Shock-induced bag breakup of droplet

The spatiotemporal dynamics of shock droplet interaction are studied for a range of Weber numbers between 8 and 15. This regime includes bag breakup mode, which is critical in understanding secondary atomization of liquid droplets and designing the optimum length of combustion unit in a Scram-jet engine. The Shockwave of the desired strength is generated in the squared section shock tube. The syringe pump produces a droplet of 1.8 mm diameter, which is exposed to shockwave for secondary atomization. The morphology of the droplet is captured using the shadowgraphy and high-speed camera at 33,000 FPS. The bag regime presents interesting flow features and mainly develops at low Weber numbers. This regime shows high sensitivity toward surface tension compared to other droplet deformation regimes. Flow visualization results in ensuing instability on droplets, their motion and evolution of bag with time will be presented. It has been observed that the critical bag size increases with an increase in Weber number. The relationship between optimal bag length and corresponding Weber number will be discussed.