Primary Atomization in an Airblast Gas Turbine Atomizer

Abstract

This study focuses on the spray atomization, transport and impact on a solid substrate under cross-flow conditions, as used in airblast atomizers with prefilmers for aero engines and gas turbines. The phenomena are observed using a high-speed video system and the spray is characterized using the phase Doppler technique. The governing mechanisms of drop formation, wall collision and aerodynamic breakup are identified. It is shown that three different mechanisms are mainly responsible for the formation of single drops from the bulk liquid. These are: primary atomization, breakup of the liquid wall film and further aerodynamic breakup of droplets. Finally, an atomization model is developed, which accounts for primary atomization, wall film formation and aerodynamic breakup. The model predicts the distribution of the drop diameters and velocities in the generated spray. The agreement between the model predictions and the experimental data is very good.