Interaction between flow topology and interface curvature of heat transfer interfaces during the evaporation process of liquid fuel droplets in a temporally evolving high-temperature gas jet

Spray evaporation is a classical fluid dynamic problem. Although many previous studies have been done, there are still blind spots in the knowledge of the turbulent spray evaporation mechanism. This work aims to reveal the evaporation mechanism of fuel droplets in high-temperature gas jet. First, a high-resolution direct numerical simulation method is used to solve the evaporation process of n-heptane droplets in a high-temperature air jet. Second, the interactions between different flow topology structures in the flow field and the curvature of the heat transfer interface is analyzed to elucidate the mechanism of the influence of flow topology on the evaporation process of n-heptane droplets in a high-temperature air jet. It can be observed that the unstable focus compressing (UFC) topology structure exerts the most significant influence on conditional strain rate of the flow field. Additionally, the curvature of the temperature iso-surfaces is negatively correlated with the conditional strain rate. It can also be found that the increasing of conditional strain rate in turn promotes the generation of sheet and concave structures, thus causes the heat transfer interfaces smoother and temperature scalar dissipation rate higher. Hence, increasing UFC topology structures may help improve evaporation efficiency.