Bubble formation from a gas jet in a liquid cross flow inside the mixing conduit of an effervescent atomizer is studied using flow visualization. Air injection rates were varied from 0.99 × 10−5 to 4.94 × 10−5 kg/s, while maintaining a constant liquid cross-flow rate of 0.298 kg/s. Though gas–liquid ratio (GLR) and flow velocities dominate bubble formation, intermittent choking at the exit nozzle is shown to have a morphological impact on the bubbly flow. This impact is visible as a pressure wave that propagates upstream from the nozzle exit. This pulse is found to have a strong influence on bubble formation at the gas injection location leading to bubble distortion and breakup. In most cases, a liquid jet is observed to propagate through the centreline of larger bubbles as the pressure pulse passes.
Graphical Abstract