal straight pipes are presented. A pipe loop with hydraulically smooth stainless steel pipes of inner diameter D of 17.5, 26.8 and 36 mm was used to study the slurry flow parameters.
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Účinek smykového namáhání, hrubozrnných částic a aditiv snižujících tření na tokové chování hustých popílkových suspenzí
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří
The dense fluidic ash-water mixtures are time dependent non-Newtonian slurry, their shearing results in the significant decrease of the pressure drops in the laminar region, also laminar/turbulent transition region was reached for lower flow velocity. Presence of bottom ash or chemical agent affects favourably the flow behaviour of dense fluidic fly ash-water mixtures. The paper is focussed on the experimental study of the effect of concentration, time and intensity of shearing and particle size distribution on the hydraulic gradient vs. the average velocity relationship in the laminar, transitional and turbulent regimes. The re-circulation pipe loop with smooth stainless steel pipes of the inner diameters D = 26.8 and 36 mm was used for measuring the ash-water mixtures flow parameters.
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Vliv velikosti částic a smykového namáhání na tokové chování jemnozrnných suspenzí
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří
Non-Newtonian behaviour of high-concentrated sand and sand-kaolin slurries was observed. At low and medium velocities the flow resistance increases with the increasing concentration of solids, at high velocities the effect of the concentration can be opposite. An intensive turbulent and even long time laminar shearing result in a significant decreasing of the laminar/turbulent transition velocity and flow resistance in the laminar region. The effect of shearing is more significant for higher slurry concentration.
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