Studies of interface deformations in single- and multi-layered liquid baths due to an impinging gas jet
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INTRODUCTION
AN impinging gas jet on molten metal baths is commonly encountered in such processes as basic oxygen furnace (BOF) and electric arc furnaces (EAF). A protective slag layer is usually found over the molten metal bath in such cases. Knowledge of interface shapes and local fluid flow fields in the impinging region is important for characterizing the interaction of the metal bath with the surroundings. Most published articles to date have focused on the impinging gas jet on a single liquid bath, while in practice, two liquid layers are encountered. For example, Matthieu,[1] Maatsch,[2] and Banks and Chandrasekhara[3] performed experiments with impinging air jet on a single liquid bath of water, and Cheslak et al.[4] conducted measurements of liquid surface deformation using two separate experimental models, viz. an axisymmetric impinging air jet on water and again on fast setting cement. The latter approach preserved the interface shape so that approximate measurement of the interface shape could be made. Wakelin[5] examined the interactions between gas jets and the surfaces of liquids, including molten metals. The experimental investigation again involved an air jet impinging on a single liquid bath. The focus of the study was on the effect of the jet characteristics on the size and shape of the depression formed in the liquid, bath circulation, mass transfer rate, and conditions at which splashing occurs. In addition, characterization of the flow field induced by the jet in the liquid bath was also made. Photographic studies showed that the liquid at the interface moved rapidly toward the vessel wall, and the return flow caused the formation of a toroidal vortex. Although Wakelin’s study yielded important insights into the impinging jet problem, his study was limited to a single-layer liquid bath. In the BOF or EAF process, a gas jet (oxygen) entrains and reacts with the surrounding gas and molten liquids (slag or metal) and exchanges mass momentum and heat with F. QIAN, Graduate Student, Mechanical Engineering Department, R. MUTHARASAN, Professor, Chemical Engineering Department, and B. FAROUK, Professor, Mechanical Engineering Department, are with Drexel University, Philadelphia, PA 19104. Manuscript submitted January 9, 1995. METALLURGICAL AND MATERIALS TRANSACTIONS B
them. The temperature, density, and compositions of the jet also vary along its path. Sharma et al.[6] studied the jet penetration and bath circulation in a 200-lb BOF. They found that the depth of jet penetration was solely governed by the mechanical forces of the oxygen jet. The bath circulation was also mainly driven by the oxygen jet force. Careful study of the literature indicates that influence of the top slag layer properties on the local transport phenomena has not been investigated for these types of processing situations. The present study is considered to be a first step in systematically investigating the effects of the upper layer liquid properties on the interface shape and flow behavior in a two-layer liquid bath dri
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