An experimental study on the influence of airflow temperature on the different silicone oil droplet breakup regimes

In industrial environments, droplet deformation and breakup in hot airflow are universal. The effect of airflow temperature (293–473 K) on the breakup of silicone oil droplets in continuous airflow was studied. The breakup morphology, deformation stage, and breakup regime map are discussed in detail by varying the airflow temperature and Weber number in this paper. The results show that the breakup regimes of silicone oil droplets are consistent with water droplets in the Weber number (5 < We < 30) considered in this paper. However, airflow temperature has an obvious effect on droplet breakup modes. The number of nodes generated at the toroidal rim of the silicone droplet is verified to be the same as that of the water droplet, following “the combined Rayleigh–Taylor /aerodynamic drag” mechanism. The rising airflow temperature will increase the droplet cross-stream diameter. The maximum cross-stream diameter relationship for droplet breakup at different temperature airflows is proposed. The liquid bag growth time can accurately describe the droplet breakup characteristics in a hot airflow environment. The correlation equation for the time characteristics is proposed. In addition, the droplet breakup angle is used to describe the space range of droplet breakup. Eventually, special attention is paid to sub-droplets. The airflow temperature has a considerable effect on the sub-droplets. The average number of sub-droplets and the average surface area ratio before and after breakup increased as the airflow temperature increased. However, the number of sub-droplets and surface area increase slowly after the airflow temperature increases to a certain level.