Bubble formation process from a novel nozzle design in liquid cross-flow

An experimental study is reported that investigated the bubble formation from a novel nozzle design in a liquid cross-flow using high speed imaging. Different configurations and orientations of the novel nozzle design were considered over a range of gas-to-liquid flow rate ratios (GLR) from 0.00031 to 0.00204. The results show that for all cases, the novel nozzle generated smaller bubbles at higher detachment frequency compared to the standard nozzle. At low liquid velocities, the novel nozzle generated bubbles that were 30% smaller in size at a detachment frequency 2-3 times higher than that for the standard nozzle. It was also found that the bubble diameter and the detachment frequency are almost independent of the liquid velocity. The underlying physical process of bubble formation and detachment in the novel nozzle under liquid cross-flow was also investigated. It was observed that the process comprised of three phases: expansion, collapse and pinch off. It was also found that the rebound force of the bubble from a side-hole under the influence of liquid drag force and hydrostatic pressure plays a key role in the early bubble detachment. The results demonstrated that the novel nozzle design performs better than the standard nozzle in the liquid cross-flow, especially at high GLRs.