Abstract:

In this study, the thermal effect of the wall coating in a 1:100 scale natural ventilated road tunnel fire was numerically investigated. A three-layer structure was formed by using Aluminum, Nickel and Calcium-silicate coating on the inner surface of the concrete tunnel model, the outer surface of which was covered with soil. The modeling was carried out at a constant heat flux depending on the gas output formed as a result of combustion in a road tunnel. The outlet temperature of the gas is 950 K, the heat release rate is 50 MW and the mass flow rate is 48.6 kg/s. The model design and solution of the flow field were made with the ANSYS/FLUENT program both in time dependent and transient regime, and the standard k-ɛ turbulence model was used in the analyses. The results showed that the temperature distribution in a road tunnel fire is affected by a third layer to be added over the concrete walls. In the models using Aluminum and Nickel layer as the third layer, the heat transfer was higher than the two-layer structure, while the difference was found to be very small in the model using the Calcium-silicate layer.

Keywords: