The atomization of liquid droplets through the interaction of aerodynamic forces has been widely exploited in liquid jet atomization, agricultural spraying, combustion engines, energy systems, nuclear fusion processes, and aerospace applications. The dynamics of the droplet-breakup process is classified into two stage: i) initial shock interaction ii) droplet breakup regimes. Stage I presents the initial impact of shock-wave with the droplet and formation of reflected, transmitted, and refracted waves adjacent to the droplet surface. Stage II includes the deformation and breakup of the droplet process. In stage I, the droplet holds in its original shape, where the external shock-induced air-flows influenced the changes in surrounding flow conditions. Two different regimes were observed in breakup phenomena, such as Shear-induced breakup and Rayleigh-Taylor piercing (depending on Kelvin-Helmholtz instability and Rayleigh-Taylor instability). The breakup regimes' transition was interpreted based on the relative magnitude of initial droplet diameter to the wavelength of surfaces waves engendered through Kelvin-Helmholtz instability. The obtained criterion methodically defines the breakup regimes for SIE and RTP breakup regimes for a wide range of We numbers varying from 30 to 15000. For We<1000, both SIE and RTP breakup processes were observed, whereas, for We > 1000, the breakup process is materialized through the shear-induced breakup process. In the present study, droplet deformation and breakup patterns (such as multi-bag, SIE) were investigated using shadowgraph and schlieren visualization techniques. The range of Weber numbers was applicable in the applications mentioned above for convenient atomization of the liquid droplets. This study can also be helpful in the idealized case of complex methodologies involved in manufacturing refining sizes of the metal powder through atomization.
Further details are available at:
S. Sharma, A.P. Singh, S. Rao S, A. Kumar and S. Basu “Shock Induced aerobreakup of a droplet”, Journal of Fluid Mechanics, 2021 (In Press). doi:10.1017/jfm.2021.860