Numerical simulations of outdoor wind effects on smoke spreading along a corridor: Physical and sensitivity analysis

In this study, the effects of outdoor wind on smoke movements along a corridor were investigated using a CFD code: Fire Dynamics Simulator (FDS). Firstly, a comparison between experimental and numerical results was carried out by varying outdoor wind velocity from 0 to 12.12 m/s, and good agreement was found between the two. Secondly, from the numerical data, it was found that smoke stratification state in the corridor depends on Froude number (Fr) and it can be divided into three cases: stable buoyant stratification (Fr < 0.38), unstable buoyant stratification (0.38 <= Fr < 0.76) and failed stratification (Fr >= 0.76). When Fr >= 0.76, smoke stratification is completely disturbed and smoke occupies the entire volume of the compartment, highlighting a risk of toxicity to people. In addition, it was observed that the velocity of the outdoor wind could influence the concentration of O-2, CO2, CO and visibility in the corridor and smoke exhaust. In view of the large amount of input data used for the numerical simulation, a global sensitivity analysis was conducted on parameters related to the material, fuel and combustion model. The analysis demonstrated that the main parameters affecting the smoke temperature near the ceiling are the mass flux of fuel and the activation energy. An analytical model was proposed to predict the time evolution of the quantity of interest for arbitrary values of mass flux and activation energy.