CFD simulation of the fire dynamic for a section of a tunnel in the event of a fire

摘要

The objective of this research is to evaluate the in- place emergency ventilation strategies of the L.H.– La Fontaine tunnel.This paper investigates the fire dynamics in one section of the 1.8 km long tunnel. CFD simulations of several fire scenarios were carried out,to gain insight into the effect of several parameters on the fire growth,thermal conditions and species concentrations in the tunnel in the event of fire.A section of the tunnel was simulated to optimize the cost of computations. rnIn the first part of the study,a sensitivity analysis was performed to determine the effect of the computational grid size and length of the investigated section of the tunnel.The results of this analysis were used to determine the appropriate grid distribution and section length for the parametric study.Results from the sensitivity study showed that the grid size influenced both the computing time and the predictions of the temperature and smoke. Moreover the analysis showed that a 300 m long section of the tunnel was appropriate to investigate the ventilation scenarios. rnA parametric study was conducted to investigate the effect of different ventilation configurations on fire- induced flows and thermal conditions in the tunnel section.This study indicated that when the side upper supply vents are open,higher temperatures and CO2 concentrations are observed in the evacuation path.In the roadway area,a smoke backlayering phenomenon was observed which may delay the removal of combustion gases and heat.It was concluded that the opening of the upper supply vents delayed smoke removal and,consequently,increased hazardous situations in both the traffic and escape paths.