High-fidelity simulation of angled liquid jet breakup in supersonic crossflow

The liquid break-up in supersonic crossflow is primarily encountered in scramjet engines. An angled liquid jet injector can be considered an effective way to enhance liquid breakup and atomization, which is particularly convenient to implement and requires no additional work. The process of liquid fuel breakup, atomization and mixing of fuel involves multiple complex phenomena that are closely interconnected. This study aims to provide a comprehensive analysis of the processes of ligament and droplet breakup and atomization in an angled jet in supersonic crossflow using the homogeneous mixture model and large eddy simulation. Without assuming an ad hoc initial droplet distribution from the injector, the entire breakup process from the primary liquid column breakup to the secondary breakup is thoroughly investigated throughout the entire flow field. The complex structures, such as shockwaves, horseshoe vortex, counter-rotating vortex pair and liquid column surface instabilities such as KH and RT unstable waves, around the liquid column are observed. Key physical and engineering information, such as surface wavelength, breakup length, spray spread angle, droplet size distribution, and pressure loss, is characterized for different injection angles, including acute, perpendicular, and obtuse angles relative to the crossflow. After comparing the numerical results with experimental data, a formula for the angled liquid jet is proposed. The spray distribution in the shape of a $\Omega$ is confirmed through secondary breakup, and Sauter mean diameter distribution at specific locations is compared. Additionally, the droplet distribution is analyzed using both a histogram and a Rossin-Rammler distribution.