Investigation in the bag breakup of water droplet in airflow with different temperatures and densities

This paper tries to clarify the respective significance of thermal effects and airflow density on the influence of bag breakup of water droplets in hot airflow. The bag breakup processes of water droplets in the airflow temperature range of 293 K ( ρ g = 1.205 kg / m 3 ) to 493 K ( ρ g = 0.716 kg / m 3 ) were investigated. Meanwhile, room-temperature gas mixtures with corresponding densities were prepared using room-temperature helium blended with room-temperature air to explore the bag breakup processes of water droplets. The results show that although the critical conventional Weber number ( W e con ) of spherical droplets for bag breakup varies significantly in both streams, the critical initiation Weber number ( W e ini ) of disk-shaped droplets for bag breakup remains almost consistent. Different deformation processes from W e con to W e ini result in different W e con . In the gas mixtures with room temperature, the critical W e con for bag breakup increases from 9.47 to 12.12 as the stream density decreases from 1.205 to 0.716 kg / m 3 . However, the critical W e con for bag breakup decreases from 9.47 to 7.80 in the hot airflow at identical airflow density variations.