Injection of bubbly gas flow into a liquid stream has wide application in chemical and biochemical industries. In these applications, generation of smaller bubble at higher frequency is desirable to achieve better reaction efficiency.
We report on an experimental study conducted to investigate the bubble formation in liquid cross-flow using a novel nozzle design developed by Gadallah and Siddiqui . This design is based on the creation of two side holes in the standard nozzle near the main nozzle hole. The experiments were performed in an acrylic square flow channel and high speed imaging was used to capture bubble dynamics. An image processing algorithm was used to quantify the size and frequency of detached bubbles and to track each individual bubble at different gas flow rates and liquid velocities.
The results show that the new design of nozzle generates more bubbles of smaller size compared to the standard nozzle with no side hole at low liquid flow rates. It was observed that while the liquid velocity has crucial affect on the bubble size and detachment frequency from a standard nozzle, these parameters are weakly dependent on the liquid flow rate in the novel nozzle. The results show that at low liquid flow rates or in the stagnant liquid, the novel nozzle generates bubbles that are more than 20% smaller in size and more than two times faster compared to the standard nozzle.