Many industrial processes deal with gas bubbles, e.g., the chlor-alkali processes or a side reaction in metal deposition reactions. It is therefore very important to describe the influence of gas bubbles on the fluid flow in a quantitative way. In the present paper, the two-phase flow is both experimentally characterized and numerically modeled in a reactor with a rotating flow field such as the inverted rotating disk electrode (IRDE). Polarization curves of the hydrogen evolution in 0.1 M
Na2SO4
at pH 2.5 are recorded at different rotation speeds. The bubble dispersion and size distribution of the hydrogen bubbles are determined by laser marked shadowgraphy and interferometric laser imaging for droplet sizing. Concerning the numerical investigations, in the first step the single-phase flow solution in the vicinity of the IRDE is compared to the analytical solution of the flow field, as proposed by Cochran [ Proc. Cambridge Philos. Soc. , 30 , 365 (1934) ]. In the following step, an Eulerian–Lagrangian two-phase flow model is used to track the bubbles. Two-way momentum coupling effects between bubbles and electrolyte flow are taken into account. The calculated two-phase flow field compares well against the experimental data of the two-phase flow field obtained from the optical imaging techniques.
A novel combination of backlighting and Glare Point Velocimetry and Sizing (GPVS) is proposed to measure the size distribution of microbubbles (or microdroplets). This new technique, which we will call Laser Marked Shadowgraphy or LMS, avoids sizing out-of-focus bubbles (or droplets) and the associated bias error. Compared to backlighting, this combination also improves the precision of the diameter measurement and allows void fraction measurements.Compared with GPVS, a more robust image processing is obtained. The applicability of the developed technique is demonstrated on a cloud of electrochemically generated hydrogen bubbles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.