Fluidization of lactose carrier powders through normally directed airflow: the effect of recirculation and particle size

This study investigates the fluidization of lactose carriers from a powder bed subjected to a normal force in a channel flow using high-speed imaging, particle image velocimetry (PIV), and high-speed, long-distance microscopy (HS-LDM). Pharmaceutical lactose carriers (LH200 and SV010) with different cohesiveness and fines percentages were examined in this study. Airflow velocities in the range of 1.4 m/s and 7m/s were tested, corresponding to flow rates ranging from 20 to 100 L/min. The use of HS-LDM in tandem with PIV has enabled measurement of the slip factor between particles and conveying airflow as well as metrics that help to identify dose homogeneity as a function of location in the channel flow. The results indicate a lower slip ratio and a larger change in powder particle size bands percentages along with channel height in the region near the powder bed, because of flow recirculation and higher velocity fluctuation observed in that region.