Combustion and Vaporization of Deformable Fuel Droplets Using Direct Numerical Simulation

Abstract

This study focuses on the effects on evaporation and combustion of a single component jet fuel surrogate. Due to an imbalance in the surface tension and aerodynamic forces, the large droplets have a tendency to deform. The effect of the shape change of a droplet on its combustion is studied at a moderate Reynolds number by varying the Weber number. A simplified chemical reaction mechanism for hydrocarbons is used for the combustion of the droplet. Through this study, the effect of different Weber numbers is investigated on the total evaporation rate, further on droplet combustion, and the flame shape. The results of this study show an increase of 2% increase in total evaporation rate (m) for higher Weber number We = 12 as compared to low Weber number (We = 1) case. Though, the increase in m is small, the results show a net positive effect of Weber number on the total evaporation. In terms of combustion, the combustion process stays unaffected by the droplet shape as the mass burning rate is nearly the same for low as well as high Weber number. The potential reasoning could be that the interaction between the flow and geometry of droplet in two dimensions (2-D) is insufficient to explain the physics. Moreover, it is possible that the reaction rate which is faster in nature is dominating over the evaporation rate. Such observations require more detailed work in three dimensions (3-D) for future.