Modelling Of A Reverse Layer Of Fire-induced Smoke In A Tunnel

Abstract

The designers of tunnels must provide comfortable conditions for occupants. This necessitates particularly the development of ventilation equipments well the same time offering the possibility of control suited for routine operation but also efficient in the case of accidental fires while at the same time offering the possibility of control. A computer model for simulation of fire growth and smoke back flow phenomenon countering the effect of ventilation is described. It permits one to predict the length of the reverse layer under a ceiling as a function of two main parameters: ventilation speed and rate of heat release of the fire. Special attention is devoted to the description of the fire source with consideration of the interaction between flow and the chemical reaction. The validation of the model against experimental results, obtained previously on a small scale prototype, appears satisfying. An application to the Paris metro tunnels is also presented. The validity of the predictive results is inferred from the similarity between small-scale and real situation based on a scaling procedure.