High-Fidelity Multi-Scale Simulation of Swirled Air-blast Atomization with Comparison against Experiments

Abstract: In liquid-fueled combustion systems, optimization of the fuel atomization process is critical to reducing fuel consumption and lowering pollutant emissions. Accurate and efficient computational modeling of liquid atomization can open the door to spray optimization, however it presents a significant challenge to modelers due to the extremely complex flow field and wide range of length and time scales involved. In this work, a multi-scale and multi-domain simulation strategy is used to model end-to-end the turbulent spray produced by a swirled two-fluid coaxial atomizer, a device that utilize a high-speed swirled gas stream to destabilize a co-flowing low-speed liquid, widely used in systems such as fuel injectors. Our computational method relies on sub-grid scale modeling; in particular, we will introduce a thin structure break-up model to account for topology changes, converting thin liquid structures into spherical Lagrangian particles. With such simulations, the impact of swirl on the break-up process can be analyzed by varying the swirl ratio, and we aim to quantitatively validate our simulations against experiments at identical operating conditions, including drop size statistics.