Heat and mass transfer during evaporation-combustion of nonisothermal droplet

For the evaporation-combustion process of a single droplet of hydrocarbon fuel in a thermal surroundings without gravity and forced flow, an evaporation model of nonisothermal droplet coupled with the flame sheet model of combustion was developed. The transient interaction among the heat conduction inside droplet, the evaporation from droplet surface, the chemical reaction at flame sheet and the convective heat and mass transfer in gas phase has been taken into account. The coupled system was divided into three calculating zones, which are the droplet, the gas phase within flame sheet and the gas phase beyond flame sheet, and they are relatively independent. By employing the method of fixed calculating zone and the following coordinates combined with the coupled interface conditions, the numerical simulation was conducted. The heat and mass heat transfer as well as the effects of ambient pressure were analyzed. The results show the intensive coupling of droplet evaporation with combustion. The evaporation and the dynamic characteristics of flame sheet in the terminal stage are both quite different from those in the earlier stage.