Abstract: Experiments were conducted in a riser of 186 mm ID and 9 m height. The different flow patterns, including turbulent, fast and pneumatic fluidized beds, were obtained by changing the superficial gas velocity from 0.95 to 10.0 m·s~-1. An optical fiber density probe was used to measure local transient signals at different radii and at different axial cross-sections for each flow regime in order to show the varied flow structures both in the axial and radial directions. Deterministic chaos theory was used to analyze the time series and consequently Kolmogorov entropy was calculated to describe the dynamic characteristics of signals. The results showed that the local Kolmogorov entropy can describe the flow structure of gas/solids two phase flow in different regimes. At the same time the entropy was strongly related with the local solids fraction in three types of flow regimes: when 1-ε is greater than 0.05, the K_mlkeeps almost constant; when 1-ε is smaller than 0.05, the K_mlincreasesdramatically with the decrease of 1-ε. This implies that the solids fraction is a dominant factor that influences the turbulent structure of two-phase flow.

摘要： 在内径 1 86mm、高 9m的提升管中 ,通过改变操作气速获得湍动流化床、快速流化床和稀相输送典型的操作状态 ,使用光纤密度探头在轴向不同截面的不同径向位置处测得密度脉动时间序列 ,以反映不同流型下 ,不同浓、稀相区的瞬态动力学行为 .利用确定性混沌理论分析了局部密度脉动信息 ,以Kolmogorov熵定量地表征系统的动力学特征 .实验结果表明 ,Kolmogorov熵随流型的变化能正确地反映相应流型的特点 ,可用来描述不同流型下的流动结构 .在忽略壁面附近行为的条件下 ,对 3种流型、不同的浓稀相区 ,局部熵值随局部固含率变化可分为两个区 :当局部固含率高于 0 0 5时 ,熵几乎不随局部固含率的变化而变化 ;当局部固含率低于 0 0 5时 ,熵随局部固含率的减小而急剧增大 .这说明系统的混沌特征与局部固含率关系密切 ,局部固含率对系统局部动态行为起控制作用 .