A Review of Bubble Dynamics in Liquid Metals

Abstract

Gas bubbles are of major importance in most metallurgical processes. They promote chemical reactions, homogenize the melt, or float inclusions. Thus, their dynamics are of crucial interest for the optimization of metallurgical processes. In this work, the state of knowledge of bubble dynamics at the bubble scale in liquid metals is reviewed. Measurement methods, with emphasis on liquid metals, are presented, and difficulties and shortcomings are analyzed. The bubble formation mechanism at nozzles and purging plugs is discussed. The uncertainty regarding the prediction of the bubble size distribution in real processes is demonstrated using the example of the steel casting ladle. Finally, the state of knowledge on bubble deformation and interfacial forces is summarized and the scalability of existing correlations to liquid metals is critically discussed. It is shown that the dynamics of bubbles, especially in liquid metals, are far from understood. While the drag force can be predicted reasonably well, there are large uncertainties regarding the bubble size distribution, deformation, and lift force. In particular, the influence of contaminants, which cannot yet be quantified in real processes, complicates the discussion and the comparability of experimental measurements. Further open questions are discussed and possible solutions are proposed.

Full‐Scale Large Eddy Simulation of a 185 t Ladle Optimizing a Hybrid Eulerian Grid and a Discrete Bubble Mapping Approach

“…However, the governing mechanisms of coagulation and breakup are not fully understood and still require additional research, especially in liquid metals. [ 30 ] Thus, these phenomena are not considered in the presented model as the uncertain of such empiric submodels are considered too high at this stage.…”

Resolving Gas Bubbles Ascending in Liquid Metal from Low-SNR Neutron Radiography Images

“…Single-bubble flow with and without applied MF has been systematically studied using ultrasound Doppler velocimetry (UDV) [9][10][11][12], ultrasound transit time techniques [13,14], X-ray imaging [14] and numerical simulations [15][16][17][18][19][20][21][22]. The most important features and physical mechanisms involved in single-bubble flow are presently rather well known [22][23][24][25][26][27], but many aspects of bubble collective dynamics, especially in the presence of MF, are not fully understood or have not been studied in-depth [28][29][30][31]. Clearly, this is a problem from the process engineering and optimization perspective, and also from the point of view of computational fluid dynamics (CFD) where it is of interest to improve effective models for bubble flow (Euler-Euler and Lagrangian) [2,[32][33][34][35].…”

Flow Structure and Deformation of Two Bubbles Rising Side by Side in a Quiescent Liquid

“…Bubbly flows are widely observed in many industrial types of equipment, such as in chemical reactors and blast furnaces because of gas injection for mass transfer enhancement [1]. Bubble-driven liquid flow structures depend on the void fraction and bubble size distribution [2].…”

“…We focus on the mechanism of repulsion without kissing and weak repulsion for two bubbles rising side by side. (1) We experimentally investigated the interaction between two bubbles rising side by side near the unstable critical curve of a single bubble. We confirmed nonkissing repulsion organized by the Galilei number (Ga = ρg 1/2 d 3/2 /µ)-Bond number (Bo = ρgd 2 /σ) map.…”