Effect of Longitudinal Ventilation on Smoke Temperature below Utility Tunnel Ceiling

Utility tunnels are widely built in many cities. When an unexpected fire occurs in the electrical compartment of utility tunnel, the smoke temperature below the utility tunnel ceiling is one of the most important factors for thermal detection and alarm. In this paper, the smoke temperature distribution under the longitudinal ventilation in a utility tunnel fire accident is studied by combining experiment and numerical simulation. The main purpose of this paper is to study the smoke temperature distribution below the ceiling under the effect of longitudinal ventilation in a utility tunnel, and provide guidance for the installation of detector in case of fire. In addition, three important factors such as ventilation velocity, heat release rate and vertical position of fire source are considered respectively. The thermocouple trees are used to measure the temperature along the longitudinal direction of utility tunnel. Results show that the maximum temperature of the utility tunnel is directly above the fire source without longitudinal ventilation. What's more, with the ventilation velocity increases, the maximum temperature below the ceiling gradually moves to the downstream of the fire source in utility tunnel. Finally, a new correlation formula is proposed to predict the temperature distribution of smoke in utility tunnels on the basis of theoretical analysis. The longitudinal temperature distribution obtained by numerical simulation is in good agreement with the experimental tests. Therefore, the research in this paper is helpful to prevent utility tunnel fire and reduce people's property loss.