A novel computational model of smoldering combustion capable of predicting both forward andudopposed propagation is developed. This is accomplished by considering the one-dimensional, transient,udgoverning equations for smoldering combustion in a porous fuel accounting for improved chemicaludkinetics. The heterogeneous chemistry is modeled with a 5-step mechanism for polyurethane foam. Theudkinetic parameters for this mechanism were obtained from thermogravimetric data in the literature andudreported by the authors elsewhere. The results from previously conducted microgravity experiments withudflexible polyurethane foam are used for calibration and testing of the numerical results. Both forward andudopposed smoldering configurations are examined. By considering the 5-step mechanism, the numericaludmodel is able to predict qualitatively and quantitatively the smoldering behavior, reproducing the mostudimportant features of the process. Specifically, the model predicts the transient temperature profiles, theudoverall structure of the reaction-front, the onset of smoldering ignition, and the propagation rate. The factudthat it is possible to predict the experimental observations in both opposed and forward propagation withuda single model is a significant improvement in the development of numerical models of smolderingudcombustion. This is particularly relevant in multidimensional simulations where distinction betweenudforward and opposed modes is no longer applicable.
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