Validation of air ventilation in tunnels, using experiments and computational fluid dynamics

Abstract

The study presented in this paper concerns the ventilation system inside tunnels. The ventilation system is responsible for the removal of exhaust gases produced by vehicles and for providing a clear view throughout the tunnels in routine operations and in the event of fire. The ventilation system has several stages, which are equipped with one or more fans and can be activated together or separately. The objective of this study is to find a better correlation between the air velocity and number of ventilation stages inside a tunnel. A small experimental model representing a miniature model of a tunnel was built for the study. In addition, the problem was modelled using computational fluid dynamics (CFD) in ANSYS® Fluent 18.0 for comparison and verification. The results from experiments with the miniature model and simulations from the CFD study were found to be in good agreement and in relation to a real-case scenario. The results also indicated that an increase in the active number of ventilation stages does not result in a linear increase in the air velocity inside the tunnel.