Abstract
The advanced knowledge of particle-water mixture flow behaviour is important for safe, reliable, and economical design and operation of the freight pipelines. The effect of the mixture velocity and concentration on the coarse particle - water mixtures flow behaviour was experimentally investigated on an experimental pipe loop of inner diameter D = 100 mm with horizontal, vertical, and inclined pipe sections. Narrow particle size distribution basalt pebbles were used as model of coarse-grained solid particles. The radiometric method was used to measure particle concentration distribution in pipe cross-section. Mixture flow behaviour and particles motion along the pipe invert were studied in a pipe viewing section. The study revealed that the coarse particle- water mixtures in the horizontal and inclined pipe sections were significantly stratified. The particles moved principally in a layer close to the pipe invert. However, for higher and moderate flow velocities the particles moved also in the central part of the pipe cross-section, and particle saltation was found to be dominant mode of particle conveying.
Highlights
Hydraulic transport pipelines are commonly used for transport of bulk materials, like coal, ores, waste materials, mostly relatively fine particles, which in the turbulent flow are supported by turbulent diffusion in the core of the flow
Pipeline transport of coarse particles in form of heterogeneous mixtures is of potential importance in dredging and mining industry, e. g. the Alberta sands petroleum extraction, or poly-metallic nodules transport from the ocean bottom to the surface [1,2,3]
From visualization of the coarse-grained mixtures flow we found, that individual particles slid and rolled along the pipe invert for mixture velocities about deposition limit
Summary
Hydraulic transport pipelines are commonly used for transport of bulk materials, like coal, ores, waste materials, mostly relatively fine particles, which in the turbulent flow are supported by turbulent diffusion in the core of the flow. Knowledge of the slurry flow behaviour, deposition limit and operational velocities, and the pressure drops associated with the slurry flow in horizontal, vertical and inclined pipe sections is essential to safe and effective design and operation of such pipeline installation [2]. Under this condition, turbulence and inter-granular contact are the two significant mechanisms of particle support. Buoyancy and fluid forces cannot balance the weight for coarse particles; they are supported mainly by inter-granular contacts to the pipe wall. The present paper is focused on evaluation of the effect of average mixture velocity and overall concentration on the pressure drop versus the slurry average velocity relationship, on slurry flow behaviour and local concentration distribution
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