Combustion and Flame, Vol.213, 441-454, 2020
Numerical simulation of small pool fires incorporating liquid fuel motion
For small-scale pool fires, Vali et al.  showed a pair of vortices in the liquid pool. The first vortex appeared just close to the sidewall of the container, and the second one emerged slightly away from the first vortex. Large-eddy simulations of small methanol pool fires coupled with liquid fuel convective flow were conducted using an in-house version of FireFOAM to investigate the above phenomenon. In this study, a three-dimensional liquid phase model is newly developed. The model incorporates the effects of thermocapillary Marangoni convection, buoyancy, shear stress, and evaporation. For the gas phase, the combustion model is the extended eddy dissipation concept model coupled with the laminar combustion model. This combustion model uses the viscous diffusion rate to consider laminar-turbulent transition. The predictions were in reasonably good agreement with the measured local mass burning rate, flame height and distributions of liquid temperature. The error of the mass burning rate was within 4%. The present predictions captured a pair of vortices in line with Vali et al.'s experiment . Their sizes increased with increasing the liquid temperature. The Reynolds analogy could explain the sensible reason behind this trend. Shear stress and thermocapillary force caused convection in the liquid pool, and this convection formed a pair of vortices. Thermocapillary force was due to the different distributions of convective and radiative heat transfer. Sensitivity test for sub-models for the liquid phase demonstrated that their effects on the mass burning rate were all less than 5.1%. Conversely, the simulation assuming zero gravity only in the liquid phase resulted in almost 64% reduction in the mass burning rate. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.