Computational Model of Smoldering Combustion in Polyurethane Foam

Abstract

Smoldering phenomenon can be described as a slow, low-temperature, flameless form of combustion, sustained by heterogeneous reactions with oxygen occurring at the surface of a condensed-phase fuel. In this work a computational study on the smoldering ignition and propagation in polyurethane foam is carried out. First, we investigated numerically the heat transfer and the fluid flow in porous media using the generalized lattice Boltzmann method (LBM). Our appropriate code is validated through the study of a thermal injected flow. LBM results are compared to analytical solutions and numerical results obtained using the Finite Difference Method. Second, the numerical model is extended to account for chemical reactions. We introduce the two-dimensional, transient, governing equations for smoldering combustion in a porous fuel. The model describes opposed and forward propagation according to appropriate assumptions. The kinetics model is based on a three-step mechanism. The temperature and char mass fraction profiles are studied at different cross-sections. Obtained results are compared to literature solutions. At the beginning, the important quantity of char is produced near the ignited boundary. To follow the phenomenon, the isotherms are presented at different instants. The results reproduce the features of the smoldering process and represent a significant step forward in smoldering combustion modeling.