Large eddy simulations of pool fires and backdraft in a compartment using FDS and FireFOAM

Abstract

This study evaluated the performance of two widely used fire simulation codes for predicting heptane pool fires and methane backdrafts occurring within a compartment. The simulation models used were Fire Dynamics Simulator (FDS), which applies a low-Mach-number approximation, and FireFOAM, which performs a compressible flow analysis. Turbulence analysis was conducted using the large eddy simulation (LES) technique. The eddy dissipation model (EDM) was applied to pool fire simulations, and the eddy dissipation concept (EDC) model, which considers a two-step chemical reaction, was applied to backdraft simulations. Both simulation codes reasonably predicted the temperature and key chemical species, such as O₂ and CO₂ concentrations, for the heptane pool fire, with FDS predicting slightly higher temperatures than FireFOAM. For methane backdrafts, both models performed similarly during the gravity current phase; however, significant differences were observed in backdraft onset and propagation. FireFOAM closely matched the experimental pressure data, whereas FDS overestimated the pressure and predicted an earlier peak. FireFOAM also simulates flame distribution and fireball formation more reasonably. FDS, which uses a low-Mach-number approximation, is computationally efficient but less accurate for backdrafts, where pressure changes are crucial.