Non-Spherical Droplet Dispersion in Homogeneous Isotropic Turbulent Flow

Abstract

Motivated by the study of spray combustion in aviation gas turbine engines, this work addresses the dispersion of nonspherical droplets in turbulence. The most popular strategy for modeling spray is using the Lagrangian particle tracking (LPT) method, which represents the spray as consisting of discrete collection of spherical particles. One limitation of this approach is that it neglects the importance of droplet deformation on the dynamics of sprays. Several past works have discussed the importance of non-sphericity in modeling real droplets including works conducted by our research group. Some of our past work has demonstrated the importance of the deformation on droplet vaporization, combustion and drag. However, those works have investigated the effect of deformation on droplets in simple configurations such as isolated droplets in uniform flows. The purpose of this work is to investigate the effect of droplet deformation on spray dynamics in a more practical configuration of droplets in turbulent flows. By utilizing an in-house code developed for multiphase flows, this work uses homogeneous isotropic turbulence (HIT) as the framework to investigate how the trajectories of non-spherical particles differ from spherical ones. The temporal Lagrangian autocorrelation of non-spherical droplet velocity is higher than that of spherical droplet, showing a better dispersion of non-spherical droplet. The mean Stokes number shows the dominance of inertia effect of droplets, and a higher mean Stokes number for non-spherical droplets indicates a weaker droplet clustering or preferential concentration.