Evaluation and prediction of rise velocity and drag coefficient of an ascending bubble affected by the impurity in continuous and discrete phases, distinctly and concurrently

Abstract

Obtaining a deep knowledge about the bubbly flow systems, which are widely applied in various chemical and industrial processes, is crucial for scholars and engineers to achieve more accurate equipment design and processes control. This paper is dedicated to experimentally investigate the distinctly and concurrently effects of fumed silica nanoparticles (NPs) and hexane vapor molecules as impurities in continuous and discrete phases, respectively, on the terminal velocity and drag coefficient of a single rising bubble in aqueous solutions. The obtained experimental data were compared to the calculated data by derived correlations in literatures. As a result, none of those can predict the experimental data and a new correlation for considering the SiO2 NPs as an impurity in liquid is required. As a novelty, this work proposed two new correlations for prediction of terminal velocity and drag coefficient of a rising bubble in NPs solutions as a function of NPs concentration in aqueous solutions. The proposed correlations of terminal velocity and drag coefficient are in excellent agreements with the experimental data over the range of Re <310 and We <1.8, and with the maximum average relative errors of about 0.5% and 1.3%, respectively. Moreover, an interesting synergistic effect at the bubble interface was shown, due to creation of hexane oily layer at the interface and its interaction with rotational and vibrational effects of NPs in 200 ppm solution, where the exerted drag force on the rising bubble was reduced by 12.5% in comparison to the pure water (Air) case.