1986 Volume 72 Issue 3 Pages 426-433
Studies have been made on physical interactions between injected gas and liquid exclusively in the initial jet formation zone. Helium or nitrogen gas was injected into the water bath through an orifice of 0.2-0.4cm in diameter located at the bottom. The jet behavior was observed directly by using a high speed cinecamera. Pressure at the orifice exit was measured by a pressure transducer.
The bubbling-jetting transition was found to occur, irrespective of the densities of gas and liquid, when the linear velocity of gas reached the sonic velocity at the orifice exit. The transition occurred more abruptly with increasing the density ratio of gas to liquid. The bubbling behavior was characterized quantitatively by analyzing linkage and severance of gas jets. Densities of gas and liquid were found to have a large effect on the bubbling behavior. On the basis of the observation of the jet expansion at the orifice exit and continuity of bubbles, apparently different views on gas jet characteristics advanced by previous investigators could be reconciled. It was confirmed that the submerged gas jet attaining a sonic flow at the orifice exit forms a supersonic jet inside the liquid phase by the pressure measurements.