Modelling the heat release rate of PRISME experimental cable fires in a confined, ventilation controlled, environment using FLASH-CAT and FDS

Abstract

Development of a Heat Release Rate (HRR) to represent a fire scenario with unknown parameters is challenging. A key step in any fire modelling approach is to define a HRR curve which accounts for the fuel type, quantities, and combustion behaviour. Without robust evidence to underpin the HRR definition, approaches must be adopted to address data uncertainty. This paper presents a methodology for defining the HRR of cable tray fires in a confined, ventilation controlled, environment. The HRR model has been developed during the PRISME-3 programme which has included both “open” and “blind” prediction exercises, giving the opportunity to develop and validate a fire growth rate model and address uncertainties. The model was developed from an existing, published, approach (FLASH-CAT, as outlined in NUREG CR-7010), which was modified, using sensitivity analysis, to better replicate experimental fire tests.The modified model, used in conjunction with the Computational Fluid Dynamics (CFD) based fire modelling tool NIST Fire Dynamics Simulator (FDS), provides comparison to experimental HRR and other HRR growth approaches, indicating the relative importance of HRR in fire model definition.