An experimental study on the evolution of flame height and extension length in tunnel fires with arched ceiling confined condition

To minimize the thermal hazards caused by fires and further improve the tunnel fire safety performance, this paper studied the evolution of flame height and flame extension length under the constrained conditions of the tunnel fires with arched ceiling. The results showed that: (1) The flame height varies as 3/2 power law of the fuel mass loss rate in the windless condition, whose expression is D rho 0H3/2 proportional to (center dot)m; (2) A new model describing the flame morphology and extension length was established under the constrained condition of the tunnel with arched ceiling, and the experimental data can be well explained by the model; (3) This paper effectively improved the theoretical model established by previous studies and further extends the knowledge about the predict of flame morphology under the tunnel with arched ceiling. This work can be helpful for the design of a fire protection system, firefighting system and evacuation system of a tunnel.