An Experimental Investigation of an Effect of Swirl Flow Field and the Aerodynamic Force on the Droplet Breakup Morphology

The interaction of an ethanol drop with a swirl flow is studied experimentally by shadowgraphy technique. In a swirling airflow, the drop has opposed, cross, and co-flow situations based on its detaching position, swirl strength, and aerodynamic force resulting in a different droplet morphology. As the droplet interacts with a differential flow field produced by the wake of the vane in swirling airflow, we observe a new breakup dynamics known as “retracting bag breakup.” For different dimensionless variables affecting the droplet morphology and its trajectories, a regime map is presented, outlining the multiple modes, such as no droplet breakup, vibrational only, retracting bag, and bag breakup modes. The breakup time for different locations and Weber number is demonstrated. The breakup time is significantly less when the drop experiences two flow configurations simultaneously.