Stephan Klüh - FOGTEC Brandschutz GmbH, Cologne, Germany
Vehicle fires in underground car parks represent a big challenge for the fire protection systems of the facility, especially concerning modern vehicles that are getting larger and contain a higher amount of burnable materials. Adding the evolution of new energy carriers, like Li-Ion batteries, the challenge further increases. By prevention or slowing down the fire spread, fixed-firefighting systems can control a fire until emergency responders arrive. The current work was part of the SUVEREN project, which was funded by the German Ministry of research and aims to produce reliable data in order to support a performance-based design of such systems, using both experimental and modelling tools in the analysis. Major parts of the analysis were fire tests of "vehicle mock-ups interacting with a water mist system" that were performed at IFAB’s facilities in Northern Germany. Based on these, the vehicle fire was modelled including the suppression and ventilation system. The fire load consisted of wooden pallets, which were placed inside the vehicle, thus being mostly covered by it. Gas temperatures and concentrations have been measured near the fire and inside the exhaust duct. The water mist system was activated manually and the heat release for the simulation was gained from a scale below the wood pallets. Common water mist is on a micrometre scale, which makes it hard to model in CFD, thus the FDS module for fire suppression uses a Lagrangian particle approach. Modelling the interaction of water mist with fire on the micro-level remains impossible while keeping the scope of the approach of performance based design analysis to be used for whole car parks. The results presented focus on the comparison and validation of the numerical model including the water mist by using the experimental data along with its limitations and its application possibilities.