Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7060251 | International Journal of Multiphase Flow | 2016 | 35 Pages |
Abstract
A direct resolution approach was proposed to decompose differential pressure signals from a gas fluidized bed into macro- and super-imposing components, which were further subjected to structure density function analysis (SDF analysis) to study dynamics of multi-scale structures in flow. Direct resolution performed well in extracting feature information of multi-scale structures, especially macro- and meso-scale structures whose dynamic behaviors majorly affected hydrodynamics in bed, from measured differential pressure fluctuations. With the assistance of Gaussian fitting and Kolmogorov-Smirnov test, SDF analysis divided the probability distribution of multiple structures with respect to their amplitude scale r into four feature regions (Regions B-I, B-II, B-III and Region A). Parameter KSDF derived from slope of Region B-II quantified frequency of various meso-scale structures in flow, and well followed the tendency of flow patterns transition after being normalized by bubble (slug) rising velocity Ub(sl). Frequency of macro-scale structures in slugging flow depended greatly on rising velocity of slugs, so SDFmacro increased with increased fluidization velocity. Developed turbulent flow had a high SDFmacro exceeded 0.8Â Hz due to the fast passage and split/integration of large voids. Structures localized in Region A mainly represented noise from measurements, other measurable micro-scale disturbances in single phases or phase-interfaces, and had an occurring frequency increased with increase of fluidization velocity.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Chen Yumin, Chen Wei, John R. Grace, Zhao Yongchun, Zhang Junying, Li Yimin,