• Journal of Industrial Technology
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• v.23 no.A
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• pp.9-13
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• 2003

Numerical experiments are done by a commercial code, PHOENICS to evaluate the backlayer phenomenon of smoke in case of the road tunnel fire. The independent and dependent variables are ventilation air velocity and the length of backlayer of smoke respectively. Hybrid scheme and ${\kappa}-{\varepsilon}$ turbulence model are adopted in the simulation process and mass residual is used as a convergence criterion. The experimental results say that the length of backlayer is reduced with the increase of ventilating air velocity and that there is a critical air velocity which prevents from the onset of backlayering phenomena. One finds that there is a fresh air region near the bottom of tunnel which could make the passenger escape safely from the polluted region by smoke. These phenomena come from the vertical stratification of the smoke air mixture in the tunnel.