This paper presents an experimental campaign achieved on a 1/3 scale model tunnel. Its aims at study the influence of the heat release rate, the introduction of an injector and the presence of vehicles on the smoke layer characteristics. Firstly, two smoke layer parameters are defined to characterise the backlayering: the smoke layer length and the dimensionless thickness of the smoke layer. Secondly, the experimental results permit to determine the influence of perturbation presence on these parameters. The analyse of the heat release rate influence shows that the scale model allows to represent correctly the backlayering comportment as in a full scale tunnel. The introduction of a jet induces a diminution of the backlayering length and the impact on the smoke layer thickness depends on the heat release rate and the velocity jet while no destratification is observed. However, the presence of vehicles does not enable to conserve visibility in the gallery, even if a thermal approach is not in accordance to experimental observation.
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