Multiple impinging jet air-assisted atomization

The growth of the aviation sector triggered the search for alternative fuels and continued improvements in the combustion process. This study addresses the technological challenges associated with spray systems and the concern of mixing biofuels with fossil fuels to produce alternative and more ecological fuels for aviation. This work proposes a new injector design based on sprays produced from the simultaneous impact of multiple jets, using an additional jet of air to assist the atomization process. The results evidence the ability to control the average droplet size through the air mass flow rate. Depending on the air mass flow rate there is a transition between atomization by a hydrodynamic breakup of the liquid sheet formed on the impact point, to an aerodynamic breakup mechanism, as found in the atomization of inclined jets under cross-flow conditions. The aerodynamic shear breakup deteriorates the atomization performance, but within the same order of magnitude of the atomization efficiency. Finally, despite using different configurations (2, 3 and 4-impinging jets), the outcome is similar is terms of the sizes of drops produced, although increasing the number of impinging jets also implies some deterioration of the atomization efficiency.