Insights into the instantaneous freeboard flow above a bubbling fluidised bed

Laser diagnostic investigation of the bubble eruption patterns in the freeboard of fluidized beds: Simultaneous acetone PLIF and stereoscopic PIV measurements

“…The out‐of‐plane component is not negligible. The observed bubble eruption patterns were in general agreement with the bubble model of Levy and Lockwood,24 Yorquez‐Ramirez and Duursma5 and Solimene et al1 No qualitative difference between the eruption of a single bubble and a stream of bubbles was observed. Based on the calculated vorticity of the gas in the freeboard, it was found that the bubble induced turbulence decays fairly rapidly.…”

“…Therefore, faster PLIF images acquired with a frequency of 5 Hz as reported in Hartung et al19 are used in conjunction with our new simultaneous PIV and PLIF measurements (acquisition frequency 2 Hz) to investigate the rather complex dynamics of bubble eruption. Beside the development of several opimisation measures the main conclusions of Hartung et al19 were: Experimental measurements support the bubble eruption model of Levy and Lockwood,24 Yorquez‐Ramarez and Duursma5 and Solimene et al1, 3 and Five different release pattern of gas at the moment of bubble eruption were identified. …”

“…This is followed by a vertical motion, carried upward by the main gas flow in the freeboard. Solimene et al1, 3 and Yorquez‐Ramirez and Duursma5 proposed very similar models, but describing in more detail the release of the gas of the erupting bubble as it forms a dome. Solimene et al1, 3 reported the formation of a “nose pocket” of gas, the size of which depends on the size of the fluidized particles comprising the dome.…”

“…This pocket of gas is released at the center of the dome. On the other hand Yorquez‐Ramirez and Duursma5 proposed a rather evenly distributed release of gas along the dome upon bubble eruption.…”

Initial particle velocity spatial distribution from 2-D erupting bubbles in fluidized beds

“…The experiments were restricted to the determination of the gas field in the freeboard above an erupting bubble but far from the bed surface. Yó rquezRamírez and Duursma [14,15] and Duursma et al [16] studied the air flow pattern above an erupting bubble in an incipiently fluidized bed, showing the applicability of PIV techniques to obtain the continuous phase flow fields in fluidized beds.…”