Evaporation of bi-component droplets in a highly turbulent channel flow

Abstract

To better understand the phenomena that occur in a jet engine combustion chamber where multi-component fuel droplets are injected, the influence of the fuel composition upon the liquid droplets’ behavior in a turbulent air flow is investigated experimentally. In particular, the effect of the presence of an alcohol in the fuel is explored. A model experiment has been designed purposely, which enables to create in a canal a heated, highly turbulent air flow with good properties of homogeneous and isotropic turbulence, and yet with high levels of turbulent fluctuations. A spray of poly-dispersed bi-component acetone/ethanol fuel droplets is injected coaxially in the established zone of the air flow. The large range of droplet sizes ensures that they have a wide variety of behaviors with regard to turbulence. An optical access allows the observation of the turbulent two-phase flow and its evolution in the channel. Measurement campaigns are conducted using Planar Laser-Induced Fluorescence to characterize the droplets’ evaporation regimes. Instantaneous acetone vapor concentrations are extracted from these measurements and it is found that acetone evaporates faster from bi-component droplets as compared with pure acetone droplets.