Sand transport characteristics in water and two-phase air/water flows in pipelines

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Sand transport characteristics in water and two-phase air/water flows in pipelines

Al-Iababidi, S. / Yan, W. / Yeung, H. / Sugarman, P. / Fairhurst, C.P.

The sand critical transport conditions in water and two-phase water/air flows have been experimentally investigated. The investigations were conducted for both horizontal and 5 degrees of angle upward inclined pipe with sand particles of an average diameter of 200 micron. The effect of the concentration was also studied. For water flow test, similar sand behaviours were observed in the horizontal and 5 degrees of angle upward inclined pipeline. The water velocity at which the sand minimum transport condition occurred for horizontal and 5 degrees of angle upward inclined pipelines was similar. For two-phase (air and water) experiments, the sand behaviour observed in the horizontal pipe was different to that in the upwardly inclined pipeline due to backflow of water in the latter. The sand minimum transport condition will be influenced by the gas supply which can cause a change of flow regime and water flow condition in air/water two phase flow. Sand concentration has a significant impact on the sand transport condition because the sand transport characteristics change with sand concentration accordingly. In horizontal air/water flows, the sand minimum transport condition mainly occurred in stratified wavy and slug flow regimes. In 5 degrees of angle uphill flow, it was found experimentally that the gas and liquid velocities required to transport sand were less for the 5 degrees of angle inclined pipe than the horizontal pipe. This is likely to be due to intermittent flows (slug and pseudo slug) are more prevailing in inclined pipe.