Dynamic behaviors of heterogeneous flow structure in gas-solid fluidization

A method was established to quantitatively describe nonlinear dynamic behav ior of heterogeneous flow structure in gas-solid fluidization by carrying o ut multiple resolution and time series reconstruction of experimental signa ls. Optimum sampling frequency was proposed by analyzing the dependence of Kolmogorov entropy of time series on sampling frequencies. Original signals could be resolved with respect first to scale, and then to time and amplit ude into a periodic function and three irregular changes (micro-scale fluct uations, and meso-scale irregular amplitude and time fluctuations). Statist ical analysis indicated that the three kinds of irregular components are of random characteristics, with a complicated evolution of their probability density distributions with changing operating conditions. A new distributio n function, called Compound Weibull distribution with seven parameters, was developed to describe the irregular fluctuations of flow structure, leadin g to a nonlinear dynamic model for simulating dynamic behaviors of heteroge neous flow structure in gas-solid fluidization, which has been coded into a software package. (C) 2000 Elsevier Science S.A. All rights reserved.