An experimental study on the evolution of flame length and tilt angle under the joint effect of tunnel curved ceiling restriction and longitudinal ventilation

The model about flame length and fuel mass loss rate in this paper was developed based on the flame morphology with different longitudinal ventilation speeds when the flame was confined by the tunnel curved ceiling restriction. Secondly, after analyzing the experimental data, it was found that the air entrainment velocity was proportional to the 0.22nd power of longitudinal ventilation speed. Thirdly, the product of flame length and air entrainment velocity was proportional to the fuel mass loss rate, and the above models could better describe the characteristic evolution behaviors of flame length. Furthermore, the relation between fuel mass loss rate and longitudinal ventilation speed was established. Finally, this paper broadened the applicability of other scholars' flame tilt angle models, and found that the flame tilt angle is smaller when the flame is attached to the wall at the same wind speed. It is obvious that the above results supplement the classical tunnel-fire theory, which can be further applied to prevention and control of tunnel fire, and ultimately ensure building safety.