Gas-solid structure in the vicinity of a sparger nozzle in a fluidized bed

► A fiber-optic probe is used to determine the jet penetration lengths. ► The approach is suitable for upward, horizontal and downward injection nozzles. ► The average local solid holdup shows linear dependence with the injection velocity. ► The transition velocities correspond to characteristic jet lengths. ► The frequency of the pulsating jet was in the order of 1 and 1.5 Hz.