Suppression effectiveness of water-mist sprays on accelerated wood-crib fires

An experimental analysis was conducted to quantify the water-mist discharge characteristics required to suppress wood-crib fires. The overall aim of this research was to investigate the effectiveness of these innovative systems in a canonical fire scenario. To this end, an experimental suppression facility was constructed including commercially available water mist nozzles, thermocouples for measuring the thermal transient in and around the wood cribs and a load cell for measuring the mass loss rate and the final wood crib damage. 510×510×380 mm wood cribs were used as the fuel source in all the experiments. The injection pressure and orifice diameter of the water-mist nozzles were varied in the experiments to modify the applied water flux and the initial spray momentum. These quantities were identified to be the governing parameters for suppression performance. They were characterized for all experiments along with the drop-size and velocity distributions. Critical values were determined for these quantities from first order kinematic and thermal analysis based on spray and fire source characteristics. The experimental results demonstrated critical suppression behavior consistent with this first order analysis.