Experimental studies of particle flow dynamics in a two-dimensional spouted bed

In this paper, both time-averaged and fluctuating behaviors of granular solids in a two-dimensional spouted bed (2DSB) were investigated by particle image velocimetry (PIV). A self-developed algorithm for the high-gradient granular flow field was employed to measure particle velocity sequences together with power spectral density, mean particle velocity and granular temperature. The incoherent spout was characterized as an ‘X’ geometry marked with a periodic upwardly moving neck consisting of particle clusters. In the annulus, particles move periodically as a process of acceleration–deceleration–stagnation that has the same domain frequency as the pressure drop of 2DSB. The time-averaged downward velocities have a maximum at a certain position between the spout wall and conical wall. In the spout, the longitudinal profiles of vertical particle velocities along the axis exhibit a fast acceleration followed by a long flat peak, while the normalized lateral profiles at all bed levels tend to collapse into a third polynomial curve with an inflection point. A mushroom-like distribution of the granular temperature exists in 2DSB. The peaks of granular temperature occur not only near the spout–annulus interface, but also at the corner zone between the annulus and the fountain.