1999 Volume 85 Issue 6 Pages 432-438
Two bubbling jets generated from two nozzles placed a short distance off on the same horizontal plane pulled each other and merged into a larger scale bubbling jet. This phenomenon is caused through the Coanda effect. The bubble and liquid flow characteristics above the merging position were measured with an electroresistivity probe and a laser Doppler velocimeter, respectively. The results were compared to those for a bubbling jet of the same total gas flow rate generated from a single nozzle. Gas holdup, mean bubble rising velocity, the axial mean velocity and the root-mean-square values of three turbulence components of water flow for the merged bubbling jet agreed with their respective values for the bubbling jet generated from the single nozzle. On the other hand, bubble frequency and mean bubble chord length for the two nozzle injection differed from those for the single nozzle injection. This fact means that when the distance from the nozzle tip to the bath surface is much larger than the distance from the nozzle tip to the merging position, mixing in the bath is not expected to be enhanced by the two nozzle injection, whereas metallurgical reactions between bubbles and liquid can be enhanced because the interfacial area increases.