Study on the smoke stratification length under longitudinal ventilation in tunnel fires

Smoke temperature distribution and smoke stratification law in the interval tunnel were studied through a series of experiments conducted in a 1/15 scale model tunnel. The small-scale experiment proved that the dimensionless temperature ratio method proposed by Newman was feasible. Based on the FDS simulation, smoke stratification under different longitudinal ventilation was studied, and the concept of smoke stable-stratification-length was presented. The influence of the heat release rate and the tunnel section on the smoke stable-stratification-length was analyzed. Thereafter, prediction models for the smoke stable-stratification-length and the critical stratification velocity were proposed. It can provide a reference for the design of longitudinal ventilation and smoke exhaust system of tunnels.