Experimental and numerical study of an elevated pool fire scenario in a confined and mechanically ventilated compartment

The present work deals with an experimental and numerical investigation of an elevated pool fire scenario in a confined and forced ventilated compartment. Although often encountered in industrial installations or in common buildings, this type of configuration is rarely studied in the literature. This study is supported by a set of two large-scale fire experiments performed in the framework of the OECD-PRISME3 project and numerical simulations (RANS and LES methods) carried out with the CALIF3S-Isis software. The objective is to improve the physical understanding of the phenomena that are experimentally highlighted and to assess the capabilities of Computational Fluid Dynamics (CFD) on this type of configuration. First, the comparison between the two large-scale fire tests (one elevated and its equivalent on the ground) exhibits a strong modification of the fuel mass loss rate associated with a change in the thermal and species stratifications. Then, a preliminary simulation using a predictive approach commonly used and efficient for the case of a ground fire scenario shows by contrast its limitations when applied to the case of the elevated fire. Therefore, in addition to the essential step consisting in the validation of the code with a prescribed approach on this type of elevated fire, the simulations also reveal a specific phenomenology (smoke filling, strong vitiation, oxygen-pumping, ...). Finally, taking into account these particularities allows in fine, for the studied case, the improvement of the prediction of the mass loss rate of the fire.