CFD validation for tunnel fires under longitudinal ventilation and application to the study of the critical velocity

The present paper deals with the work done at the Centre d'Etudes des Tunnels (CETU) on the tunnel fires under longitudinal ventilation systems using numerical simulations. A comparative study with experimental measurements performed during the H32 fire test of the Eureka Firetun project is presented. This study has shown that a simplified wall heat exchange law allowed to fit quite well with the experimental data. The same computational techniques have been used for a thorough study of the critical velocity. A sensitivity study on various parameters which may influence the critical velocity has first been performed. Finally an applied study in the case of a tunnel project with small clearance has been carried out.