Numerical Prediction of Heterogeneous Bubbly Flow Using a Multi-Fluid Model

Abstract

Numerical methods for predicting heterogeneous bubbly flows in bubble columns are indispensable in the design of bubble column reactors. The objectives of the present study are (1) to experimentally investigate the effects of a bubble size distribution on heterogeneous bubbly flows in an open vessel and (2) to examine the applicability of the NP 2 model ((N+2) -field model) to heterogeneous bubbly flows. Distributions of void fraction and liquid velocity in air-water bubble plumes in the vessel were measured using an experimental setup with a bubble injection device by which the ratio of the volume flow rate of large bubbles to that of small bubbles was controlled to a desired value. The main conclusions obtained were as follows : (1) experimental data on the effects of bubble size distribution on air-water bubble plume were obtained, and (2) the NP 2 model gave good predictions for heterogeneous bubbly plumes.