The spout of air jets upwardly injected into a water bath

The spout region of gas jets in liquids has received little attention, although it has both theoretical and practical significance. In this study, the spout of upwardly injected gas jets in water was characterized experimentally in terms of gas fraction, bubble frequency, and axial velocity distributions for ultimate incorporation into turbulent recirculating flow models. The measurements were made with a two-element electroresistivity probe coupled to a microcomputer. For the turbulent flow conditions prevailing in the jet plume and spout, special hardware and software were developed to analyze the signals generated by contact of the bubbles with the sensor in real time. Correlations of the gas fraction with axial and radial position for different gas flow rates have been established from the measurements. The dimensions of the spout were obtained from time-exposure photographs; when compared with the gas-fraction measurements, the spout boundary always corresponded to values ranging from 0.82 to 0.86. The radial profiles of bubble frequency at different levels in the spout exhibit a bell shape; the bubble frequency decreases with increasing height. The velocity of the bubbles in the spout drops linearly with increasing axial position. Formerly Graduate Student. Formerly Postdoctoral Fellow, The Centre for Metallurgical Process Engineering.