Car park fires : A parametrical study of fire spread assumptions between cars in numerical simulations with FDS

Sammanfattning

The complexity of vehicles, driven by road safety regulations and user comfort, has increasedthe weight and use of synthetic materials. This has led to a change in in vehicle fire behaviour,making the risk of fire spread in open parking garages a growing concern. While previousstudies have utilized Fire Dynamics Simulator (FDS) to study the effects of fires in openparking garages, they often lack a consistent method for calculating the effective heat ofcombustion (ΔHc) and have a limited scope regarding the fire spread between modernvehicles. This study builds upon the established foundation by first developing a repeatable Gaussianintegration approach to derive ΔHc, from experimental Heat Release Rate (HRR) data to use inFDS. Additionally, it examines the assumption of three fire spread pathways: combustibleexterior, failure of windows into the interior cabin and ignition via the tires. To determine thepotential ignition of adjacent vehicles, this study utilizes proxy ignition methods based on thecalculated incident heat flux. Four scenarios were analysed, comparing average and 80th percentile HRR curves withdifferent fire spread pathways. Results show that when a combustible exterior was assumed,fire spread occurred between vehicles for both scenarios. In opposition, no spread wasobserved via the tires or interior. It should be noted that this lack of observed spread does notnecessarily imply that these other assumptions are wrong, it rather suggests that the placementof the calculation points for the fire spread proxy method used in this study/or earlier studiesmight not capture the full mechanisms of the fire spread. Based on the results, both theassumption behind fire spread mechanisms and the placement of proxies plays a crucial rolein the potential fire spread in numerical simulations. However, further research would greatlybenefit from additional parametrical studies which investigates the fire spread mechanisms inopen parking garages, e.g. pool fires.