Analysis of slurry flow regimes downstream of a pipe bend

The influence of the pipe bend between downward and horizontal flows on transition velocities between slurry flow regimes in a horizontal pipe has been characterized using electrical resistance tomography. The experiments have been carried out using a pipe loop of diameter 0.076 and 10 m long. The slurry mixture consisted of water and 100 μm diameter glass beads. The influence of solids concentration and the distance from the bend outlet on transition velocities have been studied. Two transition velocities have been determined: the transition between a pseudo-homogenous flow and a heterogeneous flow and the limit deposit velocities at the onset of solid particle bed. Results have shown that the bend significantly contributes to the suspension of the solids particles and to the decrease in the transition velocities between the slurry flow regimes occurring in a horizontal pipe. The distance from the bend outlet where these transitions take place increases with the velocity. Furthermore, the solids concentration influences these transitions at low concentration while there is little influence at high concentration. These observations have been compared with correlations for the transition velocities in a horizontal pipe.