Experimental and numerical study of smoke temperature distribution characteristics in a sloped tunnel

The maximum ceiling temperature and smoke temperature longitudinal distribution are very important for the evaluation of tunnel fire risk. Aiming at the particularities of sloping tunnel structure, the smoke temperature distribution characteristics under different ventilation conditions were studied through the combination of theoretical analysis, small-scale model experiments and numerical simulations. The impact factors of longitudinal airflow velocity caused by stack effect in a sloped tunnel fire were deeply studied, and the induced airflow velocity prediction model has been established. Based on the ideal fire plume model and hydrodynamic equations, the influence of slope effect on the smoke temperature characteristics was deeply studied, a prediction model for the maximum ceiling temperature rise in a sloped tunnel was derived, and a new modified dimensionless longitudinal airflow velocity of the sloped tunnel was proposed as the criterion for the model. In addition, a theoretical model of smoke spread in sloped tunnel was deduced, the empirical model of temperature longitudinal distribution under different ventilation conditions was further established, and the relevant parameters were fitted. By comparing the predicted results of the modified model with the data from numerical simulation and small-scale experiment, it can be found that the fitting results are better.