Experimental study on sand transport characteristics in horizontal and inclined two-phase solid-liquid pipe flow

An experimental investigation on the hydraulic transport of sand particles in pipelines is presented in both horizontal and 30° upward inclined orientations. The pipe, with an internal diameter of 0.0254 m, had sand transported in various water superficial velocities at low and high sand concentrations [0.1%-10% volume-to-volume ratio (v/v)]. Sand particles were polydisperse (144-250 μm) with a d95 of 210 μm. The minimum transport condition (MTC) was determined by means of video recordings and pressure gradient (PG) measurements. MTC and PG were observed to increase with increase in sand concentration and mixture velocity. At high sand concentrations, there was a decline in PG with decrease in flow velocity until a minimum is reached around the MTC. The MTC at which this occurs is different in the two pipe orientations. Based on a previously reported dimensionless relationship, a correlation was derived now including the effect of pipe inclination using extensive literature data in addition to the current. The effect of key flow, geometric, and particle parameters were adequately captured in the improved closure relationship for sand minimum transport conditions in pipes.