Modelo teórico para combustão de gotas com formação de fuligem e transferência de calor por radiação

Abstract

Due to the high consumption of fossil fuels, around 90% of world consumption, it is necessary to use fuels in different applications, from domestic consumption to aerospace applications. In this sense it becomes necessary the knowledge of the physical processes resulting from the combustion to estimate levels of pollution or even its control. The present work presents a theoretical model of diffusive flame in the surroundings of a spherical drop of fuel. The model is an exten- sion of the Shvab-Zel’dovich formulation with the inclusion of heat loss by radiation and loss of heat due to the formation of soot. The methodology used to solve the problem consists of a simplified formulation of infinitely narrow flame, where the physical problem is represented by the conservation equations and their due contour conditions in the laminar regime. The great difficulty in modeling the combustion process is due to the chemical reaction term present in conservation equations that is strongly nonlinear. Following the Shvab-Zel’dovich procedure, combinations of conservation equations are used to eliminate the dependence of the chemical reaction term from the equations by reducing the problem to a system of ordinary differential equations. This system of equations is explicitly integrated by the method known as "Shootingt Method". The results show that it is possible to obtain a simple formulation that models the combustion in the presence of soot formation and heat loss by radiation. The present model also allows to describe the processes already known experimentally, as the reduction of the rate of vaporization and change of the position of the flame in relation to the surface of the fuel with the increase of the formation of soot.