A computational study has been carried out to investigateudsmoldering ignition and propagation in polyurethane foam. The onedimensional,udtransient, governing equations for smoldering combustionudin a porous fuel are solved accounting for improved solid-phase chemicaludkinetics. A systematic methodology for the determination of solid-phaseudkinetics suitable for numerical models has been developed and applied toudthe simulation of smoldering combustion. This methodology consists inudthe correlation of a mathematical representation of a reaction mechanismudwith data from previous thermogravimetric experiments. Geneticalgorithmudand trail-and-error techniques are used as the optimizationudprocedures. The corresponding kinetic parameters for two differentudmechanisms of polyurethane foam smoldering kinetics are quantified: audpreviously proposed 3-step mechanism and a new 5-step mechanism. These kinetic mechanisms are used to model one-dimensionalsmoldering combustion, numerically solving for the solid-phase and gasphaseudconservation equations in microgravity with a forced flow ofudoxidizer gas. The results from previously conducted microgravityudexperiments with flexible polyurethane foam are used for calibration andudtesting of the model predictive capabilities. Both forward and opposedudsmoldering configurations are examined. The model describes well bothudopposed and forward propagation. Specifically, the model predicts theudreaction-front thermal and species structure, the onset of smolderingudignition, and the propagation rate. The model results reproduce the mostudimportant features of the smolder process and represent a significantudstep forward in smoldering combustion modeling.
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