A numerical study of the effect of turbulence on mass transfer from a single fuel droplet evaporating in a hot convective flow

Abstract

A three-dimensional numerical model is developed to investigate the effect of turbulence on mass transfer from a single droplet exposed to a freestream of air. The freestream temperature, turbulence intensity and Reynolds number are varied to provide a wide range of test conditions, whereas the ambient pressure is kept atmospheric. The turbulence terms in the conservation equations of the gas-phase are modelled by using the shear-stress transport (SST) model. A Cartesian grid based blocked-off technique is used in conjunction with the finite-volume method to solve numerically the governing equations of the gas and liquid-phases. This study showed that the vaporization Damköhler number proposed in the literature to correlate the effect of turbulence on the droplet's vaporization rate is invalid at air temperatures higher than room temperature. Additionally, an attempt is made to correlate the effect of the freestream turbulence on the droplet's mass transfer rate by using Sherwood number over a wide range of freestream temperatures.