三相流化床流动结构特征的小波分析

Characteristics of flow patterns in three-phase fluidized bed by wavelet analysis

在横截面0.1 m×0.01 m、高0.8 m的三相流化床实验装置上，开展了小波分析特征参数定量表征流型的研究．实验中空气和水分别作为气相和液相介质，固体实验物料采用粒径为48μm的玻璃粉，对实验采集的压差脉动时间序列采用小波分析进行分解，得到不同尺度的小波信号标准差和小波熵，定量表征不同操作参数下，三相流化床中均匀流、过渡流和非均匀流3种流型对应特征值的变化规律．分析得到均匀流、过渡流、非均匀流的能量分布主要集中在宏观尺度和中尺度上，数量达到97％以上，而且中尺度、宏观尺度信号d3～d6的小波信号标准差范围值依次增大．均匀流小波熵的范围为0.1696～0.2913 det，与其他2种流型相比要大一些．结果表明，宏观尺度和中尺度信号的小波分析，能够很好地表征均匀流、过渡流、非均匀流3种流型．与小波熵相比，小波信号标准差能够更好地表征均匀流、过渡流、非均匀流3种流型．

Experimental investigations were carried out in a three-phase fluidized bed with a cross section of 0.1 m ×0.0 1 m and a height of 0.8 m.The research of characteristic parameters of wave-let analysis characterized flow patterns were developed quantitatively.Water and air were used as gas and liquid medium respectively,and glass powders of 48 μm were employed as solid experimental materials in experiment.Wavelet analysis was developed to decompose the pressure fluctuation time series collected from experiment.The standard deviations of wavelet signals and wavelet entropy were obtained at different scales.The change rule of characteristic value corresponding to three flow patterns,i.e.,homogeneous flow,transition flow,and heterogeneous flow were analyzed quantita-tively at various operating parameter.Analysis results show that more than 97% wavelet energy for homogeneous flow,transition flow,and heterogeneous flow mainly focuses on macro-scale and me-so-scale.Standard deviations of wavelet signals from d3 to d6 signals increase in turn for three pat-terns on macro-scale and meso-scale.The wavelet entropy values of homogeneous flow are from 0.169 6 to 0.291 3 det,which is larger than that of other two flow patterns.Experimental results show that wavelet analysis of macro-scale and meso-scale signals is a good characterization of the three patterns.Standard deviations of wavelet signals can better characterize the homogeneous flow, transition flow and heterogeneous flow than wavelet entropy.