Air-Solid Two-Phase Flow through a Bend : Flow Patterns and Particle Velocities

Abstract

Particle velocities were measured in air-solid two-phase flow through 90° horizontal-to-vertical bends by using an optical fiber probe. Two kinds of polystyrene spherical particles were used, the mean diameters of which were 0.406 and 1.50 mm, respectively, and the pipe diameter was 40 mm. The bend curvature to pipe diameter ratios were 10 and 6. Measured results were compared with calculations based on the conventional one dimensional models developed by Weidner and Kovacs. It was found in the course of the work that differences in the flow patterns of particles should be taken into account in order to obtain a good agreement between measurements and calculations. Thus the patterns were classified into three types according to the loading ratio and superficial air velocity; dispersed flow, dispersed biasing flow and sliding bed flow. It was found that the one dimentional model without fluid drag is applicable to fully developed dispersed biasing flow.