Plunging jets and three phase flow: Modeling foundry physics in the laboratory

Metal casting, a prominent example of two phase flow, is susceptible to defects from air entrainment. Air entrainment is the capturing of air by a plunging jet, pulling it under the surface where it can be trapped. However, for some alloys, contact between the molten metal and even trace amounts of gaseous oxygen rapidly forms a solid oxide film at the interface, which can alter the physics substantially. Such a phenomenon warrants closer investigation, yet is difficult to model under conditions amenable to room temperature optical measurement methods commonly used in fluid dynamic analysis. We have found a specific liquid phenolic urethane resin, which when exposed to an amine vapor catalyst, will rapidly form a thin solid film, enabling analog laboratory investigations of a phenomenon previously limited to high-temperature foundry environments. The current work utilizes a disturbed plunging jet flow system to induce air entrainment into this three phase system. Using a high speed camera, we examine interactions between the solid film, gaseous, and liquid phases, revealing new air entrainment and multiphase flow phenomena.