New Insights in the Primary Breakup Process of Prefilming Airblast Atomizers by SPH Predictions

Smoothed Particles Hydrodynamics (SPH) simulations of the primary breakup process have been conducted using a planar prefilming airblast atomizer geometry that has been investigated experimentally. Despite the fact that a 2D study is conducted, most of the breakup phenomena are captured by the simulations. A variation of the liquid mass flow effects the simulated air flow and spray in the same way as indicated by experimental results. Using this numerical approach new insights in the primary breakup process are obtained, which can be received only
difficultly in experiments. The presence of liquid at the trailing edge of the prefilmer is quantified from a side view perspective. In addition, the influence of a variation of the liquid mass flow on the liquid film and the presence of liquid at the trailing edge are characterized. Furthermore, three different wetting modes of the trailing edge are observed: The non-wetting mode which is characterized by one film wave per breakup event as well as the unstable and stable accumulation modes which are related to two film waves per breakup event. Finally, it is demonstrated
that the liquid film waves and the breakup of the ligaments are slightly decoupled by the accumulation of liquid at the trailing edge.