Combustão de gotas com escape de combustível pela chama para simular regime de combustão “Cool Flame”

Abstract

Recently a new regime of burning drops regime "cool flame” has been under investigation by presenting different characteristics of conventional burning. In the cool flame regime, combustion occurs in two distinct phases. At first, the droplet undergoes a normal burning with a visible flame around the same. Second, the luminous radiation from the flame is extinguished, however, the drop remains no visible flame and vaporized at a lower temperature. Furthermore, the droplet has a vaporization rate substantially equal to the first phase. At the end of the second phase, a vapor cloud is formed around the droplet. Numerical simulations of chemical kinetics attribute this cloud as a result of unburned fuel the flame. With the idea of unburned fuel, this model is designed to use a classic model of burning drops and impose a fuel exhaust the flame, a process that is one of the effects identified as responsible for keeping the flame in the cool flame regime. The classic model is based on the hypothesis closely thin flame where all fuel and oxidant are consumed in the same, so the model Shvab- Zeldovich can be used without the need to involve the chemical kinetics to the model. The results show that with increasing fuel leakage decreases the flame temperature and the flame approaches the drop. However, the vaporization rate is not as sensitive to increased fuel exhaust remaining practically constant. These behaviors are consistent with experimental analyzes observed in the cool flame regime. Whereas an exhaust highest fuel, it is possible to find the flame measuring a distance five times the droplet radius coinciding with the results obtained by chemical kinetics models. However, despite these data agree with those obtained experimentally, the model is limited because the fuel exhaust is imposed by the model parametrically serving to estimate the behavior of the properties due to fuel leak in the flame.