Spray characterization of a planar airblast prefilmer under oscillating airflow conditions

To face the problem of harmful emissions in jet engine applications, the LPP combustor concept gained more importance during the last years. Them, being more prone to thermoacoustic instabilities, the need to predict them has become of primary importance. The purpose of this work is to provide support in the understanding of these phenomena, in particular experimental data regarding the influence of air instabilities on the produced spray. These experimental data can be used to develop and train machine learning algorithms that will be able to better predict those instabilities. Outcomes concerning the spray properties such as Sauter Mean Diameter, mean diameter, distributions, droplet velocities, volume flow, mass flux and number of droplets are shown. A characterization of the spray is performed for a steady airflow. In this context, a spray characterization in the planes parallel and perpendicular to the spray axis of simmetry is done. In addition, the influence of an increasing pressure drop across the nozzle and of an increasing airflow temperature are investigated. A characterization of the spray subjected to an unsteady forcing airflow is finally observed. The forcing air excitation frequencies are 93.5 Hz, 120.2 Hz and 146.9 Hz resulting in a wide range of air velocity amplitude (from 5 m/s to 20 m/s). A comparison between the spray properties resulting from these three different frequencies is presented.