稠密气-固流中介尺度结构的识别

Identification of Meso-Scale Flow Structure in a Dense Phase Gas-Solid Fluidized Bed

在冷模气-固流化床实验装置中,研究了鼓泡床与湍流床内的介观两相流动结构。测量了床层内不同轴、径向位置处的瞬时固含率脉动信号,编写了Matlab软件对光纤信号进行解耦。采用三阶统计矩法(偏斜度法)确定了气泡相阈值,发现在床层中心区域,气泡相阈值在0.26~0.35内变化。气泡相与乳化相的平均固含率随气速的增大而减小,颗粒聚团的平均固含率在0.550~0.555之间变化,基本不受操作气速以及径向位置变化的影响,颗粒聚团的出现频率在0.5~3.2Hz之间变化。

Meso-scale flow structures were investigated in a cold mode bubbling and turbulent gas-solid fluidized bed.Solid holdup transient signals were measured in different axial and radial positions,and a Matlab program was compiled to decouple the transient signals.The third moment(skewness)analysis method was employed to identify the threshold value of the bubble phase which varied in a range of 0.26-0.35 in the center of the fluidized bed.As superficial gas velocity increases,the mean solid holdups of both bubble phase and emulsion phase decrease.The mean solid holdup of agglomerates ranges from 0.55 to 0.555,and it almost does not change with superficial gas velocity and radial position.The appearance frequency of particle agglomerates varies from 0.5 Hz to 3.2 Hz.