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Drag reduction of dense fine-grained suspensions
Vlasák, Pavel ; Chára, Zdeněk ; Štern, Petr
The effect of addition of the sodium carbonate and soda water-glass and their concentration for different kaolin slurry was investigated. The significant decreasing of the apparent viscosity and the yield stress was observed due to the addition of the both peptising agents. The viscosity difference between coagulated and peptised slurries can achieve values of several orders of magnitudes depending on peptising agent concentrations. The modification of physico-chemical environment of the transported slurry can be used also for another fine-grained dense hydro-mixture, e.g. for different mine tailings or for bauxite residue.
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Laminar and turbulent flow of dense kaolin and ash hydromixtures
Vlasák, Pavel ; Chára, Zdeněk
Two turbulent models based on rheological parameters (Wilson, Slatter) for concentrated kaolin and ash slurries were analysed. The flow behaviour of slurries was investigated on tube viscometer. It was find out that the flow behaviour index n decreases, while yield stress and fluid consistency K increase with increasing concentration. The both turbulent models can be used for prediction of flow behaviour of kaolin and ash slurries in the turbulent regime if the flow behaviour index n is determined from turbulent data.
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Lateral dispersion on solid particles in water flow
Chára, Zdeněk ; Vlasák, Pavel
The paper presents the results of investigation of solid particle motion over rough bed in an open channel flow. The turbulence characteristics of water flow were performed by means of LDA, the particle motion was analysed by a video camera. It was found that the mean deviation angle by which the particles are moving to side walls is about 2.4ř.
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