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.