On the prediction of the flame spread rate over polymer fuel surface. Effect of the gas-phase reaction kinetics

A numerical study of the two-dimensional flame spread over horizontal surface of PMMA has been performed by coupled statement describing the feedback interaction of heat and mass transfer between the gas-phase and solid fuel. The primary assumptions engaged into consideration are laminar flow and negligible radiation which both are derived from the small-scale flame occurred. The steady-state regime has been accomplished resulting in the steady flame spread rate is stated as a principal parameter which evaluates the process behavior. The one-step macroscopic reactions are employed both for gas-phase combustion and solid fuel pyrolysis. The main purpose of present study relates to the investigation of the effect of kinetic parameters (namely, pre-exponential factor and activation energy) on the flame spread rate. The basic values of combustion kinetics correspond to the low-molecular gases such the carbon monoxide or methane. Pre-exponential factor and activation energy have been varied till the limits of flame spread: flame extinguishing under lower pre-exponential factor and higher activation energy and overheating (appears as a numerical divergence) higher pre-exponential factor and lower activation energy. Through the parametric investigation a range of kinetic parameters for one-step macroscopic combustion reaction has been determined that providing proper agreement with experimental data for flame spread rate.