Multi-Scale methodology of breakup and atomization for liquid jets in crossflow

Abstract

Liquid jets in crossflow represent a highly complex phenomenon, characterized by intricate interactions across multiple temporal and spatial scales spanning orders of magnitude. To better understand the atomization mechanisms and characteristics of liquid jets in crossflow, a hybrid multi-scale methodology, integrating volume of fluid and discrete phase models with an enhanced coupling algorithm based on Large Eddy Simulation, has been developed and implemented as a multiphase solver in OpenFOAM. This methodology enables the comprehensive reproduction of the atomization process, including primary breakup and secondary atomization, obviating the requirement for complex tunable atomization models. For further reducing computational costs, a parallel acceleration technology is proposed by integrating the adaptive mesh refinement with dynamic load balancing into the solver. The multi-scale methodology is validated against experimental data regarding the trajectory of the liquid jet, as well as the distribution of droplet sizes and velocities. The validated methodology is then used to predict the behavior of Jet-A in crossflow. Simulation results demonstrate that, under the multi-mode breakup regime, large droplets are formed through the deformation of ligaments, small droplets are stripped from threads, and even smaller droplets are generated after secondary breakup. In contrast, in the shear breakup mode, large droplets are directly squeezed from the sides of the liquid column, while smaller droplets are stripped from ligaments and threads. Additionally, compared to the multi-mode breakup, droplet diameters are smaller in the downstream field for the shear breakup mode.