Shivanand Wasan

Upward Flame Spread Simulations by Coupling an Enthalpy-based Pyrolysis Model with CFD

In simulations of developing fires in enclosures, a correct prediction of flame spread is crucial in the prediction of the fire growth rate. The simulation of this phenomenon requires two different kinds of solvers: one that deals with the solid phase, to determine the thermal degradation and volatile release (pyrolysis); a second one that calculates the combustion process in the flame formed by mixing of the volatiles with the ambient air. The processes in the solid and the gas phase require proper modeling. Moreover, an adequate coupling strategy at the interface between the solid and the gas phase is an important point of interest. The paper focuses on a method to successfully combine these two types of calculations. Two types of flame spread (upward and downward) demonstrate the possibilities of this approach. We conclude that the coupling between the two phases works fine, providing a mechanism of simulating flame spread with two different codes. It is found, however, that the prediction of the gas phase requires finer grids or more accurate models than used in this study, to obtain quantitatively better results, particularly in case of upward flame spread.