Numerical Study On Droplet Breakup Regimes Of Secondary Atomization

The secondary atomization is very useful in increasing evaporation and mixing rates in a variety of engineering applications. Such as spays in vehicle engines and in fire-extinguishing system. During secondary atomization, a single droplet breakups into several or even more small droplets, which increases the total contact area with ambient. Thus it is important for understanding the characteristic of the breakup process.A numerical simulation on this phenomenon is studied here. The SIMPLE scheme and coupled VOF and Level-Set method are used. The adaptive mesh strategy is taken to balance the calculated accuracy and computational expanses. The main work of this simulation is given below:Firstly, we classify the breakup process into four regimes so as to the experiment results. Then a detailed study is made to find out the mechanism of these breakup regimes by simulating under different We number and Oh number.The division of four typical breakup regimes are observed when Oh < 0.1. The flow velocity inside the droplet is several order of magnitude less than that outside, but more important than it. During the deformation of breakup processes, the mass flows from center to the surface of droplet in all regimes at first. However, in some regimes, vortex appears after initial deformation in the flow which leads to the difference between regimes.