Combinated flow pattern map for cocurrent and countercurrent air-water flows in vertical tube.

Abstract

Flow patterns for cocurrent and countercurrent air-water flows in vertical tubes (40 and 80mm I.D.) at volumetric flux densities of air and water in the ranges −115–158 and −100–102 cm/s were observed. A flow pattern map presenting the entire data of the observed flow patterns, i.e. bubbly, slug and annular flow for each mode of flow operation (upflow, countercurrent flow and downflow) were presented on the jl vs. jg plane. The flow pattern maps showed significant difference of flow pattern transition boundaries with upflow, countercurrent flow and downflow. Flow pattern transition curves were smoothly continuous with the change of the direction of water flow, on the other hand the change of flow direction of air showed complicated effect on flow pattern transition near zero jg . Comparison of the present flow pattern data with the reported general flow pattern maps for upflow showed that the correlation of Taitel et al. for bubble-slug flow transition is applicable to both cocurrent and countercurrent air-water flows.