Influence mechanism of longitudinal ventilation and bifurcation angle on tunnel fire temperature distribution and smoke diffusion

In order to reduce the difficulty of smoke control, emergency evacuation, and rescue in the event of a fire in an underground bifurcated tunnel, a small-scale experimental platform with a ratio of 1:20 was built to conduct bifurcated tunnel fire experiments. Combined with the characteristics of Computational Fluid Dynamics simulation velocity flow field, the effects of ventilation conditions and bifurcation angles on the maximum temperature rise and longitudinal temperature rise distribution of the tunnel ceiling were studied, and a predictive model was established. By observing and measuring the flue gas temperature under different bifurcation angles, the power of each fire source and longitudinal wind speed, and analyzing the influence of bifurcation angles on temperature characteristics. A prediction model for the maximum temperature rise and longitudinal distribution of temperature rise in the roof of a bifurcated tunnel was established based on a nonlinear regression model. The model considers the effects of longitudinal ventilation and bifurcation angle on the tunnel, respectively.