Numerical study on the transverse offset of fire smoke characteristics induced by the tunnel combustion source and blocking

To study the smoke characteristics and influencing factors of transverse offset combustion source fire in tunnel under the influence of blocking effect, a full-scale model of blocked tunnel fire was constructed to study the evolution law of tunnel ceiling temperature field under different longitudinal wind speeds, blocking types and transverse offset distances of combustion source. The results show that the velocity of flue gas propagation is greater than that of non-blocking condition when there is blocking in the direction of flue gas propagation. As the combustion source is constantly offset to the side wall, the effective path of flame spread also changes. The maximum ceiling temperature of the section with combustion source is much higher than that of other sections. The maximum temperature difference is 68.64°C and 96.19°C respectively, and the maximum attenuation rate difference is 33.56% and 50.5 % respectively. The effective path of flame spread is also changed. Under different blocking conditions, the fitting degree of the longitudinal temperature rise attenuation prediction model of the tunnel ceiling with lateral offset combustion source is higher than 0.9, and the model prediction value is in good agreement with the experimental value.