Abstract
The paper deals with a flow behaviour of mixture composed of coarse glass-bead particles and non-Newtonian carrying liquid of Herschel-Bulkley type in a pressurized pipe. Essentially, there are two mechanisms governing support of particles in the flowing carrier: mutual inter-particle collisions and interaction of particles with carrier turbulent eddies. The turbulent support is quantified by a turbulent-diffusion model, which predicts a distribution of concentration of particles in the flow. In the model, the particle turbulent diffusivity is an important parameter dependent on a number of flow quantities, e.g. the carrier rheological parameters. In case of Newtonian carrier, the viscosity is the only rheological parameter and it is constant throughout the flow. In the non-Newtonian carrier, however, local values of the viscosity vary with the shear strain and so affect the particle diffusivity. The paper discusses experimental and analytical results for non-Newtonian mixture flows of measured rheological parameters and flow characteristics. Based on measured concentration profiles, a suitable method is used to determine the local particle diffusivity experimentally.
Highlights
Conveying and pumping of non-Newtonian slurries are processes which occur in many branches of industry as mining, dredging, chemistry, or food industry
In case of Newtonian carrier, the viscosity is the only rheological parameter and it is constant throughout the flow
The aim of this paper to evaluate a capability of the Newtonian-based turbulent diffusion model appropriately modified for non-Newtonian liquid to predict a distribution of volumetric concentration of coarse particles in a vertical of a pipe cross section
Summary
Conveying and pumping of non-Newtonian slurries are processes which occur in many branches of industry as mining, dredging, chemistry, or food industry. For stratified and heterogeneous flows of coarse-grain slurries with a Newtonian carrier (as water), relatively successful models are available for predicting the distribution of particles in pipe flow [6,7,8,9]. Such models are not readily available for turbulent flows of complex slurries based on a non-Newtonian carrier. The aim of this paper to evaluate a capability of the Newtonian-based turbulent diffusion model appropriately modified for non-Newtonian liquid to predict a distribution of volumetric concentration of coarse particles in a vertical of a pipe cross section. The attention focusses on the key parameter of the turbulentdiffusion model - the particle diffusivity
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