Structure and Extinction of Laminar Ethanol/Air Spray Flames

Abstract

AbstractThe paper presents the structure and extinction of both mono‐ and bidisperse ethanol/air spray flames in the counterflow configuration. A similarity transformation for monodisperse spray flames is extended to polydisperse spray flames, and the resulting one‐dimensional formulation accesses the use of detailed chemical reaction mechanisms as well as detailed transport. For the ethanol/air system, 38 species and 331 elementary reactions are used. At high strain, the droplets cross the gas stagnation plane, reverse and return towards their injector. For this situation, the width of the chemical reaction zone of bidisperse and monodisperse sprays with the Sauter mean radius is almost the same. However, the droplet oscillation causes the spray flame of the bidisperse spray to strongly increase the total spray flame thickness. For the injection velocity of the spray studied here, the droplets returning to their injector hit the boundary of the computational domain as strain is increased whereas the monodisperse spray flame extinguishs at a considerably higher value of gas strain rate. Thus, the extinction behavior of the bidisperse spray flame is not represented by the monodisperse spray flame with the Sauter mean radius. The model is also suitable to predict pollutant formation.