Comparison of detailed soot formation models for sooty and non-sooty flames in an under-ventilated ISO room

摘要

In fire simulations, it is essential to include detailed chemical kinetics for the description of the combustion process where intermediate chemical products are formed through a series of elementary reactions. A novel in-house fire field model based on Large Eddy Simulations (LES) approach incorporating fully coupled subgrid-scale (SGS) turbulence, combustion, soot formation and radiation models for the interactive and non-linear nature of the turbulent reacting flow in compartment fire phenomena has been developed in this article. It uniquely embraces the detailed reaction mechanisms for the chemical processes involved during combustion. Since the modelling of hydrocarbons by-products are enabled when considering the full chemical profile, the formation of soot particles can be related to the concentration of main incipient such as acetylene, which provides an appropriate representation of nucleation, surface growth processes. The significance of the improvement of soot particles modelling had been numerically investigated applying three different two-equations semi-empirical soot models: (ⅰ) Moss model (simplified model taken the fuel as the soot precursor); (ⅱ) Moss-Brookes model (considers acetylene as the soot precursor) and (ⅲ) Moss-Brookes-Hall model (considers acetylene, benzene ring and phenyl radical as the soot precursors). Comprehensive temperature and soot measurements from fire tests in a full-scale ISO compartment constructed purposely with a small opening gap to create the under-ventilated fire condition with which the effect of soot particles generation would be more significant. The computed results were compared with measured results for validation of the implemented soot models.