A methodology for applying the counterflow flame extinction propensity to the flame extinction determination in fire simulations

A methodology is presented herein for the determination of flame extinction in fire simulations by utilizing the flame extinction propensity obtained from the counterflow flame experiments or calculations. The methodology leverages the fact that the flame extinction in hydrocarbon fires tends to occur at critical temperatures corresponding to the strain rates acting on the flames, under the condition that the flame extinction is caused only by physical effects such as dilution and heat extraction. The methodology calls for the correlations between the adiabatic flame extinction temperature and strain rate, a functional expression of the characteristic eddy strain rate in the buoyancy-induced turbulent flow, and the determination of local adiabatic flame temperatures in the fire. The methodology was evaluated by implementing the above application elements in FireFOAM, and comparing the resulted simulations to a previously published study on propane fire intensity in a nitrogen-diluted air environment. The evaluation is deemed favorable for the methodology to be used as an alternative for the flame extinction determination in fire simulations.