Velocity distribution and pressure losses through randomly packed beds of spheres

Abstract

Measurements were made of fluid velocity distributions for a number of randomly packed beds of spheres using a flow separator between the exit face of the bed and the plane of measurement. The results for right cylindrical beds show that the departures from uniformity were small, except for a region within one half sphere diameter from the walls of the containing vessel where a marked increase in velocity occurred. The distribution was found to be independent of Reynolds number (1470 < NR < 4350) and bed length (9< L/d < 36). It was only slightly affected by the method of loading the bed, the density and tolerance of the spheres, and sphere diameter (12 < D/d < 48). A marked change was found for a bed which was peaked at exit. Measurements of the pressure losses across the beds were also made. The resulting friction factors for the right cylindrical beds were correlated using the general pressure loss correlation in its normal form and also in a modified form which took the measured velocity distributions into consideration. Both catered adequately for different packing methods and sphere diameter, but not for different bed lengths. Results are presented for the additional pressure losses caused by a peak at exit.