Combustion rate of medium scale pool fire, an unsteady parameter

International audiencePool fire is a classical dangerous phenomenon that can occur in various infrastructures and generates different consequences. Several investigations were achieved to improve the understanding of this phenomenon from theoretical to experimental. Experimental studies have lead to a classification of fuel as a function of combustion rate. These tests are generally based on constant level fire with fuel feed at the bottom of the sample. Theoretical studies have detailed the fire heat release distribution and the impact on the liquid fuel. Based on these results, the expected evolution of the fire includes three main parts: the fire increase, a constant maximal heat release period and the fire decrease. If this evolution suits with external pool fire, behaviour of the liquid can be impacted by contextual configuration. In confined infrastructures, such as building or tunnels, the liquid fuel combustion velocity becomes an unsteady parameter and the heat release rate from the fire varies, and often a runaway phase of the reaction is observed. Because such fires could be used for demonstrating the efficiency of a ventilation system, the power release must be controlled. This may have an important impact on the design of a mechanical ventilation system or the fire resistance of the infrastructure. To control the released power of such a fire, it is important to have a good understanding of this diffusion flame influenced by the environment. Then, understanding the phenomena that occur in the fire region means characterizing: the radiative fraction, the thermal exchanges and the impact of the flow on the fire. Using the results obtain along several experimental campaigns, both confined and unconfined, that were achieved in INERIS concerning pool fire, the different physical parameters are discussed and confronted with theoretical one. This paper proposed a physical characterization that finally leads to a power control strategy for pool fir