Pre-investigation on the spray combustion: Numerical simulations of the atomization from the vertically vibrating liquid layer

Performance of spray combustion is strongly dependent on the atomization, which, however, still lacks sufficient physical understandings. Atomization process in various techniques is identical. We firstly concentrate on the atomization in Faraday vibration system, due to its simple configuration, easily-controlled parameter pair and well-controlled droplet size. Two-dimensional numerical calculations based on Coupled Level-set and Volume-of-Fluid (CLSVOF) method were carried out for inviscid liquid layer in Faraday vibration system. The emergence of the local maximum pressure region at the crest root, which results from the non-linear stagnation point flow, is essential for ligament formation. The threshold Weber number for atomization, which is defined to be a process of vigorous drop ejections in this study, is also determined. A novel numerical approach is proposed to facilitate calculations. The calculated threshold Weber number for atomization is 0.923∼O(1), which is consistent with the expected condition that the inertial force is comparable with the capillary force. The parameter area where only Faraday standing wave occurs without breakup is also determined in instability chart.