The effects of different turbulence models on the fire plume characteristics of train fires in tunnels

Abstract To investigate the effects of different turbulence models on the fire plume characteristics of train fires in tunnels, we employed five turbulence models: (1) one single-equation model: Spalart–Allmaras (S–A); and (2) four two-equation models: k−ε, k−ω, improved delayed detached eddy simulation (IDDES) based on SST k−ω and large eddy simulation (LES). These models were adopted for the numerical simulation of train fire plumes in tunnels, and their outcomes were compared with those of experiments conducted on a reduced-scale train fire model in a laboratory setting. These findings highlight the substantial impact of turbulence model selection on the simulation of fire plumes resulting from train fires in tunnels. When a train fire occurs within a tunnel, it is observed that the longitudinal distributions of temperature, pressure, velocity and soot density on the tunnel ceiling exhibit asymmetry. Among the selected turbulence models, the LES model consistently provided predictions that closely aligned with the experimental data for both fire plume morphologies and tunnel ceiling temperatures. The findings will help address the current gap in turbulence model applicability studies in fire simulations and offer important references for high-precision fire dynamics simulations.