Flow Characteristics of Air-Solids Mixture in a Horizontal Pipeline : 1st Report, Relations between Loss Coefficients and Behavior of Particles

Abstract

Some experiments on two-dimensional distributions and mean free paths of particles in a horizontal pipeline for pneumatic conveyance are shown, and relations between additional pressure loss coefficients and behavior of particles are discussed. Distributions of particles for high air velocity are almost uniform in a cross-section of the pipeline. with a decrease in air velocity particles gradually concentrate in a bottom region but a perfect suspension flow is maintained and rolling or slipping of particles on the pipe wall is not investigated at all. Corresponding to the change in particle distributions, mean free paths of particles decrease with a decrease in air velocity. Loss coefficients under various combinations of air velocity and solid loading ratios are the same so long as the particle distributions are similar. Loss coefficients calculated from results of simple tests of particle velocity defects due to collisions with a wall agree relatively well with results of transportation tests.