On the Behavior of Air-Solids Mixture in a Pipeline with Varying Cross-Sections

Abstract

The flow characteristics of air-solids mixture in a horizontal pipeline for pneumatic conveyance with a contraction or an enlargement are obtained experimentally. The behavior of particles passing through a varying cross-section is analyzed in consideration of a change in the drag coefficient corresponding to an instantaneous particle velocity. The additional pressure loss of a contraction increases in proportion to a solid loading ratio and the proportional constant is severely affected by the area ratio and the cone angle of the contraction. Except for a few cases of small loading ratios for an enlargement, the agreement of a pressure loss obtained from calculation with an experimental one is quite favorable. It is shown that additional pressure losses of air-solids mixture with varying cross-sections can be represented in universal forms by the initial velocity ratio in a downstream pipeline.