Influence of the simplifications applied to the surrounding gas composition of evaporating droplets in air-blown and oxy-fuel combustion atmospheres

Abstract

Droplets evaporating in a combustion environment usually face a strong variation of the surrounding gas composition during their respective lifetimes. Studies have been demonstrated that different approaches applied to represent the surrounding gas composition do interfere with the prediction of evaporation rates, mixture properties, and, consequently, flame characteristics as the propagation speed. Effects of gas phase modeling may change when the atmosphere is less diluted with inert (or less reactive) species as in oxy-fuel combustion atmospheres, where the oxidant is depleted in nitrogen. Considering air-blown and oxy-fuel combustion atmospheres, this work proposes consistent modeling simplifications to be applied to droplet evaporation computations. To accomplish this task, numerical simulations of flames propagating in droplet mists of water are conducted in a one-dimensional framework considering a detailed description of the chemistry. Analysis evolves gradually in a systematic fashion, considering the full description of the chemistry in properties description up to the most simplified approaches. It is found that the flame speeds vary by 10% for the different approximations. Results summarize effects of the different applied simplifications and indicate their impact in simulations of combustion processes.