ZONE MODELING OF VERY-LOW-FREQUENCY UNSTABLE BEHAVIOR IN MECHANICALLY-VENTILATED COMPARTMENT FIRES

Abstract

A zone model is developed to simulate the oscillatory behavior occasionally observed in compartment fires. This oscillatory behavior is the result of an unstable coupling between the liquid fuel evaporation rate, the combustion process, the compartment pressure and the ventilation of the compartment. The governing equations use a classical zone modeling approach combined with a (N-τ) model description of the variations of the fuel evaporation rate. The equations are solved with an in-house Matlab solver. The model is evaluated by comparisons with experimental data previously obtained at Institut de Radioprotection et de Sûreté Nucléaire (IRSN) in France. Three different variations of the (N-τ) model are evaluated, corresponding to a coupling between liquid fuel evaporation and bulk oxygen, bulk temperature or admission flow rate. It is found that the variation corresponding to a coupling between liquid fuel evaporation and bulk oxygen provides the more realistic results.