Experimental and numerical study of fire in a midscale test tunnel

An experimental study has been undertaken in a 1/3 scale tunnel, using a heptane pool fire up to 4 MW. Temperatures, velocities and radiative fluxes have been registered by a set of 200 sensors located upstream and downstream from the fire location, while mass loss rate of fuel has been recorded. Experiments have been carried out for ventilation regimes below and above the critical backlayering velocity. The constituted database also allows a complete description of the fire development and of the flow regime in various conditions. Numerical simulations have been conducted in parallel. Efforts have been done in order to verify the validity of the simulation by comparing with the experimental database. Further use of the numerical model will allow a complete sensitivity study in order to improve our understanding of this kind of fire. One first analysis has for example demonstrated that the energy balance is strongly dependent on the ventilation regime. In fact, around 50% and 67% of the heat released were dissipated through exchanges with the wall in the sub-critical and over-critical regimes.

► Fire in tunnel was investigated at 1/3 scale.
► HRR, temperatures, velocities and radiative heat fluxes were measured.
► Simulations were conducted with FDS (V5.4).
► Fire and smoke flow were studied under and over critical ventilation velocity.
► A dedicated energy balance was used to study how energy was released by fire.