Large Eddy Simulation of Turbulent Wall Fires

摘要

Wall-resolved large-eddy simulations (LES) of vertical wall fires and comparisons with experimental data are presented. The modeling tool is a newly developed LES solver - FireFOAM. The convective heat transfer is found to be sensitive to the near wall turbulence model. In this work, the wall-adapting local eddy viscosity (WALE) model is found to be more suitable than the k-equation model for modeling wall fires. Combustion is modeled using the Eddy Dissipation Model (EDM) modified by introducing a diffusion mixing time scale for the near wall laminar region. In order to reduce the uncertainty related to modeling soot formation, the wall flame is treated as optically-thin and a fixed radiant fraction is assumed to calculate the radiation source term. The study is based on a previously developed experimental database. The scope of this investigation is to understand the flame to wall heat transfer, which governs the fire growth rate. The simulations are in good quantitative agreement with experimental data for different fuels.