Developed ‘laminar' bubbly flow with non-uniform bubble slzes

摘要

Bubbles with different sizes have different dynamic and kineticbehavior in a two-phase bub- bly flow. A common two-fluid model basedon the uniform bubble size assumption is not suitable for a bubblyflow with non-uniform bubble sizes. To deal with non-uniform bubblyflows, a multi-fluid model is established, with which bubbles aredivided into several groups according to their sizes and a sat of ba-sic equations is derived for each group of bubbles with almost thesame size. Through analyzing the bubble-bubble and bubble-pipe wallinteractions, two new constitutive laws for the wall-force and pres-sure difference between the liquid phase and interface are developedto close the averaged basic equa- tions. The respective phasedistributions for each group of bubbles measured by a speciallydesigned three-dimensional photographic method are used to check themodel. Comparison between model-pre- dicted values and experimentaldata shows that the model can describe laminar bubbly flow withnon-uni- form bubble sizes.