NUMERICAL INVESTIGATION OF A TUNNEL FIRE UNDER LONGITUDINAL VENTILATION

A numerical investigation was performed, applying a relatively recently developed in-house academic solver against a fire case in a tunnel with longitudinal ventilation. In particular, two such test cases were encountered, whose differences are focused on the ventilation velocity, as well as on the heat release rate of the imposed heat source. The proposed methodology considers the solution of the Navier-Stokes and energy equations in conjunction with a finite-volume radiative heat transfer method and a wall conduction model. In that way the most important aspects of fire phenomena in tunnels are taken into account and, consequently, a more realistic simulation of them is succeeded. The predicted results (temperature profiles downstream the heat source, back layering lengths, flame angles, etc.) were compared satisfactorily with those of corresponding numerical simulations and available experimental data, demonstrating the equal potential of the proposed solver for such test cases, despite different methodologies were followed. Moreover, the contribution of the aforementioned radiation and wall conduction modeling to the final solution was thoroughly examined. The incorporation of these models is revealed of crucial importance for the extraction of realistic temperature profiles and backflows, while the same does not apply for the prediction of the flame angles.