ID 108

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

 

Abstract:

In a recent experimental study of Gepperth et al. (2012) of prefilming airblast atomizers, the accumulation of liquid at the trailing edge was observed and identified to be the reason for the decoupling between the liquid film flow on the prefilmer and the disintegration of the liquid at the trailing edge. This hypothesis has been supported by a numerical study by Braun et al. (2015) who investigated the influence of trailing edge thickness on the breakup frequency and the length of the attached ligament. Nevertheless, recent numerical simulations revealed different wetting modes of the trailing edge: fully and partially wetted, which seem to influence the kind of breakup the elongated ligaments undergo. Hence, in this work detailed Smoothed Particle Hydrodynamics (SPH) simulations of Gepperth's prefilmer geometry will be used to analyze and characterize the wetting behavior of the liquid on the trailing edge. The liquid mass flow will be varied in order to assess the influence on liquid accumulation, breakup process and resulting spray characteristics. Emphasis will be put on the ligament length and the ligament breakup frequencies as introduced by Gepperth as well as by Braun and on drop size and drop position. Using this approach, new insights into the spatial distribution of the drops in close vicinity to the trailing edge will be presented.