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Abstract

The behaviour of a gas jet injected into a liquid has been studied as a function of gas and liquid densities, gas flow rate, tuyere diameter and tuyere design. A novel technique has been developed to study the interaction of a submerged gas jet into injected opaque liquids. The jet is blown through a "half-tuyere" fastened to the plexiglas side wall of the liquid-containing vessel. In this way the jet can be viewed and photographed with a high speed camera. Also pressure measurements have been made at various points along the tuyere using a fast-response pressure transducer. This method was employed to study air, helium and argon injected into mercury, zinc chloride solution and water, as a function of gas rate. The results of pressure and cinematography show that two limiting types of behaviour can be identified: jet pulsations at low gas flow rates and steady jetting at high gas rates. For a high-density liquid the transition occurs at the point where, with increasing back pressure, the jet becomes underexpanded. Industrial experiments performed in a nickel converter confirmed that these two types of regimes are also found when blowing into a high-temperature melt. From the results obtained, a modified operating practice for matte converting has been suggested, in order to improve substantially tuyere and refractory life.